JP5077744B2 - Exposure method, exposure apparatus, and device manufacturing method - Google Patents

Description

  The present invention relates to an exposure method, an exposure apparatus, and a device manufacturing method, and more particularly, an exposure method and an exposure apparatus used in a lithography process for manufacturing a semiconductor element, a liquid crystal display element, and the like, and a device manufacturing using the exposure method Regarding the method.

  Conventionally, in a lithography process for manufacturing microdevices (electronic devices, etc.) such as semiconductor elements and liquid crystal display elements, a step-and-repeat type reduction projection exposure apparatus (so-called stepper) or a step-and-scan type projection exposure is used. An apparatus (a so-called scanning stepper (also called a scanner)) or the like is mainly used.

  In such a stepper or scanner, the position of a substrate to be exposed, for example, a stage that holds a wafer, is generally measured using a laser interferometer. However, the required performance becomes severe due to the miniaturization of the pattern accompanying the high integration of the semiconductor element. For example, regarding the overlay error, the overall tolerance of the overlay error is on the order of several nanometers. The permissible value of the position control error is less than sub-nano order, and now, short-term fluctuations in measured values due to temperature fluctuations (air fluctuations) of the atmosphere on the beam optical path of the laser interferometer can no longer be ignored.

  Therefore, recently, high-resolution encoders that are less susceptible to air fluctuations than interferometers have attracted attention, and an exposure apparatus that uses the encoders to measure the position of a wafer stage or the like has been developed. Yes.

  However, when an encoder is used, there are a number of problems that need to be solved in order to enable highly accurate position measurement of the wafer stage over a wide range similar to that of an interferometer and to maintain the throughput of the entire apparatus. One of them is to improve the alignment accuracy without reducing the throughput during wafer alignment.

The present invention has been made under the circumstances described above. From a first viewpoint, the present invention is an exposure method in which an object is exposed by an energy beam to form a pattern on the object, and the object is formed within a predetermined plane. A second direction orthogonal to the first direction, which is disposed on one surface of a moving body that holds and moves, and has a pair of first gratings each having a grating having a first direction parallel to the plane as a periodic direction position based on the measurement values of different first encoder head with respect to the while managing the position of the rotation direction of the first direction and the plane of the movable body, before parallel to the moving body in said plane Stories is moved in the second direction, the position of the detection area with respect to the second direction using a plurality of different marks detection system, by detecting at least one mark is present on the movable body, the double Characteristic measurement step of performing a mark detection system characteristic measurement of a exposure method comprising.

According to this, the position with respect to the second direction based on the measurement values of different first encoder head you respectively opposed to the pair of first grating, the position in the rotational direction of the first direction and in the plane of the movable body While moving with high accuracy, the moving body is moved in the second direction, and at least one mark existing on the moving body is detected by using a plurality of mark detection systems in which the positions of the detection areas are different in the second direction. Thus, the characteristics of the plurality of mark detection systems are measured. As a result, the position information of the mark can be obtained for each mark detection system with the position control error in the first direction and the rotation direction of the moving body eliminated as much as possible. As a result, the characteristics of the plurality of mark detection systems can be accurately obtained. It becomes possible to measure well.

  From a second viewpoint, the present invention is a device manufacturing method including a step of forming a pattern on an object using the exposure method of the present invention; and a step of developing the object on which the pattern is formed.

  According to a third aspect of the present invention, there is provided an exposure apparatus that exposes an object with an energy beam to form a pattern on the object, moves the object while holding the object in a predetermined plane, A moving body in which a pair of first gratings each having a grating whose periodic direction is a first direction parallel to the plane is disposed with a placement region of the object sandwiched in a second direction orthogonal to the first direction; The plurality of first heads having different positions with respect to the second direction, and the first direction and the plane of the moving body based on the measurement values of the two first heads respectively facing the pair of first gratings An encoder system for measuring a position in the rotational direction of the plurality of mark detection systems, wherein a plurality of mark detection systems differ in the position of the detection region with respect to the second direction; and based on a measurement result of the encoder system, While managing the position of the moving body in the first direction and the rotational direction in the plane, the moving body is moved in a second direction parallel to the plane and orthogonal to the first direction, and the plurality of mark detection systems And a control device that measures the characteristics of the plurality of mark detection systems by detecting at least one mark that is present on the moving body.

  According to this, the control device moves the moving body in the second direction while managing the position of the moving body in the first direction and the rotational direction in the plane based on the measurement result of the encoder system, and a plurality of marks. Characteristic measurement of a plurality of mark detection systems is performed by sequentially detecting at least one mark present on the moving body using each detection system. As a result, the position information of the mark can be obtained for each mark detection system in a state in which the position control error in the first direction and the rotation direction of the moving body is eliminated as much as possible. It becomes possible to measure well.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to FIGS.

  FIG. 1 schematically shows a configuration of an exposure apparatus 100 according to an embodiment. The exposure apparatus 100 is a step-and-scan type scanning exposure apparatus, that is, a so-called scanner. As will be described later, in the present embodiment, a projection optical system PL is provided. In the following description, a direction parallel to the optical axis AX of the projection optical system PL is a Z-axis direction, and a reticle in a plane perpendicular to the Z-axis direction. The direction in which the wafer is relatively scanned is the Y-axis direction, the direction orthogonal to the Z-axis and the Y-axis is the X-axis direction, and the rotation (tilt) directions around the X-axis, Y-axis, and Z-axis are θx, θy, And the θz direction will be described.

  The exposure apparatus 100 is emitted from an illumination system 10, a reticle stage RST and a reticle R that hold a reticle R that is illuminated by exposure illumination light (hereinafter referred to as illumination light or exposure light) IL from the illumination system 10. A projection unit PU including a projection optical system PL that projects the illumination light IL onto the wafer W, a stage device 50 having a wafer stage WST and a measurement stage MST, and a control system thereof. Wafer W is placed on wafer stage WST.

  The illumination system 10 includes, for example, an illuminance uniformizing optical system including a light source, an optical integrator, and the like, as disclosed in JP 2001-313250 A (corresponding US Patent Application Publication No. 2003/0025890). And an illumination optical system having a reticle blind or the like (both not shown). The illumination system 10 illuminates a slit-shaped illumination area IAR on a reticle R defined by a reticle blind (masking system) with illumination light (exposure light) IL with substantially uniform illuminance. Here, as the illumination light IL, for example, ArF excimer laser light (wavelength 193 nm) is used. As the optical integrator, for example, a fly-eye lens, a rod integrator (internal reflection type integrator), a diffractive optical element, or the like can be used.

  On reticle stage RST, reticle R on which a circuit pattern or the like is formed on its pattern surface (the lower surface in FIG. 1) is fixed, for example, by vacuum suction. The reticle stage RST can be slightly driven in the XY plane by a reticle stage drive system 11 (not shown in FIG. 1, refer to FIG. 6) including a linear motor, for example, and also in the scanning direction (left and right direction in FIG. 1). Can be driven at a scanning speed designated in the Y-axis direction).

  Position information within the moving plane of reticle stage RST (including rotation information in the θz direction) is transferred by reticle laser interferometer (hereinafter referred to as “reticle interferometer”) 116 to moving mirror 15 (actually in the Y-axis direction). Through a Y-moving mirror (or retro reflector) having an orthogonal reflecting surface and an X moving mirror having a reflecting surface orthogonal to the X-axis direction), detection is always performed with a resolution of, for example, about 0.25 nm. Is done. The measurement value of reticle interferometer 116 is sent to main controller 20 (not shown in FIG. 1, refer to FIG. 6). Main controller 20 calculates the position of reticle stage RST in the X-axis direction, Y-axis direction, and θz direction based on the measurement value of reticle interferometer 116, and controls reticle stage drive system 11 based on the calculation result. Thus, the position (and speed) of reticle stage RST is controlled. Instead of the movable mirror 15, the end surface of the reticle stage RST may be mirror-finished to form a reflective surface (corresponding to the reflective surface of the movable mirror 15). In addition, reticle interferometer 116 may be capable of measuring position information of reticle stage RST with respect to at least one of the Z-axis, θx, and θy directions.

  Projection unit PU is arranged below reticle stage RST in FIG. The projection unit PU includes a lens barrel 40 and a projection optical system PL having a plurality of optical elements held in the lens barrel 40 in a predetermined positional relationship. As the projection optical system PL, for example, a refractive optical system including a plurality of lenses (lens elements) arranged along an optical axis AX parallel to the Z-axis direction is used. The projection optical system PL is, for example, both-side telecentric and has a predetermined projection magnification (for example, 1/4, 1/5, 1/8, etc.). For this reason, when the illumination area IAR is illuminated by the illumination light IL from the illumination system 10, the illumination that has passed through the reticle R, in which the first surface (object surface) of the projection optical system PL and the pattern surface are substantially aligned, is passed. A reduced image of the circuit pattern of the reticle R in the illumination area IAR (a reduced image of a part of the circuit pattern) passes through the projection optical system PL (projection unit PU) by the light IL, and its second surface (image surface). It is formed in a region (hereinafter also referred to as an exposure region) IA that is conjugated to the illumination region IAR on the wafer W, the surface of which is coated with a resist (photosensitive agent). The reticle stage RST and wafer stage WST are driven synchronously to move the reticle relative to the illumination area IAR (illumination light IL) in the scanning direction (Y-axis direction) and to the exposure area (illumination light IL). By moving the wafer W relative to the scanning direction (Y-axis direction), scanning exposure of one shot area (partition area) on the wafer W is performed, and a reticle pattern is transferred to the shot area. That is, in this embodiment, a pattern is generated on the wafer W by the illumination system 10, the reticle, and the projection optical system PL, and the pattern is formed on the wafer W by exposure of the sensitive layer (resist layer) on the wafer W by the illumination light IL. It is formed.

  Although not shown, the projection unit PU is mounted on a lens barrel surface plate supported by three support columns via a vibration isolation mechanism. However, the present invention is not limited to this. For example, as disclosed in the pamphlet of International Publication No. 2006/038952, a main frame member (not shown) disposed above the projection unit PU or a base member on which the reticle stage RST is disposed. For example, the projection unit PU may be supported by being suspended.

  In the exposure apparatus 100 of the present embodiment, since exposure using a liquid immersion method is performed, the reticle side aperture increases as the numerical aperture NA of the projection optical system PL substantially increases. Therefore, in order to satisfy Petzval's conditions and avoid the enlargement of the projection optical system, a catadioptric system including a mirror and a lens can be adopted as the projection optical system. good. In addition to the photosensitive layer, for example, a protective film (top coat film) for protecting the wafer or the photosensitive layer may be formed on the wafer W.

  Further, in the exposure apparatus 100 of the present embodiment, in order to perform exposure using a liquid immersion method, an optical element on the most image plane side (wafer W side) constituting the projection optical system PL, here a lens (hereinafter referred to as “tip”). A nozzle unit 32 constituting a part of the local liquid immersion device 8 is provided so as to surround the periphery of the lower end portion of the lens barrel 40 holding the 191) (also referred to as a “lens”). In the present embodiment, as shown in FIG. 1, the lower end surface of the nozzle unit 32 is set substantially flush with the lower end surface of the tip lens 191. Further, the nozzle unit 32 is connected to the supply port and the recovery port of the liquid Lq, the lower surface on which the wafer W is disposed and provided with the recovery port, and the supply connected to the liquid supply tube 31A and the liquid recovery tube 31B, respectively. A flow path and a recovery flow path are provided. As shown in FIG. 3, the liquid supply pipe 31 </ b> A and the liquid recovery pipe 31 </ b> B are inclined by 45 ° with respect to the X-axis direction and the Y-axis direction in plan view (viewed from above). It is symmetrically arranged with respect to a straight line (reference axis) LV that passes through the optical axis AX of the projection optical system PL (in this embodiment, also coincides with the center of the exposure area IA described above) and is parallel to the Y axis.

  The other end of the supply pipe (not shown) whose one end is connected to the liquid supply device 5 (not shown in FIG. 1, see FIG. 6) is connected to the liquid supply pipe 31A. The other end of a recovery pipe (not shown) whose one end is connected to the liquid recovery device 6 (not shown in FIG. 1, see FIG. 6) is connected.

  The liquid supply device 5 includes a tank for supplying liquid, a pressure pump, a temperature control device, a valve for controlling supply / stop of the liquid to the liquid supply pipe 31A, and the like. As the valve, for example, it is desirable to use a flow rate control valve so that not only the supply / stop of the liquid but also the flow rate can be adjusted. The temperature control device adjusts the temperature of the liquid in the tank to, for example, the same temperature as the temperature in a chamber (not shown) in which the exposure apparatus is accommodated. Note that the tank, pressure pump, temperature control device, valve, and the like need not all be provided in the exposure apparatus 100, and at least a part of them may be replaced by equipment such as a factory in which the exposure apparatus 100 is installed. it can.

  The liquid recovery device 6 includes a tank and a suction pump for recovering the liquid, a valve for controlling recovery / stop of the liquid via the liquid recovery pipe 31B, and the like. As the valve, it is desirable to use a flow rate control valve similarly to the valve of the liquid supply device 5. Note that the tank, the suction pump, the valve, and the like do not have to be all provided in the exposure apparatus 100, and at least a part of them can be replaced by equipment such as a factory in which the exposure apparatus 100 is installed.

  In this embodiment, pure water that transmits ArF excimer laser light (light having a wavelength of 193 nm) (hereinafter, simply referred to as “water” unless otherwise required) is used as the liquid. Pure water can be easily obtained in large quantities at a semiconductor manufacturing factory or the like, and has an advantage that it does not adversely affect the photoresist, optical lens, etc. on the wafer.

  The refractive index n of water with respect to ArF excimer laser light is approximately 1.44. In this water, the wavelength of the illumination light IL is shortened to 193 nm × 1 / n = about 134 nm.

  Each of the liquid supply device 5 and the liquid recovery device 6 includes a controller, and each controller is controlled by the main controller 20 (see FIG. 6). The controller of the liquid supply apparatus 5 opens a valve connected to the liquid supply pipe 31A at a predetermined opening degree according to an instruction from the main control apparatus 20, and the tip is provided through the liquid supply pipe 31A, the supply flow path, and the supply port. A liquid (water) is supplied between the lens 191 and the wafer W. At this time, the controller of the liquid recovery apparatus 6 opens the valve connected to the liquid recovery pipe 31B at a predetermined opening degree in response to an instruction from the main control apparatus 20, and sets the recovery port, the recovery flow path, and the liquid recovery pipe The liquid (water) is recovered from between the tip lens 191 and the wafer W into the liquid recovery apparatus 6 (liquid tank) via 31B. At this time, the main controller 20 controls the controller of the liquid supply device 5 and the liquid recovery so that the amount of water supplied between the tip lens 191 and the wafer W is always equal to the amount of recovered water. Commands are given to the controller of the device 6. Accordingly, a certain amount of liquid (water) Lq (see FIG. 1) is held between the front lens 191 and the wafer W. In this case, the liquid (water) Lq held between the tip lens 191 and the wafer W is always replaced.

  As is apparent from the above description, in this embodiment, the local liquid immersion device 8 is configured including the nozzle unit 32, the liquid supply device 5, the liquid recovery device 6, the liquid supply tube 31A, the liquid recovery tube 31B, and the like. Yes. Note that a part of the local liquid immersion device 8, for example, at least the nozzle unit 32, may be supported by being suspended from a main frame (including the lens barrel surface plate) holding the projection unit PU. You may provide in another frame member. Alternatively, when the projection unit PU is supported by being suspended as described above, the nozzle unit 32 may be suspended and supported integrally with the projection unit PU, but in the present embodiment, the projection unit PU is suspended and supported independently of the projection unit PU. A nozzle unit 32 is provided on the measurement frame. In this case, the projection unit PU may not be suspended and supported.

  Even when the measurement stage MST is positioned below the projection unit PU, it is possible to fill water between a measurement table (to be described later) and the front lens 191 in the same manner as described above.

  In the above description, one liquid supply pipe (nozzle) and one liquid recovery pipe (nozzle) are provided as an example. However, the present invention is not limited to this, and the relationship with surrounding members is considered. However, if the arrangement is possible, for example, as disclosed in International Publication No. 99/49504, a configuration having a large number of nozzles may be employed. In short, as long as the liquid can be supplied between the lowermost optical member (tip lens) 191 constituting the projection optical system PL and the wafer W, any configuration may be used. For example, an immersion mechanism disclosed in International Publication No. 2004/053955 pamphlet or an immersion mechanism disclosed in European Patent Publication No. 1420298 can be applied to the exposure apparatus of this embodiment.

  Returning to FIG. 1, the stage apparatus 50 includes a wafer stage WST and a measurement stage MST disposed above the base board 12, a measurement system 200 (see FIG. 6) that measures positional information of these stages WST and MST, and a stage. A stage drive system 124 (see FIG. 6) for driving WST and MST is provided. As shown in FIG. 6, the measurement system 200 includes an interferometer system 118, an encoder system 150, and the like. As shown in FIG. 2, interferometer system 118 includes Y interferometer 16 for measuring the position of wafer stage WST, X interferometers 126, 127, and 128, and Y interferometer 18 for measuring the position of measurement stage MST and Y interferometer 130 and the like are included.

  Returning to FIG. 1, non-contact bearings (not shown), for example, vacuum preload type aerostatic bearings (hereinafter referred to as “air pads”) are provided at a plurality of locations on the bottom surfaces of wafer stage WST and measurement stage MST. The wafer stage WST and the measurement stage MST are supported in a non-contact manner above the base board 12 with a clearance of about several μm by the static pressure of the pressurized air ejected from the air pads toward the upper surface of the base board 12. Has been. The stages WST and MST are independent in the Y-axis direction (left and right direction in the drawing in FIG. 1) and X-axis direction (in the direction orthogonal to the drawing in FIG. 1) by a stage drive system 124 (see FIG. 6) including a linear motor and the like. And can be driven.

  Wafer stage WST is mounted on stage body 91 driven in the XY plane by a linear motor (not shown) and the like, and is mounted on stage body 91 via a Z / leveling mechanism (for example, a voice coil motor). It includes a wafer table WTB that is finely driven relative to the main body 91 in the Z-axis direction, the θx direction, and the θy direction.

On wafer table WTB, a wafer holder (not shown) for holding wafer W by vacuum suction or the like is provided. Although the wafer holder may be formed integrally with wafer table WTB, in this embodiment, the wafer holder and wafer table WTB are separately configured, and the wafer holder is fixed in the recess of wafer table WTB by, for example, vacuum suction. In addition, the upper surface of wafer table WTB has a surface (liquid repellent surface) that has been made liquid repellent with respect to liquid Lq and is substantially flush with the surface of wafer W placed on wafer holder, and has an outer shape. A plate (liquid repellent plate) 28 having a rectangular (contour) and a circular opening that is slightly larger than the wafer holder (wafer mounting region) is provided at the center thereof. The plate 28 is made of a material having a low coefficient of thermal expansion, such as glass or ceramics (Shot Corporation's Zerodur (trade name), Al ₂ O _3, TiC, or the like). A liquid repellent film is formed of a fluorine resin material such as (Teflon (registered trademark)), an acrylic resin material, or a silicon resin material. Further, as shown in the plan view of wafer table WTB (wafer stage WST) in FIG. 4, plate 28 surrounds a circular opening and has a first liquid repellent area 28 a having a rectangular outer shape (contour), and a first liquid repellent area. And a rectangular frame-shaped (annular) second liquid repellent region 28b disposed around the region 28a. The first liquid repellent area 28a is formed with, for example, at least a part of the liquid immersion area 14 protruding from the surface of the wafer during the exposure operation, and the second liquid repellent area 28b is formed with a scale for an encoder system described later. . It should be noted that at least a part of the surface of the plate 28 may not be flush with the surface of the wafer, that is, it may have a different height. The plate 28 may be a single plate, but in the present embodiment, a plurality of plates, for example, first and second liquid repellent plates corresponding to the first and second liquid repellent areas 28a and 28b, respectively, are combined. . In the present embodiment, since water is used as the liquid Lq as described above, the first and second liquid repellent regions 28a and 28b are also referred to as first and second water repellent plates 28a and 28b, respectively.

  In this case, the inner first water repellent plate 28a is irradiated with the exposure light IL, whereas the outer second water repellent plate 28b is hardly irradiated with the exposure light IL. In view of this, in the present embodiment, the surface of the first water repellent plate 28a is provided with a water repellent coat that is sufficiently resistant to the exposure light IL (in this case, light in the vacuum ultraviolet region). One water-repellent region is formed, and the second water-repellent plate 28b is formed with a second water-repellent region on the surface of which a water-repellent coat that is less resistant to the exposure light IL than the first water-repellent region is formed. ing. In general, a glass plate is difficult to be provided with a water-repellent coating that is sufficiently resistant to exposure light IL (in this case, light in the vacuum ultraviolet region). Thus, the first water-repellent plate 28a and the second water-repellent layer around it are thus formed. It is effective to separate the board 28b into two parts. The first water repellent region and the second water repellent region may be formed by applying two types of water repellent coatings having different resistances to the exposure light IL on the upper surface of the same plate. Further, the same type of water repellent coating may be used in the first and second water repellent areas. For example, only one water repellent region may be formed on the same plate.

  As is clear from FIG. 4A, a rectangular notch is formed at the center of the first water repellent plate 28a on the + Y side in the X-axis direction. A measurement plate 30 is embedded in a rectangular space surrounded by the water repellent plate 28b (inside the cutout). At the center in the longitudinal direction of the measurement plate 30 (on the center line LL of the wafer table WTB), a reference mark FM is formed, and the center of the reference mark is formed on one side and the other side of the reference mark in the X-axis direction. A pair of aerial image measurement slit patterns (slit-like measurement patterns) SL are formed in a symmetric arrangement with respect to FIG. As each aerial image measurement slit pattern SL, as an example, an L-shaped slit pattern having sides along the Y-axis direction and the X-axis direction, or two linear slits extending in the X-axis and Y-axis directions, respectively. A pattern or the like can be used.

  The wafer stage WST below each aerial image measurement slit pattern SL has an L shape in which an optical system including an objective lens, a mirror, a relay lens, and the like is housed as shown in FIG. 4B. The housing 36 is attached in a partially embedded state in a state of penetrating a part of the inside of the stage main body 91 from the wafer table WTB. Although not shown, the housing 36 is provided in a pair corresponding to the pair of aerial image measurement slit patterns SL.

  The optical system inside the housing 36 guides the illumination light IL transmitted through the aerial image measurement slit pattern SL along the L-shaped path and emits it in the −Y direction. In the following, for convenience, the optical system inside the housing 36 is described as a light transmission system 36 using the same reference numerals as the housing 36.

Furthermore, a large number of grid lines are directly formed on the upper surface of the second water repellent plate 28b at a predetermined pitch along each of the four sides. More specifically, Y scales 39Y ₁ and 39Y ₂ are formed in regions on one side and the other side (left and right sides in FIG. 4) of the second water repellent plate 28b, respectively, and the Y scale 39Y ₁ , 39Y ₂ is a reflection type in which, for example, lattice lines 38 having a longitudinal direction in the X-axis direction are formed along a direction (Y-axis direction) parallel to the Y-axis at a predetermined pitch, and the Y-axis direction is a periodic direction. (For example, a diffraction grating).

Similarly, the X scales 39X ₁ and 39X ₂ are sandwiched between the Y scales 39Y ₁ and 39Y ₂ in the region on one side and the other side (upper and lower sides in FIG. 4) of the second water repellent plate 28b. Each of the X scales 39X ₁ and 39X ₂ is formed, for example, by forming lattice lines 37 having the Y axis direction as a longitudinal direction along a direction parallel to the X axis (X axis direction) at a predetermined pitch. It is configured by a reflection type grating (for example, a diffraction grating) having an axial direction as a periodic direction. As each of the scales, a scale in which a reflective diffraction grating RG (FIG. 8A) is formed on the surface of the second water repellent plate 28b by using a hologram or the like is used. In this case, each scale is provided with a grid made up of narrow slits or grooves as scales at a predetermined interval (pitch). The type of the diffraction grating used for each scale is not limited, and may be not only those in which grooves or the like are mechanically formed, but may also be created by baking interference fringes on a photosensitive resin, for example. . However, each scale is formed by, for example, engraving the scale of the diffraction grating on a thin glass plate at a pitch between 138 nm and 4 μm, for example, 1 μm pitch. These scales are covered with the liquid repellent film (water repellent film) described above. In FIG. 4, for the convenience of illustration, the pitch of the grating is shown much wider than the actual pitch. The same applies to the other drawings.

  Thus, in this embodiment, since the second water repellent plate 28b itself constitutes a scale, a glass plate having a low coefficient of thermal expansion is used as the second water repellent plate 28b. However, the upper surface of wafer table WTB is not limited to this, for example, by a leaf spring (or vacuum suction) or the like so as to prevent local expansion and contraction of the scale member made of a glass plate having a low thermal expansion coefficient on which a lattice is formed. In this case, a water repellent plate having the same water repellent coating on the entire surface may be used in place of the plate 28. Alternatively, wafer table WTB can be formed of a material having a low coefficient of thermal expansion. In such a case, the pair of Y scales and the pair of X scales may be formed directly on the upper surface of wafer table WTB. .

  In order to protect the diffraction grating, it is also effective to cover it with a glass plate having a low thermal expansion coefficient having water repellency. Here, as the glass plate, a glass plate having the same thickness as the wafer, for example, a thickness of 1 mm can be used, and the wafer table so that the surface of the glass plate is the same height (level) as the wafer surface. Installed on top of WST.

  A positioning pattern (not shown) for determining a relative position between an encoder head and a scale, which will be described later, is provided near the end of each scale. This positioning pattern is composed of, for example, grid lines having different reflectivities. When the encoder head scans the positioning pattern, the intensity of the output signal of the encoder changes. Therefore, a threshold is set in advance, and a position where the intensity of the output signal exceeds the threshold is detected. Based on the detected position, a relative position between the encoder head and the scale is set.

  The -Y end surface and -X end surface of wafer table WTB are mirror-finished to form reflecting surface 17a and reflecting surface 17b shown in FIG. The Y interferometer 16 of the interferometer system 118 and the three X interferometers 126, 127 and 128 (in FIG. 1, X interferometers 126 to 128 are not shown, see FIG. 2) are connected to these reflecting surfaces 17a and 17b. By projecting an interferometer beam (length measuring beam) and receiving each reflected light, a reference position of each reflecting surface (for example, a fixed mirror is arranged on the side surface of the projection unit PU and used as a reference surface) ), That is, positional information of wafer stage WST in the XY plane is measured, and this measured value is supplied to main controller 20. In the present embodiment, a multi-axis interferometer having a plurality of measurement axes is used as each interferometer except for a part (for example, the interferometer 128), and the Y interferometer 16 and the X interferometer 126 or 127 are used. Based on one of the measured values, main controller 20 adds rotation information (that is, pitching) in the θx direction, rotation information in the θy direction (that is, rolling), and rotation information in the θz direction in addition to the X and Y positions of wafer table WTB. Rotational information (ie yawing) can also be measured. However, in this embodiment, position information (including rotation information in the θz direction) of wafer stage WST (wafer table WTB) in the XY plane is mainly measured by an encoder system described later, and interferometers 16, 126 to 128 are included. This measurement value is used as an auxiliary when correcting (calibrating) long-term fluctuations (for example, due to deformation of the scale over time) of the measurement value of the encoder system.

  Y interferometer 16 is used for measuring the Y position of wafer table WTB in the vicinity of an unloading position, which will be described later, and the loading position, for wafer replacement. An interferometer 128 is used to measure the X position of wafer table WTB in the unloading position and in the vicinity of the loading position.

  In addition, for example, in the movement of wafer stage WST between the loading operation and the alignment operation and / or between the exposure operation and the unloading operation, the measurement information of interferometer system 118, that is, the direction of 5 degrees of freedom (X-axis) , Y axis, θx, θy, and θz directions) at least one of the positional information is used. The interferometer system 118 is at least partially (for example, an optical system) provided on the main frame that holds the projection unit PU or integrally provided with the projection unit PU that is suspended and supported as described above. However, in this embodiment, it is provided on the measurement frame described above.

  In the present embodiment, wafer stage WST is mounted on stage main body 91 that can move freely in the XY plane, and in the Z-axis direction, θx direction, and θy direction with respect to stage main body 91. The wafer table WTB that can be driven relatively finely is included. However, the present invention is not limited to this, and a single stage that can move with six degrees of freedom may be adopted as the wafer stage WST. Further, instead of the reflecting surface 17a and the reflecting surface 17b, a movable mirror composed of a plane mirror may be provided on the wafer table WTB. Furthermore, the position information of wafer stage WST is measured using the reflecting surface of the fixed mirror provided in projection unit PU as a reference plane, but the position where the reference plane is arranged is not limited to projection unit PU, and is not necessarily limited. It is not necessary to measure the position information of wafer stage WST using a fixed mirror.

  Further, in the present embodiment, the position information of wafer stage WST measured by interferometer system 118 is not used in the exposure operation and alignment operation described later, and mainly the calibration operation of the encoder system (that is, the calibration of the measurement value). However, the measurement information of the interferometer system 118 (that is, at least one of position information in the direction of 5 degrees of freedom) may be used in, for example, an exposure operation and / or an alignment operation. In the present embodiment, the encoder system measures position information of wafer stage WST in three degrees of freedom, that is, in the X axis, Y axis, and θz directions. Therefore, in an exposure operation or the like, of the measurement information of the interferometer system 118, a direction different from the measurement direction (X axis, Y axis, and θz direction) of the position information of the wafer stage WST by the encoder system, for example, the θx direction and / or θy. Only position information related to the direction may be used. In addition to the position information in the different directions, position information related to the same direction as the measurement direction of the encoder system (that is, at least one of the X-axis, Y-axis, and θz directions) It may be used. Further, interferometer system 118 may be capable of measuring position information of wafer stage WST in the Z-axis direction. In this case, position information in the Z-axis direction may be used in the exposure operation or the like.

  The measurement stage MST includes a stage main body 92 that is driven in the XY plane by a linear motor (not shown) and the like, and a measurement table MTB mounted on the stage main body 92. The measurement table MTB is also mounted on the stage main body 92 via a Z / leveling mechanism (not shown). However, the present invention is not limited to this. For example, a measurement stage MST having a so-called coarse / fine movement structure in which the measurement table MTB can be finely moved in the X axis direction, the Y axis direction, and the θz direction with respect to the stage main body 92 may be adopted. Alternatively, the measurement table MTB may be fixed to the stage main body 92, and the stage main body 92 including the measurement table MTB may be configured to be driven in directions of six degrees of freedom.

  6 includes a linear motor and the Z / leveling mechanism for driving the stage body 91 of the wafer stage WST, and a linear motor and the Z / leveling mechanism for driving the stage body 92 of the measurement stage MST. Shown as system 124.

  Various measurement members are provided on the measurement table MTB (and the stage main body 92). As this measuring member, for example, as shown in FIGS. 2 and 5A, an illuminance unevenness sensor 94 having a pinhole-shaped light receiving portion that receives illumination light IL on the image plane of the projection optical system PL. , An aerial image measuring device 96 for measuring an aerial image (projected image) of a pattern projected by the projection optical system PL, and Shack-Hartman disclosed in, for example, WO 03/065428 A wavefront aberration measuring instrument 98 of the type is adopted. As the wavefront aberration measuring instrument 98, for example, the one disclosed in International Publication No. 99/60361 pamphlet (corresponding European Patent No. 1,079,223) can be used.

  As the illuminance unevenness sensor 94, for example, a sensor having the same structure as that disclosed in Japanese Patent Application Laid-Open No. 57-117238 (corresponding US Pat. No. 4,465,368) can be used. Further, as the aerial image measuring device 96, for example, one having the same configuration as that disclosed in Japanese Patent Laid-Open No. 2002-14005 (corresponding to US Patent Application Publication No. 2002/0041377) can be used. . In the present embodiment, three measurement members (94, 96, 98) are provided on the measurement stage MST, but the type and / or number of measurement members are not limited to this. As the measurement member, for example, a transmittance measuring instrument that measures the transmittance of the projection optical system PL, and / or a measuring instrument that observes the above-described local liquid immersion device 8, such as the nozzle unit 32 (or the tip lens 191), or the like. May be used. Further, a member different from the measurement member, for example, a cleaning member for cleaning the nozzle unit 32, the tip lens 191 and the like may be mounted on the measurement stage MST.

  In this embodiment, as can be seen from FIG. 5A, the frequently used sensors, the illuminance unevenness sensor 94, the aerial image measuring device 96, and the like are the center line CL (Y axis passing through the center) of the measurement stage MST. Is placed on top. For this reason, in this embodiment, measurement using these sensors can be performed by moving only the Y-axis direction without moving the measurement stage MST in the X-axis direction.

  In addition to the sensors described above, illumination light IL is received on the image plane of the projection optical system PL disclosed in, for example, Japanese Patent Application Laid-Open No. 11-16816 (corresponding US Patent Application Publication No. 2002/0061469). An illuminance monitor having a light receiving portion with a predetermined area may be adopted, and it is desirable that this illuminance monitor is also arranged on the center line.

  In the present embodiment, the illumination light IL is applied in response to the immersion exposure that exposes the wafer W with the exposure light (illumination light) IL via the projection optical system PL and the liquid (water) Lq. The illuminance unevenness sensor 94 (and the illuminance monitor), the aerial image measuring device 96, and the wavefront aberration measuring device 98 used for the measurement to be used receive the illumination light IL through the projection optical system PL and water. . In addition, for example, each sensor may be mounted on the measurement table MTB (and the stage body 92) only partially, for example, or the entire sensor may be arranged on the measurement table MTB (and the stage body 92). May be.

  As shown in FIG. 5B, a frame-shaped attachment member 42 is fixed to the end surface on the −Y side of the stage main body 92 of the measurement stage MST. A pair of light receiving systems 44 is arranged on the end surface on the −Y side of the stage main body 92 in the vicinity of the center position in the X-axis direction inside the opening of the mounting member 42 so as to face the pair of light transmitting systems 36 described above. Is fixed. Each light receiving system 44 includes an optical system such as a relay lens, a light receiving element, such as a photomultiplier tube, and a housing for housing these. As can be seen from FIGS. 4B and 5B and the above description, in this embodiment, wafer stage WST and measurement stage MST are close to each other within a predetermined distance (contact) in the Y-axis direction (contact). (Including the state), the illumination light IL transmitted through each aerial image measurement slit pattern SL of the measurement plate 30 is guided by each of the light transmission systems 36 described above and received by the light receiving element of each light receiving system 44. That is, the measurement plate 30, the light transmission system 36, and the light reception system 44 are similar to those disclosed in the aforementioned Japanese Patent Application Laid-Open No. 2002-14005 (corresponding US Patent Application Publication No. 2002/0041377), etc. An aerial image measurement device 45 (see FIG. 6) is configured.

  On the mounting member 42, a fiducial bar (hereinafter abbreviated as “FD bar”) 46 made of a rod-shaped member having a rectangular cross section is extended in the X-axis direction. The FD bar 46 is kinematically supported on the measurement stage MST by a full kinematic mount structure.

  Since the FD bar 46 is a prototype (measurement standard), an optical glass ceramic having a low thermal expansion coefficient, for example, Zerodure (trade name) manufactured by Schott is used as the material. The flatness of the upper surface (front surface) of the FD bar 46 is set to be as high as that of a so-called reference flat plate. In addition, a reference grating (for example, a diffraction grating) 52 having a periodic direction in the Y-axis direction as shown in FIG. 5A is provided near one end and the other end of the FD bar 46 in the longitudinal direction. Is formed. The pair of reference gratings 52 are formed in a symmetrical arrangement with respect to the center of the FD bar 46 in the X-axis direction, that is, the center line CL described above, with a predetermined distance L therebetween.

  A plurality of reference marks M are formed on the upper surface of the FD bar 46 in an arrangement as shown in FIG. The plurality of reference marks M are formed in an array of three rows with respect to the Y-axis direction at the same pitch, and the arrays of rows are formed with a predetermined distance from each other in the X-axis direction. As each reference mark M, a two-dimensional mark having a size detectable by a primary alignment system and a secondary alignment system described later is used. Although the shape (configuration) of the reference mark M may be different from the above-described reference mark FM, in this embodiment, the reference mark M and the reference mark FM have the same configuration and the same as the alignment mark of the wafer W. It has a configuration. In the present embodiment, the surface of the FD bar 46 and the surface of the measurement table MTB (which may include the above-described measurement member) are also covered with a liquid repellent film (water repellent film).

  Reflective surfaces 19a and 19b similar to the wafer table WTB described above are also formed on the + Y end surface and the −X end surface of the measurement table MTB (see FIGS. 2 and 5A). The Y interferometer 18 and the X interferometer 130 (in FIG. 1, the X interferometer 130 is not shown, see FIG. 2) of the interferometer system 118 are placed on these reflecting surfaces 19a and 19b as shown in FIG. By projecting an interferometer beam (measurement beam) and receiving each reflected light, the displacement of each reflecting surface from the reference position, that is, position information of the measurement stage MST (for example, at least the X-axis and Y-axis directions) And the rotation information in the θz direction) are measured, and this measured value is supplied to the main controller 20.

In the exposure apparatus 100 of the present embodiment, illustration is omitted in FIG. 1 from the viewpoint of avoiding complication of the drawing, but actually, as shown in FIG. 3, the optical axis on the reference axis LV described above. A primary alignment system AL1 having a detection center is arranged at a position a predetermined distance from AX on the -Y side. The primary alignment system AL1 is fixed to the lower surface of the main frame (not shown) via a support member 54. Secondary alignment systems AL2 ₁ , AL2 ₂ , AL2 ₃ , AL2 _{4 in} which detection centers are arranged almost symmetrically with respect to the reference axis LV are disposed on one side and the other side of the X-axis direction across the primary alignment system AL1. Each is provided. That is, the five alignment systems AL1, AL2 _{1 to} AL2 ₄ have their detection centers arranged at different positions in the X-axis direction, that is, arranged along the X-axis direction.

Each secondary alignment system AL2 _n (n = 1 to 4) rotates in a predetermined angle range clockwise and counterclockwise in FIG. 3 around the rotation center O as representatively shown for the secondary alignment system AL2 ₄ . The movable arm 56 _n (n = 1 to 4) is fixed to the tip (rotating end). In the present embodiment, each secondary alignment system AL2 _n includes a part thereof (for example, at least an optical system that irradiates the detection region with the alignment light and guides the light generated from the target mark in the detection region to the light receiving element). It is fixed to the arm 56 _n and the remaining part is provided on the main frame that holds the projection unit PU. The secondary alignment systems AL2 ₁ , AL2 ₂ , AL2 ₃ , AL2 ₄ are each rotated about the rotation center O to adjust the X position. That is, the secondary alignment systems AL2 ₁ , AL2 ₂ , AL2 ₃ , AL2 ₄ have their detection areas (or detection centers) independently movable in the X-axis direction. Therefore, the primary alignment system AL1 and the secondary alignment systems AL2 ₁ , AL2 ₂ , AL2 ₃ , AL2 ₄ can adjust the relative positions of their detection areas in the X-axis direction. In the present embodiment, secondary alignment systems AL2 ₁ by the rotation of the arm, AL2 _2, but AL2 _3, AL2 ₄ in the X position is assumed to be adjusted is not limited to this, secondary alignment systems AL2 _1, AL2 ₂ , AL2 ₃ , AL2 ₄ may be provided with a driving mechanism that reciprocates in the X-axis direction. Further, at least one of the secondary alignment systems AL2 ₁ , AL2 ₂ , AL2 ₃ , AL2 ₄ may be movable not only in the X axis direction but also in the Y axis direction. Since each secondary alignment system AL2 _n part is moved by arm 56 _n, a sensor (not shown), such as by an interferometer or an encoder, and a part of the location information that is fixed to arm 56 _n Measurement is possible. This sensor may only measure the positional information of the secondary alignment system AL2 _{n in} the X-axis direction, but in other directions, for example, the Y-axis direction and / or the rotational direction (including at least one of the θx and θy directions). The position information may be measurable.

A vacuum pad 58 _n (n = 1 to 4) made of a differential exhaust type air bearing is provided on the upper surface of each arm 56 _n . Further, the arm 56 _n can be rotated in accordance with an instruction from the main controller 20 by a rotation drive mechanism 60 _n (n = 1 to 4, not shown in FIG. 3, see FIG. 6) including a motor or the like. . After adjusting the rotation of arm 56 _n , main controller 20 operates each vacuum pad 58 _n to adsorb and fix each arm 56 _n to a main frame (not shown). Thereby, the state after adjusting the rotation angle of each arm 56 _n , that is, the desired positional relationship between the primary alignment system AL1 and the four secondary alignment systems AL2 _{1 to} AL2 ₄ is maintained.

If the portion of the main frame facing the arm 56 _n is a magnetic material, an electromagnet may be used instead of the vacuum pad 58.

In the present embodiment, as each of the primary alignment system AL1 and the four secondary alignment systems AL2 _{1 to} AL2 ₄ , for example, a broadband detection light beam that does not expose the resist on the wafer is irradiated to the target mark, and the reflected light from the target mark The target mark image formed on the light receiving surface and the image of the index (not shown) (the index pattern on the index plate provided in each alignment system) are imaged using an image sensor (CCD, etc.) An image processing type FIA (Field Image Alignment) system that outputs the image pickup signal is used. Imaging signals from each of the primary alignment system AL1 and the four secondary alignment systems AL2 _{1 to} AL2 ₄ are supplied to the main controller 20 in FIG. 6 via an alignment signal processing system (not shown).

The alignment system is not limited to the FIA system. For example, the target mark is irradiated with coherent detection light to detect scattered light or diffracted light generated from the target mark, or 2 generated from the target mark. Of course, it is possible to use an alignment sensor that detects two diffracted lights (for example, diffracted lights of the same order or diffracted in the same direction) by interference alone or in appropriate combination. In the present embodiment, the five alignment systems AL1, AL2 _{1 to} AL2 ₄ are fixed to the lower surface of the main frame holding the projection unit PU via the support member 54. For example, you may provide in the measurement frame mentioned above.

  Furthermore, in the exposure apparatus 100 of the present embodiment, a pair of TTR (Through The Reticle) alignment systems using light having an exposure wavelength disclosed in, for example, Japanese Patent Application Laid-Open No. 7-176468 is provided above the reticle R. Reticle alignment detection systems 13A and 13B (not shown in FIG. 1, refer to FIG. 6) are provided, and detection signals from the reticle alignment detection systems 13A and 13B are sent to main controller 20 via an alignment signal processing system (not shown). Supplied.

  In the exposure apparatus 100 of the present embodiment, as shown in FIG. 3, four head units 62 </ b> A to 62 </ b> D of the encoder system are arranged so as to surround the nozzle unit 32 from four directions. Although these head units 62A to 62D are not shown in FIG. 3 and the like from the viewpoint of avoiding complication of the drawings, they are actually suspended from the main frame holding the projection unit PU described above via a support member. It is fixed in the state.

As shown in FIG. 3, each of the head units 62A and 62C includes a plurality of (here, five) Y heads 65 _i and 64 _i (i = 1 to 5) having different positions in the X-axis direction. More specifically, the head units 62A and 62C are arranged at a distance WD on a straight line (reference axis) LH that passes through the optical axis AX of the projection optical system PL along the X-axis direction and is parallel to the X-axis. multiple and Y heads 65 _{2-65 5,} 64 _{1-64 4} (here four), four distance WD spaced projection optical system PL side of the Y head, and a predetermined distance in the -Y direction from the reference axis LH One Y head 65 ₁ , 64 ₅ disposed at the position on the −Y side of the remote immersion unit 32 is provided.

The head unit 62A uses the Y scale 39Y ₁ described above to measure a Y-axis position (Y position) of the wafer stage WST (wafer table WTB) in a multi-lens (here, 5 eyes) Y linear encoder ( Hereinafter, 70A (refer to FIG. 6) is configured as appropriate. Similarly, the head unit 62C uses the above-described Y scale 39Y ₂ to measure the Y position of the wafer stage WST (wafer table WTB), which is a multi-lens (here, 5 eyes) Y encoder 70C (see FIG. 6). Configure. Here, the distance WD in the X-axis direction of the five Y heads 65 and 64 (that is, the measurement beams) included in the head units 62A and 62C is the width of the Y scales 39Y ₁ and 39Y _{2 in} the X-axis direction (more accurately, Is set slightly narrower than the length of the grid line 38).

As shown in FIG. 3, the head unit 62B is disposed on the + Y side of the liquid immersion unit 32 (projection unit PU), and a plurality of head units 62B are disposed on the reference axis LV at intervals WD along the Y-axis direction. Then, four X heads 66 are provided. The head unit 62D is disposed on the −Y side of the primary alignment system AL1 on the opposite side to the head unit 62B via the liquid immersion unit 32 (projection unit PU), and is disposed on the reference axis LV with an interval WD. A plurality of, in this case, four X heads 66 are provided. The head unit 62B uses the above-described X scale 39X ₁ to measure the position (X position) of the wafer stage WST (wafer table WTB) in the X axis direction (multiple eyes (here, four eyes) X linear encoder). (Hereinafter abbreviated as “X encoder” or “encoder” where appropriate) 70B (see FIG. 6). Further, the head unit 62D uses the above-described X scale 39X ₂ to measure the X position of the wafer stage WST (wafer table WTB), and a multi-lens (here, four eyes) X linear encoder 70D (see FIG. 6). Configure.

Here, the interval WD between the adjacent X heads 66 (measurement beams) included in the head units 62B and 62D is the width of the X scales 39X ₁ and 39X _{2 in} the Y-axis direction (more precisely, the length of the grid line 37). It is set narrower than The interval between the X head 66 on the most −Y side of the head unit 62B and the X head 66 on the most + Y side of the head unit 62D is switched between the two X heads by moving the wafer stage WST in the Y-axis direction ( The width of the wafer table WTB is set slightly narrower than the width in the Y-axis direction so that it can be connected.

  In the present embodiment, head units 62E and 62F are further provided at a predetermined distance on the −Y side of the head units 62C and 62A, respectively. The head units 62E and 62F are not shown in FIG. 3 and the like from the viewpoint of avoiding complication of the drawings, but are actually suspended from the main frame holding the projection unit PU described above via a support member. It is fixed with. Note that the head units 62E and 62F and the head units 62A to 62D described above may be suspended and supported integrally with the projection unit PU, for example, when the projection unit PU is suspended and supported, or may be mounted on the measurement frame described above. It may be provided.

The head unit 62E includes four Y heads 67 having different positions in the X-axis direction. More specifically, the head unit 62E includes three Y heads 67 arranged on the straight line parallel to the X axis on the −X side of the secondary alignment system AL2 ₁ at substantially the same interval as the interval WD, and the innermost ( + somewhat shorter distance than the predetermined distance (WD from Y head 67 on the + X side of the X side)) apart, and one disposed in a position at a predetermined distance in the secondary alignment systems AL2 ₁ on the + Y side and a Y head 67 ing.

The head unit 62F is symmetrical with the head unit 62E with respect to the reference axis LV described above, and includes the four Y heads 67 and the four Y heads 68 arranged symmetrically with respect to the reference axis LV. At the time of an alignment operation, which will be described later, at least one Y head 67 and 68 is respectively opposed to the Y scale 39Y ₂ and 39Y _1, and the Y heads 67 and 68 (that is, the Y heads 67 and 68 are configured by these Y heads 67 and 68). Y encoder 70C, 70A) measures the Y position (and θz rotation) of wafer stage WST.

In this embodiment, the Y heads 67 and 68 adjacent to the secondary alignment systems AL2 ₁ and AL2 ₄ in the X-axis direction at the time of baseline measurement (Sec-BCHK (interval)) of the secondary alignment system described later, The Y positions of the FD bar 46 are measured at the positions of the respective reference gratings 52 by the Y heads 67 and 68 facing the pair of reference gratings 52 of the FD bar 46 respectively. In the following, encoders composed of Y heads 67 and 68 facing the pair of reference gratings 52 are respectively Y linear encoders (also abbreviated as “Y encoder” or “encoder” as appropriate) 70E and 70F (see FIG. 6). Call it.

  The measured values of the six linear encoders 70A to 70F described above are supplied to the main controller 20, and the main controller 20 determines the XY plane of the wafer table WTB based on the three measured values of the linear encoders 70A to 70D. And the rotation of the FD bar 46 in the θz direction is controlled based on the measurement values of the linear encoders 70E and 70F.

  In FIG. 3, the measurement stage MST is not shown, and a liquid immersion region formed by the water Lq held between the measurement stage MST and the tip lens 191 is indicated by reference numeral 14. In FIG. 3, reference sign UP indicates an unloading position where the wafer is unloaded on wafer table WTB, and reference sign LP indicates a loading position where the wafer is loaded onto wafer table WTB. In the present embodiment, the unload position UP and the loading position LP are set symmetrically with respect to the reference axis LV. Note that the unload position UP and the loading position LP may be the same position.

  FIG. 6 shows the main configuration of the control system of the exposure apparatus 100. This control system is mainly configured of a main control device 20 composed of a microcomputer (or a workstation) for overall control of the entire apparatus. In FIG. 6, various sensors provided on the measurement stage MST such as the uneven illuminance sensor 94, the aerial image measuring device 96, and the wavefront aberration measuring device 98 are collectively shown as a sensor group 99.

Since the exposure apparatus 100 of the present embodiment employs the X scale and Y scale arrangement on the wafer table WTB as described above and the X head and Y head arrangement as described above, FIG. 7 (B) and the like, in the effective stroke range of wafer stage WST (that is, the range moved for alignment and exposure operations in this embodiment), Y scales 39Y ₁ and 39Y ₂ are always used. , Y heads 65 and 64 (head units 62A and 62C) or Y heads 68 and 67 (head units 62F and 62E) face each other, and X heads 66 (heads) are placed on _{one of} X scales 39X ₁ and 39X _2. Units 62B or 62D) face each other. In FIGS. 7A and 7B, the head facing the corresponding X scale or Y scale is indicated by a solid circle.

  Main controller 20 controls wafers WST by controlling each motor constituting stage drive system 124 based on three measurement values of encoders 70A to 70D within the effective stroke range of wafer stage WST described above. Position information in the XY plane (including rotation information in the θz direction) can be controlled with high accuracy. Since the influence of air fluctuations on the measurement values of the encoders 70A to 70D is negligibly small when compared with the interferometer, the short-term stability of the measurement due to the air fluctuation is much better than that of the interferometer.

Further, main controller 20 drives Y head for measuring the position of wafer stage WST in the Y-axis direction when driving wafer stage WST in the X-axis direction as indicated by the white arrow in FIG. 65 and 64 are sequentially switched to the adjacent Y heads 65 and 64 as indicated by an arrow e ₁ in FIG. For example switching from Y heads 64 ₂ surrounded by the circle in a solid line to Y head 64 ₃ surrounded by a dotted circle. That is, in this embodiment, in order to smoothly switch (connect) the Y heads 65 and 64, as described above, the interval WD between the adjacent Y heads 65 and 64 included in the head units 62A and 62C is set to the Y scale. It is set narrower than the width of 39Y ₁ and 39Y _{2 in} the X-axis direction.

  Further, at the time of Sec-BCHK (lot head), which will be described later, main controller 20 measures Y head 67 for measuring the position of wafer stage WST in the Y-axis direction when driving wafer stage WST in the X-axis direction. 68 is sequentially switched to the adjacent Y heads 67 and 68 in the same manner as described above.

In the present embodiment, as described above, the interval WD between the adjacent X heads 66 included in the head units 62B and 62D is set to be narrower than the width of the X scales 39X ₁ and 39X _{2 in} the Y-axis direction. Therefore, as described above, when main controller 20 drives wafer stage WST in the Y-axis direction as indicated by a white arrow in FIG. 7B, position of wafer stage WST in the X-axis direction is determined. the X heads 66 measure the, as indicated by the arrow e ₂ in the drawing are sequentially switched to X head 66 of the next (e.g. X head surrounded from X heads 66 ₅ surrounded by the circle in a solid line by a dotted circle To 66 ₆ ).

Next, the configuration and the like of the encoders 70A to 70F will be described by taking the Y encoder 70C shown in an enlarged manner in FIG. FIG. 8A shows one Y head 64 of the head unit 62C that irradiates the Y scale 39Y ₂ with detection light (measurement beam).

  The Y head 64 is roughly divided into three parts: an irradiation system 64a, an optical system 64b, and a light receiving system 64c.

  The irradiation system 64a is disposed on the optical path of a light source, for example, a semiconductor laser LD, and a laser beam LB emitted from the semiconductor laser LD that emits the laser light LB in a direction that forms 45 ° with respect to the Y axis and the Z axis. Lens L1.

  The optical system 64b includes a polarizing beam splitter PBS whose separation surface is parallel to the XZ plane, a pair of reflecting mirrors R1a and R1b, lenses L2a and L2b, a quarter-wave plate (hereinafter referred to as a λ / 4 plate). WP1a, WP1b, reflection mirrors R2a, R2b, and the like are provided.

  The light receiving system 64c includes a polarizer (analyzer) and a photodetector.

In this Y encoder 70C, the laser beam LB emitted from the semiconductor laser LD enters the polarization beam splitter PBS through the lens L1, and is polarized and separated into two beams LB ₁ and LB ₂ . The beam LB ₁ transmitted through the polarization beam splitter PBS reaches the reflection type diffraction grating RG formed on the Y scale 39Y ₁ via the reflection mirror R1a, and the beam LB ₂ reflected by the polarization beam splitter PBS passes through the reflection mirror R1b. Through the reflection type diffraction grating RG. Here, “polarized light separation” means that an incident beam is separated into a P-polarized component and an S-polarized component.

A diffracted beam of a predetermined order generated from the diffraction grating RG by irradiation of the beams LB ₁ and LB ₂ , for example, a first-order diffracted beam is converted into circularly polarized light by the λ / 4 plates WP1b and WP1a via the lenses L2b and L2a, respectively. Thereafter, the light is reflected by the reflection mirrors R2b and R2a, passes through the λ / 4 plates WP1b and WP1a again, follows the same optical path as the forward path in the reverse direction, and reaches the polarization beam splitter PBS.

The polarization directions of the two beams that have reached the polarization beam splitter PBS are each rotated by 90 degrees with respect to the original direction. For this reason, the first-order diffracted beam of the beam LB ₁ that has passed through the polarizing beam splitter PBS first is reflected by the polarizing beam splitter PBS and enters the light receiving system 64c, and the beam LB previously reflected by the polarizing beam splitter PBS. ₂ of the first-order diffracted beams are synthesized through polarization beam splitter PBS first order diffracted beam is coaxial with the beam LB ₁ and is incident on photodetection system 64c.

  The two first-order diffracted beams are aligned in the polarization direction by the analyzer inside the light receiving system 64c and interfere with each other to become interference light, which is detected by the photodetector, It is converted into an electrical signal corresponding to the intensity.

As can be seen from the above description, in the Y encoder 70C, since the optical path lengths of the two beams to be interfered are extremely short and almost equal, the influence of air fluctuation can be almost ignored. When the Y scale 39Y ₂ (that is, the wafer stage WST) moves in the measurement direction (in this case, the Y-axis direction), the phases of the two beams change and the intensity of the interference light changes. The change in the intensity of the interference light is detected by the light receiving system 64c, and position information corresponding to the intensity change is output as a measurement value of the Y encoder 70C. The other encoders 70A, 70B, 70D and the like are configured in the same manner as the encoder 70C. Each encoder has a resolution of, for example, about 0.1 nm. In the encoder of the present embodiment, as shown in FIG. 8B, a laser beam LB having a cross-sectional shape that extends long in the periodic direction of the grating RG may be used as detection light. In FIG. 8B, the beam LB is exaggerated and enlarged as compared with the grating RG.

Next, the baseline measurement operation of the secondary alignment system AL2 _n (n = 1 to 4) performed mainly immediately before the start of the processing on the lot wafers (the lot head) will be described. Here, the baseline of secondary alignment system AL2 _n, means the relative position of each secondary alignment system AL2 _n relative to the primary alignment system AL1 (detection center of) (detection center of). Note that the secondary alignment system AL2 _n (n = 1 to 4) is driven by the rotary drive mechanism 60 _n described above, for example, according to shot map data of wafers in a lot, and the position in the X-axis direction is set. Shall.

a. In the baseline measurement of the secondary alignment system performed at the beginning of the lot (hereinafter also referred to as Sec-BCHK (lot beginning) as appropriate), the main controller 20 firstly, as shown in FIG. A specific alignment mark on the wafer W (process wafer) is detected by the primary alignment system AL1 (see the star mark in FIG. 9A), the detection result and the measurement of the encoders 70A, 70C, and 70D at the time of detection. The value is stored in the memory in association with the value. In the state of FIG. 9A, the position of the wafer table WTB in the XY plane is two Y heads 68 and 67 (encoders 70A and 70C) surrounded by black circles facing the Y scales 39Y ₁ and 39Y _2. And the X head 66 (encoder 70D) surrounded by a black circle facing the X scale 39X ₂ is controlled by the main controller 20.

b. Next, main controller 20 moves wafer stage WST by a predetermined distance in the −X direction, and detects the specific alignment mark with secondary alignment system AL2 ₁ as shown in FIG. 9B ( The detection result and the measured values of the encoders 70A, 70C, and 70D at the time of detection are stored in the memory in association with each other. In the state of FIG. 9B, the position of the wafer table WTB in the XY plane is two Y heads 68 and 67 (encoders 70A and 70C) surrounded by black circles facing the Y scales 39Y ₁ and 39Y _2. When, X X heads 66 to the scale 39X ₂ are surrounded by black circles facing the (encoder 70D), it is controlled on the basis of.

c. Similarly, main controller 20 sequentially moves wafer stage WST in the + X direction, sequentially detects the specific alignment marks with the remaining secondary alignment systems AL2 ₂ , AL2 ₃ , AL2 ₄ , and the detection results thereof. And the measured values of the encoders 70A, 70C, and 70D at the time of detection are sequentially associated with each other and stored in the memory.

d. Then, the main controller 20 sends the above a. And the above b. Or c. Based on the result of the above, the baseline of each secondary alignment system AL2 _n is calculated.

Thus, by using the wafer W (process wafer) at the head of the lot and detecting the same alignment mark on the wafer W by the primary alignment system AL1 and each secondary alignment system AL2 _n , each secondary alignment system AL2 is detected. _Since the baseline of _n is obtained, this process eventually corrects the difference in detection offset between the alignment systems caused by the process.

In the present embodiment, since the head units 62E and 62F are respectively provided with four Y heads 67 and 68 having different positions in the X-axis direction, when measuring the baseline of each of the secondary alignment systems AL2 _n described above, Even if the primary alignment system AL1 or the secondary alignment system AL2 _n is used to detect a specific alignment mark on the wafer, the Y position and θz rotation of the wafer stage WST at the time of detection are determined by the Y scale. Measurement and management can be performed based on the measurement values of the Y heads 68 and 67 (encoders 70A and 70C) facing 39Y ₁ and 39Y ₂ . At this time, X position of wafer stage WST can be measured, managed based on the measurement values of X head 66 facing X scale 39X ₂ (encoders 70D).

Note that the baseline measurement of the secondary alignment system AL2 _n may be performed using a reference mark on wafer stage WST or measurement stage MST instead of the wafer alignment mark. In this case, the reference mark FM of the measurement plate 30 used in the baseline measurement of the primary alignment system AL1 may also be used, that is, the reference mark FM may be detected by the secondary alignment system AL2 _n . Alternatively, for example, it provided the n reference mark at the same position relationship as the secondary alignment system AL2 _n wafer stage WST or measurement stage MST, substantially may be executed simultaneously with detection of the reference mark by secondary alignment system AL2 _n. As this reference mark, for example, the reference mark M of the FD bar 46 may be used. Further, a reference mark for baseline measurement of the secondary alignment system AL2 _n is provided on the wafer stage WST in a predetermined positional relationship with respect to the reference mark FM for baseline measurement of the primary alignment system AL1, and the reference by the primary alignment system AL1 is used. Almost simultaneously with the detection of the mark FM, the detection of the reference mark by the secondary alignment system AL2 _n may be executable. In this case, the reference marks for baseline measurement of secondary alignment system AL2 _n may be one, more, for example, may be provided the same number as the secondary alignment system AL2 _n. In the present embodiment, since the primary alignment system AL1 and the secondary alignment system AL2 _n can each detect a two-dimensional mark (X, Y mark), the two-dimensional mark is used when measuring the baseline of the secondary alignment system AL2 _n. Thus, the baselines of the secondary alignment system AL2 _{n in} the X-axis and Y-axis directions can be obtained simultaneously. In the present embodiment, the reference marks FM and M and the wafer alignment mark include, for example, a one-dimensional X mark and Y mark in which a plurality of line marks are periodically arranged in the X-axis and Y-axis directions, respectively.

  Next, a parallel processing operation using wafer stage WST and measurement stage MST in exposure apparatus 100 of the present embodiment will be described with reference to FIGS. During the following operations, the main controller 20 controls the opening and closing of the valves of the liquid supply device 5 and the liquid recovery device 6 of the local liquid immersion device 8 as described above, and the leading end lens of the projection optical system PL. 191 is always filled with water. However, in the following, in order to make the explanation easy to understand, explanation regarding the control of the liquid supply device 5 and the liquid recovery device 6 is omitted. Further, the following description of the operation will be made with reference to a number of drawings, and the same members may or may not be labeled with the same members for each drawing. In other words, although the reference numerals described in the drawings are different, the drawings have the same configuration regardless of the presence or absence of the reference numerals. The same applies to each drawing used in the description so far.

  FIG. 10 shows a state in which step-and-scan exposure is performed on wafer W placed on wafer stage WST. In this exposure, wafer stage WST is moved to the scanning start position (acceleration start position) for exposure of each shot area on wafer W based on the result of wafer alignment (EGA: Enhanced Global Alignment) performed before the start. It is performed by repeating the movement between the moving shots and the scanning exposure in which the pattern formed on the reticle R is transferred to each shot area by the scanning exposure method. Further, the exposure is performed in order from the shot area located on the −Y side on the wafer W to the shot area located on the + Y side.

During the exposure described above, main controller 20 causes wafer stage WST (wafer table WTB) to have a position in the XY plane (including rotation in the θz direction) of two Y encoders 70A and 70C, two X encoders 70B, Control is performed based on the measurement results of a total of three encoders with one of 70D. Here, the two X encoders 70B and 70D are constituted by two X heads 66 facing the X scales 39X ₁ and 39X ₂ respectively, and the two Y encoders 70A and 70C are the Y scales 39Y ₁ and 39Y ₂ . The Y heads 65 and 64 are opposed to each other. Further, main controller 20 manages θy rotation (rolling) and θx rotation (pitching) of wafer table WTB based on the measurement values of X interferometer 126 and Y interferometer 16 described above. It should be noted that at least one of the position (Z position), θy rotation (rolling), and θx rotation (pitching) in the Z-axis direction of wafer table WTB, for example, the Z position and θy rotation is determined based on the other sensor, for example, the upper surface of wafer table WTB. You may measure by the sensor which detects Z position. In any case, the position of the wafer table WTB during the exposure, the control of θy rotation and θx rotation (focus / leveling control of the wafer W) is performed by the main controller 20 on the surface position information on the surface of the wafer W. This is performed based on the result of real-time surface position detection using a surface position detection system (not shown) that detects the above. The main controller 20 detects the surface position of the wafer table WTB during exposure using a surface position sensor (not shown), and based on the measurement result of the surface position information of the wafer W measured in advance. Focus leveling control may be performed.

At the position of wafer stage WST shown in FIG. 10, X head 66 ₅ (shown in a circle in the figure) faces X scale 39X ₁ , but X head faces X scale 39X _2. There is no 66. Therefore, main controller 20 executes position (X, Y, θz) control of wafer stage WST using one X encoder 70B and two Y encoders 70A, 70C. In this case, when wafer stage WST moves from the position shown in FIG. 10 moves in the -Y direction, the X heads 66 ₅ (no longer faces) off the X scales 39X _1, instead X head 66 ₄ (the dashed line in FIG. shown circled) faces X scale 39X _2. Therefore, main controller 20 switches to stage control using one X encoder 70D and two Y encoders 70A and 70C.

  Thus, main controller 20 performs stage control by constantly switching the encoder to be used according to the position coordinates of wafer stage WST.

  Note that the position (X, Y, Z, θx, θy, θz) measurement of wafer stage WST using interferometer system 118 is always performed independently of the position measurement of wafer stage WST using the encoder system described above. It has been broken. For example, one of X interferometers 126, 127, and 128 is used according to the Y position of wafer stage WST. During the exposure, an X interferometer 126 is used as shown in FIG. For example, the measurement results of wafer stage WST in the X, Y, and θz directions by interferometer system 118 are supplementarily used for position control of wafer stage WST.

  When exposure of wafer W is completed, main controller 20 drives wafer stage WST toward unload position UP. At that time, the wafer stage WST and the measurement stage MST, which are separated from each other during the exposure, are brought into contact with each other with a separation distance of about 300 μm therebetween and shift to the scram state. Here, the −Y side surface of the FD bar 46 on the measurement table MTB and the + Y side surface of the wafer table WTB come into contact with or approach each other. The liquid immersion region 14 formed under the projection unit PU moves on the measurement stage MST by moving both stages WST and MST in the −Y direction while maintaining this scram state (for example, FIG. 11 and FIG. 12).

  After wafer stage WST moves to the scrum state and further moves in the -Y direction and moves out of the effective stroke area (area where the wafer stage moves during exposure and wafer alignment), all X heads constituting encoders 70A to 70D , Y head deviates from the corresponding scale on wafer table WTB. Therefore, stage control based on the measurement results of the encoders 70A to 70D becomes impossible. Immediately before that, main controller 20 switches to stage control based on the measurement result of interferometer system 118. Here, among the three X interferometers 126, 127, and 128, the X interferometer 128 is used.

  Thereafter, as shown in FIG. 11, wafer stage WST releases the scrum state with measurement stage MST and moves to unload position UP. After the movement, main controller 20 unloads wafer W on wafer table WTB. Then, as shown in FIG. 12, wafer stage WST is driven in the + X direction to move to loading position LP, and next wafer W is loaded on wafer table WTB.

In parallel with these operations, main controller 20 adjusts the position of FD bar 46 supported by measurement stage MST in the XY plane, baseline measurement of _four secondary alignment systems AL2 _{1 to} AL2 ₄ , Execute Sec-BCHK (interval). Here, in order to measure the position (θz rotation) in the XY plane, the Y heads 67 ₃ and 68 ₂ and the Y heads 67 ₃ and 68 ₂ are respectively measured from the pair of reference gratings 52 on the measurement stage MTB facing each other. The constructed Y encoders 70E and 70F are used. Here, the measurement control by the encoder for the components other than the θz rotation, that is, the components in the X-axis and Y-axis directions is not performed because time synchronization is performed between the plurality of alignment systems in the following measurement. This is because the stage control error can be canceled as a result.

Next, as shown in FIG. 13, main controller 20 drives wafer stage WST, positions reference mark FM on measurement plate 30 within the detection field of primary alignment system AL1, and aligns alignment systems AL1, AL2. performing _{1 ~AL2 4} Pri-BCHK former processing of the determining the reference position of the baseline measurement of.

At this time, as shown in FIG. 13, two Y heads 68 ₂ and 67 ₃ and one X head 66 (indicated by circles in the figure) are respectively connected to Y scales 39Y ₁ and 39Y ₂ . It comes to face the X scale 39X _2. Therefore, main controller 20 switches from interferometer system 118 to stage control using encoder system 150 (encoders 70A, 70C, and 70D). The interferometer system 118 is again used auxiliary. Of the three X interferometers 126, 127, and 128, the X interferometer 127 is used.

Thereafter, main controller 20 performs wafer alignment (EGA) using primary alignment system AL1 and secondary alignment systems AL2 _{1 to} AL2 ₄ (see the star mark in FIG. 14).

  In the present embodiment, wafer stage WST and measurement stage MST are in the scrum state before the wafer alignment shown in FIG. 14 is started. Main controller 20 drives both stages WST and MST in the + Y direction while maintaining the scrum state. Thereafter, the water in the immersion area 14 moves from the measurement table MTB to the wafer table WTB.

  In parallel with wafer alignment (EGA), main controller 20 executes the latter half of the Pri-BCHK that measures the intensity distribution of the projected image with respect to the XY position of wafer table WTB using aerial image measurement device 45.

  When the above operations are completed, main controller 20 releases the scram state of both stages WST and MST. Then, as shown in FIG. 10, step-and-scan exposure is performed to transfer a reticle pattern onto a new wafer W. Thereafter, the same operation is repeatedly executed.

As described above, according to the exposure apparatus 100 of the present embodiment, the encoder system 150 included in the measurement system 200 has different positions in the X-axis direction, the primary alignment system AL1 and the secondary alignment systems AL2 _{1 to} AL2. There are four Y heads 67 and 68 that are arranged on both outer sides of the _four detection areas and that have different positions with respect to the X-axis direction that constitute part of the head units 62E and 62F, respectively. Then, main controller 20 performs wafer stage WST based on the measurement values of Y heads 68 and 67 (Y linear encoders 70A and 70C) facing the pair of Y scales 39Y ₁ and 39Y ₂ , for example, during alignment. The position information in the Y-axis direction (and the position information in the θz direction) is measured.

For this reason, for example, at the time of the above-described Sec-BCHK (lot head), main controller 20 uses a specific alignment mark (or reference mark FM on wafer stage WST) held on wafer stage WST as a primary. Even when the wafer stage WST is moved in the X-axis direction in order to detect each of the alignment system AL1 and the secondary alignment systems AL2 _{1 to} AL2 ₄ , at least the position of the wafer stage WST in the Y-axis direction and the θz-direction The rotation is measured with high accuracy based on the measurement results of the Y linear encoders 70A and 70C with good short-term measurement stability, and the position of the wafer stage WST in the Y-axis direction and the rotation in the θz direction are determined based on the measurement results. It can be controlled with high accuracy. Therefore, main controller 20 determines the mark (specific alignment mark (or a specific alignment mark) (or based on the detection results of alignment systems AL1, AL2 _{1 to} AL2 ₄ and the measurement values of Y linear encoders 70A and 70C at the time of detection). It is possible to accurately obtain the position information regarding the Y-axis direction of the reference mark FM)) on the wafer stage WST. The position of the X-axis direction of wafer stage WST during Sec-BCHK is measured by X head 66 facing X scale 39X ₂ (encoders 70D). Accordingly, the baselines (X-axis direction and Y-axis direction) of the secondary alignment systems AL2 _{1 to} AL2 ₄ can be obtained with high accuracy for each lot head.

Further, in the present embodiment, the base lines (X-axis direction and Y-axis direction) of the secondary alignment systems AL2 _{1 to} AL2 ₄ are obtained by processing of Sec-BCHK (interval) performed at a predetermined interval (here, every wafer exchange). Is measured.

  Then, based on the latest baseline obtained in this way and the result of wafer alignment (EGA), the wafer stage is moved to the scanning start position (acceleration start position) for exposure of each shot area on the wafer W. By repeating the movement operation between shots in which the WST is moved and the scanning exposure operation in which the pattern formed on the reticle R is transferred to each shot area by the scanning exposure method, the pattern of the reticle R is transferred to a plurality of shots on the wafer W. It becomes possible to transfer to the area with high accuracy (overlay accuracy).

According to the present embodiment, the position information of wafer table WTB (wafer stage WST) is measured by three of the four linear encoders 70A to 70D during exposure. Here, the linear encoders 70A to 70D are a plurality of gratings (that is, Y scales 39Y ₁ , 39Y _2, or X) that are arranged on the wafer table WTB and have a grating whose direction is parallel to the Y axis and the X axis. A reflective encoder including a scale 39X ₁ , 39X ₂ ) and a plurality of heads (Y heads 65, 64 or X head 66) on which the scales 39Y ₁ , 39Y ₂ , 39X ₁ , 39X ₂ are arranged to face each other. is there. For this reason, the linear encoders 70A to 70D are affected by air fluctuations because the optical path length of the beam irradiated from the respective heads to the opposing scale (grating) is much shorter than that of the Y interferometer 18 and the X interferometer 130. It is difficult, and the short-term stability of measured values is superior to that of the Y interferometer 18 and the X interferometer 130. Therefore, it is possible to stably control the position of wafer table WTB (wafer stage WST) that holds the wafer.

Further, according to the exposure apparatus 10 of the present embodiment, among the four Y heads 67 and 68 provided in the head units 62E and 62F, the Y heads 67 and 68 located on the innermost side are the other in the Y-axis direction. The position is different from Y head. Thus, the Y heads 67 and 68 positioned on its innermost and placed alignment systems AL1, AL2 ₁ AL24 around the ₄ empty space, i.e., in accordance with the arrangement of the alignment systems AL1, AL2 ₁ AL24 ₄ It becomes possible to arrange.

Further, the distance in the X-axis direction between each of the four Y heads 67 and 68 provided in the head units 62E and 62F is the width in the X-axis direction of the Y scales 39Y ₁ and 39Y ₂ (more precisely, the length of the grid line 38). Therefore, when the wafer stage WST moves in the X-axis direction, the Y head used for measuring the position of the wafer stage WST in the X-axis direction can be switched to the adjacent Y head without any trouble. . As a result, at the time of the Sec-BCHK, at least one Y head 67 and 68 is respectively opposed to the Y scale 39Y ₂ and 39Y _1, and the Y heads 67 and 68 (that is, the Y heads 67 and 68) The Y position (and θz rotation) of wafer stage WST is measured by the constructed Y encoders 70C and 70A).

Further, main controller 20 detects a pair of Y scales out of four Y heads 67 and 68 of head units 62E and 62F when alignment marks on wafer W are detected by alignment systems AL1 and AL2 _{1 to} AL2 _{4. One} Y head 67 and 68 each facing 39Y ₂ and 39Y ₁ is selected, and a corresponding X scale (of X scales 39Y ₁ and 39Y ₂₎ is selected from the plurality of X heads 66 of the head units 62B and 62D. One X head 66 facing the predetermined one) is selected, and based on the measured values of the two selected Y heads and the measured values of the selected X heads, Control position and rotation (θz rotation).

In addition, as is apparent from the above description, the exposure apparatus of the present embodiment can perform the servo control from the start of servo control of the position of the wafer stage WST in the XY plane based on the measurement value of the encoder system to the end of exposure. A sequence is adopted in which wafer stage WST moves within the range. For example, in the case of the above-described Sec-BCHK (lot head), the wafer stage WST does not go out of the above-described range where the servo control can be performed, regardless of whether the alignment system AL2 ₁ or AL2 ₄ is used for detection. It is desirable to select an alignment mark on W as a specific alignment mark to be detected.

In the above embodiment, the Sec-BCHK (lot head) process is exemplified as the characteristic measurement of the plurality of alignment systems AL2 _{1 to} AL2 ₄ (mark detection system). However, the present invention is not limited to this. Absent. In short, the wafer stage WST is moved in the X-axis direction while managing the positions of the wafer stage WST in the Y-axis direction and the θz direction based on the measurement results of the encoders 70A and 70C of the encoder system 150 performed by the main controller 20. And at least one reference mark on wafer stage WST or at least one alignment mark on wafer W is detected using a plurality of mark detection systems (at least two of alignment systems AL1, AL21 to AL24). As long as the characteristic measurement of the plurality of mark detection systems is performed, any measurement may be performed. For example, the same mark on the wafer W is detected in sequence while moving the wafer table WTB stepwise in the Z-axis direction with at least two of the alignment systems AL1, AL21 to AL24, thereby correcting aberrations of the alignment system. For example, the focus dependency of the mark position detection error (TIS: Tool Induce Shift) may be obtained.

In the above embodiment, the case where each of the head units 62E and 62F includes four Y heads has been described. However, the present invention is not limited to this, and a plurality of mark detection systems (in the above embodiment, alignment systems AL1, AL2 _1). ˜AL2 ₄ ), there may be a plurality of Y heads on both outer sides. Specifically, when a specific alignment mark on the wafer W is detected by each of the plurality of mark detection systems, at least one Y head 68 and 67 can face the pair of Y scales 39X ₁ and 39X _2. good. In the above embodiment, the case has been described in which the Y position of the innermost Y head among the plurality of Y heads on both outer sides of the plurality of mark detection systems is different from the other Y heads. However, the Y position of any Y head may be different. In short, the Y position of any Y head may be different from the Y position of other Y heads depending on the empty space. Alternatively, when there is sufficient free space on both outer sides of the plurality of mark detection systems, all Y heads may be arranged at the same Y position.

  Also, the number of mark detection systems (alignment systems) is not limited to five, and it is sufficient if there are two or more mark detection systems having different detection area positions in the second direction (X-axis direction in the above embodiment). Any number is acceptable.

  In the above embodiment, the lower surface of the nozzle unit 32 and the lower end surface of the tip optical element of the projection optical system PL are substantially flush with each other. However, the present invention is not limited to this. You may arrange | position near the image plane (namely, wafer) of projection optical system PL rather than the output surface of an element. That is, the local liquid immersion device 8 is not limited to the above-described structure. For example, European Patent Publication No. 1420298, International Publication No. 2004/055803 Pamphlet, International Publication No. 2004/057590 Pamphlet, International Publication No. 2005/029559. Pamphlet (corresponding US Patent Publication No. 2006/0231206), pamphlet of International Publication No. 2004/086468 (corresponding US Patent Publication No. 2005/0280791), JP-A-2004-289126 (corresponding US Patent No. 6,952,253) Etc.) can be used. Further, as disclosed in, for example, International Publication No. 2004/019128 (corresponding US Patent Publication No. 2005/0248856), in addition to the optical path on the image plane side of the tip optical element, the object plane side of the tip optical element The optical path may be filled with liquid. Furthermore, a thin film having a lyophilic property and / or a dissolution preventing function may be formed on a part (including at least a contact surface with the liquid) or the entire surface of the tip optical element. Quartz has a high affinity with a liquid and does not require a dissolution preventing film, but fluorite preferably forms at least a dissolution preventing film.

In the above embodiment, pure water (water) is used as the liquid. However, the present invention is not limited to this. As the liquid, a safe liquid that is chemically stable and has a high transmittance of the illumination light IL, such as a fluorine-based inert liquid, may be used. As this fluorinated inert liquid, for example, Fluorinert (trade name of 3M, USA) can be used. This fluorine-based inert liquid is also excellent in terms of cooling effect. Further, a liquid having a refractive index higher than that of pure water (refractive index of about 1.44), for example, 1.5 or more may be used as the liquid. Examples of the liquid include predetermined liquids having C—H bonds or O—H bonds such as isopropanol having a refractive index of about 1.50 and glycerol (glycerin) having a refractive index of about 1.61, hexane, heptane, decane, and the like. Or a predetermined liquid (organic solvent) or decalin (Decalin: Decahydronaphthalene) having a refractive index of about 1.60. Alternatively, any two or more of these liquids may be mixed, or at least one of these liquids may be added (mixed) to pure water. Alternatively, the liquid may be one obtained by adding (mixing) a base or an acid such as H ⁺ , Cs ⁺ , K ⁺ , Cl ⁻ , SO ₄ ²⁻ or PO ₄ ^{2− to} pure water. Further, pure water may be added (mixed) with fine particles such as Al oxide. These liquids can transmit ArF excimer laser light. As the liquid, the light absorption coefficient is small, the temperature dependency is small, and the projection optical system (tip optical member) and / or the photosensitive material (or protective film (topcoat film) coated on the wafer surface is used. ) Or an antireflection film) is preferable. Further, when the F ₂ laser is used as the light source, fomblin oil may be selected. Furthermore, as the liquid, a liquid having a higher refractive index with respect to the illumination light IL than that of pure water, for example, a liquid having a refractive index of about 1.6 to 1.8 may be used. It is also possible to use a supercritical fluid as the liquid. Further, the leading optical element of the projection optical system PL is made of, for example, quartz (silica) or a fluoride compound such as calcium fluoride (fluorite), barium fluoride, strontium fluoride, lithium fluoride, and sodium fluoride. A single crystal material may be used, or a material having a higher refractive index than quartz or fluorite (for example, 1.6 or more) may be used. Examples of the material having a refractive index of 1.6 or more include sapphire, germanium dioxide and the like disclosed in International Publication No. 2005/059617, or potassium chloride disclosed in International Publication No. 2005/059618. (Refractive index is about 1.75) or the like can be used.

  In the above embodiment, the recovered liquid may be reused. In this case, it is desirable to provide a filter for removing impurities from the recovered liquid in the liquid recovery device or the recovery pipe. .

  In the above embodiment, the case where the exposure apparatus is an immersion type exposure apparatus has been described. However, the present invention is not limited to this, and a dry type exposure that exposes the wafer W without using liquid (water). It can also be employed in devices.

  In the above embodiment, the case where the present invention is applied to a scanning exposure apparatus such as a step-and-scan method has been described. However, the present invention is not limited to this, and the present invention is applied to a stationary exposure apparatus such as a stepper. May be. Even in the case of a stepper, etc., by measuring the position of the stage on which the object to be exposed is mounted with an encoder, the occurrence of position measurement errors due to air fluctuations can be made almost zero. Based on the measured value, the stage can be positioned with high accuracy, and as a result, a highly accurate reticle pattern can be transferred onto the object. The present invention can also be applied to a step-and-stitch reduction projection exposure apparatus, a proximity exposure apparatus, or a mirror projection aligner that synthesizes a shot area and a shot area. Further, for example, JP-A-10-163099 and JP-A-10-214783 (corresponding US Pat. No. 6,590,634), JP 2000-505958 (corresponding US Pat. No. 5,969,441). As disclosed in US Pat. No. 6,208,407 and the like, the present invention can also be applied to a multi-stage type exposure apparatus having a plurality of wafer stages.

  In addition, the projection optical system in the exposure apparatus of the above embodiment may be not only a reduction system but also an equal magnification and an enlargement system, and the projection optical system PL may be not only a refraction system but also a reflection system or a catadioptric system. The projected image may be either an inverted image or an erect image. Further, the exposure area IA irradiated with the illumination light IL through the projection optical system PL is an on-axis area including the optical axis AX within the field of the projection optical system PL. For example, International Publication No. 2004/107011 pamphlet. An optical system having a plurality of reflecting surfaces and forming an intermediate image at least once (a reflecting system or a reflex system) is provided in a part thereof, and has a single optical axis. Similar to the so-called inline catadioptric system, the exposure area may be an off-axis area that does not include the optical axis AX. In addition, the illumination area and the exposure area described above are rectangular in shape, but the shape is not limited to this, and may be, for example, an arc, a trapezoid, or a parallelogram.

The light source of the exposure apparatus of the above embodiment is not limited to the ArF excimer laser, but is a KrF excimer laser (output wavelength 248 nm), F ₂ laser (output wavelength 157 nm), Ar ₂ laser (output wavelength 126 nm), Kr ₂ laser ( It is also possible to use a pulse laser light source with an output wavelength of 146 nm, an ultrahigh pressure mercury lamp that emits a bright line such as g-line (wavelength 436 nm), i-line (wavelength 365 nm), and the like. A harmonic generator of a YAG laser or the like can also be used. In addition, as disclosed in, for example, pamphlet of International Publication No. 1999/46835 (corresponding US Pat. No. 7,023,610), an infrared region oscillated from a DFB semiconductor laser or a fiber laser as a vacuum ultraviolet light, or visible For example, a single wavelength laser beam in the region may be amplified by a fiber amplifier doped with erbium (or both erbium and ytterbium), and a harmonic wave converted into ultraviolet light using a nonlinear optical crystal may be used.

  In the above embodiment, it is needless to say that the illumination light IL of the exposure apparatus is not limited to light having a wavelength of 100 nm or more, and light having a wavelength of less than 100 nm may be used. For example, in recent years, in order to expose a pattern of 70 nm or less, EUV (Extreme Ultraviolet) light in a soft X-ray region (for example, a wavelength region of 5 to 15 nm) is generated using an SOR or a plasma laser as a light source, and its exposure wavelength Development of an EUV exposure apparatus using an all-reflection reduction optical system designed under (for example, 13.5 nm) and a reflective mask is underway. In this apparatus, since a configuration in which scanning exposure is performed by synchronously scanning the mask and the wafer using arc illumination is conceivable, the present invention can also be suitably applied to such an apparatus. In addition, the present invention can be applied to an exposure apparatus using a charged particle beam such as an electron beam or an ion beam.

  In the above-described embodiment, a light transmission mask (reticle) in which a predetermined light-shielding pattern (or phase pattern / dimming pattern) is formed on a light-transmitting substrate is used. Instead of this reticle, For example, as disclosed in US Pat. No. 6,778,257, based on electronic data of a pattern to be exposed, an electronic mask (variable molding mask, active pattern) that forms a transmission pattern, a reflection pattern, or a light emission pattern is disclosed. Also called a mask or an image generator, for example, a DMD (Digital Micro-mirror Device) which is a kind of non-light emitting image display element (spatial light modulator) may be used.

  Further, as disclosed in, for example, International Publication No. 2001/035168, an exposure apparatus (lithography system) that forms line and space patterns on a wafer by forming interference fringes on the wafer. The present invention can be applied.

  Further, as disclosed in, for example, Japanese translations of PCT publication No. 2004-51850 (corresponding US Pat. No. 6,611,316), two reticle patterns are synthesized on a wafer via a projection optical system, and The present invention can also be applied to an exposure apparatus that performs double exposure of one shot area on a wafer almost simultaneously by scanning exposure.

  Note that the object on which the pattern is to be formed in the above embodiment (the object to be exposed to the energy beam) is not limited to the wafer, but other objects such as a glass plate, a ceramic substrate, a film member, or a mask blank. But it ’s okay.

  The use of the exposure apparatus is not limited to the exposure apparatus for semiconductor manufacturing. For example, an exposure apparatus for liquid crystal that transfers a liquid crystal display element pattern onto a square glass plate, an organic EL, a thin film magnetic head, an image sensor ( CCDs, etc.), micromachines, DNA chips and the like can also be widely applied to exposure apparatuses. Further, in order to manufacture reticles or masks used in not only microdevices such as semiconductor elements but also light exposure apparatuses, EUV exposure apparatuses, X-ray exposure apparatuses, electron beam exposure apparatuses, etc., glass substrates or silicon wafers, etc. The present invention can also be applied to an exposure apparatus that transfers a circuit pattern.

  An electronic device such as a semiconductor element includes a step of designing a function / performance of the device, a step of manufacturing a reticle based on the design step, a step of manufacturing a wafer from a silicon material, and the exposure apparatus (pattern forming apparatus) of the above-described embodiment. ) Through a step of transferring a reticle pattern to a wafer, a device assembly step (including a dicing process, a bonding process, and a packaging process), an inspection step, and the like. In this case, in the lithography step, the exposure method described above is executed using the exposure apparatus of the above embodiment, and a device pattern is formed on the wafer. Therefore, a highly integrated device can be manufactured with high productivity.

  As described above, the pattern forming apparatus of the present invention is suitable for forming a pattern on an object such as a wafer. The device manufacturing method of the present invention is suitable for manufacturing an electronic device such as a semiconductor element.

It is a figure which shows schematically the structure of the exposure apparatus which concerns on one Embodiment. It is a top view which shows the stage apparatus of FIG. It is a top view which shows arrangement | positioning of an encoder, an alignment system, etc. with which the exposure apparatus of FIG. 1 is provided. 4A is a plan view showing the wafer stage, and FIG. 4B is a schematic side view showing a part of the wafer stage WST. FIG. 5A is a plan view showing the measurement stage, and FIG. 5B is a schematic sectional side view showing a part of the measurement stage. It is a block diagram which shows the main structures of the control system of the exposure apparatus which concerns on one Embodiment. FIGS. 7A and 7B are diagrams for explaining position measurement in the XY plane of the wafer table and switching (connection) of the heads by a plurality of encoders each including a plurality of heads. FIG. 8A is a diagram illustrating an example of the configuration of an encoder, and FIG. 8B is a diagram illustrating a case where a laser beam LB having a cross-sectional shape that extends long in the periodic direction of the grating RG is used as detection light. . 9A and 9B illustrate the baseline measurement operation of the secondary alignment system performed at the lot head. It is a figure for demonstrating the position measurement of the wafer stage by the encoder and interferometer at the time of exposure. It is a figure for demonstrating the position measurement of the wafer stage by the interferometer at the time of unloading of a wafer. It is a figure for demonstrating the position measurement of the wafer stage by the interferometer at the time of wafer loading. It is a figure which shows arrangement | positioning of a wafer stage and an encoder head at the time of switching from the stage servo control by an interferometer to the stage servo control by an encoder. It is a figure for demonstrating the position measurement of the wafer stage by the encoder and interferometer at the time of wafer alignment.

Explanation of symbols

8 ... local liquid immersion apparatus, 39X _1, 39X ₂ ... X scales, 39Y _1, 39Y ₂ ... Y scales, 62a to 62f ... head unit, 64 ... Y head, 65 ... Y head, 66 ... X head, 67 ... Y Head, 68 ... Y head, 70A ... Y encoder, 70C ... Y encoder, 100 ... Exposure device, 150 ... Encoder system, PL ... Projection optical system, AL1 ... Primary alignment system, AL2 _{1 to} AL2 ₄ ... Secondary alignment system, W ... wafer, WST ... wafer stage.

Claims (21)

An exposure method for exposing an object with an energy beam to form a pattern on the object,
The first direction that is disposed on one surface of a moving body that moves while holding an object in a predetermined plane, and that faces a pair of first gratings each having a grating having a first direction parallel to the plane as a periodic direction Based on the measurement values of a plurality of first encoder heads whose positions are different with respect to a second direction orthogonal to the first direction, the position of the movable body in the first direction and the rotational direction in the plane is managed while the movable body is move Previous Stories second direction parallel to the plane, the position of the detection area with respect to the second direction using a plurality of different marks detection system, by detecting at least one mark is present on the movable body An exposure method including a characteristic measurement step of measuring characteristics of the plurality of mark detection systems.   In the characteristic measurement step, based on a measurement value of a second encoder head disposed on the one surface of the moving body and facing a second grating having a grating whose periodic direction is the second direction, the moving body The exposure method according to claim 1, wherein the position in the second direction is managed. Forming a pattern on the object using the exposure method according to claim 1;
And developing the object on which the pattern is formed. An exposure apparatus that exposes an object with an energy beam to form a pattern on the object,
A pair of first gratings that move while holding an object in a predetermined plane and have a grating whose periodic direction is a first direction parallel to the plane on one surface of the object are placed in the first direction. A moving body arranged in a second direction orthogonal to
A plurality of first heads having different positions with respect to the second direction, and based on the measurement values of the two first heads respectively facing the pair of first gratings, An encoder system for measuring a position in a rotational direction in a plane;
A plurality of mark detection systems in which positions of detection areas are different with respect to the second direction;
Based on the measurement result of the encoder system, the movable body is parallel to the plane and orthogonal to the first direction while managing the position of the movable body in the first direction and the rotational direction in the plane. And a control device that measures the characteristics of the plurality of mark detection systems by detecting at least one mark existing on the moving body using each of the plurality of mark detection systems. apparatus. At least one second grating having a grating whose periodic direction is the second direction is provided on the one surface of the moving body,
The encoder system further includes at least one second head, and further measures a position of the movable body in the second direction based on a measurement value of the second head facing the second grating. 4. The exposure apparatus according to 4.   The exposure apparatus according to claim 5, wherein the control device further manages the position of the movable body in the second direction based on a measurement result of the encoder system when the characteristic is measured.   The exposure apparatus according to claim 5 or 6, wherein the plurality of first heads are separated into first and second head groups, each of which is disposed on both outer sides of the plurality of detection regions.   8. The exposure apparatus according to claim 7, wherein each of the first and second head groups includes at least one first head having a position different from that of another first head in the first direction.   9. The position of a first head located on the innermost side among the plurality of first heads included in each of the first and second head groups is different from other first heads in the first direction. The exposure apparatus described in 1.   10. The plurality of first heads included in each of the first and second head groups are arranged at an interval narrower than a width of the first grating in the second direction. The exposure apparatus described in 1.   The plurality of mark detection systems include a first mark detection system in which the position of the detection area is fixed, and a second mark detection system in which the position of the detection area can be adjusted at least with respect to the second direction. The exposure apparatus according to any one of 10.   12. The exposure apparatus according to claim 11, wherein the plurality of mark detection systems include at least one pair of the second mark detection systems whose detection centers can be set symmetrically with respect to the detection center of the first mark detection system.   The exposure apparatus according to any one of claims 5 to 12, further comprising an optical member arranged on one side of the plurality of detection regions in the first direction.   The exposure apparatus according to claim 13, wherein the encoder system includes a plurality of the second heads, and the positions of the plurality of second heads are different with respect to the first direction.   The exposure apparatus according to claim 14, wherein the plurality of second heads are arranged along a reference line that is a straight line in a first direction passing through the vicinity of the center of the optical member. The plurality of second heads are disposed on the reference line on one side of the optical member in the first direction and on the other side of the plurality of detection regions in the first direction, and each of the plurality of second heads is disposed on the reference line. Separated into third and fourth head groups,
The exposure apparatus according to claim 15, wherein a pair of the second gratings are disposed on the one surface of the movable body so as to be separated from each other in the first direction with the placement area of the object interposed therebetween.   The exposure apparatus according to claim 16, wherein the plurality of second heads belonging to each of the third and fourth head groups are arranged at an interval narrower than a width of the second grating in the first direction.   The encoder system includes fifth and sixth head groups each including a plurality of first heads arranged on one side and the other side of the second direction across the optical member and having different positions with respect to the second direction. And in the first direction and the plane of the movable body based on the measurement values of the respective one heads belonging to the fifth and sixth head groups respectively facing the pair of first gratings The exposure apparatus according to any one of claims 13 to 17, which measures a position in a rotation direction.   Among the plurality of first heads included in each of the fifth and sixth head groups, the first head located closest to the center of the optical member is the other first head in the first direction. The exposure apparatus according to claim 18, wherein the position is different from that of the exposure apparatus.   20. The exposure apparatus according to claim 18, wherein the plurality of first heads of each of the fifth and sixth head groups are arranged at an interval narrower than a width of the first grating in the second direction.   21. The exposure apparatus according to any one of claims 13 to 20, further comprising an immersion system that fills a space between the optical system and the object with a liquid to form an immersion area.

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