JP2775988B2 - Position detection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a position detecting device, for example, in an exposure apparatus for manufacturing a semiconductor element, on a first object surface such as a mask or a reticle (hereinafter, referred to as a “mask”). When exposing and transferring the fine electronic circuit pattern formed on the second object surface such as a wafer, the distance between the mask and the wafer is measured and controlled to a predetermined value. The present invention relates to a position detecting device suitable for performing positioning (alignment) in the inside.

2. Description of the Related Art Conventionally, in an exposure apparatus for manufacturing a semiconductor, relative positioning between a mask and a wafer has been an important factor for improving performance. In particular, in recent aligners in an exposure apparatus, for high integration of semiconductor elements,
For example, one having a positioning accuracy of sub-micron or less is required.

At that time, the distance between the mask and the wafer is measured by a plane distance measuring device or the like, and after controlling the distance to be a predetermined distance, position information obtained from a so-called alignment pattern for positioning provided on the mask and the wafer surface is obtained. Utilization is used to perform both alignments. As an alignment method at this time, for example, the amount of deviation between the two alignment patterns is detected by performing image processing, or alignment is proposed as proposed in U.S. Pat. No. 4,037,969 or Japanese Patent Application Laid-Open No. 56-157033. This is performed by using a zone plate as a pattern, irradiating the zone plate with a light beam, and detecting the position of a light-converging point on a predetermined surface of the light beam emitted from the zone plate.

FIG. 11 is a schematic view of a conventional position detecting device using a zone plate.

In the same figure, a parallel light beam emitted from a light source 72 passes through a half mirror 74, is condensed at a converging point 78 by a converging lens 76, and is then mounted on a support 62, which is a mask alignment pattern 68a on a mask 68 surface. The wafer alignment pattern 60a on the surface of the wafer 60 is irradiated. These alignment patterns 68a and 60a are constituted by reflection type zone plates,
Focus points are formed on planes orthogonal to the optical axis each including the focus point 78. At this time, the amount of shift of the condensing point position on the plane is detected by guiding the light onto the detection surface 82 by the condensing lenses 76 and 80.

Then, based on the output signal from the detector 82, the control circuit 84
Drives the drive circuit 64 to position the mask 68 relative to the wafer 60.

FIG. 12 shows the mask alignment pattern shown in FIG.
FIG. 8 is an explanatory diagram showing an image forming relationship of a light beam from 68a and a wafer alignment pattern 60a.

In the figure, a part of the luminous flux diverging from the converging point 78 is diffracted from the mask alignment pattern 68a to form a converging point 78a indicating the mask position near the converging point 78.
Further, some other light beams pass through the mask 68 as zero-order transmission light and enter the wafer alignment pattern 60a on the wafer 60 without changing the wavefront. At this time, after the light beam is diffracted by the wafer alignment pattern 60a, the light beam is transmitted again through the mask 68 as zero-order transmission light, condensed in the vicinity of the converging point 78, and forms a converging point 78b representing the wafer position. In the figure, when the light beam diffracted by the wafer 60 forms a converging point, the mask 68 acts as a simple transparent state.

The position of the focal point 78b by the wafer alignment pattern 60a formed in this way is determined by the amount of deviation Δσ in the direction (lateral direction) along the mask / wafer surface with respect to the mask 68 of the wafer 60. It is formed as a shift amount Δσ ′ of an amount corresponding to the shift amount Δσ along a plane orthogonal to the included optical axis.

FIG. 13 is a schematic view of an interval measuring device proposed in Japanese Patent Application Laid-Open No. 61-111402. And is focused on a point P _S between the mask M and the wafer W and arranged opposite, the mask M and the wafer W to the light beam by the lens L1 of the second object as the first object in the drawing.

In this case the light beam is respectively reflected by the above mask M surface and the wafer W surface, a point P _W on the screen S surface through the lens L2, the are converged projected to P _M. The distance between the mask M and the wafer W focal point P _W of the light beam on the screen S surface is measured by detecting the distance between the P _M.

Since the devices shown in FIGS. 11 and 13 have completely different structures, the relative directions of the first object and the second object in both the facing direction (interval direction) and the direction perpendicular to the facing direction (lateral direction, in-plane direction). In order to detect the positional relationship, it is necessary to separately provide a relative position detecting device in the lateral direction (in-plane direction) and a distance measuring device.

For this reason, there has been a tendency that the entire apparatus becomes larger and more complicated.

In these apparatuses, when the wafer is tilted, the luminous flux from the wafer fluctuates, which causes a detection error. Therefore, it has been very difficult to accurately detect the positional deviation and measure the interval of a wafer having irregularities and warpage.

On the other hand, the present applicant has disclosed in Japanese Patent Application No. 1-209928, while simplifying the entire apparatus, and being less susceptible to the tilt of the wafer, and always detecting the lateral displacement and the surface spacing with high accuracy. We propose a position detection device that can be used.

The position detecting device of the same publication arranges a first object and a second object so as to face each other, and when detecting a relative positional relationship between the first object and the second object, the first object and the second object are respectively assigned to the first object and the second object. A light source means for irradiating a light beam, and two light beams from the first object or the second object, and a predetermined surface according to a relative positional relationship along a direction perpendicular to the facing direction of the first object and the second object. Light detecting means for detecting two light beams whose relative relationship between incident positions into the light changes, and a relative position in a direction perpendicular to the facing direction of the first object and the second object using an output signal from the light detecting means Position detecting means for detecting the relationship, and detecting a relative positional relation between the first object and the second object in the facing direction using a signal based on at least one of the two light beams detected by the light detecting means. And an interval detecting means.

(Problems to be Solved by the Invention) In general, when detecting the surface interval between the mask and the wafer and detecting the in-plane positional deviation between the mask and the wafer, the mask and the wafer are arranged close to each other by, for example, 10 μm to 50 μm and opposed to each other. It goes in the following order:

(B) The surface interval between the mask and the wafer is slightly larger than the proximity exposure interval (gap), and the next exposure wafer
The wafer is moved to the area (wafer stage movement).

This means that the distance between the mask and the wafer is
When the wafer stage is moved to about 20 μm, the wafer is not perfectly flat but has irregularities, and when the mask surface is inclined, the wafer may come into contact with the mask.

(B) Detect the surface interval between the mask and the wafer. For example, this is performed by a method proposed in Japanese Patent Application Laid-Open No. Hei 2-1512.

(C) The wafer is moved in the space direction so as to have the space between the mask and the wafer at the time of exposure based on the detected value of the surface space between the mask and the wafer.

(D) In-plane positional deviation between the mask and the wafer is detected with the mask and the wafer set at the time of exposure. For example, it is performed by the method proposed in the above-mentioned Japanese Patent Application Laid-Open No. 2-1512. Then, both the mask and the wafer are adjusted so that there is no displacement.

(E) Exposure to X-rays to expose and transfer the circuit pattern on the mask surface onto the wafer surface.

(F) The mask and the wafer are slightly separated from the exposure gap, and the wafer stage is moved to the next exposure wafer area.

Returning to (A) below, the detection of the surface interval, the detection of the displacement, and the exposure are repeated one after another.

In such an apparatus, an AF alignment mark for detecting a surface interval and an AA alignment mark for detecting a positional deviation are provided on the mask surface. An AA alignment mark is provided on the wafer surface so as to face the AA alignment mark on the mask surface.

Then, the light beam passing through the AA alignment mark is detected by the AA sensor to detect the positional deviation, and the light beam passing through the AF alignment mark is detected by the AF sensor to detect the surface interval. Although the embodiment shows the case of a line sensor, it may be an area sensor (two-dimensional).

FIGS. 6A and 6B show the AF line sensor at this time.
FIG. 7A and FIG. 7B are schematic views showing spot states of the AF light beam and the AA light beam incident on the surface of the A and the AA line sensor 41. FIGS. 7A and 7B show the relationship between the mask M and the wafer W at this time. FIG.

The state in FIG. 6 (A) is the mask M and the wafer W as shown in Figure No. 7 (A) has become exposed gap [delta] _1, FIG. 6 (B) is the mask M and the wafer W is first Fig. 7 (B)
Shows the state when it is in surface spacing detection gap [delta] _2, as shown in.

For example, δ ₁ = 10 μm to 70 μm, δ ₂ = δ ₁ + α (α =
10 μm to 50 μm), and if δ ₁ = 20 μm, δ ₂ = 70 μm.

6 (A) and 6 (B) is characterized by δ ₂ >
AA of AA light beam on the line sensor surface spots δ Figure 6 from ₁ (A), 43,44 is set such that the best focus focus and spacing of the zone plate on the mask and the wafer surface during exposure gap It is that you are. Therefore, the spot diameter on the surface of the AA line sensor 41 becomes a minimum sharp image. On the other hand, the spot of the AF luminous flux on the surface of the AF line sensor 42 sets the mask-to-wafer surface gap range larger than the exposure gap at the mask-to-wafer surface gap in accordance with the sequence (b). Since it is set so that it can be detected, it does not enter the AF line sensor 42 surface.

At the time of detecting the surface interval shown in FIG. 6B, spots 45 and 46 of the AF light flux are incident on the surface of the AF line sensor 42 in a sharp shape. However, if the gap between the mask and the wafer is large on the surface of the AA line sensor 41, the seventh
As shown in FIG. 6B, the focusing state of the spot on the surface of the AA line sensor 41 changes, and becomes a state similar to a so-called defocus, and the spot 43 'spreads as shown by a dotted line in FIG. 6B. , 44 '. For this reason, as shown in FIG. 6 (B), spots 43 'and 44'
However, there is a problem that a part of the signal is mixed and becomes noise, and as a result, a detection error occurs.

As described above, the position detecting device proposed in Japanese Patent Application No. 1-209928 can detect the positional deviation between the mask and the wafer and the surface interval by detecting means having one light projecting means and two sensors. AF when detecting the distance between faces
In some cases, unnecessary light for detecting a position shift is incident on the line sensor, resulting in noise and reducing the detection accuracy of the surface interval.

The present invention effectively prevents unnecessary light for position shift detection from being incident on the AF line sensor when detecting the surface interval between the mask and the wafer and causing noise, and performs both surface interval detection and position shift detection with high accuracy. It is an object of the present invention to provide a position detection device that can perform the position detection.

(Means for Solving the Problems) The position detecting device of the present invention is for detecting, using an AA sensor, relative in-plane positional deviations of a first object and a second object, which are arranged opposite to each other, respectively. An AA alignment mark is provided, and an AF alignment mark is provided on the first object to detect a relative surface distance between the two using an AF sensor, and a relative surface distance between the first object and the second object is determined. At the time of detection, the relative in-plane positional relationship between the two is displaced by a predetermined amount in a direction in which noise light from the AA alignment mark does not enter the AF sensor, and then the light flux from the light source means is applied to the first object. And the light flux from the AF alignment mark is reflected by the second object surface to be incident on a predetermined surface, and the position of incidence on the predetermined surface is detected by the AF sensor. Surface spacing inspection Output means, and when detecting a relative in-plane displacement between the first object and the second object, the light flux from the light source means is used to detect the AA alignment marks of both the first object and the second object. And a position detecting means for detecting the position of incidence on the predetermined surface by detecting the position of incidence on the predetermined surface with the AA sensor.

In particular, in the present invention, when detecting the relative surface distance between the first object and the second object, the relative positional relationship between both surfaces is determined by the alignment direction of a single mark of the AA alignment marks. It is characterized in that the adjustment is performed after being adjusted so as to be shifted by 1/2 or more of the length of the. The exposure apparatus of the present invention performs relative positioning between the first object and the second object using the above-described position detection device, and exposes and transfers a pattern on the first object surface onto the second object surface. It is characterized by having.

(Embodiment) FIG. 1 is a perspective view of an essential part of an embodiment of the present invention, FIGS. 2 and 3 are enlarged explanatory views of a part of FIG. 1, and FIGS. FIG. 4 is a diagram illustrating the principle of detecting positional deviation and detecting a surface interval.

In the figure, 1 is a light source, a semiconductor laser, H _e -N _e laser, consist A _r source emits coherent light beam such as a laser or light source or Xray source such emits incoherent light beam such as a light emitting diode I have. Reference numeral 2 denotes a collimator lens, which adjusts a light beam diameter by a slit 3 using a light beam from the light source 1 as a parallel light beam and makes the light beam enter a lens system 5 via a λ / 4 plate 4. The lens system 5 converts the incident light beam to a desired beam diameter, and then reflects the light beam on the mirror 6 so that the Xray-resistant window 7
(When an Xray is used as a light source), an alignment mark (hereinafter, referred to as an “AA mark”) 20M for detecting a positional shift on the mask 18 as a first object, or an AF alignment mark for detecting a surface interval. (Hereinafter referred to as the “AF mark”.)

The AA mark 20M and the AF mark 21M are provided at four locations around the mask 18. Reference numeral 19 denotes a wafer as a second object, on which an AA mark to be aligned with the mask 18 is provided.
20W is provided. AA mark 20M, 20W and AF mark 21M
Consists of a physical optical element such as a one-dimensional or two-dimensional zone plate.

Reference numeral 10 denotes a light receiving lens, and an AA mark 20M on the mask 18 surface.
And a predetermined order of diffracted light 16 that has passed through the AF mark 21M is condensed on the surface of the light receiving means 11. The light receiving means 11 is configured by providing two line sensors, an AA line sensor 12 for detecting a displacement and an AF line sensor 13 for detecting a surface interval, on the same substrate.

FIG. 2 shows an AA mark 20 provided on the surface of the mask 18 and the wafer 19.
It is an explanatory view of M, 20W and AF mark 21M. FIG. 3 shows the mask 18
3 shows the optical path of the light beam through each mark on the surface of the wafer 19. The AA mark 20M is composed of two AA marks 20M1, 20M2, the AA mark 20W is composed of two AA marks 20W1, 20W2, and the AF mark 21M is composed of two AF marks 21M1, 21M3 for incidence and two AF marks 21M2, 21M4 for emission. Made up of In addition, AF on the 19 wafer
No mark is provided, and light that is 0-order reflected (specularly reflected) on the surface of the wafer 19 is used.

AA mark 20M1 and 20W1 are combined into one set, AA mark 20M2 and 20W1
W2 is one set, each AA mark 20M1,20M2
The two diffracted lights (hereinafter, referred to as “AA diffracted lights”) 26-1 and 26-2 by the respective marks of the two light beams 15 incident on the AA line sensor 12 move on the surface of the AA line sensor 12 in accordance with the displacement. Is set. The luminous flux 15 incident on the AF marks 21M1 and 21M3
The two diffracted lights reflected on the surface of the wafer 19 and emitted from the AF marks 21M2 and 21M4 (hereinafter referred to as "AF diffracted lights") 27-1.27-
Numeral 2 is set so as to move on the AF line sensor 13 in accordance with the surface interval. In FIG. 3, each incident light
Numeral 15 uses light rays in one common beam emitted from the light source 1.

The position detecting device of the present invention detects both the distance between the mask and the wafer by displacing both the position of the mask and the wafer by a predetermined amount according to the size of the AA mark, and thereafter refers to the result of detecting both the distances between the mask and the wafer. Before detecting the positional deviation, the principle of the method for detecting the positional deviation and the method for detecting the surface interval according to the present invention will be described.

First, a method of detecting the relative position between the mask 18 and the wafer 19 in the present invention will be described with reference to FIG.

FIG. 4 shows a state in which the optical path is developed when viewed from a direction perpendicular to the position detection direction (alignment direction) and perpendicular to the surface normal of the mask 18 and the wafer 19 in FIG. In the figure, the same elements as those shown in FIGS. 1 to 3 are denoted by the same reference numerals. At the AA mark on the surface of the wafer 19, the incident light beam is reflected and diffracted, but in FIG.

20M1 is an AA mark provided on the mask 18 and 20W1 is an AA mark provided on the wafer 19, and forms a single mark for obtaining a first signal. Reference numeral 20M23 denotes an AA mark provided on the mask 18 and reference numeral 20W2 denotes an AA mark provided on the wafer 19, forming a single mark, for obtaining a second signal.

Reference numerals 26-1 and 26-2 denote AA diffracted lights for the first and second signals, and reference numeral 32 denotes a primary focus surface, which is conjugate with the light receiving means 11 with respect to the light receiving lens 10.

Now, the distance from the wafer 19 to the primary focus plane 32 is L, the distance between the mask 18 and the wafer 19 is g, and the focal lengths of the AA marks 20M1 and 20M2 are f _a1 and f _a2 , respectively. The amount of displacement is Δσ, and the AA diffracted light 26-1, 26-2 at this time is
Let S ₁ and S ₂ denote the displacement amounts of the light flux centroids from the matching state.

The light beam 15 incident on the mask 18 is a plane wave for convenience,
The symbols are as shown in the figure.

The displacement amounts S ₁ and S ₂ of the luminous flux centroids of the AA diffracted lights 26-1 and 26-2 are
It is geometrically determined as an intersection between a straight line connecting the focal points F ₁ and F ₂ of the AA marks 20M1 and 20M2 and the optical axis centers of the AA marks 20W1 and 20W2 and the primary focus plane 32. Accordingly, the displacement amounts S ₁ , S ₂ of the luminous flux centroids of the respective AA diffracted lights with respect to the relative displacement between the mask 18 and the wafer 19.
AA mark 20W1,20W
This can be achieved by reversing the signs of the two optical imaging magnifications.

Also, quantitatively The shift magnification can be defined as β ₁ = S ₁ / Δσ and β ₂ = S ₂ / Δσ. Therefore, in order to make the deviation magnification the opposite sign Should be satisfied. Of these, one of the practically appropriate configuration conditions
For example, there is a condition of L 条件 | f _a1 | f _a1 / f _a2 <0 | f _a1 |> g | f _a2 |> g. That is, AA marks 20M1, 20M2, focal length
With respect to f _a1 and f _a2 , the distance L to the primary focus surface 32 is increased, and the distance g between the mask 18 and the wafer 19 is reduced.
One of the AA marks is a convex lens, and the other is a concave lens.

The upper side of FIG. 4 and condensed light beam incident light beam by AA mark 20M1, the before reaching the focal point F ₁ is irradiated with the light beam to the AA mark 20W1, further imaged on the primary focal plane 32 so I have. The focal length f _b1 of the AA mark 20W1 is the lens formula It is determined to satisfy Similarly, in the lower side of Figure 4 instead of the light beam diverging from the F ₂ is the point on the incident side of the incident light flux by AA marks 20M2, this through AA mark 20W2 1
An image is formed on the next focus plane 32. AA mark 20 at this time
The focal length f _{b2 of} W2 is It is determined to satisfy AA mark 20 under the above configuration conditions
Imaging magnification for converged image of W1,20W2 is clearly positive power from the figure, the direction of the light spot displacement amount S ₁ of shift amount Δσ a primary focal plane 32 of the wafer 19 becomes reversed, previously defined Shift magnification β
₁ is negative. Similarly magnification of the AA mark 20W2 for the point image (virtual image) of the AA mark 20M2 is negative, the deviation amount Δσ and direction of the light spot displacement amount S ₂ on the primary focal plane 32 of the wafer 19 in the same direction , The shift magnification β ₂ is positive.

Therefore, the AA marks 20M1 and 20W1 and the AA marks 20M2 and 20W2
The shift amounts S ₁ and S ₂ of the diffracted lights 26-1 and 26-2 are opposite to each other.

That is, the spot 30 on the primary focus surface 32 formed by the diffraction of the pattern of the AA marks 20M1 and 20W1,
The distance between the spot 31 on the primary focus surface 32 formed by the diffraction of the pattern of M2 and 20W2 changes according to the amount of displacement between the mask 18 and the wafer 19, and the two spots 30 and 31 are changed.
Is projected on the surface of the AA line sensor 12 of the light receiving means 11 by the light receiving lens 10. And AA line sensor 12
By detecting the light intensity of the two spots 30 and 31, the relative displacement between the mask 18 and the wafer 19 is detected.

In this embodiment, the wafer 19 is tilted (Til
t), the two spots 30, 31 both move on the primary focus surface 32 by the same amount in the same direction, so that the spot interval is unchanged, and as a result, a position detection error does not occur. ing. The above is the configuration of the position detecting means according to the present invention.

Although the embodiment in which the AA and AF sensors are provided on the same substrate surface has been described, the AA sensor and the AF sensor may be set on different substrate surfaces even if they are not on the same substrate surface. Also, a single sensor may be used as both AA and AF sensors.

Next, a method of detecting a surface interval between the mask 18 and the wafer 19 in the present invention will be described with reference to FIG. In the figure, the same elements as those shown in FIGS. 1 to 3 are denoted by the same reference numerals.

In this embodiment, the incident light 15 is made incident on two AF marks 21M1 (21M3) on the mask 18 surface. AF mark 21M1 (21M
The light incident on 3) is diffracted by the mark. For example, the first-order diffracted light is specularly reflected on the surface of the wafer 19 separated from the mask 18 by an interval g ₁ (g ₂ ), and the AF mark 21M2 (21M4) on the surface of the mask 18 Incident on. The AF mark 21M2 (21M4) has a pattern in which the diffracted light receives the same focusing action as the lens. When the light reflected by the wafer 19 is incident on the AF mark 21M2 (21M4), it has an optical action such that the exit angle of the output diffracted light changes according to the incident position (pupil position of the grating area).

E.g. mask 18 and the surface spacing between the wafer 19 AF light diffracted by the AF marks when g ₂ is two in the AF line sensor 13 surface on through the light receiving lens 10 advances the optical path indicated by a solid line in the spot 51 and 52 To form Matamen interval AF light diffracted by the AF marks similarly when g ₁ form two spots 53 and 54 to the AF line sensor 13 surface on advances the optical path shown by a dotted line.

As described above, the interval between two spots generated on the surface of the AF line sensor 13 changes in accordance with the interval between the mask 18 and the wafer 19, and the interval between the two spots is measured by measuring the interval between the two spots at this time. Are detected.

In this embodiment, as in the position detection method, even if the wafer 19 is tilted (Tilt) with respect to the mask 18, the two spots move on the AF line sensor 13 in the same direction by the same amount. Is unnecessary, and as a result, there is a feature that no surface interval detection error occurs. The above is the configuration of the surface interval detecting means according to the present invention.

Next, the operation for detecting the relative position between the mask and the wafer in the present invention will be specifically described.

8 and 9 show AA provided on the surface of the mask 18 and the wafer 19.
It is an explanatory view of a mark and an AF mark. FIG. 8A is a schematic diagram showing the relative positions of the AA mark and the AF mark when the position detection direction is taken along the x-axis, as viewed from a direction perpendicular to the mask surface and the wafer surface. An example is shown. FIG. 8 (B) shows a case where the positional relationship between the mask and the wafer is shifted by a distance Δ corresponding to the length of a single AA mark on the wafer surface in the x-axis direction, and a case where a surface interval is detected. Is shown.

FIGS. 9A and 9B show AA on the mask 18 and wafer 19 surfaces.
FIG. 4 is a perspective view of a main part showing a mark and an AF mark. Figure (A)
8 (A) corresponds to FIG. 8 (A), and FIG. 8 (B) corresponds to FIG. 8 (B).

In the figure, 15 is incident light, 20M1 and 20M2 are AA marks on the mask 18 surface, 21M1 is an AF mark on the mask 18 surface, and 20W1 and 20W2 are AA marks on the wafer 19 surface. The optical action is the same as that described with reference to FIGS.

In this embodiment, when detecting the relative position between the mask 18 and the wafer 19, first, as shown in FIGS. 8B and 9B, the position of the mask 18 and the wafer 19 is detected by the AA mark. At least the dimension (length) of a single mark in the direction (x-axis direction)
The mask 18 and the wafer are shifted relative to each other by 1/2 (in the figure, a single mark is shifted by a length Δ).
The detection of the surface interval with the position 19 is performed by the method shown in FIG.

At this time, the AA marks 20M1 and 20M2
A part of the A mark 20W2 corresponds to a no mark (a region where no mark exists). Therefore, no AA diffracted light is generated and a part of a large blurred image of the AA diffracted light does not enter the AF line sensor surface. As a result, it is possible to detect a surface interval having a good S / N ratio. In the present invention, even if noise light about 1/2 of the nozzle light does not shift the position to the AF line sensor, it is possible to relatively accurately detect the position even if noise light enters the AF line sensor. At least 1/2 or more.

Thus, in the present invention, AA for position detection
In order to prevent the diffracted light from entering the AF line sensor as noise, the relative position between the mask and the wafer must be at least 1 / A of the length of a single AA mark in the direction of detection of the AA mark on the wafer surface. Two or more (distance Δ / 2) are shifted using the length measuring device on the wafer stage.

Then, when detecting the position in the plane between the mask and the wafer, the value obtained by the plane distance detection is used, and the wafer stage is moved by X,
It is moved in the tertiary directions of Y and Z (x direction in this embodiment) to return to the original position, and the AA mark on the mask surface and the AA mark on the wafer surface
After the marks are substantially matched, the marking is performed by the method shown in FIG. In this manner, highly accurate relative position detection between the mask and the wafer is enabled.

Next, a sequence for performing position detection in the present invention will be described with reference to FIG.

10 (A), (B) and (C) are schematic diagrams when the mask and the wafer are viewed from a direction perpendicular to each surface. In the figure, 91 is a circuit pattern area on the mask surface, 93 _{1 to} 9
3 ₄ are indicated by solid lines respectively are marked area AA mark and AF marks on the mask surface. 92 circuit pattern area on the wafer surface, is 94 ₁ to 94 ₄ is shown with a dotted line, respectively a mark area AA marks on the wafer surface.

As the sequence, for example, (I) the surface interval between the mask and the wafer is set slightly larger than the proximity exposure gap, and the sequence moves to the next exposure wafer area.

(II) The distance between the mask and the wafer is detected. At this time, as shown in FIG. 10 (B), the wafer is shifted by a distance ΔX from a state where the mask and the wafer are intentionally substantially aligned (a state where the mask and the wafer substantially match by pre-alignment is measured in advance), and the wafer is moved in the XY direction.
Performing surface spacing detection in the state in which the mark area 93 _{1-93 4} set in the plane, 94 _{1-94 4} out of position.

At this time, the mark area of the area on the wafer side of the AF mark
93 ₁ and 93 there is no pattern in the position corresponding to the _third pattern is the mark areas 93 ₂ and 93 ₄ corresponding to the pattern (projected from AA marks and AF marks on the mask plane to the plane in the vertical direction the wafer plane Area), there is a circuit pattern.

Therefore, the presence / absence of a circuit pattern on the wafer surface causes the presence / absence of unevenness on the wafer surface, resulting in a difference in the absolute value of the surface interval detection. The amount of this difference is measured in advance as a representative value for each wafer process and prepared as a correction value, which is used at the time of detecting a surface interval. That is, the amount subtraction is a value when coming the circuit pattern on the wafer mark areas 93 ₂ and 93 ₄ to the plane interval detection value when there is no circuit patterns on the wafer opposite the mark areas 93 ₁ and 93 ₃ What is necessary is to convert it.

Further, as shown in FIG. 10 (C), the wafer is intentionally shifted by a distance ΔY in the Y direction to detect the surface interval. No pattern in this case FIG. 10 (B) if the opposite to the mark area 93 _2, 93 ₄ opposite the wafer, there is the circuit patterns on the wafer opposite the mark areas 93 _1, 93 ₃ Thus, the correction of the surface interval detection corresponding to this will be performed.

Here, the distances .DELTA.X and .DELTA.Y correspond to the distances .DELTA. Shown in FIGS. 8 (B) and 9 (B).
What is necessary is just to shift to at least 1/2 or more of the area size of 0M2.

When the wafer is shifted by the distance ΔX or the distance ΔY, the movement of the wafer stage is measured by a length measuring device, and the movement is performed based on the value of the length measuring device.

(III) Further, the wafer is moved in the plane (X and Y directions) and in the direction of the spacing so that the surface spacing between the mask and the wafer at the time of exposure is made based on the detection of the spacing between the mask and the wafer.

(IV) With the distance between the mask and the wafer set at the time of exposure, the in-plane position between the mask and the wafer is detected, and the wafer is rotated and moved in parallel so that it is completely zero in the plane. .

(V) The circuit pattern on the mask surface is exposed to X-rays and transferred onto the wafer surface.

(VI) The mask and the wafer are slightly separated from the exposure gap, and the wafer stage is moved to the next exposure wafer area.

 Hereinafter, returning to (I), the same process is repeated.

(Effects of the Invention) According to the present invention, when the relative position detection regarding the surface gap between the first object and the second object and the positional deviation in the plane is performed by one light projecting unit and one light receiving unit, as described above. By configuring each element, when detecting the surface interval between the first object and the second object, it is possible to prevent the light for detecting the displacement from being incident on the AF line sensor as noise, and to generate a signal having a high S / N ratio. This makes it possible to detect the surface interval with high accuracy.
It is possible to achieve a position detection device capable of detecting the position of the object and the second object in the plane with high accuracy.

[Brief description of the drawings]

FIG. 1 is a perspective view of an essential part of an embodiment of the present invention, FIGS. 2 and 3 are enlarged explanatory views of a part of FIG. 1, and FIGS. 4 and 5 are positional deviation detection and surface interval detection in the present invention. 6 and 7
Figures are explanatory diagrams showing the state of a light beam incident on a light receiving means surface in a conventional position detecting device, FIGS. 8 and 9 are explanatory diagrams of AA marks and AF marks provided on a mask and a wafer surface according to the present invention,
FIG. 10 is an explanatory view showing a relative positional relationship between a mask and a wafer, and FIGS. 11, 12, and 13 are schematic views of a conventional position detecting device. In the figure, 1 is a light source, 2 is a collimator lens, 3 is a slit, 4 is an entrance / 4 plate, 6 is a mirror, 10 is a light receiving lens, 18 is a mask, 19 is a wafer, and 20A, 20M1, 20M2, 20W1, and 20W2 are AA. Mark, 2
1M1 to 21M4 are AF marks.

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI H01L 21/30 502M (56) References JP-A-2-74815 (JP, A) JP-A-1-209305 (JP, A) (58) Field surveyed (Int.Cl. ⁶ , DB name) G01B 11/00-11/30 H01L 21/30

Claims (3)

(57) [Claims] An AA alignment mark is provided on each of a first object and a second object disposed opposite to each other to detect a relative in-plane displacement using an AA sensor, and both the first object and the second object are provided on the first object. An AF alignment mark for detecting the relative distance between the first object and the second object is provided by using an AF sensor.
When detecting both relative distances to the object, the light source means after displacing the relative in-plane positional relationship by a predetermined amount in a direction in which noise light from the AA alignment mark does not enter the AF sensor. From the AF alignment mark on the first object, and the light beam from the AF alignment mark is reflected on the second object surface to be incident on a predetermined surface;
A surface interval detecting unit configured to obtain an incident position on the predetermined surface by detecting the position with the AF sensor; and a method for detecting a relative in-plane displacement between the first object and the second object. Irradiates a light beam from the light source means on a predetermined surface after passing through the AA alignment marks of both the first object and the second object, and detects an incident position on the predetermined surface by the AA sensor. A position detecting device comprising: a position detecting means that is obtained by the following. 2. The method according to claim 1, wherein when detecting a relative surface distance between the first object and the second object, the relative positional relationship between the two surfaces is determined by an alignment direction of a single mark among the AA alignment marks. 2. The position detection device according to claim 1, wherein the adjustment is performed after adjusting the length to be at least 1/2 of the length. 3. The method according to claim 1, wherein the first object and the second object are positioned relative to each other by using the position detecting device according to claim 1 or 2.
An exposure apparatus for exposing and transferring a pattern on an object surface onto a second object surface.