JPH07192987A - Projection aligner - Google Patents

Abstract

PURPOSE:To detect the focal position or the angle of inclination of a photosensitive substrate over a wide detection range without arranging a complicated optical system near the side of the photosensitive substrate in a projection optical system even when the projection optical system becomes large. CONSTITUTION:Detection light AL from a light-sending system 20 is applied to a measuring point Q on a glass substrate 102 via a projection optical system 100 and a mirror 9A, and a slit image is projected obliquely onto the measuring point Q. Reflected light from the slit image is guided to a light-receiving system 21 via a mirror 9B and the projection optical system 100, and the focal position of the galss substrate 102 is detected on the basis of the transverse deviation amount of the slit image which has been formed again inside the light-receiving system 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus for projecting and exposing, for example, a pattern of a photomask or a reticle onto a photosensitive substrate via a projection optical system, and more particularly, to a focus position or an inclination angle of an exposure surface of the photosensitive substrate. It is suitable for application to a projection exposure apparatus that has a detection mechanism and is used for manufacturing a liquid crystal display element.

[0002]

2. Description of the Related Art When manufacturing a semiconductor device, a liquid crystal display device or the like by a photolithography process, a pattern image of a photomask or reticle (hereinafter, "reticle" is used as an example) is used as a photoresist through a projection optical system. A projection exposure apparatus that exposes each shot area on a substrate (semiconductor wafer, glass plate, or the like) coated with is used. In such a projection exposure apparatus, since the pattern image of the reticle is always projected on the substrate with high resolution, the height (focus position) of a predetermined measurement point on the exposure surface of the substrate is set with respect to the image plane of the projection optical system. An autofocus mechanism for adjusting and an autoleveling mechanism for adjusting the tilt angle of the exposure surface to the tilt angle of the image surface are provided. The auto focus mechanism and the auto leveling mechanism are respectively provided with a focus position detection system and a tilt angle detection system of an oblique incidence type.

FIG. 8 shows a grazing incidence type focus position detection system provided in a projection exposure apparatus (liquid crystal exposure apparatus) for manufacturing a liquid crystal display element. In FIG. 8, a reticle pattern not shown is shown. The image is projected and exposed under exposure light onto the glass substrate 102 coated with the photoresist through the projection optical system 100. In the focus position detection system arranged on the side surface of the projection optical system 100, the light emitted from the light source 1 such as a light emitting diode (LED) is radiated onto the light transmission slit plate 3 via the condenser lens 2 to transmit the light. The light that has passed through the slit portion of the slit plate 3 is irradiated onto the glass substrate 102 obliquely with respect to the optical axis of the projection optical system 100 via the light transmitting system objective lens 7A, and a slit pattern image is formed on the glass substrate 102. Projected.

The reflected light from the glass substrate 102 is condensed on the light receiving surface of the photoelectric detector 13 including a photodiode through the light receiving system objective lens 7B, and the photoelectric detector 13 is formed.
The slit pattern image is re-formed on the light receiving surface of. In this case, when the Z axis is taken parallel to the optical axis of the projection optical system 100 and the glass substrate 102 is displaced in the Z direction, the position of the slit pattern image re-imaged on the light receiving surface of the photoelectric detector 13 is in the horizontal direction. Displace. By processing the photoelectric conversion signal of the photoelectric detector 13, a focus signal corresponding to the lateral displacement thereof is generated. Calibration is performed in advance so that the focus signal becomes 0 when the surface of the glass substrate 102 matches the image plane of the projection optical system 100, and thereafter, the glass substrate 1 is adjusted so that the focus signal becomes 0.
Autofocusing is performed by adjusting the position of 02 in the Z direction.

Further, the oblique incidence type tilt angle detection system is shown in FIG.
As described above, instead of projecting the slit pattern image on the glass substrate 102, a parallel light flux is irradiated and the change in the inclination angle of the surface of the glass substrate 102 is detected from the lateral shift amount of the condensing point of the reflected light.

[0006]

In general, an exposure apparatus for liquid crystal requires a smaller resolution than a projection exposure apparatus for semiconductor elements (exposure apparatus for semiconductors), and therefore, the projection optical system has a magnification of 1 ×. The big one is being used.
Moreover, with the recent increase in the size of the liquid crystal panel, the exposure field of the liquid crystal exposure apparatus tends to be further expanded, and the projection optical system also tends to become larger. On the other hand, the working distance between the projection optical system and the glass substrate cannot be increased due to the height limitation of the exposure apparatus. Therefore, in the exposure apparatus for liquid crystal, the oblique incidence method is used between the projection optical system and the glass substrate. It is becoming difficult to install the focus position detection system (or part thereof).

Even if a grazing incidence type focus position detection system (or part thereof) can be installed, the incident angle of light from the focus position detection system with respect to the glass substrate becomes large, and the focus position detection range is increased. Becomes narrower
There is an inconvenience that the necessary detection range cannot be secured. In addition, in an exposure apparatus for liquid crystals, an off-axis type alignment optical system used for pattern alignment is usually arranged near the projection optical system 100 above the glass substrate to be exposed, and further, A glass substrate transport system and the like move in and out of the space between the projection optical system and the glass substrate 102. Therefore, if a space such as a transport system is secured near the glass substrate side of the large-sized projection optical system and the oblique incidence type focus position detection system is arranged while avoiding the alignment optical system, the entire apparatus becomes more and more useful. There is an inconvenience that it becomes large.

Similarly, it is becoming difficult to arrange the oblique incidence type tilt angle detection system as the projection optical system becomes larger. In view of the above problems, the present invention does not arrange a complicated optical system in the vicinity of the photosensitive substrate side of the projection optical system even when the projection optical system becomes large in size, and the focus position or tilt of the exposure surface of the photosensitive substrate. An object of the present invention is to provide a projection exposure apparatus that can detect an angle in a wide detection range.

[0009]

A projection exposure apparatus according to the present invention, as shown in FIG. 1, for example, projects an image of a transfer pattern formed on a mask (101) into a projection optical system (10).
In the projection exposure apparatus that detects the surface position (focus position or tilt angle) of the exposure surface of the photosensitive substrate (102) when projecting onto the photosensitive substrate (102) via the optical axis (0) of the projection optical system (100). The photosensitive substrate (10
2) A light-transmitting system (1-8A) for injecting non-photosensitive displacement detection light (AL), and displacement detection emitted from the exit surface of the projection optical system (100) on the photosensitive substrate side. Optical system (100) for deflecting light for displacement and projecting light for displacement detection
A first optical path deflecting member (9A) for irradiating the exposed surface of the photosensitive substrate (102) obliquely with respect to the optical axis of the optical axis, and projection light for reflected light of displacement detection light from the exposed surface of the photosensitive substrate. Second optical path deflecting member (9B) returning to the exit surface of the system (100)
A second optical path deflecting member (9B) and a projection optical system (10
0) through which the light for displacement detection returned to the incident surface of the projection optical system (100) is focused, and the position of the light focused by this light receiving system is detected. And a condensing position detection system (13), and the surface position of the exposure surface of the photosensitive substrate (102) is detected from the position detected by the condensing position detection system.

In this case, by the light transmitting system (1-8A), the projection optical system (100) and the first optical path deflecting member (9A),
Projection optical system (100) on the exposed surface of the photosensitive substrate (102)
An image of a pattern having a predetermined shape is projected obliquely with respect to the optical axis of the second optical path deflecting member (9B) and the projection optical system (10).
0) and the light receiving system (8B to 12) to re-image the pattern of the predetermined shape, and the projection optical system of the exposure surface of the photosensitive substrate (102) from the position detected by the condensing position detection system (13). Position of (100) in the optical axis direction (focus position)
You may make it detect.

Further, for example, as shown in FIG. 6, generally, the effective projection field 201 of the projection optical system (100) is circular, and the exposure area 202 on which the mask pattern image is actually exposed is rectangular, and between them. Since there is a predetermined gap between the first and second optical path deflecting members (9
It is desirable to arrange A, 9B). With such an arrangement, the exposure area 202 is not restricted by the first and second optical path deflecting members (9A, 9B).

[0012]

According to the present invention, the light transmitting system (1-8A),
Projection optical system (100) and first optical path deflecting member (9A)
A pattern image (for example, a slit pattern image) of a predetermined shape is projected onto the photosensitive substrate (102) via the
The pattern image of the predetermined shape is re-imaged on the light receiving surface of the condensing position detection system (13) via the optical path deflecting member (9B), the projection optical system (100), and the light receiving system (8B-12). Based on the lateral shift amount of the re-formed image, the photosensitive substrate (102)
The focus position of the exposure surface of is detected.

On the other hand, instead of projecting a pattern image of a predetermined shape, the exposure surface of the photosensitive substrate (102) is irradiated with a parallel light flux, and the parallel light flux is focused on the light receiving surface of the focus position detection system (13). , By detecting the amount of lateral deviation of the focal point,
The tilt angle of the exposed surface of the photosensitive substrate (102) is detected. However, the tilt angle of the surface of the photosensitive substrate (102) can also be detected by detecting the focus positions at multiple points other than the method of irradiating the photosensitive substrate (102) with the parallel light flux as described above. In order to detect the focus positions at multiple points as described above, a first optical path deflecting member (9) is provided between the projection optical system (100) and the photosensitive substrate (102) as shown in FIG. 7, for example.
C, 9J, 9F, 9G) and the second optical path deflecting member (9
D, 9I, 9E, 9H) may be arranged in plural pairs, and the focus position of the corresponding measurement point on the photosensitive substrate may be detected by the optical path deflecting member of each pair.

According to the present invention, only the first and second optical path deflecting members (9A, 9B) are arranged between the projection optical system (100) and the photosensitive substrate (102) for detection. Most of the optical system is arranged between the mask (101) and the projection optical system (100), which have a sufficient space. Therefore, for example, other alignment optics or the photosensitive substrate (10
It is possible to minimize mechanical interference with the transportation system for 2). Further, a first optical path deflecting member (9) installed at a position almost inscribed in the effective projection field of the projection optical system.
The light reflected by A) is obliquely reflected by the photosensitive substrate (102).
Since the light is incident on the photosensitive substrate (102), the incident angle of the light is such that the optical system is arranged between the projection optical system (100) and the photosensitive substrate (102) as in the conventional example. It can be made smaller than when doing. Therefore, the detection range of the focus position or the tilt angle is widened.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the projection exposure apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration in the vicinity of the projection optical system of the projection exposure apparatus of this embodiment. In FIG. 1, the pattern on the reticle 101 is exposed under the exposure light IL supplied from an illumination optical system (not shown). The image is projected and exposed through the projection optical system 100 onto the glass substrate 102 coated with the photoresist. Projection optical system 100
Is at least telecentric to the glass substrate 102 side (or both sides), and the projection magnification is, for example, 1 ×. The glass substrate 102 is held on a substrate stage 103, and the substrate stage 103 positions the glass substrate 102 in the Z direction parallel to the optical axis AX of the projection optical system 100, in the XY plane perpendicular to the Z axis. It is composed of an XY stage for positioning the glass substrate 102, a leveling stage for adjusting the inclination angle of the glass substrate 102, and the like.

Reticle 1 of projection optical system 100 of the present embodiment
The light transmission system 20 of the focus position detection system is provided near the 01 side.
And a light receiving system 21 are arranged. First, in the light sending system 20, the detection light AL emitted from the light source 1 composed of a halogen lamp is condensed on the light sending slit plate 3 by the condenser lens 2. The detection light AL is emitted from the glass substrate 1
02 is light in a wavelength band that is non-photosensitive to the photoresist above. A light emitting diode (LED) or the like can also be used as the light source 1. The detection light AL that has passed through the slit of the light-sending slit plate 3 is transmitted to the projection optical system 100 via the parallel flat plate glass (harbing) 4, the cylindrical lens 5A, the optical path bending mirror 6A, and the light-sending system objective lens 7A. The light enters the mirror 8A for bending the optical path, which is arranged between the reticle 101 and the reticle 101.

The mirror 8A is an optical axis A of the projection optical system 100.
The detection light AL, which is inclined outward at an angle of about 45 ° with respect to the axis parallel to X and is fixed and is reflected by the mirror 8A, is incident on the projection optical system 100. The image of the slit of the light-sending slit plate 3 is formed at the intermediate image forming point P1 between the mirror 8A and the projection optical system 100 by the light-sending system objective lens 7A.
In this case, in the projection optical system 100 of the present embodiment, for example, a part of the lenses forming the projection optical system 100 is provided with the optical axis AX.
Is provided with an imaging characteristic correction mechanism that adjusts the projection magnification of the projection optical system 100 by moving in the direction or adjusting the pressure of the air in the air chamber between the predetermined lenses forming the projection optical system 100. ing. For example, when the atmospheric pressure fluctuates and the projection magnification of the projection optical system 100 fluctuates, the projection magnification of the projection optical system 100 is corrected via the imaging characteristic correction mechanism, or the substrate or the like expands or contracts. in case of,
The projection magnification of the projection optical system 100 is positively changed and corrected through the imaging characteristic correction mechanism.

However, the projection optical system 100 uses the exposure light IL.
The imaging characteristics are defined for the detection light AL, and a magnification error may occur in the detection light AL due to a difference in wavelength with respect to the exposure light IL. When the projection magnification is corrected by the imaging characteristics correction mechanism, the magnification of the detection light AL is May change.
Therefore, the variation amount of the magnification with respect to the detection light AL when the projection magnification of the projection optical system 100 is corrected is obtained in advance, the tilt angle of the parallel flat plate glass 4 is adjusted, and the intermediate result is adjusted by the variation amount of the magnification. The position of the image point P1 is shifted laterally. Further, even when the projection magnification of the projection optical system 100 is positively changed, the tilt angle of the parallel flat glass 4 is adjusted so that the detection light AL always enters the detected point before and after the magnification change. The cylindrical lens 5A is for correcting astigmatism generated by the projection optical system 100 with respect to the detection light AL.

Detection light AL diverging from the intermediate image formation point P1
Is reflected by a mirror 9A that is fixed in proximity to the bottom surface (the surface on the glass substrate 102 side) of the projection optical system 100 via the projection optical system 100, and the measurement point Q on the glass substrate 102 is aligned with the optical axis AX. On the other hand, the light is collected obliquely. As a result, the image of the slit of the light-sending slit plate 3 is re-formed on the measurement point Q. The measurement point Q is set on the optical axis AX. Further, the direction parallel to the orthogonal projection of the principal ray of the detection light AL focused on the measurement point Q from the mirror 9A onto the surface of the glass substrate 102 is R.
Direction.

In this case, a mirror 9B is fixed near the bottom surface of the projection optical system 100 and symmetrical to the mirror 9A with respect to the optical axis AX, and the light is received between the projection optical system 100 and the reticle 101 symmetrically with respect to the optical axis AX. The mirror 8B on the system 21 side is fixed. Then, the detection light AL reflected from the measurement point Q returns to the projection optical system 100 via the mirror 9B,
The slit image is re-imaged at the intermediate image point P2 by the detection light AL transmitted through the projection optical system 100. The intermediate image point P2
The detection light AL diverged from the slit image of is incident on the mirror 8B of the light receiving system 21. In the light receiving system 21, the mirror 8
The detection light AL reflected by B is received by the light receiving system objective lens 7
A slit image is re-imaged on the light-receiving slit plate 11 through B, the mirror 6B, the cylindrical lens 5B, and the parallel flat plate glass (harbing) 10. The detection light that has passed through the slit on the light receiving slit plate 11 is condensed via a condenser lens 12 on the light receiving surface of a photoelectric detector 13 including a photodiode or the like.

Cylindrical lens 5 in light receiving system 21
B plays a role of correcting astigmatism generated with respect to the detection light AL by the projection optical system 100, similarly to the cylindrical lens 5A in the light transmitting system 20. Further, the parallel plate glass 10 in the light receiving system 21 corrects lateral chromatic aberration with respect to the detection light AL by the projection optical system 100, similarly to the parallel plate glass 4 in the light transmitting system 20. However, if the parallel plate glass 10 alone can completely correct the chromatic aberration of magnification, the parallel plate glass 4 on the side of the light transmitting system 20 may be omitted.

An aperture stop 104 is arranged on the pupil plane of the projection optical system 100 (Fourier transform plane with respect to the pattern forming plane of the reticle 101), and the mirror 8 of the light transmitting system 20.
The detection light AL traveling from A to the mirror 9A is generated by the projection optical system 1
00 through the central portion of the aperture stop 104 (the portion including the optical axis AX), from the mirror 9B to the mirror 8B of the light receiving system 21.
The detection light AL heading for passes through the center of the aperture stop 104. That is, the detection light AL traveling from the light transmitting system 20 to the mirror 9A and the detection light AL traveling from the mirror 9B to the light receiving system 21 intersect near the optical axis AX of the pupil plane of the projection optical system 100. In this way, the detection light AL traveling back and forth in the projection optical system 100 intersects in the vicinity of the pupil plane, and the optical axis AX
By passing through an optical path that is substantially axisymmetric with respect to, there is an advantage that the influence of the fluctuation of the imaging characteristics of the projection optical system 100 due to the fluctuation of atmospheric pressure does not affect the focus position detection system.

In this embodiment, the images of the slits in the light-transmitting slit plate 3 are formed on the intermediate image forming point P1, the measuring point Q on the glass substrate 102, the intermediate image forming point P2, and the light receiving slit plate 11, respectively. Is imaged. When the surface of the glass substrate 102 is displaced in the Z direction, the position of the slit image formed on the light receiving slit plate 11 is laterally displaced. Further, in a state where the surface of the glass substrate 102 matches the image plane of the projection optical system 100 in advance, calibration is performed so that the slit of the light-receiving slit plate 11 and the re-formed slit image overlap each other. There is. Therefore, for example, the photoelectric detector 13
So as to maximize the photoelectric conversion signal output from the glass substrate 10 via the Z stage in the substrate stage 103.
Autofocusing is performed by adjusting the position (focus position) of the surface of 2 in the Z direction.

It should be noted that the photoelectric conversion signal of the photoelectric detector 13 is not controlled so as to be maximized, but the mirror 6B is vibrated by a drive signal of a predetermined frequency, and the photoelectric conversion signal of the photoelectric detector 13 is changed. The focus signal may be generated by synchronously rectifying the drive signal. The focus signal thus obtained becomes a signal which changes substantially in proportion to the displacement when the surface of the glass substrate 102 is displaced within a predetermined range with respect to the image plane of the projection optical system 100. The position of the surface of the glass substrate 102 in the Z direction can be known from the signal.

Further, a one-dimensional or two-dimensional image pickup device such as a one-dimensional or two-dimensional CCD (charge coupled image pickup device) is installed at the position of the light receiving slit plate 11, and the position of the slit image is determined by this image pickup device. You may make it measure directly. The position of the surface of the glass substrate 102 in the Z direction is obtained from the position of the slit image measured in this way.

When the light source 1 is, for example, a halogen lamp and the detection light AL has a wavelength band of a predetermined width,
Before performing magnification correction in the projection optical system 100 via the parallel plate glasses 4 and 10, first, the objective lens 7A for the light transmitting system is first provided.
Also, it is desirable to correct chromatic aberration (axial chromatic aberration) in the optical axis direction of the projection optical system 100 by the light receiving system objective lens 7B. When the light source 1 has a predetermined wavelength band, the chromatic aberration of magnification caused by the projection optical system 100 within the wavelength band is corrected as disclosed in Japanese Patent Laid-Open No. 4-223326. Therefore, it is desirable to include a color correction prism or the like in the light receiving system 20 and the light transmitting system 21.

Here, the relationship between the intermediate image formation points P1 and P2 of FIG. 1 and the surface (test surface) of the glass substrate 102 will be described with reference to FIGS. The positions of the intermediate image formation points P1 and P2 are determined by the angle of incidence of the detection light AL on the surface of the glass substrate 102 and the like. FIG. 2 shows the arrangement on the glass substrate 102 side. In FIG. 2, after being emitted from the projection optical system 100, the glass substrate 1 is reflected by the mirror 9A.
The detection light AL focused on the measurement point Q on 02 is reflected by the mirror 9
Light that is symmetrically folded back with respect to A is defined as detection light AL1 indicated by a broken line. Further, the light that passes through the mirror 9A and is condensed on the surface of the glass substrate 102 is referred to as detection light AL2. Then, the glass substrate 1 of the chief ray of the detection light AL focused on the measurement point Q
When the incident angle with respect to 02 is θ and the distance between the principal ray of the detection light AL1 and the measurement point Q is x, the positional deviation amount Δ in the Z direction between the condensing point of the detection light AL1 and the surface of the glass substrate 102 is as follows. Like

[0028]

## EQU1 ## Δ = x (1 / sin θ-1 / tan θ) FIG. 3 is a conceptual diagram near the projection optical system 100.
In FIG. 3, the reticle 101 of the projection optical system 100 is shown.
The projection optical system 100 is a double-sided telecentric optical system, where β is the projection magnification from the substrate to the glass substrate 102. In this case, the intermediate image forming points P1 and P2 of FIG. 1 are formed on the surface 22 which is shifted downward from the glass substrate 102 by Δ and the surface 23 which is conjugate with respect to the projection optical system 100, and the reticle 1 is formed.
The amount of positional deviation from the pattern formation surface of No. 01 to the surface 23 is Δ / β ² . Actually, since the detection light AL having a wavelength different from the wavelength of the exposure light IL (exposure wavelength) is used, the position of the surface 23 on which the intermediate image formation points P1 and P2 are located slightly moves in the optical axis AX direction. However, the detection light AL may be incident so that the detection light AL forms a slit image on the surface 23.

Returning to FIG. 1, the exposure wavelength and the detection light AL
If the detection light AL from the projection optical system 100 on the glass substrate 102 side (the surface to be inspected) does not become telecentric because of the difference in the wavelength of, the mirror 8A in FIG. The incident angle of the detection light AL with respect to the projection optical system 100 may be adjusted by changing the installation angle. Alternatively, a deviation prism may be provided between the projection optical system 100 and the mirror 9A, and the deviation prism may adjust the traveling direction of the detection light AL.

Next, in FIG. 4, the surface of the glass substrate 102 is actually the image plane (best focus plane) of the projection optical system 100.
4 shows the optical path of the detection light AL when it is on the surface (surface shown by the broken line) that is decreased by ΔZ1 from, and in FIG. 4, the reflected light of the detection light AL when the surface of the glass substrate 102 is on the best focus surface. The main light of the reflected light of the detection light AL when the surface thereof is on the surface lowered by ΔZ1 is shown by the broken detection light 14B.
As shown in FIG. 4, when the surface of the glass substrate 102 is lowered by ΔZ1, the detection light 14A is reflected by the mirror 9B.
And the detection light 14B are laterally offset by ΔY1 in the R direction.

Therefore, in the mirror 8B above the projection optical system 100, the position of the detection light 14B is the same as that of the detection light 14A.
With respect to the opposite direction, the image is laterally offset by ΔY2, and ΔY2≈Δ using the approximate value β of the projection magnification from the reticle 101 of the projection optical system 100 to the glass substrate 102 under the detection light AL.
Y1 / β holds. Further, the detection light 14B laterally displaced by ΔY2 on the mirror 8B is laterally displaced by ΔY3 on the light receiving slit plate 11 via the light receiving system objective lens 7B and the like. That is, according to this embodiment, the glass substrate 102
The displacement ΔZ1 in the Z direction of the surface of the light receiving slit plate 11
The above is converted into the lateral shift amount of ΔY3.

FIG. 5 is an optical path diagram in the vicinity of the glass substrate 102. In FIG. 5, the measurement point Q of the glass substrate 102 is shown.
The chief ray of the reflected light of the detection light AL from is indicated by the detection light 15A. At this time, when the glass substrate 102 is displaced by ΔZ in the optical axis direction of the projection optical system 100, the measurement point on the glass substrate 102 is laterally displaced to Q ′, and the principal ray of the reflected light from the measurement point Q ′ is detected by a broken line. In terms of light 15B, the detection lights 15A and 15B are reflected by the mirror 9B and become substantially parallel to the optical axis of the projection optical system 100. Therefore, the detection light 15
Assuming that the angle of reflection from the glass substrate 102 of A and 15B is θ, the detection lights 15A and 15 after being reflected by the mirror 9B.
The distance ΔY from B is approximately expressed by the following equation.

[0033]

ΔY = 2 · ΔZ · sin θ Therefore, the larger the reflection angle θ, that is, the incident angle of the principal ray of the detection light AL to the glass substrate 102, the larger the lateral deviation amount ΔY becomes, and the focus position of the glass substrate 102 becomes larger. The detection sensitivity to the deviation is improved. However, as the reflection angle θ increases, the lateral shift amount of the measurement point Q with respect to the shift of the focus position also increases, and the focus position detection range for a predetermined measurement point on the glass substrate 102 narrows. In this respect, according to the present embodiment, the incident angle of the detection light AL can be set to a desired value simply by adjusting the tilt angles of the mirrors 9A and 9B, regardless of the aperture of the projection optical system 100. The sensitivity and the detection sensitivity can be balanced.

In particular, when manufacturing a liquid crystal display element, the focus position detection accuracy may be lower than when manufacturing a semiconductor element, and it is rather desirable to widen the detection range.
In such a case, the angle of the mirror 9A may be adjusted to reduce the incident angle of the detection light incident on the glass substrate 102. On the other hand, in the conventional example of FIG.
The larger the diameter of 00, the glass substrate 102 for the detection light.
Since it is necessary to increase the incident angle with respect to, the detection range of the focus position becomes narrow.

Next, FIG. 6 is a plan view of the projection optical system 100 of FIG. 1 as viewed from the bottom surface of the glass substrate 102 side. In FIG. 6, the outer circular contour 203 is the projection optical system of FIG. A circular area of broken line corresponding to the aperture of 100 on the glass substrate 102 side is the effective projection field 201 of the projection optical system 100 in the contour 203. The solid rectangular area inscribed in the effective projection field 201 is the exposure field 202 onto which the pattern of the reticle 101 is actually projected. The exposure field 202 is a rectangular area having a predetermined width in each of the X direction and the Y direction, and is used to return the reflected light from the glass substrate 102 to the mirror 9A that reflects the detection light from the light transmitting system and the light receiving system. The mirror 9B is fixed at a position outside the exposure field 202 and inscribed in the effective projection field 201 so as to face each other.

The direction of the straight line connecting the mirrors 9A and 9B is the R direction in FIG. 1, and the R direction intersects the X direction at an angle of about 45 °. The exposure field 20
The mirror 9A is located at the center of 2 inside, that is, at a measurement point Q1 (corresponding to the measurement point Q in FIG. 1) between the mirrors 9A and 9B.
The slit image is projected via. Therefore, in this embodiment, the central measurement point Q in the exposure field 202 is
The focus position at 1 is detected. Moreover, the exposure light applied to the exposure field 202 is reflected by the mirrors 9A and 9A.
Since the light is not shielded by B, the reticle 10 for detecting the focus position at the measurement point Q1 and the exposure field 202 is detected.
The exposure of one pattern image can be performed simultaneously. That is, the pattern image of the reticle 101 can be exposed on the glass substrate 102 while performing the autofocus of the glass substrate 102.

Next, another embodiment of the present invention will be described with reference to FIG. In the present embodiment, four sets of focus position detection systems including the light sending system 20, the mirrors 9A and 9B, and the light receiving system 21 are provided in the embodiment of FIG. 1 so that not only autofocus but also auto leveling can be performed. It is a thing. In the following, parts corresponding to those in the embodiment of FIG.

FIG. 7 is a plan view of the glass substrate to be exposed as seen from the bottom of the projection optical system of this embodiment.
In FIG. 1, a rectangular exposure field 202 is set so as to be inscribed in the circular effective projection field 201 of the projection optical system 100 within the contour 203 corresponding to the aperture of the projection optical system 100 of FIG. In this embodiment, a pair of mirrors 9A and 9J for reflecting the detection light from the light transmitting system of the focus position detection system and another pair of mirrors 9F and 9G.
Are fixed in positions outside the exposure field 202 in the Y direction and inscribed in the effective projection field 201, and a pair of mirrors 9D and 9E for returning the reflected light from the glass substrate to the light receiving system, and another mirror A pair of mirrors 9I and 9
H and H are fixed to positions outside the exposure field 202 in the X direction and inscribed in the effective projection field 201, respectively.

The detection light reflected by the mirrors 9C and 9J projects slit images at the measurement points Q2 and Q5 in the exposure field 202, and the reflected light from the slit images is projected by the mirrors 9D and 9I. The detection light guided to the system 100 and reflected by the mirrors 9F and 9G causes measurement points Q in the exposure field 202, respectively.
A slit image is projected on 3 and Q4, and reflected light from the slit image is projected onto the projection optical system 10 by the mirrors 9E and 9H.
Lead to zero. Mirrors 9C and 9H and mirror 9 respectively
The direction of the straight line connecting D and 9G is the R1 direction, and the direction of the straight line connecting the mirrors 9E and 9J and the mirrors 9F and 9I is the R2 direction, and the R1 direction and the R2 direction are approximately with respect to the X direction. They intersect at ± 45 °.

In this embodiment, the measurement points Q2 to Q5 are arranged at four corners in the exposure field 202, and the focus positions at these four measurement points Q2 to Q5 are detected. For example, an average value of these four focus positions is set as an average focus position of the exposure field 202, and an average surface tilt angle determined by these four focus positions is set as the tilt angle of the exposure field 202. , The focus position and tilt angle of the exposure field 202 are detected. Focusing and leveling are performed by adjusting the focus position and the tilt angle to the best focus surface. Moreover, exposure field 2
Since the exposure light radiated on 02 is not shielded by the mirrors 9C to 9J, the focus position detection at the measurement points Q2 to Q5 and the exposure of the reticle pattern image on the exposure field 202 can be performed simultaneously. That is, the pattern image of the reticle 101 can be exposed on the glass substrate while performing the auto focus and the auto leveling of the glass substrate.

In the above embodiment, since the slit image is projected on the glass substrate 102, the focus position at the projection point (measurement point) is detected.
It is also possible to irradiate a parallel light flux onto 02 at an angle and to detect the position of the focal point of the reflected light of the parallel light flux in the light receiving system 21. Thereby, the inclination angle of the irradiation area of the parallel light flux can be detected.

Further, although the present invention is applied to the liquid crystal exposure apparatus in the above-mentioned embodiment, even if it is a semiconductor exposure apparatus, when the exposure field is wide, the projection optical system is used as in the present invention. By detecting the focus position or the tilt angle of the wafer via the system, the incident angle of the detection light with respect to the wafer can be reduced and the detection range can be widened. Further, in the above-described embodiment, the light transmitting system 20 and the light receiving system 21.
Is disposed between the reticle 101 and the projection optical system 100, but the light transmitting system 20 and the light receiving system 21 are connected to the reticle 101.
A TTR (through the reticle) system may be used in which the TTR is arranged above.

Further, the present invention can be applied to the case where the projection optical system is a catadioptric system. As described above, the present invention is not limited to the above-described embodiments, and various configurations can be adopted without departing from the gist of the present invention.

[0044]

According to the present invention, since the detection light at the focus position or the tilt angle is irradiated onto the photosensitive substrate through the projection optical system, the incident angle of the detection light with respect to the surface to be inspected is the same as in the conventional case. In addition, there is an advantage that the detection light can be made smaller than that when the detection light is incident from the optical system outside the projection optical system, and the detection range can be made large even when the exposure field (projection optical system) is enlarged.

There is also an advantage that the detection system can be arranged on the side of the mask having a relatively large space, and the detection system can be arranged without being restricted by the arrangement of other alignment systems and the like.
In addition, in the conventional example, since the projection optical system is not used, it is affected by the magnification correction control of the projection optical system and other heat generation. Therefore, a mechanism for correcting the influence is required.
However, according to the present invention, since the projection optical system is used, even if the projection optical system itself has some magnification variation, focus position variation, etc., the focus position is tracked without any particular correction. Alternatively, there is an advantage that the tilt angle can be detected.

[Brief description of drawings]

FIG. 1 is an optical system layout diagram showing a main part of an embodiment of a projection exposure apparatus according to the present invention.

FIG. 2 is a diagram showing an image formation relationship near the glass substrate 102 in FIG.

FIG. 3 is an explanatory diagram of a position of an intermediate image forming point in FIG.

FIG. 4 is a view showing an actual glass substrate 10 in the embodiment of FIG.
FIG. 6 is an optical path diagram showing a deviation of an optical path of detection light when the surface of 2 (the surface to be inspected) is displaced in the Z direction.

5 is a diagram showing an optical path in the vicinity of the glass substrate 102 of FIG.

FIG. 6 is a plan view of the glass substrate 102 seen from the projection optical system 100 in FIG.

FIG. 7 is a plan view of a glass substrate seen from a projection optical system in another embodiment of the present invention.

FIG. 8 is a configuration diagram showing a main part of a conventional oblique incidence type focus position detection system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 light source 2 condenser lens 3 light-transmitting slit plate 4, 10 parallel plate glass (harbing) 7A light-transmitting system objective lens 7B light-receiving system objective lens 8A, 8B mirror 9A, 9B mirror 12 condenser lens 13 photoelectric detector 100 projection optical system 101 reticle 102 glass substrate 201 effective projection field 202 exposure field

Claims (2)

[Claims] 1. When projecting an image of a transfer pattern formed on a mask onto a photosensitive substrate via a projection optical system,
In a projection exposure apparatus for detecting the surface position of the exposure surface of the photosensitive substrate, a light transmission system for making non-photosensitive displacement detection light incident on the photosensitive substrate on the mask-side incident surface of the projection optical system. And deflecting the displacement detection light emitted from the exit surface of the projection optical system on the side of the photosensitive substrate so that the displacement detection light is obliquely exposed to the optical axis of the projection optical system. A first optical path deflecting member that irradiates the exposed surface of the substrate, and a second optical path deflecting member that returns the reflected light of the displacement detection light from the exposed surface of the photosensitive substrate to the exit surface of the projection optical system. A light receiving system for collecting the displacement detecting light returned to the incident surface of the projection optical system via the second optical path deflecting member and the projection optical system, and a light receiving system for collecting the light for collecting the displacement. And a condensing position detection system for detecting the position of the emitted light. Out projection exposure apparatus being characterized in that to detect the surface position of the exposure surface of the photosensitive substrate from the detected position by the system. 2. An image of a pattern having a predetermined shape, which is oblique to the optical axis of the projection optical system, on the exposure surface of the photosensitive substrate by the light sending system, the projection optical system, and the first optical path deflecting member. The second optical path deflecting member, the projection optical system and the light receiving system to re-image an image of the pattern of the predetermined shape, and the photosensitive substrate from the position detected by the condensing position detection system. The projection exposure apparatus according to claim 1, wherein the position of the exposure surface in the optical axis direction of the projection optical system is detected.