JP2897085B2 - Horizontal position detecting apparatus and exposure apparatus having the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reference position detecting device, and more particularly to a horizontal position detecting device for accurately setting a wafer surface or a test object surface at a vertical position with respect to the optical axis of an objective lens.

[0002]

2. Description of the Related Art In general, a projection objective lens having a large numerical aperture (NA) is used in a reduction projection type exposure apparatus for manufacturing an integrated circuit, so that an allowable focal range is very small. Therefore, unless the exposure area of the wafer is maintained at an accurate vertical position with respect to the optical axis of the projection objective lens, a clear pattern cannot be exposed over the entire exposure area. The entire wafer can be aligned almost perpendicularly to the optical axis of the objective lens by detecting at least three points on the wafer surface by a separately provided auto-focus mechanism. If the performance is unstable, partial vertical position detection of the wafer is required. Since the deformation of the wafer is further increased by each exposure and chemical treatment, accurate horizontal detection of the exposure area is indispensable.

[0003]

For this reason, in order to maintain the best condition for each area to be exposed, an apparatus for detecting the state of inclination of a plane in each area has been proposed. Japanese Patent Application No. 58-13 by the same applicant as the present application
No. 706 is proposed. The apparatus disclosed herein is capable of accurately measuring the perpendicularity to the optical axis of a projection objective lens for each exposure region of a wafer in a projection exposure apparatus, and has an extremely excellent configuration. However, when the wafer to be tilt-detected is made of a transparent glass substrate, the reflected light from the back surface in addition to the light reflected from the front surface of the glass substrate also reaches the light-receiving element, so that an error occurs in the tilt detection. There was a case.

[0004] An object of the present invention is to provide a method of forming a region on a test surface formed in a predetermined conjugate relation with respect to an objective lens by using the objective lens even when the test region or the exposure region by the objective lens is formed of a transparent substrate. It is an object of the present invention to provide a horizontal position detecting device capable of accurately detecting that the position is perpendicular to the optical axis.

[0005]

According to the horizontal position detecting device of the present invention, as shown in FIGS. 1 and 4 shown in the embodiment of the present invention, a predetermined area on the surface of the object to be detected is set in a predetermined conjugate relationship. An irradiation optical system having a main objective optical system for forming, a light source and an irradiation objective lens for supplying a parallel light beam from outside the optical axis of the main objective optical system onto the surface of the test object, and the irradiation optical system A converging optical system having a converging objective lens for converging a light beam supplied from the system and reflected on the surface of the test object onto a light receiving element; In a horizontal position detection device that is arranged symmetrically with respect to the optical axis of the system, and detects inclination of the conjugate region from the optical axis of the main objective optical system with respect to the optical axis of the main objective optical system by an output signal of the light receiving element.
The irradiation optical system has a first light shielding plate having a plurality of slit-shaped openings projected onto a conjugate region of the test object, and the light condensing optical system has a plurality of light shielding plates having the same or similar shape as the first light shielding plate. A second light-shielding plate having a slit-shaped opening, wherein the second light-shielding plate is arranged conjugate with the object to be inspected, and the first light-shielding plate and the second light-shielding plate are reflected through the surface of the object to be inspected. (2) The light-shielding plate is conjugated with the light-shielding plate, and the longitudinal direction of the slit-shaped openings of the first and second light-shielding plates is set perpendicular to the incident surface including the optical axes of the irradiation optical system and the condensing optical system. This is the configuration that is performed.

The surface to be measured is a wafer made of a transparent substrate on which a predetermined pattern is projected and exposed by the main objective lens, and the irradiation area of the parallel light beam onto the wafer surface by the irradiation optical system is the main objective lens. It is desirable that the size of the exposure area on which the predetermined pattern is projected by the lens is substantially the same as that of the exposure area.

[0007]

According to the structure of the present invention, a plurality of slit-shaped patterns are projected onto the surface of the object to be inspected by the first light-shielding plate of the irradiation optical system, and light is received through the second light-shielding plate disposed in the light-collecting optical system. Accordingly, the first and second light-shielding plates are conjugate to each other with respect to the reflection on the surface of the test object, so that only the light reflected from the surface of the test object can be received, and the reflection from the back surface of the test object can be received. It is possible to eliminate the influence of light.

[0008] Then, the irradiation area of the parallel light beam on the test surface by the irradiation optical system is made substantially the same size as the conjugate area on the test surface formed in a predetermined conjugate relationship by the main objective lens. An average plane inclination can be detected for a conjugate region on the inspection surface. In a projection type exposure apparatus, the optimal angular position for the exposed partial region is set for each exposure of the wafer. can do.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments. FIG. 1 is a schematic optical path diagram showing a configuration in which a horizontal position detecting device according to the present invention is employed in a reduction projection type exposure apparatus. The reticle 2 and the surface of the wafer 3 are arranged conjugate with respect to the projection objective lens 1, and a pattern on the reticle 2 illuminated by an illumination optical system (not shown) is reduced and projected on the surface of the wafer 3. Such wafer printing exposure is repeated by moving the wafer by a predetermined amount, which is called step-and-repeat, and the same operation is repeated every time a reticle having a different pattern is replaced.

With the optical axis 1a of the reduction projection optical system interposed,
Light is irradiated from the irradiation optical system 10 onto the wafer 3 as a test object, and reflected light from the wafer 3 is received by the condensing optical system 20 to detect a horizontal position of an exposure area of the wafer 3, that is, Optical axis 1 of projection objective 1
The inclination from the vertical with respect to a is detected. The irradiation optical system 10 includes a light source 11, a collimator lens 12a, a condenser lens 12b, an aperture 13 having a small circular aperture, and an irradiation objective lens 14. The collimator lens 12a is
Is converted into a parallel light beam, and the condenser lens 12b collects the parallel light beam to form an image of the light source on the minute aperture of the stop 13. The irradiation objective lens 14 has a focal point on the minute opening of the aperture 13, and converts the divergent light beam from the minute opening into a parallel light beam by the irradiation objective lens 14 and supplies the parallel light beam onto the wafer 3. A first light-shielding plate 18 having a plurality of slit-shaped openings 18a is arranged between the collimator lens 12a and the condenser lens 12b as shown in the plan view of FIG. Projected on the surface. The longitudinal direction of the slit-shaped opening 18a is perpendicular to the incident surface (the paper surface in FIG. 1) including the optical axis 10a of the irradiation optical system 10 and the optical axis 20a of the light collecting optical system 20. The light supplied from the irradiation optical system 10 has a different wavelength from that of the exposure light for illuminating the reticle 2 so as not to expose the resist on the wafer 3.

The condenser optical system 20 includes a condenser objective lens 21, a collimator lens 22a, and condenser lenses 22b and 4c.
A light beam supplied from the irradiation optical system 10 and reflected by the surface of the wafer 3 has a divided light receiving element 23.
After being condensed at the focal position of the condenser objective lens by 1, it is converted into a parallel light beam by the collimator lens 22 a, and is condensed by the condenser lens 22 b on the four-division light receiving element 23 provided at the rear focal position. . Further, the condensing optical system 20
A second light-shielding plate 28 is disposed between the collimator lens 22a and the condenser lens 22b, and this position is conjugate with the surface of the wafer 3 as the object to be inspected. With respect to the reflection at the optics, the first
It is conjugate with the light shielding plate 18. The second light-shielding plate 28 has a plurality of slit-like openings similarly to the first light-shielding plate 18, and has a shape similar to that shown in FIG. 2, and the longitudinal direction of the slit-like opening is Similarly, it is arranged perpendicular to the plane of incidence.

In FIG. 1, light rays indicating the conjugate relationship with the light source are indicated by solid lines, and light rays indicating the conjugate relation with the respective light shielding plates and the wafer surface are indicated by broken lines. As shown by the solid line in the figure, the light beam irradiated on the wafer surface is a parallel light beam,
The light shielding plate 18 is also arranged in the parallel light beam. As described above, the projection system of the first light shielding plate 18 by the irradiation optical system is telecentric on both the object side and the image side. Similarly, the second light-shielding plate 28 disposed conjugate with the wafer surface in the condensing optical system is also telecentric on both sides. Therefore, the first light shielding plate 18 and the second
Even if the light-shielding plates 28 are arranged obliquely with respect to the optical axes 10a and 20a of the respective optical systems, and so-called tilted arrangements based on the Scheimpflug's principle, the light-shielding plates 28 are projected onto the wafer surface. There is no partial magnification difference, and a constant interval (pitch) between the plurality of slit openings on the light shielding plate is strictly maintained even on the wafer surface.

The so-called tilt arrangement based on Scheimpflug's principle is generally an arrangement in which three planes of an object plane, an image plane, and a main plane of an imaging optical system intersect on a straight line. In this arrangement, since the object distance and the image distance are different between the conjugate planes, it is inevitable that the imaging magnification differs depending on the position. However, a clear image is formed over the entire surface by adjusting the object plane or the image plane to a desired inclination. Can be formed. For this reason, based on Scheimpflug's principle, even when the conjugate area on the wafer surface, that is, the area where the pattern on the reticle is projected onto the wafer surface by the projection objective lens 1 is large, each light shielding plate Image can be clearly formed.

Here, the first light shielding plate 1 which is a feature of the present invention.
The configuration and operation of the eighth and second light shielding plates 28 will be described with reference to FIG. As described above, the light shielding plate 18 shown in FIG.
The second light shielding plate 28 projected on the surface of the wafer 3 and arranged in the condensing optical system 20 is also arranged conjugate with the surface of the wafer 3. When the wafer 3 is made of a transparent substrate such as glass, the generation of reflected light from the back surface is inevitable, but the reflected light from the back surface can be removed by the conjugate relationship described above. For this purpose, in a state where the plurality of slit-shaped openings provided in the first light-shielding plate 18 and the second light-shielding plate 28 are projected on the wafer 3, the pitch p of the images of the plurality of slit-shaped openings and the The width w needs to be determined in the following relationship.

FIG. 3 is an optical path showing an image of the first light shielding plate 18 projected on the surface of the wafer 3 as an object to be inspected and a state in which a parallel light beam reaching the wafer surface is reflected on the wafer surface and the back surface. FIG. In FIG. 3, light reflected on the front surface of the wafer is indicated by a solid line, and light reflected on the rear surface is indicated by a broken line. In FIG. 3, the first projected by the irradiation optical system
Light shielding plate 18 and second light shielding plate 2 provided in condensing optical system
The relationship 8 is shown as being synthesized at the conjugate position on the wafer 3.

In the plurality of slit images projected by the irradiation optical system, only the reflected light on the surface of the wafer 3 passes through the slit-shaped opening of the second light shielding plate 28 disposed in the condensing optical system. Be composed. Specifically, in FIG.
The opening 38a is formed between the opening 18a of the first light shielding plate 18 and the second
The light-shielding portion 38b corresponds to the light-shielding portion 18b of the first light-shielding plate 18 and the light-shielding portion 28b of the second light-shielding plate 28. Then, as shown in the figure, the light (broken line) reflected on the back surface 3 b of the wafer 3 is
8 b, that is, light is shielded by the light shielding portion 28 b of the light shielding plate 28.

When the incident angle of light supplied to the wafer surface by the irradiation optical system 10 is θ ₁ , the refraction angle in the wafer substrate 3 is θ ₂ , the thickness of the wafer substrate is d, and the refractive index is n. ,
According to the well-known law of refraction, sin θ ₁ = nsin θ ₂ (1) holds. Then, the lateral shift amount between the reflected light on the front surface 3a and the reflected light on the back surface 3b, that is, the deviation amount x of the back surface reflected light due to the back surface reflection in the wafer substrate is given by x = 2dtan θ ₂ (2) Can be

The lateral displacement amount x of the reflected light on the back surface 3b, the opening width w of the slit on the wafer, and the pitch p satisfy the relations x + w <p (3) and w <x (4). There is a need. If these relationships are combined, the condition is w <x <p−w (5), and it is necessary to satisfy this relationship.

The pitch p on the wafer surface and the width w of the opening are arbitrary within a range that satisfies the above relationship, but are selected as appropriate values from the relationship such as the variation width of the thickness of the wafer substrate. It is desirable to do. However, it is clear from the above relationship that the width w of the opening must not exceed 1/2 of the pitch p. However, assuming that w = p / 2 in order to maximize the aperture ratio (w / p), the thickness d of the substrate satisfying the relationship of the above equation (5) is: d = p / (4tan θ ₂ ) ( 6) It is limited to only one value of. In this case, inconvenience occurs when the thickness of the wafer substrate varies or when a substrate having a different thickness is used. Therefore, it is necessary to reduce the aperture ratio to less than 50%. If the aperture ratio is smaller than 50%, it is possible to cope with a substrate having a thickness d in a certain range. However, it is desirable to set the aperture ratio between 10% and 50% in view of the light quantity and the like.

For example, the refractive index of the wafer substrate is n = 1.50, the incident angle of the parallel light beam irradiated on the wafer by the irradiation optical system is θ ₁ = 60 °, and the pitch of the plurality of slit-shaped aperture images on the wafer is 3 mm. And the width w of the opening image 38a is 1 mm.
From the above equation (5), 1 mm <x <2 mm, and the thickness d of the wafer substrate is obtained from the relation of the above equation (2).
Is in the range of 0.7 mm <d <1.4 mm. Within this range, the above conditions can be satisfied.

As described above, the values of the plurality of slit-shaped aperture images on the wafer surface are used to determine the first light shielding plate 1 in the irradiation optical system.
8, the pitch p ₁ and the opening width w ₁ of the plurality of slit upper openings, and the pitch p ₂ and the opening width w ₂ of the plurality of slit openings in the second light shielding plate 28 in the condensing optical system are determined. . That is, each value for the plurality of slit-shaped openings in the first light shielding plate 18 and the second light shielding plate 28 is given by the product of the reciprocal of the projection magnification to the wafer surface. For this reason, when the first light-shielding plate 18 and the second light-shielding plate have an equal conjugate relationship via reflection on the wafer surface, the two light-shielding plates have the same shape and the same slit-shaped opening. , And p ₁ = p ₂ and w ₁ = w ₂ . However, when the conjugate relationship between the first light-shielding plate and the second light-shielding plate deviates from the same magnification, the shapes become similar.

In a practical configuration, the first light shielding plate 18 is projected onto the surface of the wafer 3 at a magnification of 1/2 and the second light shielding plate 28 is projected.
Also has a conjugated relationship of 1/2 with respect to the surface of the wafer 3, in which case the values for the plurality of slit-shaped openings on both light-shielding plates are the same as the values for the above-described wafer surface. 2
Will have twice the value. That is, p ₁ = p ₂ = 2p and w ₁ = w ₂ = 2w.

With the above configuration, it is possible to satisfactorily remove the reflected light from the back surface which cannot be avoided when the wafer as the test object is transparent. Since the optical axis 10a of the irradiation optical system 10 and the optical axis 20a of the condensing optical system 20 are arranged symmetrically with respect to the optical axis 1a of the projection objective lens 1, the optical axis 1a of the projection objective lens is On the other hand, if the exposure area on the surface of the wafer 3 is kept vertical, the light beam from the irradiation optical system 10 is focused on the center position of the four-divided light receiving element 22. If the exposure area on the surface of the wafer 3 is inclined by α from the vertical, the parallel light flux from the irradiation optical system 10 reflected by the wafer 3 is inclined by 2α with respect to the optical axis 20a of the condensing optical system. The light is condensed on the light receiving element 22 at a position off the center. The inclination direction of the exposure area of the wafer 3 is detected from the position of the condensing point on the four-divided light receiving element 22, and the control means 31 controls the displacement direction and the amount of displacement of the condensing point on the four-divided light receiving element And driving means 3
The support device 33 is moved by 2 to move the stage 34 on which the wafer 3 is placed so as to correct the inclination of the surface of the exposure area of the wafer 3.

Then, partial tilt detection is performed on the wafer surface in the range irradiated by the irradiation optical system 10,
By setting the irradiation area on the wafer 3 to be substantially the same size as the exposure area by the projection objective lens 1, the exposure area is automatically set to an accurate vertical position on average with respect to the optical axis 1a of the projection objective lens 1. can do. The detection of the inclination of the surface of the wafer 3 based on the position of the condensed spot formed on the light receiving element as described above is as described in the above-mentioned JP-A-58-113706.

In the configuration of the embodiment shown in FIG. 1, as described above, the first light shielding plate 1 projected by the irradiation optical system is used.
8 and the second light-shielding plate 28 arranged in the condensing optical system are telecentric on both sides with respect to the respective image formation, so that the slit image having a constant pitch can be formed without causing a partial magnification difference even in the tilted arrangement. Can be accurately projected. However, as described in relation to the pitch of the slit-shaped openings on the wafer surface, the width of the openings, and the like, there is a certain allowable range in practical use, so that both sides of the first and second light-shielding plates are required. Telecentricity is not necessary. However, since it is necessary to use a parallel light beam on the wafer side,
Telecentricity on the wafer side is required.

Although the first and second light-shielding plates are both so-called tilted arrangements based on the Scheimpflug principle, if the size of the light source is sufficiently small and the depth of focus is large, each light-shielding plate should be connected to the optical axis. It is also possible to arrange them perpendicularly to them.
In this case, the image of each light-shielding plate on the wafer surface slightly blurs in the peripheral portion thereof, but even if the light-shielding plate side (object side) is not telecentric, the magnification between the periphery and the center of the image is large. There is no difference. Therefore, the amount of blur at the peripheral portion, which depends on the size of the area of each light-shielding plate on the wafer surface to be projected, that is, the size of the area where the image of the reticle 2 is reduced and projected by the projection objective lens 1 can be tolerated. Then, it is possible to make the change in the pitch of the plurality of slit-shaped aperture images of each light shielding plate smaller than in the case of tilting.

FIG. 5 is a schematic optical path diagram showing the configuration of another embodiment in which the horizontal position detecting device according to the present invention shown in FIG. 4 is employed in a reduction projection type exposure apparatus. In the figure, members having the same functions as those shown in FIG. 1 are denoted by the same reference numerals. In this embodiment, only the wafer 3 side is telecentric with respect to the image forming relationship between the first light shielding plate 18 and the second light shielding plate 28 disposed in the irradiation optical system 10 and the condensing optical system 20, respectively. The plate side is not telecentric, and each light shielding plate is arranged perpendicular to the optical axis. That is, in the irradiation optical system 10, the light beam from the light source 11 is condensed on the minute opening of the stop 13 by the condenser lens 12, and the first light shielding plate 18 is arranged in the convergent light beam by the condenser lens 12. Further, in the condensing optical system 20, the light beam from the condensing point by the condensing objective lens 21 is condensed on the light receiving element 23 by the condenser lens 22, and the second light shielding plate 28 is in the diverging light path to the condenser lens 22. Are located. The other configuration is substantially the same as the configuration described above with reference to FIG.

In such a configuration, the first light shielding plate 18
And the second light shielding plate 28 is perpendicular to each optical axis,
In each conjugate relationship with the wafer surface, the image on the wafer surface of the plurality of slit-shaped openings with a constant pitch is maintained at a substantially constant pitch, and blurring at the periphery of the projected image is to reduce the size of the light source 11. Can be practically ignored. Also in this embodiment, similarly to the case described with reference to FIG. 3, it is possible to satisfactorily remove reflected light from the back surface which cannot be avoided when the wafer as the test object is transparent. Strictly speaking, each light shielding plate 1
The images 8 and 28 on the wafer surface are perpendicular to the optical axis and are not parallel to the wafer surface as shown in FIG. 3, but if the size of the light source is small and the depth of focus can be increased as described above, It can be seen that the configuration is substantially the same as that of FIG. Further, the wafer 3 is placed at the optimum position by the control means 31 via the driving means 32 in accordance with the output of the light receiving element 23, similarly to the above embodiment.

By the way, in the above description, it is possible to detect whether or not the partial area which is the exposure area on the wafer surface by the projection objective lens is located at a position perpendicular to the optical axis of the projection objective lens. However, the reticle image projected on the wafer surface by the projection objective lens is deliberately tilted by a small angle from perpendicular to the optical axis in order to overlap with the pattern already exposed and transferred on the wafer surface. In some cases. In such a case, it is needless to say that whether or not the surface of the wafer as the object surface to be detected is parallel to the image plane by the projection objective lens. However, since the wafer surface is basically arranged perpendicular to the optical axis of the projection objective lens, in the present invention, for the sake of clarification and simplification of the configuration, the above case is also included. It is detected whether or not the test object is positioned perpendicular to the optical axis of the main objective lens.

[0030]

As described above, according to the present invention, even when a partial area formed in a predetermined conjugate relationship with the main objective lens, such as an exposure area of a wafer by a reduced projection objective lens, is formed of a transparent substrate, it is possible to detect an object. Since the reflected light generated on the back surface of the object can be satisfactorily removed, the area on the surface to be measured which is formed in a predetermined conjugate relationship with the main objective lens is located at a position perpendicular to the optical axis of the objective lens. Can be accurately detected.

Even if the partial area irradiated with the parallel light beam has minute irregularities, the average plane of this partial area can be arranged perpendicularly to the optical axis of the main objective lens. The best image can be obtained over the entire partial area even when the range is very small. Note that the horizontal position detection device according to the present invention can be used not only for the reduction projection type exposure device shown in the embodiment but also for inspecting a test object with a microscope. It goes without saying that the conjugate area corresponds to the observation area by the microscope.

[Brief description of the drawings]

FIG. 1 is an optical path diagram showing a schematic configuration in which a horizontal position detecting device according to the present invention is applied to a reduction projection type exposure apparatus.

FIG. 2 is a plan view showing a configuration of a first light shielding plate and a second light shielding plate.

FIG. 3 is an optical path diagram illustrating a state of light on a test object (wafer).

FIG. 4 is an optical path diagram showing a schematic configuration in which a horizontal position detection device having another configuration according to the present invention is applied to a reduction projection type exposure apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Main objective lens 3 ... Test object (wafer) 10 ... Irradiation optical system 20 ... Condensing optical system 18 ... 1st light-shielding plate 28 ... 2nd light-shielding plate

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01B 11/26 H01L 21/30

Claims (5)

(57) [Claims] A main objective optical system for forming a predetermined area on a surface of a test object in a predetermined conjugate relationship, and a parallel light beam from outside the optical axis of the main objective optical system onto the surface of the test object. An irradiation optical system having a light source and an irradiation objective lens for supplying, and a condensing objective lens for condensing a light beam supplied from the irradiation optical system and reflected on the surface of the test object onto a light receiving element. A condensing optical system having the optical axes of the two optical systems arranged symmetrically with respect to the optical axis of the main objective optical system, and the output signal of the light receiving element with respect to the optical axis of the main objective optical system in the conjugate region. In a horizontal position detection device that performs tilt detection from a vertical direction, the irradiation optical system includes a first light shielding plate having a plurality of slit-shaped openings projected onto a conjugate region of the test object; Are a plurality of stripes having the same or similar shape as the first light shielding plate. A second light-shielding plate having a slot-shaped opening, wherein the second light-shielding plate is arranged conjugate with the object to be inspected, and the first light-shielding plate and the second light-shielding plate are reflected through the surface of the object to be inspected. (2) The light-shielding plate is conjugated with the light-shielding plate, and the longitudinal direction of the slit-shaped openings of the first and second light-shielding plates is set perpendicular to the incident surface including the optical axes of the irradiation optical system and the condensing optical system. A horizontal position detection device characterized in that: 2. The object to be inspected is a wafer made of a transparent substrate on which a predetermined pattern is projected and exposed by the main objective optical system, and the irradiation area of the parallel light beam onto the wafer surface by the irradiation optical system is 2. The horizontal position detecting device according to claim 1, wherein the size of the exposure area on which the pattern is projected by the main objective optical system is substantially the same. 3. The horizontal position detecting device according to claim 1, wherein said first and second light shielding plates are tilted with respect to said irradiation optical system and said condensing optical system. 4. An aperture ratio of said first and second light shielding plates is one.
4. The horizontal position detecting device according to claim 1, wherein the horizontal position is set between 0% and 50%. 5. An illumination optical system for illuminating a pattern on a reticle, and a main objective optical system for projecting a pattern image of the illuminated reticle onto a predetermined area on a substrate via the main objective optical system. In the exposure apparatus, a supporting means for mounting the substrate and correcting the inclination of the substrate; a light source and an irradiation objective lens for supplying a parallel light beam from outside the optical axis of the main objective optical system onto the substrate surface And a condensing optical system having a condensing objective lens for condensing a light beam supplied from the irradiation optical system and reflected on the substrate surface onto a light receiving element. The optical axes of both optical systems are symmetrically arranged with respect to the optical axis of the main objective optical system; the irradiation optical system includes a first light shielding plate having a plurality of slit-shaped openings projected onto the predetermined area of the substrate. The light-collecting optical system includes the first light-shielding plate; A second light-shielding plate having a plurality of slit-shaped openings of the same or similar shape; the second light-shielding plate is arranged conjugate with the substrate; the first light-shielding through reflection on the surface of the test object The plate and the second light-shielding plate are conjugated with each other; the longitudinal direction of the slit-shaped openings of the first and second light-shielding plates is with respect to an incident surface including the optical axes of the irradiation optical system and the light-collecting optical system. Control means for controlling the support means in accordance with an inclination of the predetermined area from a perpendicular to an optical axis of the main objective optical system according to an output signal of the light receiving element. Exposure apparatus.