JP2006135346A - Exposure method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide immersion type exposure method and apparatus capable of forming a required pattern by preventing image formation performance from being deteriorated due to the influence of polarization and securing prescribed contract. <P>SOLUTION: In the exposure method for immersing the surface of an object to be exposed and the final surface of a projection optical system in liquid and projecting a pattern formed on a mask to the object by the projection optical system; when an incident angle of light on the object, where the incident light is emitted from a part of an axis parallel to the repeating direction of the pattern and orthogonal to the optical axis of the projection optical system in an effective light source formed on a pupil of the projection optical system and made obliquely incident on a resist, is defined as θ and the maximum value of the incident angle θ is defined as θ<SB>NA</SB>, light corresponding to a range of the incident angle θ satisfying 90°-θ<SB>NA</SB>≤θ≤θ<SB>NA</SB>includes only an S polarized component. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is generally used for manufacturing fine patterns used in various devices such as semiconductor chips such as IC and LSI, display elements such as liquid crystal panels, detection elements such as magnetic heads, imaging elements such as CCDs, and micromechanics. More particularly, the present invention relates to a so-called immersion type exposure method and apparatus in which the final surface of a projection optical system and the surface of an object to be exposed are immersed in a liquid and the object to be exposed is exposed through the liquid.

  When a fine semiconductor element such as a semiconductor memory or a logic circuit or a liquid crystal display element is manufactured using a photolithography technique, drawing is performed on a reticle or a mask (in this application, these terms are used interchangeably). 2. Description of the Related Art Conventionally, a reduction projection exposure apparatus that projects a circuit pattern on a wafer or the like by a projection optical system to transfer the circuit pattern has been used.

  The minimum dimension (resolution) that can be transferred by the reduction projection exposure apparatus is proportional to the wavelength of light used for exposure and inversely proportional to the numerical aperture (NA) of the projection optical system. Therefore, the shorter the wavelength and the higher the NA, the better the resolution. In recent years, with a demand for miniaturization of semiconductor elements, a smaller resolution is required. Accordingly, the resolution is expected to be improved by shortening the wavelength of the exposure light and increasing the NA of the projection optical system. Currently, the NA of projection optical systems advances at an accelerating rate, and the development of optical systems exceeding NA = 0.9 is in the field of view.

  On the other hand, the light source of the exposure apparatus has changed from a KrF laser (wavelength 248 nm) to an ArF laser (wavelength 193 nm) as the wavelength becomes shorter. Currently, development is underway to realize an F2 laser (wavelength 157 nm) or EUV (13.5 nm) as the next light source.

Under such circumstances, immersion exposure has attracted attention as a method for further increasing the resolution while using a light source of ArF laser (wavelength 193 nm) or F2 laser (wavelength 157 nm) (for example, see Patent Document 1). In immersion exposure, the NA on the wafer side of the projection optical system is made liquid to further increase the NA. In other words, the NA of the projection optical system is NA = n · sin θ where n is the refractive index of the medium. Therefore, NA is increased to n by satisfying a medium having a refractive index higher than the refractive index of air (n> 1). can do.
JP-A-10-303114 U.S. Pat. No. 4,346,164

  However, as the NA increases, the influence of light polarization on the imaging performance cannot be ignored. This is because the larger the incident angle of light on the wafer, the more difference in imaging performance depending on the polarization direction of light.

  The influence on the imaging performance due to the polarization of light is much greater for two-beam interference than for three-beam interference. This is because the three-beam interference that forms an image by interfering with a total of three lights of the 0th-order diffracted light and the ± 1st-order diffracted light is the 0th-order light and the 1st-order diffracted light that form the fundamental frequency of the image formation, The effect of polarized light does not appear greatly because the angle of the second-order diffracted light does not reach 90 °. On the other hand, in the image formation by two-beam interference, two first-order diffracted lights such as a phase shift mask interfere with each other or oblique incidence There is a case where either one of the 0th order diffracted light and ± 1st order diffracted light such as illumination interferes with each other. However, since the angle of the two light beams forming the fundamental frequency is increased, the influence of polarization on the imaging performance is large. Because it appears.

  Furthermore, when the medium becomes liquid, there arises a big problem that there is a condition that no image is formed depending on the polarization direction of light. This is a phenomenon that did not occur in the conventional non-immersion optical system. This is because, as shown in FIG. 16A, when considering two-beam imaging that intersects in the plane of the paper, P-polarized light whose polarization direction is in the plane of the plane does not interfere if the angle formed by the two beams is 90 °. The problem is that it does not contribute to image formation. When the angle formed by the two light beams is 90 °, the incident angle is 45 °, so that the sine is sin 45 ° = 0.7.

  On the other hand, as shown in FIG. 16B, the two S-polarized light beams whose polarization directions are perpendicular to the paper surface form images with good contrast because the polarization directions coincide. Hereinafter, in the present application, a polarization direction for performing imaging with good contrast is defined as an S polarization component. As described herein, S-polarized light has a polarization direction orthogonal to the paper surface with respect to the light beams that intersect in the paper surface. The polarization direction is closely related to the direction in which the pattern is formed. Considering the direction of the interference fringes formed by two light beams, the longitudinal direction of each interference fringe and the direction of the S-polarization coincide. ing. Therefore, the direction of S-polarized light when producing an interference pattern having a fine structure extending in the X direction is the X direction, and the direction of S-polarized light when producing an interference pattern having a fine structure extending in the Y direction is the Y direction.

Here, the refractive index of the medium between the projection optical system and the wafer is n _o , the angle in the medium is θ _o , the refractive index of the resist formed on the wafer is n _r, and the incident angle of the resist is ± θ _Consider two-beam interference in which two beams of _r interfere to form an image. From Snell's law, the following formula 1 is established.

When the medium is air, since n _o = 1 and sin θ _o <1, the following formula 2 is established.

In the case of an ArF excimer laser, a typical resist refractive index is n _r = 1.7, so that sin θ _r <0.59 from Equation 2. Thus, when the medium is air, the angle θr in the resist does not become sin θ _r = 0.7.

On the other hand, consider immersion where the medium is a liquid. Assuming that the refractive index of the medium is n _o = 1.47, the following Expression 3 is established.

Since the resist refractive index is usually n _r = 1.7, sin θ _r <0.86. Therefore, when the medium is a liquid, there is a condition that sin θ _r = 0.7.

As described above, when the medium is air, sin θr = 0.7 has not been obtained. However, when the medium is liquid, there is a condition that sin θ _r = 0.7, and the P-polarized light does not interfere with the P-polarized light. The contrast due to the luminous flux is zero. When the illumination light is in a non-polarized state that does not consider polarization, only S-polarized light, which accounts for half of the incident light, is involved in the image formation, so the contrast is halved and the contrast is not a problem in non-immersion systems. The decrease becomes noticeable.

For example, in the case of an ArF excimer laser, if the medium is water and n ₀ = 1.47, the following formula 4 is established.

As a result, when the medium is water, P-polarized light does not interfere at sin θ _o = 0.81. Accordingly, the P-polarized light does not form an image near the incident angle sin θ _o = 0.8 to the medium. This problem is unavoidable because an optical system having an angle of sin θ _o = 0.8 or more is also desired when immersion exposure is required. In the case of the F2 excimer laser, since the refractive index of the resist is 1.5 and the refractive index of the medium is around 1.36, the same relationship is established around sin θ _o = 0.8.

In order to increase the NA, it is known that the refractive index of the resist and the liquid should be increased and the refractive index difference should be reduced. The refractive index of the resist and the liquid differs depending on the substances, and the difference in refractive index between the resist and the liquid is preferably small (Patent Document 2), but sin θ _{r in} the medium is slightly larger than sin θ _o in the resist. In consideration of the direction of developing a resist dedicated to immersion, the inventors have found that it is preferable to set sin θ _r in the medium almost equivalent to sin θ _o in the resist on the exposure apparatus side. Therefore, the condition that P-polarized light does not interfere can be considered as sin θ _o ≈sin θ _r = 0.7.

  As described above, in order to form a fine pattern, it is necessary to increase the NA of the projection optical system. However, in an immersion type projection optical system, the imaging performance is reduced due to the influence of polarization due to the increase in NA, and the desired optical performance can be reduced. A pattern cannot be formed.

  Therefore, the present invention illustratively provides an immersion type exposure method and apparatus capable of preventing a deterioration in imaging performance due to the influence of polarized light, ensuring a predetermined contrast, and forming a desired pattern. With a purpose.

In order to achieve the above object, an exposure method according to one aspect of the present invention includes immersing a surface of an object to be exposed and a final surface of a projection optical system in a liquid, and applying a (fine) pattern formed on a mask to the projection optical system. In an exposure method of projecting onto an object to be exposed by a system, the effective light source formed on the pupil of the projection optical system is parallel to the repetition direction of the (fine) pattern and orthogonal to the optical axis of the projection optical system 90 ° −θ _NA ≦ θ ≦ θ, where θ is the incident angle of the light emitted from the part on the axis to be obliquely incident on the resist to the exposed body and θ _NA is the maximum value of the incident angle θ. _The light corresponding to the range of the incident angle θ satisfying _NA has only an S-polarized component.

  Further objects and other features of the present invention will be made clear by the preferred embodiments described below with reference to the accompanying drawings.

  ADVANTAGE OF THE INVENTION According to this invention, the exposure method and apparatus which can be exposed with sufficient image formation performance than before can be provided.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

  Hereinafter, an exposure apparatus 100 according to an embodiment of the present invention will be described with reference to FIG. Here, FIG. 1 is a schematic block diagram of the exposure apparatus 100. As shown in FIG. 1, the exposure apparatus 100 includes an illumination device 110, a mask or reticle 130, a reticle stage 132, a projection optical system 140, a main control unit 150, a monitor and input device 152, and a wafer 170. Wafer stage 176 and liquid 180 as a medium. As described above, the exposure apparatus 100 partially or entirely immerses the final surface on the wafer 170 side of the projection optical system 140 in the liquid 180, and applies the pattern formed on the mask MS through the liquid 180 to the wafer W. It is an immersion type exposure apparatus that exposes the light. Although the exposure apparatus 100 of the present embodiment is a step-and-scan projection exposure apparatus, the present invention can apply a step-and-repeat system and other exposure systems.

  The illumination device 100 illuminates a mask 130 on which a transfer circuit pattern is formed, and includes a light source unit and an illumination optical system.

  The light source unit includes a laser 112 as a light source and a beam shaping system 114. The laser 112 can use light from a pulse laser such as an ArF excimer laser having a wavelength of about 193 nm, a KrF excimer laser having a wavelength of about 248 nm, or an F2 excimer laser having a wavelength of about 157 nm. The type and number of lasers are not limited, and the type of light source unit is not limited.

  For example, a beam expander including a plurality of cylindrical lenses can be used as the beam shaping system 114, and the aspect ratio of the dimension of the cross-sectional shape of the parallel light from the laser 112 is converted into a desired value (for example, the cross-section The beam shape is formed into a desired one by changing the shape from a rectangle to a square. The beam shaping system 114 forms a light beam having a size and a divergence angle necessary for illuminating an optical integrator 118 described later.

  The illumination optical system is an optical system that illuminates the mask 130. In this embodiment, the condensing optical system 116, the polarization control means 117, the optical integrator 118, the aperture stop 120, the condensing lens 122, and the bending lens. A mirror 124, a masking blade 126, and an imaging lens 128 are included. The illumination optical system can also realize various illumination modes such as conventional illumination, annular illumination, and quadrupole illumination.

  The condensing optical system 116 is composed of a plurality of optical elements, and efficiently introduces the optical integrator 118 in a desired shape. For example, the collection optics 116 includes a zoom lens system and controls the distribution of the shape and angle of the incident beam to the optical integrator 118.

  The condensing optical system 116 includes an exposure amount adjustment unit that can change the exposure amount of the illumination light to the mask 130 for each illumination. The exposure adjustment unit is controlled by the main control unit 150. It is also possible to place an exposure monitor, for example, between the optical integrator 118 and the reticle 130 or at another location and measure the exposure and feed back the result.

  The polarization control unit 117 includes, for example, a polarization element and is disposed at a position substantially conjugate with the pupil 142 of the projection optical system 140. The polarization control means 117 controls the polarization state of a predetermined area of the effective light source formed on the pupil 142, as will be described later. A polarization control means 117 composed of a plurality of types of polarization elements may be provided on a turret that can be rotated by an actuator (not shown), and the main control unit 150 may control driving of the actuator.

  The optical integrator 118 makes the illumination light illuminated on the mask 130 uniform. In the present embodiment, the optical integrator 118 is configured as a fly-eye lens that converts the angle distribution of incident light into a position distribution and emits it. The fly-eye lens is configured by combining a large number of rod lenses (that is, microlens elements) with its entrance and exit surfaces maintained in a Fourier transform relationship. However, the optical integrator 118 in which the present invention can be used is not limited to the fly-eye lens, but includes an optical rod, a diffraction grating, and a plurality of sets of cylindrical lens array plates arranged so that each set is orthogonal.

Immediately after the exit surface of the optical integrator 118, an aperture stop 120 having a fixed shape and diameter is provided. As will be described later, the aperture stop 120 is disposed at a position almost conjugate with the effective light source formed on the pupil 142 of the projection optical system 140, and the aperture shape of the aperture stop 120 is effective on the pupil plane 142 of the projection optical system 140. Corresponds to the light source shape. The aperture stop 120 controls the shape of the effective light source, as will be described later.
The aperture stop 120 can be switched by an aperture replacement mechanism (actuator) 121 so that various aperture stops (to be described later) are positioned in the optical path according to the illumination conditions. Driving of the actuator 121 is controlled by a drive control unit 151 controlled by the main control unit 150. The aperture stop 120 may be configured integrally with the polarization control unit.

  The condensing lens 122 is emitted from a secondary light source in the vicinity of the exit surface of the optical integrator 118, condenses a plurality of light beams that have passed through the aperture stop 120, and is reflected by a mirror 124 to form a masking blade 126 surface as an illuminated slope. Illuminate uniformly with Koehler illumination.

  The masking blade 126 is composed of a plurality of movable light shielding plates, and has an approximately rectangular arbitrary opening shape corresponding to the effective area of the projection optical system 140. The light beam transmitted through the opening of the masking blade 126 is used as illumination light for the mask 130. The masking blade 126 is an aperture whose opening width is automatically variable, and can change the transfer area. In addition, the exposure apparatus 100 may further include a scan blade having a structure similar to the above-described masking blade, which makes it possible to change the transfer region in the scan direction. The scanning blade is also a stop whose opening width can be automatically changed, and is provided at a position optically conjugate with the mask 12 surface. By using these two variable blades, the exposure apparatus 100 can set the size of the transfer region in accordance with the size of the shot to be exposed.

  The imaging lens 128 irradiates and transfers the opening shape of the masking blade 126 onto the surface of the reticle 130, and reduces and projects the pattern on the surface of the reticle 130 onto the surface of the wafer 170 placed on a wafer chuck (not shown).

  The mask 130 is formed with a pattern to be transferred thereon, and is supported and driven by the mask stage 132. Diffracted light emitted from the mask 130 passes through the projection optical system 140 and is projected onto the wafer 170. The wafer 170 is an object to be exposed, and a resist 172 is applied on the substrate 174. The mask 130 and the wafer 170 are arranged in an optically conjugate relationship. Since the exposure apparatus 100 is a step-and-scan exposure apparatus (ie, a scanner), the pattern of the mask 130 is transferred onto the wafer 170 by scanning the mask 130 and the wafer 170. In the case of a step-and-repeat type exposure apparatus (ie, “stepper”), exposure is performed with the mask 130 and the wafer 170 being stationary.

  FIG. 2 shows an example of a mask pattern. Here, FIG. 2A is a plan view showing a mask pattern having a repeating direction in the X-axis direction and a longitudinal direction in the Y-direction, and FIG. 2B shows a repeating direction in the Y-axis direction. FIG. 2C is a plan view of a mask pattern in which these are mixed, and FIG. 2C is a plan view showing a mask pattern having a longitudinal direction in the X direction.

  Note that the mask 130 is not limited to a binary mask, and may be a phase shift mask. The pattern formed on the mask 130 may be a line pattern such as a gate pattern, a contact hole, or other patterns.

  The mask stage 132 supports the mask 130 and is connected to a moving mechanism (not shown). The mask stage 132 and the projection optical system 140 are provided, for example, on a stage barrel surface plate that is supported by a base frame placed on a floor or the like via a damper or the like. Any configuration known in the art can be applied to the mask stage 132. A moving mechanism (not shown) includes a linear motor or the like, and the mask 130 can be moved by driving the mask stage 132 in the XY directions. The exposure apparatus 100 scans the mask 200 and the wafer 170 in a synchronized state by the main control unit 150.

  The projection optical system 140 has a function of forming an image on the wafer 170 of diffracted light that has passed through the pattern formed on the mask 130. The projection optical system 300 includes an optical system including only a plurality of lens elements, an optical system (catadioptric optical system) having a plurality of lens elements and at least one concave mirror, a plurality of lens elements, and at least one kinoform. An optical system having a diffractive optical element such as can be used. When correction of chromatic aberration is required, a plurality of lens elements made of glass materials having different dispersion values (Abbe values) can be used, or the diffractive optical element can be configured to generate dispersion in the opposite direction to the lens element. To do. Otherwise, chromatic aberration compensation is achieved by narrowing the spectrum of the laser. Recently, such narrowband lasers are one of the main streams.

The main control unit 150 performs drive control of each unit, and in particular, controls lighting based on information input from the input device of the monitor and input device 152, information from the lighting device 100, and a program stored in a memory (not shown). I do. More specifically, the main control unit 150 controls the shape and polarization state of the effective light source formed on the pupil 142 of the projection optical system 140, as will be described later. Control information and other information by the main control unit 150 are displayed on the monitor of the monitor and input device 152. In another embodiment, the wafer 170 is replaced with a liquid crystal substrate or other object to be exposed. In the wafer 170, a photoresist 172 is applied on the substrate 174.

  Wafer 170 is supported by wafer stage 176. Since any configuration known in the art can be applied to the stage 176, a detailed description of the structure and operation is omitted here. For example, the stage 176 moves the wafer 170 in the XY directions using a linear motor. For example, the mask 130 and the wafer 170 are scanned synchronously, and the positions of the mask stage 132 and the wafer stage 176 are monitored by a laser interferometer, for example, and both are driven at a constant speed ratio. The stage 176 is provided on a stage surface plate supported on a floor or the like via a damper, for example, and the mask stage 132 and the projection optical system 140 are mounted on the floor surface or the like, for example. It is provided on a lens barrel surface plate (not shown) supported on the base frame via a damper or the like.

  The liquid 180 is immersed in the final surface of the projection optical system 140 on the wafer 170, and a substance that has good transmittance at the exposure wavelength, does not attach dirt to the projection optical system, and has good matching with the resist process is selected. . The final surface of the projection optical system 140 is coated to protect the influence from the liquid 180.

  Hereinafter, the polarization control performed by the main control unit 150 will be described. First, the effect of polarization will be described with reference to FIG. Here, FIGS. 3A and 3B are schematic diagrams for defining S-polarized light and P-polarized light, respectively. As shown in FIG. 3A, light polarized in a direction perpendicular to the cross section of the projection optical system 140 (ie, perpendicular to the paper surface) is S-polarized, that is, as shown in FIG. Light that is polarized perpendicular to the plane containing the imaging light beam is S-polarized light. Light that is polarized in a direction parallel to the cross section of the projection optical system 140 (that is, in the plane of the paper) and is polarized parallel to a plane including two imaging light beams as shown in FIG. To do. In other words, the light traveling direction is taken as the Z-axis, the direction orthogonal to the Z-axis and parallel to the surface (paper surface) containing the two imaging light beams is the X-axis, and the surface (paper surface) containing the two imaging light beams. If the orthogonal direction is taken as the Y axis, the S-polarized light is polarized in the Y-axis direction, and the P-polarized light is polarized in the X-axis direction. Further, the longitudinal direction of the fine structure of the fine pattern by the light beam drawn in the paper is perpendicular to the paper and coincides with the S-polarized light.

  In order to achieve the high-resolution imaging performance expected with high NA, it is only necessary to cut the light in the P-polarized polarization state that lowers the contrast of the imaging and to image only the S-polarized light. That is, as shown in FIG. 2A, an image may be formed using S-polarized light having a polarization direction in the Y-axis direction indicated by an arrow with respect to a line pattern having a mask pattern long in the Y-axis direction.

  In the present embodiment, when ½ of the angle formed by the two light beams of the diffracted light that is the imaging light beam of the pattern in the liquid 180 is φ (deg), the two light beams forming an angle of sin φ = 0.7 are formed. It is an object of the present invention to construct an effective light source region that can be used only with S-polarized light as much as possible.

In one embodiment, such a region has an emission angle of light in the liquid 180 in the case of two-beam interference due to + 1st order light and −1st order light, such as 0th order light and 1st order light, or a Levenson type phase shift mask. When θ and the maximum emission angle are θ _NA , 90 ° −θ _NA ≦ θ ≦ θ _NA is actually an area on the effective light source formed in the pupil 142 corresponding to a range satisfying 90 ° −θ _NA ≦ θ ≦ θ _NA . However, if the refractive index of the liquid and the resist is close, it can be considered that θ ₀ = θ _r , so θNA can be considered as the maximum angle common to the liquid and the resist. it can. In yet another embodiment, such a region is a region on the effective light source formed in the pupil 142 where the orthogonal state may occur between the two exposure light beams to be imaged.

The S-polarized light and the direction of the pattern have been described above. If this is converted into the expression of the effective light source in the pupil coordinates, the following is obtained. That is, S-polarized light refers to a polarization direction directed in a tangential direction, which is a direction orthogonal to a radiation line drawn from the center of the pupil 142 in the effective light source of illumination light when considered by the pupil 142 of the projection optical system 140. . However, in practice, the S-polarized light is determined by the direction of the pattern to be imaged. Since there are many actual LSI patterns in the X and Y directions, S-polarized light basically has the X or Y polarization direction, and the effective light source region with the X polarization direction is the projection optics. This includes the case where the effective light source region having the center on the X axis of the pupil of the projection optical system is present in the region having the center on the Y axis of the pupil 142 of the system 140. . Further, in the case of including the 45 ° direction, an example having four directions of X, Y, and ± 45 ° is also included.

To further examine the above-mentioned conditions, for example, in FIG. 16B, this is the case in the projection optical system 140 with θ _NA ≧ 45 ° that satisfies sin θ _NA ≧ 0.7, where θ _NA is the maximum incident angle. In the illumination light emitted to the liquid 180 at an angle θ, the component represented by the following formula is changed to S-polarized light.

Here, referring to FIG. 16 (b), θ in Equations 5 and 6 is an incident angle formed by the exposure light and a straight line perpendicular to the surface of the substrate inside the resist. Θ _NA is the maximum incident angle of the exposure light as the maximum value of the incident angle θ.

  When the effective light source in which the light source distribution of the illumination optical system is projected onto the pupil 142 without considering the refractive index is assumed to be 1, and the effective light source has a maximum radius of σ, Equation 6 is expressed by Equation 7 below. This corresponds to making the effective light source in the range of S-polarized light.

Here, σ _MAX is a parameter corresponding to the outermost side of the set effective light source distribution, and σ _MAX sin θ _NA indicates the maximum angle of illumination light in the liquid 180.

  Since an actual LSI pattern often has a specific directionality in the X and Y directions, it is necessary to consider the shape of the effective light source. When the effective light source in the case of directivity is shown in a two-dimensional distribution, it is as shown in FIGS. Here, FIG. 4A shows an effective light source distribution that defines polarized light for exposing the mask pattern shown in FIG. FIG. 4B is an effective light source distribution that defines the polarization for exposing the mask pattern shown in FIG. FIG. 5 shows an effective light source distribution that defines the polarization for exposing the mask pattern shown in FIG.

  Next, the relationship between the effective light source region and the polarization direction will be described with reference to FIGS. Consider imaging of a mask pattern parallel to the Y direction as shown in FIG. As shown in FIG. 6, the normal effective light source has a light source within the radius σ on the effective light source coordinate normalized to the maximum radius 1, and does not consider polarization, so that the polarized light in the X direction and the polarized light in the Y direction. Are mixed and distributed.

The S-polarized light is the polarization direction in the Y direction indicated by an arrow in the image formation of the mask pattern shown in FIG. FIG. 7 shows the pupil plane of the optical system, and the set effective light source region (≦ σ _MAX ) is shown in white. The light emitted from the projection optical system 140 to the liquid 180 at an angle θ ₁ is incident on the effective light source on the sin pupil at the position of sin θ ₁ / sin θ _NA on the normalized effective light source coordinates. 0.5 The following sufficiently fine pattern in Figure 2 the mask pattern shown in (a) is k ₁ factor Rayleigh equation which is an index of resolving power (= R / (λ / NA )), the dotted line in FIG. Two connected black circles indicate a zero-order and first-order, or a minus first-order and zero-order two-beam interference pair. The distance between two black circles is indicated by 1 / (2k ₁ ) in the above normalized coordinate system. The extending direction of the line segment is a direction orthogonal to the extending direction of each fine pattern.

In the liquid immersion, as described above, there are cases where these two light beam pairs form an angle in the vicinity of sin φ = 0.7 and have no contrast at all with P-polarized light. Accordingly, if the polarization direction is controlled only in the Y direction, which is S-polarized light, in the region where such a pair exists, the contrast of the image can be improved. Thus, the region where the polarization direction is to be controlled according to the pattern is shown as a hatched region. The hatched area is a condition that one of the two black circles indicating the 0th-order light is in the white portion indicating the effective light source and the other black circle indicating the ± first-order light is in the pupil. . The hatched area is found by searching for a condition in which both ends of a line segment having a distance 1 / (2k ₁ ) between black circles are in the pupil. In this case, the two hatched areas are shaped like an asymmetric canoe where two circles intersect each other. At this time, when the boundary on the X-axis is obtained, the feature of this embodiment is that the angle θ in the liquid 180 satisfies the following condition.

Here, σ _MAX is a parameter corresponding to the outermost side of the set effective light source distribution, and σ _MAX sin θ _NA corresponds to the maximum angle of illumination light in the liquid.

In FIG. 7, the line outside the region is a circle centered on X = 0 with the set maximum effective light source σMAX as the radius, while the inside is a radius 1 indicating the size of the pupil, and X = − ( It is a circle centered on σ _IN +1). From Equation 7, σ _IN is expressed by the following equation.

That is, the region to be S-polarized light is a region where a circle centered on X = 0 and having a radius of the maximum effective light source σ _MAX and a circle having a radius of 1 centered on X = ± (σ _IN +1). However, FIG. 8 shows only one side of a circle whose center is X = − (σ _IN +1) and radius 1.

Equation 8 defines the angle range only on the X-axis or Y-axis of the pupil, but there are not only light parallel to the optical axis direction of the projection optical system but also light incident obliquely. Given the angle range of the light beam incident obliquely, the minimum value alpha of α ≦ θ ≦ θ _NA next angle is a function of Y.

The coordinate for obtaining the minimum value α of the angle is radius 1, the center is on a circle centered on X = X ₁ or X = X ₂ and Y = 0, and X ₁ = + (σ _IN +1), X ₂ = − Since (σ _IN +1), considering only the circle centered on X = X ₁ , (X−X ₁ ) ² + Y ² = 1, X = X ₁ ± √ (1-Y) ² , X ≦ 1, since X = X ₁ −√ (1−Y) ² and α = tan ⁻¹ (Y / X) (0 ≦ α ≦ 45 °), α = tan ⁻¹ (Y / X) = tan ⁻¹ (Y / (X ₁ −√ (1−Y) ² )) Therefore, the angle range with respect to the XZ plane parallel to the X axis other than on the X axis is as follows. α ≦ θ ≦ θ _NA , (0 ≦ α ≦ 45 °), α = tan ⁻¹ (Y / X) = tan ⁻¹ (Y / (X ₁ −√ (1−Y) ² ), X ₁ = + (Σ _IN +1) and σ _IN are obtained from Equation 9.

σ _IN = sin (90 ° −θ _NA ) / sin θ _NA , and within this angle range, only S-polarized light, that is, linearly polarized light in the Y direction perpendicular to the X axis should be used.

On the other hand, illumination light with a small incident angle that emits light rays into the immersion medium at an angle of θ ₁ that satisfies sin θ ₁ ≦ sin (90 ° −θ _NA ) does not contribute to the formation of a fine pattern, and has a diffraction angle. Is small. In this case, the polarization effect is small, and the polarization control need not be particularly taken into consideration. That is, this region can be assigned either unpolarized or polarized light to this region, showing little difference between them.

  Therefore, it is a feature of this embodiment that the polarization is considered only for the light incident on the shaded portion in the effective light source existing region. As shown in FIG. 4A, these hatched areas are symmetrical with respect to the Y axis, and the polarization direction is the S direction, that is, the cut line direction in the circle representing the pupil 142 of the projection optical system 140. It has become.

  In addition, for a mask pattern parallel to the X direction as shown in FIG. 2B, as shown in FIG. 4B, the shape shown in FIG. Is symmetrical with respect to the X axis, and the polarization direction is the X direction which is S polarization. The boundary on the Y axis is the same as Equation 8 as the boundary condition obtained previously with respect to the X axis.

Further, as shown in FIG. 2C, when a mask pattern having the same fineness and parallel to the X direction and a mask pattern parallel to the Y direction are mixed, as shown in FIG. In addition, the hatched area is symmetric with respect to the X axis and the Y axis, and the polarization direction is the tangential X and Y directions for S polarization. Further, the boundary points on the X axis and the Y axis satisfy Expression 8. theta _NA is increased, as shown in FIG. 5 (b), to S-polarized light region and S portion polarizing region are overlapped in the Y direction in the X direction okay to unpolarized area of the light source and the intensity zero Distribution may be eliminated. Further, as shown in FIG. 5C, the polarization state may be divided with the center as a boundary. In addition, as shown in FIG. 5D, the effect is the same even if the effective light source has a polarization direction distribution.

  As shown in FIG. 2A, when the size of the mask pattern is limited to a fine one and the direction of the mask pattern is one direction, the optimum effective light source is shown in FIG. A dipole illumination as shown is appropriate. The effective light source in FIG. 8 (a) satisfies Expression 8 on the X axis, and when the 0th order light enters the oblique light source region, the other + 1st order light or −1st order light is all transmitted through the pupil. Since the light source incident area in the pupil is large and the two light beams are incident without incident, they are involved in image formation without waste. In addition, since it is sufficient that the double pole satisfies Expression 8 on the X axis, the circle shown in FIG. 8B is cut out with a straight line, and the annular zone shown in FIG. Various shapes such as a partially cut shape and a circular shape shown in FIG. 8C can be applied. In FIG. 8, the shaded portion is a light-transmitting portion whose polarization is controlled, and the gray portion is a light-shielding portion.

  The example shown in FIG. 5 is shown as an effective light source that is optimal for a plurality of patterns in which the direction of the mask pattern shown in FIG. The object can be achieved even with annular illumination as shown. Here, in FIGS. 9A and 9B, the shaded portion is polarization-controlled, and the gray portion is a light shielding portion. The white part in FIG. 9A is a translucent part. At this time, the outer and inner diameters of the annular illumination are set within a range satisfying Expression 8 on the X-axis and the Y-axis, and the polarization direction is set to the tangential direction as shown in the figure. The polarization boundary located at the ± 45 ° portion may be non-polarized, or the polarization directions in the X and Y directions may be interchanged here.

  In addition, regarding a pattern in which an oblique direction inclined by 45 ° with respect to the XY axis is also mixed, an area satisfying Equation 8 may be S-polarized light according to the pattern direction as shown in FIG. In this case, the 45 ° direction is rotationally symmetric and Equation 8 is applied in the same manner.

  In an actual optical system, it is difficult to insert a polarizing element into the projection optical system 140 due to a problem of thermal aberration. Therefore, in the present embodiment, the polarization of a predetermined region of the effective light source is controlled before the reticle 130. For example, the polarization is controlled by using the polarization control means 117 provided in the front stage of the optical integrator 118. The optical integrator 118 includes a portion conjugate to the pupil 142 of the projection optical system 140, and it is preferable to control the polarization at the position of the optical integrator 118 in order to simplify the configuration of the optical system. The shape of the effective light source is adjusted by the aperture stop 120. The polarization may be controlled at the aperture stop 120.

  The projection optical system 140 has no polarization directionality in the optical system itself except for a special example. Therefore, in the conventional non-immersion system, the illumination light is processed so as not to have polarization characteristics, and the effective light source does not have a special state such as P-polarized light or S-polarized light in an illumination region having a radius σ (σ ≦ 1) or less. It was a non-polarized state. However, in the case of immersion, considering the frequency component of the light beam in image formation, it can be seen that polarization characteristics suitable for image formation in the X-direction and Y-direction patterns are generated. This condition is the polarization characteristic in the tangential direction, that is, the S polarization characteristic described so far. This is because the degree of deterioration is different between p-polarized light and low-frequency patterns. That is, the high-frequency component around the pupil of the optical system is very sensitive to the polarization effect, and the inside of the optical system's pupil. This is because the low-frequency component of does not affect the polarization effect.

  For this reason, the low-frequency component inside the pupil 142 of the projection optical system 140 has little decrease in contrast, and the influence of polarization need not be considered. Therefore, in the image formation of a non-fine pattern, there is little influence on the resolution performance by polarized light, and the optical system may be configured by ignoring polarized light.

  Accordingly, in the effective light source shapes shown in FIGS. 4, 5, and 8 to 10 proposed in the present embodiment, the shaded portion must be S-polarized, but the region on the effective light source other than the shaded portion is arbitrarily polarized. The state is fine. The method of obtaining the region to be S-polarized light is determined by the number of pattern directions, and the region is determined by Equation 8 on the axis in the direction orthogonal to the direction in which the pattern extends. That is, if the direction of the pattern is one direction, two regions are shown in FIG. If the direction of the pattern is two directions, there are four areas including S-polarized light, including the overlap, as shown in FIG. If the direction of the pattern is three directions or four directions, the region to be s-polarized has an almost annular shape as shown in FIG. In the case where the pattern does not include a large pattern and is composed of only a fine pattern, the effective light source shape shown in FIGS. 8 and 9 can provide a fine resolution improvement effect. The method for selecting the region to be S-polarized light is the same as in FIGS. 4 and 5, except that the central portion is shielded from light.

  In the present embodiment, the effective light source shape shown in FIGS. 4, 5, 8 to 10 is realized by the aperture shape of the aperture stop 120. Therefore, these effective light source shapes are embodied as the shapes of light transmission and light shielding portions of the aperture stop 120. In the present embodiment, a plurality of types of aperture stops having a plurality of effective light source shapes are arranged on the turret so that the actuator 121 can switch them. In addition, the polarization element is also configured such that a plurality of types of polarization elements having polarization elements in a shape corresponding to the aperture shape of the aperture stop are arranged on the turret and can be switched by an actuator (not shown). An illumination optical system and an exposure apparatus having such an aperture stop 120 and a polarizing element also constitute one aspect of the present invention. The exposure apparatus has various exposure modes that control both the shape and polarization of the effective light source.

  In exposure, the light beam emitted from the laser 112 is incident on the illumination optical system after its beam shape is shaped into a desired shape by the beam shaping system 114. The condensing optical system 116 efficiently introduces the light beam into the optical integrator 118. At that time, the exposure amount adjusting unit adjusts the exposure amount of the illumination light.

  In addition, the main control unit 150 recognizes the user by inputting mask pattern information via the monitor and the input device of the input device 152 or by reading a barcode or the like formed on the mask. An aperture shape and a polarization state as suitable illumination conditions are selected by driving an actuator (not shown) of the polarization control unit 117 and an actuator 121 of the aperture stop 120. For example, the main control unit 150 sets the polarization state of FIG. 4A for the mask pattern of FIG.

  The optical integrator 118 makes the illumination light uniform, and the aperture stop 120 sets a desired effective light source shape. Such illumination light illuminates the mask 200 under optimum illumination conditions via the condenser lens 122, the bending mirror 124, the masking blade 126, and the imaging lens 128.

  The light beam that has passed through the mask 130 is reduced and projected onto the wafer 170 at a predetermined magnification by the projection optical system 140. In the case of a step-and-scan exposure apparatus, the light source 112 and the projection optical system 140 are fixed, and the mask 130 and the wafer 170 are synchronously scanned to expose the entire shot. Further, the wafer stage 176 is stepped to move to the next shot, and a new scanning operation is performed. This scan and step are repeated to expose and transfer a large number of shots onto the wafer 170. If the exposure apparatus adopts a step-and-repeat method, exposure is performed with the mask 130 and the wafer 170 being stationary.

  Since the final surface of the projection optical system 140 on the wafer 170 is immersed in the liquid 180 having a refractive index higher than that of air, the NA of the projection optical system 140 becomes high, and the resolution formed on the wafer 170 becomes fine. Further, an image with high contrast is formed on the resist 172 by polarization control. Thereby, the exposure apparatus 100 can provide a high-quality device (semiconductor element, LCD element, imaging element (CCD, etc.), thin film magnetic head, etc.) by transferring the pattern onto the resist with high accuracy.

The first embodiment of the present invention will be described below using the immersion type exposure apparatus 100. The exposure apparatus 100 uses an ArF excimer laser (wavelength 193 nm) as the light source 112, the projection optical system 140 has a numerical aperture of 1.32, and the maximum angle θNA in the liquid satisfies sin θ _NA = 0.9. . The refractive index of the liquid 180 is 1.47, and σ _{MAX of} the illumination system is 0.9. The projection exposure apparatus is generally reduced projection exposure. In the case of reduced projection exposure, the pattern size to be created and the mask pattern differ depending on the magnification of the exposure apparatus, but the pattern size on the mask 130 will be described below in terms of the dimensions on the wafer 170.

  In the mask pattern in which the line and space (hereinafter abbreviated as “L / S”) patterns in the X direction and the Y direction having the same line width and interval as shown in FIG. FIG. 11A and FIG. 11B show the contrast depth (μm) when the pitch is changed.

At this time, when sin θ _NA = 0.9, θ _NA = 64 °. sin (90 ° −θ _NA ) / sin θ _NA = 0.44 / 0.9 = 0.49, corresponding to the incident region of only S-polarized light on the axis corresponding to the pattern direction, corresponding to Equation 8. Since the value of σ is 0.44 / 0.90 ≦ σ ≦ σ _MAX , the illumination system may be designed so that the range of about 0.5 ≦ σ ≦ 0.9 is the S polarization region.

For a non-polarized circular effective light source with σ _MAX = 0.9 shown in FIG. 6, 0.5 ≦ σ ≦ 0.9 as shown in FIG. FIG. 11A shows the contrast depth (μm) in the case where the inner side with a value of 0.5 or less is used as an unpolarized circular effective light source. By controlling the polarization state, the depth increases at a fine line width, the marginal resolution increases, and the depth hardly changes at a large line width, and only the fine line width has the effect of improving the depth. It is confirmed. In resolving fine patterns, contrast reduction as in the non-polarized state is a major problem, but it has been found that fine patterns can be resolved by using an effective light source with controlled polarization. Contrast that decreases during non-polarization is a big problem in resolving fine patterns. However, it can be seen that a fine pattern can be resolved by using an effective light source with controlled polarization.

For a non-polarized circular effective light source with σ _MAX = 0.9 shown in FIG. 6, 0.5 ≦ σ ≦ 0.9 as shown in FIG. 9B is set as tangential polarization as shown in FIG. FIG. 11B shows the contrast depth (μm) in the case of annular illumination in which the inner side with a value of 0.5 or less is shielded. By shielding σ ≦ 0.5 and cutting the low frequency component inside the pupil of the optical system, the depth of the pattern with a fine line width increases instead of the depth of the pattern with a large line width slightly decreasing, Furthermore, the limit resolution is greatly extended, and the effect of S-polarized light is confirmed.

  Hereinafter, an immersion type exposure apparatus according to a second embodiment of the present invention will be described. Similar to the first embodiment, this exposure apparatus uses an ArF excimer laser (wavelength 193 nm) as the light source 112, the projection optical system 140 has a numerical aperture of 1.32 and the maximum angle in the liquid is θNA is sinθNA = 0.9 is satisfied. The refractive index of the liquid 180 is 1.47, and σMAX of the illumination system is 0.9.

  In the mask pattern of only one direction of the L / S pattern parallel to the Y direction having the same line width and interval as shown in FIG. 2A, the contrast depth when the line width and interval, that is, the pitch is changed. (Μm) is shown in FIGS. 12 (a) and 12 (b).

At this time, when sin θNA = 0.9, θNA = 64 °. Furthermore, sin (90 ° −θNA) /sinθNA=0.44/0.9=0.49, corresponding to the incident region of only S-polarized light on the axis corresponding to the pattern direction, corresponding to Equation 8. From the value of σ to be 0.44 / 0.90 ≦ σ ≦ σMAX, the illumination system may be designed so that the range of approximately 0.5 ≦ σ ≦ 0.9 is the S polarization region. With respect to the non-polarized circular effective light source of σMAX = 0.9 shown in FIG. 6, 0.68 ≦ σ ≦ 0.9 is polarized in the tangential direction as shown in FIG. 4 by the illumination method shown in FIG. FIG. 12A shows the contrast depth (μm) in the case where the inner side of the σ value of 0.5 or less is used as a non-polarized circular effective light source. Here, the illumination A having a polarization in the tangential direction in the range of 0.68 ≦ σ ≦ 0.9 satisfies a part of the previously defined S-polarized region, but 0.5 ≦ σ ≦ 0.9. Polarized light orthogonal to the tangential direction is not used. That is,
It can be said that the condition that the polarized light in the cut line direction is used when 0.5 ≦ σ ≦ 0.9 is the condition that the polarized light orthogonal to the cut line direction is not used when 0.5 ≦ σ ≦ 0.9. By controlling the polarization state, the depth increases at a fine line width, the marginal resolution increases, and the depth of a pattern with a large line width decreases slightly, but not so much as a problem. The effect of improving the depth is confirmed. The effect is great when the pattern is unidirectional. In resolving fine patterns, contrast reduction as in the non-polarized state is a major problem, but it has been found that fine patterns can be resolved by using an effective light source with controlled polarization.

  Further, with respect to the non-polarized circular effective light source with σMAX = 0.9 shown in FIG. 7, 0.5 ≦ σ ≦ 0.9 as shown in FIG. FIG. 12B shows the contrast depth (μm) when X = 0.7 and the radius is 0.2 in the system. By shielding σ ≦ 0.5 and cutting the low frequency component inside the pupil of the optical system, the depth of the pattern with a fine line width increases instead of the depth of the pattern with a large line width slightly decreasing, Since the limit resolution is greatly extended, there is no problem even if the light is shielded from areas other than the S-polarized region when the line width is composed of only a fine pattern. Further, even if the shape of the dipole illumination is set to FIGS. 8 (a), 8 (b) and 8 (d), almost the same effect is exhibited, so the result is omitted. In resolving fine patterns, contrast reduction as in the non-polarized state is a major problem, but it was found that fine patterns can be resolved by using an effective light source with controlled polarization.

  In this embodiment, the case of NA = 1.32 has been described. However, the effect of this exposure method becomes more prominent as the NA becomes higher and the pattern becomes finer. Moreover, since the imaging contrast of P-polarized light becomes zero in the immersion optical system, it goes without saying that it appears more conspicuously than the conventional projection optical system.

In the present embodiment, the polarization peculiar to the immersion type projection optical system has been described. Another major problem in the case of immersion is the fluctuation of the liquid 180 itself. Although the refractive index of the liquid 180 is set to n _o , it is assumed that a certain lump portion due to fluctuation has a refractive index n _o + Δn as shown in FIG. The absolute value ΔW of the fluctuation of the wavefront aberration when the fluctuation is entered is expressed by the following equation as a maximum value, compared with the case where there is no fluctuation.

Here, d is the thickness of the immersion medium. Also, the following formula 11 is derived from the formula 15.

Substituting numerical values from Equation 11 with an allowable generation amount of ΔW of 30 mλ, θ _MAX = 60 °, wavelength 193 nm, Δn = 10 ppm, d ≦ 3000λcos θNA = 0.29 mm, and a numerical value close to the actual value is obtained. As long as d is small, the influence of all fluctuations can be suppressed to a small level. In an immersion system, how much d can be reduced is a big decision point.

  Also, pure water is suitable as the liquid for immersion with the ArF excimer laser. However, the optical element closest to the wafer 170 of the projection optical system 140 that comes into contact with the liquid is also the portion where the light energy is most concentrated in the projection optical system 140. Accordingly, quartz cannot be used due to the problem of durability of the glass material such as compaction, and it is necessary to use fluorite. However, because fluorite has deliquescence, it will be damaged if it comes into contact with water. Conventionally, in the ArF region, a film is usually deposited on fluorite by a vapor deposition method, but the film formed by vapor deposition is porous, and the fluorite of the substrate is damaged through the hole. Therefore, the present embodiment is characterized in that a sputtered film is used on the final surface of the projection optical system 140 that comes into contact with the liquid to protect the fluorite substrate and simultaneously achieve antireflection. For this purpose, for example, a sputtered film made of a material such as MgF2 is suitable.

  Next, an embodiment of a device manufacturing method using the above-described exposure apparatus will be described with reference to FIGS. FIG. 14 is a flowchart for explaining how to fabricate devices (ie, semiconductor chips such as IC and LSI, LCDs, CCDs, and the like). Here, the manufacture of a semiconductor chip will be described as an example. In step 1 (circuit design), a device circuit is designed. In step 2 (mask production), a mask on which the designed circuit pattern is formed is produced. In step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by the lithography technique of the present invention using the mask and the wafer. Step 5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer created in step 4. The assembly process (dicing, bonding), packaging process (chip encapsulation), and the like are performed. Including. In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device created in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

  FIG. 15 is a detailed flowchart of the wafer process in Step 4. In step 11 (oxidation), the surface of the wafer is oxidized. In step 12 (CVD), an insulating film is formed on the surface of the wafer. In step 13 (electrode formation), an electrode is formed on the wafer by vapor deposition or the like. Step 14 (ion implantation) implants ions into the wafer. In step 15 (resist process), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the exposure apparatus to expose a circuit pattern on the mask onto the wafer. In step 17 (development), the exposed wafer is developed. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), the resist that has become unnecessary after the etching is removed. By repeatedly performing these steps, multiple circuit patterns are formed on the wafer. According to the device manufacturing method of the present invention, it is possible to manufacture a higher quality device than before. As described above, the device manufacturing method using the lithography technique of the present invention and the resulting device also constitute one aspect of the present invention. The present invention also covers the device itself that is an intermediate and final product of the device manufacturing method. Such devices include, for example, semiconductor chips such as LSI and VLSI, CCDs, LCDs, magnetic sensors, thin film magnetic heads, and the like.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

It is a schematic block diagram of the exposure apparatus as one Embodiment of this invention. It is a top view which shows some examples of the pattern formed in the mask shown in FIG. It is a conceptual diagram for demonstrating the effect of P polarized light and S polarized light. 4 (a) and 4 (b) are effective light source distributions that define the polarization for exposing the mask patterns shown in FIGS. 2 (a) and 2 (b), respectively. It is effective light source distribution which prescribes | regulates the polarization for exposing the mask pattern shown in FIG.2 (c). It is a schematic diagram for demonstrating the relationship between the area | region of an effective light source, and a polarization direction. It is a schematic diagram for demonstrating the relationship between the area | region of an effective light source, and a polarization direction. It is a schematic diagram which shows an example of an effective light source shape in case the mask pattern shown to Fig.2 (a) is comprised only by the thing of a micro size. It is a schematic diagram which shows an example of an effective light source shape in case the mask pattern shown in FIG.2 (c) is comprised only by the thing of a micro size. It is a schematic diagram which shows an example of the effective light source shape used in order to resolve the pattern of various directions. 3 is a graph showing the relationship between pitch and contrast depth in the mask pattern shown in FIG. 3 is a graph showing the relationship between pitch and contrast depth in the mask pattern shown in FIG. 3 is a graph showing the relationship between pitch and contrast depth in the mask pattern shown in FIG. 3 is a graph showing the relationship between pitch and contrast depth in the mask pattern shown in FIG. It is the schematic for demonstrating the fluctuation | variation of the medium (liquid) shown in FIG. It is a flowchart for demonstrating the device manufacturing method which has the exposure apparatus of this invention. It is a detailed flowchart of step 4 shown in FIG. It is the schematic for demonstrating the relationship between the image formation and polarization | polarized-light in immersion type exposure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Exposure apparatus 112 Light source 120 Aperture stop 121 Actuator 130 Mask or reticle 140 Projection optical system 142 Pupil (plane)
150 Main control unit 170 Wafer 172 Reticle 174 Substrate 180 Medium (liquid)

Claims (21)

In the exposure method of immersing the surface of the object to be exposed and the final surface of the projection optical system in a liquid, and projecting the pattern formed on the mask onto the object to be exposed by the projection optical system,
Of the effective light source formed on the pupil of the projection optical system, the light that is emitted obliquely from the portion on the axis parallel to the pattern repeat direction and orthogonal to the optical axis of the projection optical system and obliquely incident on the resist When the incident angle to the object to be exposed is θ and the maximum value of the incident angle θ is θ _NA , the light corresponding to the range of the incident angle θ satisfying 90 ° −θ _NA ≦ θ ≦ θ _NA is the S polarization component. The exposure method characterized by having only. In an exposure method in which a pattern formed on a mask is immersed in a liquid to be exposed and at least part of the pattern is immersed in a liquid, and numerical aperture n ₀ sin θ _NA , n ₀ is an image using a projection optical system having a liquid refractive index. ,
90 °, where one of the repeating direction of the pattern formed on the mask and the direction orthogonal to the direction is the X axis, the other is the Y axis, and the incident angle of the exposure light to the projection optical system is θ. A region on the effective light source formed in the pupil of the projection optical system corresponding to the range of the incident angle θ satisfying −θ _NA ≦ θ ≦ θ _NA is a straight line in a direction perpendicular to the X axis or the Y axis. An exposure method characterized by irradiating the exposure light so as to have a polarization component. In an exposure method for forming an image using a projection optical system in which a pattern formed on a mask is at least partially immersed in a liquid on an object to be exposed.
An exposure method characterized by illuminating an area on an effective light source formed on a pupil of the projection optical system with only S-polarized light, in which an orthogonal state can occur between two exposure light beams that form an image.   4. The exposure method according to claim 1, wherein the region has a sharp canoe-like shape formed by the intersection of two circles.   4. The exposure method according to claim 1, wherein the region has a shape formed by partially cutting a circle with a straight line.   4. The exposure method according to claim 1, wherein the region has a shape formed by partially cutting a ring zone with a straight line. 5.   The exposure method according to claim 1, wherein the region has a circular shape. In an exposure method for forming an image using a pattern formed on a mask on an object to be exposed using an exposure light having a wavelength λ and a projection optical system having a numerical aperture n ₀ sin θ _NA at least partly immersed in a liquid,
An exposure method, wherein the thickness d of the liquid is set so as to satisfy d ≦ 3000λ cos θ _NA . In an exposure method of forming an image using a projection optical system in which at least a part is immersed in a liquid, a pattern formed on a mask on an object to be exposed,
An exposure method, wherein the projection optical system protects a final surface in contact with the liquid from the liquid. An exposure apparatus that images a pattern formed on a mask onto an object to be exposed,
A projection optical system at least partially immersed in a liquid and having a numerical aperture n ₀ sin θ _NA ;
An effective light source formed on the pupil of the projection optical system corresponding to a range in which the angle θ at which the exposure light exits from the projection optical system satisfies 90 ° −θNA ≦ θ ≦ θNA so as to ensure a predetermined contrast An exposure apparatus comprising polarization control means for controlling the polarization state of the upper region. An exposure apparatus that images a pattern formed on a mask onto an object to be exposed,
A projection optical system at least partially immersed in a liquid;
Polarization control for controlling the polarization state of the exposure light in the region on the effective light source formed in the pupil of the projection optical system so as to ensure a predetermined contrast, in which an orthogonal state can occur between the two exposure light beams that form an image And an exposure apparatus.   12. The exposure apparatus according to claim 10, wherein the polarization control unit controls the polarization state to only S-polarized light.   12. The exposure apparatus according to claim 10, wherein the polarization control means includes a polarizing element disposed substantially conjugate with the pupil plane of the projection optical system. The polarization control means includes an aperture stop disposed substantially conjugate to the pupil plane of the projection optical system,
12. The exposure apparatus according to claim 10, wherein the aperture stop has a sharp canoe-like aperture shape formed by the intersection of two circles. The polarization control means includes an aperture stop disposed substantially conjugate to the pupil plane of the projection optical system,
12. The exposure apparatus according to claim 10, wherein the aperture stop has an aperture shape formed by partially cutting a circle along a straight line. The polarization control means includes an aperture stop disposed substantially conjugate to the pupil plane of the projection optical system,
12. The exposure apparatus according to claim 10, wherein the aperture stop has an aperture shape formed by partially cutting a ring zone in a straight line. The polarization control means includes an aperture stop disposed substantially conjugate to the pupil plane of the projection optical system,
12. The exposure apparatus according to claim 10, wherein the aperture stop has a circular aperture shape.   12. The exposure apparatus according to claim 10, wherein the predetermined contrast is 0.7.   In an exposure apparatus that immerses the surface of the object to be exposed and the final surface of the projection optical system in a liquid and projects a mask pattern onto the object to be exposed by the projection optical system, the wavelength of light used for the projection is λ (nm) When the refractive index of the liquid is n0, the numerical aperture of the projection optical system is n0 sin θ0, and the thickness of the liquid in the optical axis direction of the projection optical system is d, d ≦ 3000λ cos θ0 is satisfied. Exposure device.   20. The exposure apparatus according to claim 19, wherein the final surface of the projection optical system in contact with the liquid is a surface on the fluorite substrate, and a sputtered film is formed on the final surface. Exposing the object to be exposed using the exposure apparatus according to any one of claims 10 to 20;
And performing a predetermined process on the exposed object to be exposed.