JPH05259029A - Position detector - Google Patents

Abstract

PURPOSE:To avert the effect of interference fringe without devising any specific means for a luminescence optical system to reduce the interference fringe. CONSTITUTION:A luminescence optical system is composed of a beam fairing optical system 4 emitting parallel light fuxes, a fly-eye lens 5 forming multiple secondary light sources by the parallel light fuxes as well as focussing optical systems 6, 9, 11 focussing the light emitted from those multiple secondary light sources to illuminate a reticle mark RM while the fly-eye lens 5 is to be free rotatively arranged centering on an axle in parallel with an optical axis of the luminescence optical system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting apparatus suitable for application to an alignment system of an exposure apparatus used for manufacturing a semiconductor device or the like.

[0002]

2. Description of the Related Art For example, a projection exposure apparatus is used for transferring a circuit pattern or the like drawn on a reticle onto a photosensitive substrate such as a wafer in a lithography process for manufacturing a semiconductor device or the like. In general, since a semiconductor element or the like is composed of a plurality of layers, it is necessary to sequentially expose different patterns of different reticles on the same photosensitive substrate via a projection optical system. In the case of exposing different reticle patterns on the previous layer in an overlapping manner as described above, an alignment step, which is a step of aligning the reticle pattern of this time with the previous layer, is necessary.

One of the methods for performing such alignment with high accuracy is a TTR (through-the-reticle) alignment method. In this TTR method, alignment marks are provided on each shot area of the reticle and the photosensitive substrate. It is formed. Then, as an example, the alignment light from the illumination optical system for alignment is used as an alignment mark on the reticle side (hereinafter referred to as “reticle mark”).
The image of the reticle mark is formed by the reflected light on the light receiving surface of the image pickup element in the light receiving optical system for alignment. Also, the alignment light transmitted near the reticle mark is focused on the alignment mark on the photosensitive substrate side (hereinafter referred to as “wafer mark”) by the projection optical system, and the alignment light reflected from this wafer mark is projected by the projection optical system. It is incident on the light receiving optical system for alignment through the system and the reticle, and the image of the wafer mark is formed on the light receiving surface of the image pickup device by this alignment light.

By setting the relative positional relationship between the image of the reticle mark and the image of the wafer mark to a predetermined state, the reticle and each shot area of the photosensitive substrate can be aligned. In this case, in order to perform the alignment with higher accuracy, the reticle mark and the wafer mark are illuminated with almost the same light flux of the alignment light, and the image of the reticle mark and the image of the wafer mark are formed on the same light receiving surface of the image sensor. It is desirable to form an image. For this purpose, the light receiving surface, the pattern forming surface of the reticle, and the exposure surface of the photosensitive substrate must be conjugated under the alignment light.

In this regard, conventionally, with emphasis on not exposing the photosensitive material such as the resist of the photosensitive substrate to light, as the alignment light, light having low photosensitivity to the photosensitive material, for example, light in the vicinity of red has been used. When the wavelength bands of the exposure light and the alignment light are different as described above, the pattern formation surface of the reticle and the exposure surface of the photosensitive substrate are not conjugate under the alignment light due to the chromatic aberration of the projection optical system. Therefore, in order to form the image of the reticle mark and the image of the wafer mark on the same light receiving surface of the image pickup device, for example, a focal length for the light from the reticle mark and the light from the wafer mark as in a bifocal optical system. However, it is necessary to provide a different correction optical system.

In order to avoid the provision of such a correction optical system and perform alignment with higher accuracy, the wavelength band of the exposure light and the wavelength band of the alignment light may be the same. Even in this case, generally, the wafer mark is formed in the vicinity of the actual circuit pattern and the like, and by removing the photosensitive material on the wafer mark in advance, the absorption of alignment light by the photosensitive material and the photosensitive material and the wafer can be prevented. It is possible to prevent interference of alignment light and the like that occur with the substrate and form a good wafer mark image on the light receiving surface.

Recently, in order to expose a finer circuit pattern, as the exposure light, g rays of a mercury lamp, i
Laser light having a relatively large coherence such as an excimer laser such as a KrF laser or a metal vapor laser having a wavelength shorter than that of light such as a line has come to be used. If an illumination optical system for alignment that uses the exposure light made of such laser light as it is as the alignment light is configured, the following will be given as an example.

That is, laser light as alignment light from a laser light source is applied to an optical integrator or the like to form a large number of secondary light sources, and the laser light from these secondary light sources is superposed through a condenser lens. The reticle mark is illuminated, and the wafer mark is also illuminated by the laser light that has passed near the reticle mark. In this case, since the secondary light source has a predetermined size, the σ value, which is a factor representing the coherency of the illumination light, is a value larger than 0 corresponding to perfect coherent light. Further, in this case, since the reticle mark and the wafer mark are conjugated with respect to the projection optical system, in the light receiving optical system for alignment, the reflected light from the reticle mark and the reflected light from the wafer mark are the same with a simple configuration. Images can be simultaneously formed on the light receiving surface of the.

[0009]

However, the light from the reticle mark and the wafer mark illuminated by the laser light having a σ value (coherency factor) larger than 0 is detected, and the relative positional relationship between these marks is detected. When measuring, due to the strong coherence characteristic of laser light,
The laser light has a disadvantage that interference fringes such as speckles and fringes are generated in the illumination field on the marks. Due to such interference fringes, the illuminance in the illumination field becomes non-uniform, erroneous detection of these marks may occur, and the alignment accuracy may deteriorate.

In addition, interference fringes such as speckles have been conventionally observed in a measuring instrument or the like using a laser beam. In the past, however, special contrivances were made in the illumination system of the laser beam to generate the interference fringes. Was suppressed. As a method of reducing the interference fringes, there are a dynamic reducing method and a static reducing method. In the dynamic reduction method, the interference fringes in the illumination field are moved by vibrating the angle of the reflection mirror placed in the optical path or rotating the diffuser plate placed in the optical path around the optical axis. Thus, by making the illuminance distribution of the laser light uniform throughout the time during position detection, the appearance of interference fringes can be suppressed in appearance. On the other hand, in the static reduction method, the
Occurrence of interference fringes itself by arranging some kind of optical member in the optical path between the secondary light source and the laser light source so that each secondary light source has a phase difference or an optical path difference exceeding the coherence length. Things are reduced.

However, the dynamic reduction method requires a certain amount of time for averaging and is disadvantageous in shortening the measurement time and improving throughput. In particular, pulse lasers such as excimer lasers have variations in power between each pulse and there is a limit to shortening the pulse repetition period. Dynamic reduction methods are not suitable because they are difficult to average. Further, even if the static reduction method is used, there is a problem that interference fringe reduction is insufficient due to manufacturing error of the optical member for that purpose.

In view of the above point, the present invention disposes a special optical member or the like for reducing interference fringes in the illumination optical system even when light having strong coherence such as laser light is used as the illumination light. It is an object of the present invention to provide a position detection device that is not easily affected by interference fringes.

[0013]

A position detecting apparatus according to the present invention comprises an illumination optical system for illuminating a position detection mark RM formed on an object (13) to be inspected with light AL, as shown in FIG. 1, for example. In a position detecting device having a detecting means (11, 19, 20) for detecting the light from the position detecting mark and detecting the position of the position detecting mark, the illumination optical system supplies a parallel luminous flux. Luminous flux source (1,4)
An optical integrator (5) that forms a plurality of secondary light sources by the parallel light flux, and a condensing optical system (6) that condenses light from the plurality of secondary light sources and illuminates the position detection mark RM. 9, 11), and the optical integrator (5) of the optical axis AX of the illumination optical system.
It is arranged rotatably around an axis parallel to the.

[0014]

According to the present invention, the optical integrator (5) is rotated about its axis and fixed at an appropriate angle. At this time, the interference fringes also rotate in the illumination field of the illumination optical system. In this case, the rotation amount of the optical integrator (5) is determined by the position with respect to the direction of, for example, a lattice-shaped interference fringe formed on the position detection mark RM due to the interference of light from the plurality of secondary light sources. It is set so that the detection direction of the detection mark RM is displaced. As a result, the arrangement direction of the periodical illuminance unevenness in the illumination field of the illumination optical system caused by the interference fringes is determined by the position detection mark R.
It can be set to a direction in which unevenness is reduced with respect to the measurement direction of M. Therefore, the uneven illuminance detected by the detecting means is smaller than the actual uneven illuminance.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the position detecting device according to the present invention will be described below with reference to the drawings. In this embodiment, the present invention is applied to a projection exposure apparatus that includes a TTR type alignment system and uses laser light as alignment light.

FIG. 1 shows a projection exposure apparatus of this example, and the alignment system in FIG. 1 will be described first. Reference numeral 1 denotes a laser light source including an excimer laser, and laser light AL as alignment light emitted from the laser light source 1
Is reflected by the shutter 2 and made incident on the beam shaping optical system 4. By rotating the shutter 2 via the drive motor 3, the laser light is supplied to the illumination optical system for exposure light described later. The cross section of the laser light emitted from the laser light source 1 is generally a small rectangle, but the laser light is converted by the beam shaping optical system 4 which also serves as a beam expander into a parallel light flux having a square cross section of a desired size. ..

Reference numeral 5 denotes a fly-eye lens as an optical integrator, and a parallel laser beam AL having a square cross section of a desired size is incident on the front surface of the fly-eye lens 5. A large number of secondary light sources are formed on the focal plane on the rear side (reticle side) of the optical integrator 5. The optical integrator 5 is rotatably supported around the optical axis AX, and is attached so that it can be fixed at a position rotated by a desired angle.
At this time, for example, the beam shaping optical system 4 may be integrally rotated.

The laser light emitted from the secondary light source is guided to the beam splitter 10 via the condenser lens 6, the field stop 7, the mirror 8 and the illumination lens 9. The field stop 7 is arranged on a surface conjugate with the pattern forming surface of the reticle 13 described later, and this can limit the illumination area on the reticle 13. The laser light reflected by the beam splitter 10 is irradiated onto the reticle mark RM of the reticle 13 via the objective lens 11 and the mirror 12. The reticle mark RM is formed near the pattern area of the reticle 13. Reference numeral 14 denotes a projection optical system which is both-side telecentric and whose chromatic aberration has been corrected with respect to the laser light emitted from the light source 1. The pattern in the pattern area of the reticle 13 is transferred to the wafer 16 on the wafer stage 15 via the projection optical system 14. The wafer marks WM are transferred to the respective upper shot areas, and wafer marks WM are formed (for example, by the first exposure) at predetermined positions in the respective shot areas of the wafer 16 or in the vicinity thereof. Further, the surface of the fly-eye lens 5 on which the secondary light source is formed and the surface of the reticle 13 on which the reticle mark RM is formed have an optical Fourier transform relationship.

The laser light AL transmitted through the reticle mark RM itself or in the vicinity thereof is applied to a region on the wafer 16 which is conjugate with the reticle mark RM via the projection optical system 14. The laser beam AL is applied to the wafer mark WM on the wafer 16 or the vicinity thereof in advance by another rough alignment with high accuracy. The wafer stage 15 on which the wafer 16 is placed is an XY stage that is two-dimensionally movable in a plane perpendicular to the optical axis of the projection optical system 14, and Z that moves the wafer 16 in the optical axis direction of the projection optical system 14. Stage and wafer 1
It is composed of a wafer stage or the like for rotating 6 by a slight angle. Reference numeral 18 is a control system for controlling the operation of the entire apparatus,
Indicates a stage drive unit, and the control system 18 operates the wafer stage 15 via the stage drive unit 17 to position the wafer 16 three-dimensionally. The coordinates of the position corresponding to the optical axis of the projection optical system 14 on the wafer stage 15 are constantly monitored by a laser interferometer (not shown).

Also, the reticle mark RM of the reticle 13
The reticle mark RM within the laser light AL irradiated on the
The laser light reflected from the laser beam is returned to the beam splitter 10 via the mirror 12 and the objective lens 11. The laser light transmitted through the beam splitter 10 is focused by the relay lens 19 on the light receiving surface of the two-dimensional charge-coupled image pickup device (CCD) 20.
An image of the reticle mark RM is formed on the light receiving surface of 20.

On the other hand, the reflected light from the wafer mark WM of the wafer 16 or its vicinity is returned to the reticle mark RM of the reticle 13 or its vicinity via the projection optical system 14.
An image of the wafer mark WM is formed on the surface on which the reticle mark RM is formed. The laser light from the image of the wafer mark WM is returned to the beam splitter 10 via the mirror 12 and the objective lens 11. Then, the laser light transmitted through the beam splitter 10 is focused on the light receiving surface of the CCD 20 by the relay lens 19, whereby the CCD 20
An image of the wafer mark WM is formed on the light-receiving surface of the image in the form of being superimposed on the image of the reticle mark RM.

The light receiving surface of the CCD 20, the pattern forming surface of the reticle 13, and the exposure surface of the wafer 16 are laser light AL.
Since they are conjugate with respect to each other, the image of the reticle mark RM and the image of the wafer mark WM are clearly formed on the light receiving surface of the CCD 20. Therefore, the positional relationship between the reticle 13 and the shot area of the wafer 16 can be measured with high accuracy based on the positional relationship between these two images. Its CCD2
The image pickup signal output from 0 is supplied to the control system 18. The control system 18 sets the measured positional relationship between the reticle 13 and the wafer 16 to a predetermined relationship.
The wafer stage 15 is positioned via the stage drive system 17.

Next, the illumination optical system for the exposure light will be explained. With the shutter 2 opened, the illumination optical system 22 for the exposure light emits the laser light emitted from the laser light source 1 through the mirror 21. Lead to. The illumination optical system 22 includes a beam shaping optical system, an optical integrator, an aperture stop, an output lens, a reticle blind, and the like. The laser light emitted from the illumination optical system 22 is a first condenser lens 23, a mirror 24, and a second condenser. The principal ray is converted into a substantially parallel laser beam for exposure through the lens 25, and this laser beam illuminates the reticle 13 with a substantially uniform illuminance.

The setting position of the fly-eye lens 5 in the illumination optical system for alignment will be described with reference to FIG. FIG. 2 shows the alignment illumination optical system of FIG. 1 in a simplified manner. In FIG. 2, reference numeral 26 is a condenser lens representing the optical system including the condenser lens 6, the illumination lens 9 and the objective lens 11 of FIG. Is. On the front focal plane of the condenser lens 26, a plurality of secondary light sources formed by the fly-eye lens 5 from the laser light AL as alignment light are arranged.
An interference fringe 27 as a Fourier transform image of the secondary light source formed by the fly-eye lens 5 is formed in the illumination field on the surface Q1 that matches the rear focal plane. Also, this surface Q1 is shown in FIG.
The pattern formation surface of the reticle 13 and the exposure surface of the wafer 16 are conjugated, and the purpose is to reduce the unevenness of the intensity distribution of the interference fringes in the measurement direction on the surface Q1.

When the fly-eye lens 5 is constructed by arranging a large number of minute rectangular lens elements in a lattice pattern, the interference fringes 27 on the surface Q1 are also included in the fly-eye lens 5.
The pattern is a grid pattern that is substantially similar to the grid of the exit surface.
When the measurement direction of the reticle mark RM and the like is the X direction in FIG. 2 and the Y direction perpendicular thereto, the angle φ formed by the grating of the interference fringes 27 with respect to the X axis is 4 in this example.
Set around 5 ° ± 10 °. In this case, the angle φ formed by the lattice with respect to the Y axis is also about 45 ° ± 10 °. For this purpose, the angle φ formed by the grating of the fly-eye lens 5 with respect to the X direction may be set to about 45 ° ± 10 °. It was found that this suppresses the illuminance unevenness caused by the interference fringes in the measurement direction, but the theoretical consideration will be given below.

First, FIG. 3 shows the illumination optical system for alignment of FIG. 1 in a simplified manner. In FIG. 3, reference numeral 26 represents an optical system comprising the condenser lens 6, illumination lens 9 and objective lens 11 of FIG. It is a condenser lens represented by. The laser light AL emitted from the laser light source 1 of FIG. 1 and having passed through the beam shaping optical system 4 has a fly-eye lens 5 as an optical integrator composed of elements having a rectangular cross section arranged in a grid pattern as shown in FIG. The laser light from the secondary light source formed by the fly-eye lens 5 illuminates the alignment mark such as the reticle mark RM on the surface Q1 which is the rear focal plane through the condenser lens 26. Secondary light sources are generated on the exit surface side of each element of the fly-eye lens 5,
For example, when the laser light AL is the laser light of an excimer laser, the degree of coherence of the laser light is relatively weak, and therefore it may be considered that only adjacent secondary light sources interfere weakly with each other.

In this case, as shown in FIG. 4, the secondary light source 2
Consider the light that is emitted from 8 and has an angle θ (which is assumed to be sufficiently small) with respect to the optical axis of the illumination optical system and satisfies the following equation. Here, λ is the wavelength of the laser light, d is the arrangement pitch of the elements of the fly-eye lens 5, and m is an integer. θ = mλ / d This light strengthens each other where the height Y from the optical axis on the rear focal plane Q1 of the condenser lens 26 is expressed by the following equation to form a bright portion. However, f is the condenser lens 26
Is the focal length of. Y = fθ = fmλ / d

On the other hand, when the angle θ formed with respect to the optical axis of the illumination optical system (θ is assumed to be sufficiently small), the light satisfying the following equation is θ = (m + 1/2) λ / d of the condenser lens 26. The height Y from the optical axis on the rear focal plane Q1 cancels each other out at a position represented by the following equation, and forms a dark portion. Y = fθ = f (m + 1/2) λ / d A curve 29 on the surface Q1 in FIG. 4 shows the intensity distribution of the cross section of the interference fringe 27 in FIG. 3, and is formed on the surface Q1 as shown in FIG. In the interference fringes formed, the bright portion 29a and the dark portion 29b are periodically repeated in the Y direction, and similarly, the bright portion and the dark portion are also periodically repeated in the X direction perpendicular to the Y direction.

When the array of elements forming the fly-eye lens 5 has a periodicity in this way, periodical illuminance unevenness occurs in the illumination area of the alignment mark. Figure 5
As shown in, the image of the alignment mark on the surface Q1 is projected on the light receiving surface of the CCD 20 by the objective lens 30 to detect the position of the mark. When the numerical aperture of the objective lens 30 is NA and the coherency factor (σ value) of the illumination light is σ, the diameter D of the aperture stop arranged on the front focal plane of the condenser lens 26 is 2σfNA. Further, assuming that the number of elements having the above-described rectangular cross section (square shape with one side length d) is n (n is an integer of 1 or more) in the circle of the aperture stop, the following equation is established. To do. π (σfNA) ² ≈nd ^{2 From} this equation, the following equation is derived. d≈σfNA (π / n) ^1/2

When the period (pitch) of the interference fringes generated in the illumination area of the alignment mark is P, the period P is as follows. P = fλ / d ≈fλ (n / π) ^1/2 / (σfNA) = λ (n) ^1/2 / {(π) ^1/2 σNA}

For example, considering that σ = 0.5,
(Π) ^1/2 σ≈1, and the following equation holds. P≈ (n) ^1/2 × λ / NA In order to guarantee the denseness of the illumination light flux, the larger the number of elements n of the fly-eye lens 5, the better, but it is about 10 or more in practice. Therefore, the interval of the period P of the interference fringes is several times the resolution of the objective lens 30.

When the optical axis of the illumination optical system for the alignment light is straight, as shown in FIG. 6, the direction of the array period of the elements of the fly-eye lens 5 and the direction of the uneven illuminance period coincide with each other. In addition, the cycle of the uneven illuminance is about several times the resolution of the objective lens 30, and the size of the uneven illuminance is about several percent depending on the degree of coherence of the laser beam. In FIG.
6A shows a distribution of secondary light sources arranged vertically and horizontally at a pitch d on the rear focal plane of the fly-eye lens 5, and FIG.
Is the period P in the vertical and horizontal directions on the back focal plane of the condenser lens 26.
6C shows the state of the interference fringes 27 formed in FIG. 6C, and FIG. 6C shows the illuminance distribution E on the X axis where the Y coordinate of the interference fringes 27 is y _0.
(X, y ₀ ) is shown. In this example, as shown in FIG. 6A, the secondary light sources 28a and 28b (or 2) that are vertically and horizontally adjacent to each other are used.
The light from the secondary light sources 28b and 28c) interferes weakly,
Light from the secondary light sources 28c and 28d adjacent to each other in an oblique direction does not interfere, but even if they interfere, they are very weak and can be ignored. Further, in FIG. 6C, the illuminance distribution in the X direction, which is the measurement direction, has unevenness of the width Δ.

Considering the case where an alignment mark in an illumination field, which generally has illuminance unevenness, is detected by image processing of an image pickup signal of the CCD 20, the light intensity distribution and the illuminance unevenness due to the image of the alignment mark are caused on the light receiving surface of the CCD or the like. Light intensity unevenness is mixed. As a result of the uneven illuminance distorting the original alignment mark image, a measurement error such as deterioration of reproducibility of position measurement of this mark and offset of the measurement result occurs.

In the case of measuring the position of the alignment mark in the illumination field where the above-mentioned periodical illuminance unevenness occurs,
In addition to the size of the illuminance unevenness and the interval of the cycle, the angle formed by the direction of the cycle of the illuminance unevenness and the direction of position measurement has a significant influence on the measurement accuracy. This is because if the illuminance nonuniformity is extremely small with respect to the resolution of the objective lens 30 or the detection accuracy of the CCD 20, or if the illuminance nonuniformity is very large, even if the illuminance nonuniformity is large, there is no effect on the position measurement accuracy. No big deal. However, when the cycle is not so different from the resolution and the like in the illuminance unevenness due to the fly-eye lens 5, the measurement accuracy is deteriorated even if the illuminance unevenness is small.

However, even if such illuminance unevenness occurs, it is possible to suppress deterioration of measurement accuracy by changing the direction of the cycle of the illuminance unevenness. FIG. 7A shows the state of the interference fringes 27 in the illumination field plane, where the X axis is the measurement direction of the position of the alignment mark and the Y axis is the non-measurement direction, and the X axis direction and the periodic direction of the illuminance unevenness are The illuminance distribution when they match is shown. On the other hand, FIG. 8A shows the illuminance distribution of the interference fringes 27 when the fly-eye lens 5 is rotated about the optical axis of the illumination optical system and the periodic direction of the illuminance unevenness is shifted from the X-axis direction. Shows. Further, FIGS. 7B and 8B show coordinates X1 to X1 on the X-axis corresponding to FIGS. 7A and 8A, respectively.
The illuminance distribution E (x, 0) of X2 is shown. In both cases, it is shown that periodical illuminance unevenness occurs, but the longer illuminance unevenness cycle shown in FIG. 8B is due to the X-axis and the illuminance unevenness cycle direction. This is because they are out of alignment. The size of the uneven illuminance is the same in both cases.

On the other hand, FIGS. 7 (c) and 8 (c) similarly show the illuminance distributions in the X-axis direction corresponding to FIGS. 7 (a) and 8 (a), respectively. To + y1 are integrated (integrated) in the illuminance distribution. That is, the illuminance distribution E (X) in this case is expressed as follows, where the integral symbol ∫ represents the integral from −y1 to + y1 with respect to y. E (x) = ∫E (x, y) dy

The illuminance distribution of FIG. 7C is a distribution in which there is a periodical illuminance unevenness similar to the case of FIG. 7B, but the illuminance distribution of FIG. 8C is that of FIG. 8B. Unlike the periodic illuminance unevenness distribution in the above case, the distribution has almost no illuminance unevenness.
In FIG. 8C, the illuminance unevenness is smoothed by integrating the illuminance distribution in the non-measurement direction (Y direction), and an apparently uniform illuminance distribution is obtained. By effectively equalizing the periodic illuminance unevenness in this manner, deterioration of measurement reproducibility is prevented.

Although the alignment illumination systems 2 to 10 are installed in FIG. 1 in the above embodiment, the mirror 12 is made into a half mirror to align a part of the laser light of the exposure illumination optical systems 21 to 25. It may be used as illumination light for use. In this case, the reticle blind in the illumination optical system 22 is used instead of the field stop 17 to limit the field of view to illuminate only the reticle mark RM of the reticle 13 or its vicinity, and the fly eye in the illumination optical system 22. When the lens is aligned, the optical axis center of the illumination optical system 22 is rotated about 45 ° ± 10 ° and the cycle of the interference fringes is shifted from the measurement direction of the reticle mark RM or the wafer mark WM. The effect of reducing interference fringes is obtained. Further, although the fly-eye lens is used as the optical integrator in the above-described embodiment, a rod lens, for example, may be used as the optical integrator in addition to the fly-eye lens. Further, the present invention can be widely applied not only to the TTR type alignment system as shown in FIG. 1 but also to generally detecting a mark for positioning an object to be inspected. As described above, the present invention is not limited to the above-described embodiments, and various configurations can be taken without departing from the gist of the present invention.

[0039]

According to the present invention, the optical integrator is rotatably arranged. Therefore, by rotating the optical integrator, the detection direction of the position detection mark deviates from the direction of, for example, a lattice-shaped interference fringe formed on the position detection mark by the interference of light from the plurality of secondary light sources. By setting in this way, there is an advantage that the interference fringes formed by the interference of the illumination light in the illumination field of the illumination optical system can be reduced and the position can be detected with high accuracy.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a projection exposure apparatus of an embodiment of a position detection apparatus according to the present invention.

FIG. 2 is a simplified perspective view for explaining a method for adjusting the fly-eye lens 5 in FIG.

3 is a perspective view showing a simplified illumination optical system for alignment of FIG. 1. FIG.

FIG. 4 is a side view of FIG.

5 is a side view showing a simplified illumination optical system and detection optical system for alignment of FIG. 1. FIG.

6A is a diagram showing a distribution of a secondary light source by the fly-eye lens 5 in FIG. 3, FIG. 6B is a diagram showing a state of interference fringes on a surface Q1 in FIG. 3, and FIG. It is a distribution diagram which shows the illuminance distribution along the cross section of the direction parallel to the X-axis of FIG.6 (b).

7A is a diagram showing a state of interference fringes on a surface Q1 of FIG. 3 when the cycle direction of the fly-eye lens 5 of FIG. 3 is parallel to the measurement direction, and FIG. 7B is FIG. ) Is a distribution diagram showing an illuminance distribution along a cross section in a direction parallel to the X axis, and FIG.
It is a distribution chart which expands the illuminance distribution obtained by integrating the illuminance distribution of (a) over a predetermined range of the Y-axis direction in the direction parallel to the X-axis.

8A is a diagram showing a state of interference fringes on the surface Q1 of FIG. 3 when the cycle direction of the fly-eye lens 5 of FIG. 3 is inclined with respect to the measurement direction, and FIG. 7 (a) is a distribution diagram showing an illuminance distribution along a cross section in a direction parallel to the X axis, (c)
FIG. 8 is a distribution diagram showing an illuminance distribution obtained by integrating the illuminance distribution of FIG. 7A over a predetermined range in the Y-axis direction in a direction parallel to the X-axis.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 laser light source 4 beam shaping optical system 5 fly eye lens 6 condenser lens 9 illumination lens 11 objective lens 13 reticle RM reticle mark 14 projection optical system 16 wafer WM wafer mark 19 relay lens 20 two-dimensional CCD 26 condenser lens 27 interference fringe 30 Objective lens

Claims (1)

[Claims] 1. An illumination optical system for illuminating a position detection mark formed on an object to be inspected with light, and a detection means for detecting light from the position detection mark, the position of the position detection mark being detected. In the position detecting device for detecting, the illumination optical system includes a parallel light flux supply source that supplies a parallel light flux, an optical integrator that forms a plurality of secondary light sources by the parallel light flux, and light from the plurality of secondary light sources. A condensing optical system for condensing and illuminating the position detection mark, wherein the optical integrator is rotatably provided around an axis parallel to an optical axis of the illuminating optical system. Position detection device.