JP3298212B2 - Position detection method and apparatus, exposure method, projection exposure apparatus, and element manufacturing method - Google Patents

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 for detecting the position of a test object, and more particularly, to a method for forming a circuit pattern in a projection exposure apparatus used for manufacturing, for example, a semiconductor device or a liquid crystal display device. The present invention relates to a position detection device suitable for being applied to an alignment device for relatively positioning (aligning) a reticle on which a circuit pattern is transferred and a photosensitive substrate onto which the circuit pattern is transferred.

[0002]

2. Description of the Related Art When a semiconductor element or a liquid crystal display element is manufactured by a photolithography process, a pattern of a photomask or a reticle (hereinafter, collectively referred to as a "reticle") is coated with a photoresist at a high resolution. A projection exposure apparatus for transferring the image onto a photosensitive substrate is used. As such a projection exposure apparatus, a step-and-repeat type reduction projection type exposure apparatus (a so-called stepper) is frequently used. In general, a semiconductor element is formed by superimposing a multi-layer circuit pattern on a wafer, so that a stepper forms a projected image of a pattern of a reticle to be exposed and a matrix on the wafer by the steps up to that point. There is provided an alignment device for accurately overlapping the circuit pattern (chip).

[0003] Such an alignment apparatus uses an alignment mark (reticle mark) formed on a reticle.
And the positional relationship between the alignment mark (wafer mark) formed on the wafer by the previous steps,
The positioning of the reticle and each shot area of the wafer is performed. Therefore, in the alignment apparatus, first, an alignment system for detecting the positions of the reticle mark and the wafer mark plays an important role.

As a conventional alignment apparatus, for example, Japanese Patent Application Laid-Open No. Sho 60-130742 discloses an alignment apparatus of a TTL (through-the-lens) type and a laser step alignment type. The alignment system of the laser step alignment method
An elongated strip-shaped spot light is irradiated onto a diffraction grating wafer mark via a projection optical system, and photoelectrically detects diffracted light (or scattered light) generated from the wafer mark.

A so-called die-by-die type alignment apparatus is known as another conventional alignment apparatus.
This method mainly uses light having an exposure wavelength for exposing a circuit pattern or broadband white light as an alignment light, and uses a reticle mark and a wafer mark before exposing each shot area on a wafer. Are detected individually or simultaneously. As an alignment system for the die-by-die method, an alignment system for photoelectrically detecting a wafer mark or the like, or an image of a reticle mark and a wafer mark as in the laser step alignment method.
There has been used an FIA (field image alignment) type alignment system which performs position detection by taking an image with a D camera or the like and processing it as image data.

[0006]

Among the conventional techniques described above, when the positions of a reticle mark and a wafer mark are detected by an FIA type alignment system, a reticle mark is usually formed by using a one-dimensional image pickup device. In addition, the wafer mark is projected on a screen of a monitor receiver, for example, and the positional deviation of each mark is obtained from the state of the image on the screen.

Since the detection target is a position in two-dimensional coordinates consisting of an X coordinate and a Y coordinate, at least two lines are required to perform position detection on two-dimensional coordinates using a one-dimensional image sensor. It is necessary to use a one-dimensional image sensor or to rotate the one-dimensional image sensor within two-dimensional coordinates. In this case, since the system in which the one-dimensional imaging device is rotated lacks stability, conventionally, the optical path from each mark is divided and two one-dimensional imaging devices are used. However, when two one-dimensional image sensors are used in this manner, two display screens corresponding to the two one-dimensional image sensors due to astigmatism generated due to an assembling error of an optical system for position detection and the like. There is a disadvantage that one or both of the images are blurred, and the position cannot be accurately detected by the image processing.

However, when the amount of the astigmatism is fixed, the influence of the astigmatism can be eliminated by adjusting the positions of the imaging surfaces of the two one-dimensional imaging elements. . However, even in this case, when the amount of astigmatism changes due to external conditions such as temperature, it is necessary to adjust the positions of the imaging surfaces of the two one-dimensional imaging elements again. It is difficult to make such a readjustment.

Further, in the case of detecting the position of, for example, a wafer mark in an alignment system of the FIA system, the use of a two-dimensional image pickup device simplifies the optical system. However, 2
When a two-dimensional image sensor is used, images in two directions
Since imaging is performed on two imaging surfaces, it is not possible to correct astigmatism by shifting the position of the imaging element, and the effect of astigmatism due to the position detection optical system is particularly large. Further, in the above-described laser step alignment type alignment system, imaging by the image sensor is not performed, but in order to perform position detection more accurately, it is necessary to reduce astigmatism in the position detection optical system. Is desirable.

In view of the foregoing, the present invention guides position detection light from a measurement mark on a test object to an observation surface via a position detection optical system, and detects the position on the observation surface. if the position of the light use to detect the position of the test object, and aims to carry out a more accurate position detection of the object to correct the astigmatism occurring in the optical system for the position detection I do.

[0011]

According to a first position detecting device of the present invention, for example, as shown in FIG. 1, a position detecting light from a measuring mark (WM) on a test object (W) is transmitted to a position detecting device. An apparatus for guiding the object (W) to the observation surface (10) via the detection optical system (6, 7) and detecting the position of the test object (W) from the position of the position detection light on the observation surface (10). , Test object (W)
A first toric lens (8) and a second toric lens (9) are arranged along the optical path of the position detecting light between the toric lens and the observation surface (10), and at least one of the two toric lenses is provided. Is provided so as to be rotatable about the optical axis of this lens or to be movable along this optical axis, and at least one of the two toric lenses is rotated or moved to detect its position. Position detection optical system (6,
The astigmatism generated in 7) is corrected.

A second position detecting device according to the present invention collects light for position detection from a measurement mark (WM) on a test object (W) as shown in FIG. A position detection optical system (6, 6) for forming an image of the measurement mark (WM) on the reference mark plate (10) on which the mark (IM) is formed.
7), reference mark (IM) and measurement mark (WM)
Measuring means (1) for detecting the two-dimensional displacement amount of the image of
1, 12, 13M, 13S) and the reference mark (I
M) and the position of the test object (W) based on the amount of displacement between the image of the measurement mark (WM) and the position of the test object (W) and the reference mark plate (10). A first toric lens (8) and a second toric lens (9) are arranged along the optical path of the light for detection, and at least one of the two toric lenses is placed around the optical axis of this lens. A driving means (50) that rotates or moves along this optical axis is provided, and by rotating or moving at least one of the two toric lenses, the light for detecting the position thereof is The astigmatism generated in the position detection optical system (6, 7) is corrected.

Further, as shown in FIG. 8, for example, as shown in FIG. 8, a third position detecting device according to the present invention transfers an image of a pattern formed on a mask (R) to a photosensitive substrate (W) via a projection optical system (PL). It is provided in an exposure apparatus for projecting an image on a photosensitive substrate (W) and a projection optical system (P)
L), the position detection optical system (PL, 28, 27, 29) for condensing the position detection light obtained through (L) and forming an image of the measurement mark (WM) on the observation surface (35 imaging surface). , 51,
36, 34) and measuring means (35, 4) for detecting a two-dimensional displacement amount of the image of the measurement mark on the observation surface.
1) and a position detecting device for detecting the position of the photosensitive substrate (W) from the amount of positional deviation of the image of the measurement mark (WM), the distance between the projection optical system (PL) and its observation surface. A first toric lens (9) and a second toric lens (8) are arranged along the optical path of light for position detection, and at least one of the two toric lenses is centered on the optical axis of this lens. Is provided so as to be rotatable or movable along the optical axis, and by rotating or moving at least one of the two toric lenses, the projection optical system can use the projection optical system for the position detection light. The astigmatism that occurs is corrected. Next, a projection exposure apparatus according to the present invention includes an illumination optical system that illuminates a reticle, a projection optical system that projects a pattern image of the reticle onto a photosensitive substrate as the test object, and any one of the above-described present invention. And a position detecting device for detecting the position of the photosensitive substrate. A first element manufacturing method of the present invention is an element manufacturing method of manufacturing a semiconductor element or a liquid crystal display element using the projection exposure apparatus of the present invention, wherein the reticle is manufactured using the illumination optical system. The reticle is illuminated and the pattern image of the reticle is projected and exposed on the photosensitive substrate using the projection optical system. Further, a first exposure method of the present invention is an exposure method using the projection exposure apparatus of the present invention, wherein the reticle is illuminated by using the illumination optical system, and the reticle is illuminated by using the projection optical system. Is projected onto the photosensitive substrate.
Next, a first position detection method of the present invention includes a step of guiding position detection light from a measurement mark on a test object to an observation surface via a position detection optical system; Detecting the position of the test object from the position of the position detection light,
In order to correct astigmatism generated in the position detection optical system, two of the toric lenses arranged along the optical path of the position detection light between the test object and the observation surface are used. Rotating or moving at least one of the toric lenses. Further, the second aspect of the present invention
The position detection method is a step of guiding the light for position detection from the measurement mark on the test object to the observation surface via the position detection optical system, and from the light for position detection on this observation surface, and detecting the position of the object, a step of determining the astigmatism generated at the position detecting optical system, in order to correct astigmatism occurring at that position detecting optical system, and its specimen thereof View
Two toric wrens arranged in the light path between the observation surface
Rotating at least one of the toric lenses
Moving step. Further, a second element manufacturing method of the present invention includes a step of detecting the position of the photosensitive substrate as the test object using the position detecting method of the present invention, and illuminating the reticle using the illumination optical system. And a step of projecting and exposing a pattern image of the reticle to the photosensitive substrate using a projection optical system to manufacture a semiconductor element or a liquid crystal display element. According to a second exposure method of the present invention, there is provided a step of detecting the position of a photosensitive substrate as a test object using the above-described position detection method of the present invention, and illuminating a reticle using an illumination optical system. And a step of projecting and exposing a pattern image of the reticle to the photosensitive substrate using a projection optical system.

[0014]

According to the first position detecting device of the present invention,
A correction optical system having first and second optical members for correcting astigmatism is provided, and two toric lenses (8, 9) are used as the first and second optical members. Generally, a toric lens is a lens having different refractive powers in two orthogonal directions in a plane perpendicular to the optical axis, and a rotation angle (absolute rotation angle) of the two toric lenses as one, and a relative rotation of the two toric lenses. By changing the angle or the interval, it is possible to change the amount of shift between the focal positions of the light passing through the two toric lenses in two orthogonal directions. In other words, by changing the absolute rotation angle, the relative rotation angle, or the interval between the two toric lenses, a desired amount of astigmatism can be given to light passing through these two toric lenses. Therefore, by canceling the astigmatism generated by the position detection optical system with, for example, the astigmatism generated by the two toric lenses,
The two-dimensional position of the image of the measurement mark (WM) can be accurately detected.

Similarly, in the second position detecting device of the present invention, a correction optical system having first and second optical members and correcting astigmatism is provided, and the first and second optical members are provided. In this case, two toric lenses (8, 9) are used. In the present invention, the measurement mark (WM) is placed on the reference mark plate (10) on which the reference mark (IM) is formed.
Since the astigmatism occurs in the position detection optical system, if no correction is performed, the two-dimensional position of the image of the measurement mark (WM) is changed. It cannot be detected accurately. Accordingly, in the present invention, the relative rotation angle or interval between the two toric lenses is adjusted by the driving means (50), and the astigmatism generated by the position detecting optical system is generated by the two toric lenses. , The two-dimensional position of the image of the measurement mark (WM) can be accurately detected.

Also, in the third position detecting device of the present invention, a correction optical system having first and second optical members and correcting astigmatism is provided, and the first and second optical members are used as the first and second optical members. Uses two toric lenses (8, 9). Further, in the present invention, the light for position detection from the measurement mark (WM) on the photosensitive substrate (W) is transmitted by the projection optical system (P).
L), the projection optical system (PL) has been corrected for various aberrations with respect to the exposure light. Therefore, particularly when the wavelength of the position detecting light is different from the exposure wavelength, astigmatism may occur in the projection optical system (PL) with respect to the position detecting light. Therefore, in the present invention, those 2
By adjusting the absolute rotation angle, relative rotation angle, or interval of the two toric lenses, and canceling astigmatism generated by the projection optical system (PL) with astigmatism generated by the two toric lenses, the measurement mark ( The two-dimensional position of the image of the WM) can be accurately detected, and thus the position of the photosensitive substrate (W) can be accurately detected.

[0017]

1 to 6 show a first embodiment of the present invention .
This will be described with reference to FIG. In the present embodiment, the present invention is applied to an off-axis FIA type alignment system provided in a projection exposure apparatus. FIG. 1 shows a main part of a projection exposure apparatus according to the present embodiment. In FIG. 1, the pattern of the reticle R is illuminated with uniform illuminance by exposure light from an illumination optical system (not shown). The image is reduced or enlarged at the same magnification or at a predetermined magnification through the projection optical system PL and is exposed to each shot area on the wafer W. A reticle mark RM for alignment is formed near the pattern area of the reticle R, and a wafer mark WM for alignment is formed near each shot area on the wafer W in correspondence thereto. The wafer W is placed on the wafer stage 1, and the wafer stage 1
An XY stage for positioning the wafer W on a two-dimensional plane perpendicular to the optical axis AX1 of the projection optical system PL (the orthogonal coordinate axes are the X axis and the Y axis), and the wafer W in the Z direction parallel to the optical axis AX1. It is composed of a Z stage for positioning.

On the reticle R, an objective lens 2 for a reticle alignment system for detecting the position of the reticle mark RM is arranged, and a mirror 3 for bending the optical path is arranged between the objective lens 2 and the reticle R. I have. The optical axis AX2 of the reticle alignment system extends toward the wafer W via the projection optical system PL. In the reticle alignment system, for example, a reticle mark RM and an index mark (not shown) on the wafer stage 1 via the objective lens 2. Can be detected.

An off-axis FIA type alignment system 4 is arranged on a side surface of the projection optical system PL. In the alignment system 4, of the illumination light (alignment light) emitted from the light source 5 for position detection. The light transmitted through the beam splitter 6 is irradiated onto the wafer mark WM on the wafer W via the objective lens 7. Then, the alignment light reflected by the wafer mark WM returns to the beam splitter 6 via the objective lens 7, and the alignment light reflected by the beam splitter 6 passes through the negative cylindrical lens 8 and the positive cylindrical lens 9 to form a focusing plate. An image of the wafer mark WM is formed on the reference numeral 10.

An index mark IM is formed on the reticle 10, and the alignment light transmitted through the reticle 10 reaches the half prism 12 via the relay lens 11, and the light transmitted through the half prism 12 is two-dimensional. An image of the wafer mark WM and the index mark IM is formed on the imaging surface of the first imaging device 13M including a CCD. Half prism 1
The light reflected by the light source 2 reflects the wafer mark WM and the index mark I on the imaging surface of the second imaging device 13S composed of a two-dimensional CCD.
An image of M is formed. The optical axis AX3 of the alignment system 4
Is assumed to be shifted in the X direction with respect to the optical axis AX1 of the projection optical system PL, the projection optical system P
The meridional direction of L becomes the X direction, and the projection optical system PL
Is the Y direction.

In the first image pickup device 13M of this embodiment, the direction of the horizontal scanning line is set in a direction conjugate to the meridional direction on the image pickup surface, and the image of the wafer mark WM is obtained from the image pickup signal of the first image pickup device 13M. And the index mark IM in the meridional direction (in this example, the X direction) can be detected. On the other hand, in the second imaging device 13S, the direction of the horizontal scanning line is set in a direction conjugate to the sagittal direction on the imaging surface, and the image of the wafer mark WM and the index mark IM are obtained from the imaging signal of the second imaging device 13S. Can be detected in the sagittal direction (Y direction in this example).

In this embodiment, by processing image signals of the first image sensor 13M and the second image sensor 13S, a two-dimensional image of the wafer mark WM on the wafer W on the reticle 10 and the index mark IM is formed. It is possible to obtain a large displacement amount. Therefore, a baseline amount which is an interval between the optical axis AX3 of the alignment system and the optical axis AX1 of the projection optical system PL in FIG. 1 is obtained in advance, and, for example, the wafer stage 1 is driven so that the image of the wafer mark WM is After moving the amount of displacement from the index mark IM to within a predetermined range, the wafer stage 1 is moved by the amount of the base line to move the shot area to which the wafer mark WM belongs within the exposure field of the projection optical system PL. Can be set to

However, if astigmatism is generated in the alignment light by the objective lens 7 or the beam splitter 6 for guiding the optical path at this time, the image of the wafer mark WM formed on the focusing screen 10 will be merged in the meridional direction. And a sagittal direction defocus occurs. Therefore, if the focus position of the image of the wafer mark WM in the meridional direction is adjusted on the focusing screen 10, the focus position of the image of the wafer mark WM in the sagittal direction will deviate from the focusing screen 10, and the image of the wafer mark WM and the image of the wafer mark WM It becomes impossible to simultaneously focus on the index mark IM in the meridional direction and the sagittal direction. Therefore, the first image sensor 13M or the second image sensor 1
In any one or both of 3S, it becomes impossible to accurately detect the amount of displacement between the image of the wafer mark WM and the index mark IM.

Therefore, in the present embodiment, the relative rotation angle of the negative cylindrical lens 8 and the positive cylindrical lens 9 constituting the correction optical system for correcting astigmatism or the distance between the two cylindrical lenses is changed. Accordingly, the astigmatism generated by the two cylindrical lenses cancels the astigmatism generated by the objective lens 7 or the beam splitter 6. Accordingly, the amount of misalignment between the image of the wafer mark WM and the index mark IM in the meridional direction and the sagittal direction is determined by the first image sensor 13.
It can be accurately obtained from M and the image signal of the second image sensor 13S.

In this embodiment, a setting device 50 is provided for setting the relative rotation angle and the interval between the two cylindrical lenses to desired states.
In this example, the reticle 10 and the imaging devices 13M, 1
3S, that is, when astigmatism occurs in the relay lens 11, for example, the optical axes AX of the imaging devices 13M and 13S.
Focusing can be performed by adjusting the positions in the three directions. Therefore, the reticle 10 and the image sensor 13M,
In the case where astigmatism occurs only between 13S, there is no need to install the cylindrical lenses 8 and 9.

Next, with reference to FIG. 2 and FIG. 3, how the astigmatism changes depending on the relative rotation angles of the cylindrical lenses 8 and 9 or the interval between them will be quantitatively described. Here, the focal length of the negative cylindrical lens 8 is -f _C , the focal length of the positive cylindrical lens 9 is f _C , and the two cylindrical lenses 8 and 9 are treated as a thin lens system.

A. Change in Astigmatism When Rotated First, as shown in FIG. 2A, the amount of astigmatism when the negative cylindrical lens 8 is rotated by the angle θ about the optical axis AX3 is obtained. The direction in which the angle θ is 0 and the refractive powers of the cylindrical lenses 8 and 9 are both 0, that is, the fixed direction when the generatrix direction of the first cylindrical lens 8 and the generatrix direction of the second cylindrical lens 9 match each other. The meridional direction (M direction) is defined as the generatrix direction of the second cylindrical lens 9, and the direction perpendicular to the M direction is defined as the sagittal direction (S direction). As shown in FIG. 2B, the distance from the principal point of the cylindrical lenses 8 and 9 to the object point is a, and the distances from the principal point to the image points in the meridional and sagittal directions are b _M and b, respectively. _S.

[0028] In this case, when the combined focal length in the meridional direction of the two cylindrical lenses 8, 9 and F _M, the following two equations from imaging official meridional direction thin lenses obtained.

[0029]

(Equation 1)

[0030]

(Equation 2)

Similarly, two cylindrical lenses 8,
Assuming that the composite focal length in the sagittal direction of No. 9 is F _S , the following two equations are obtained from the imaging formula of the thin lens in the sagittal direction.

[0032]

(Equation 3)

[0033]

(Equation 4)

When the incident light beam is a parallel light beam, the emitted light beam in the meridional or sagittal direction diverges. Therefore, hereinafter, the incident light beam is a parallel system of parallel light beams and the incident light beam is a convergent light beam. The image system will be described separately.

A-1. In the case of a parallel system FIG. 2C shows an optical path diagram of the parallel system. As shown in FIG. 2C, in the parallel system, a convex lens 14 having a focal length f is disposed after two cylindrical lenses 8 and 9. Then, an image forming position by the convex lens 14 is considered. Then, in the meridional direction, an imaging relationship as shown by a solid line in FIG. 2C is established, and by substituting (a = ∞) into (Equation 2), the following equation is obtained.

[0036]

(Equation 5)

In the sagittal direction, an imaging relationship as shown by a two-dot chain line in FIG. 2C is established. By substituting (a = ∞) into (Equation 3) and (Equation 4), The following equation is obtained.

[0038]

(Equation 6)

Further, the distance between the principal point of the principal point and the convex lens 14 of the cylindrical lenses 8 and 9 (imaging lens) as x _1, in the meridional direction and the sagittal direction is focused by the convex lens 14 the image of the convex lens 14 _Assuming that the distances from the principal point are C _M and C _S , respectively, the convex lens 1 in the meridional direction is obtained from the relationship shown by the solid line in FIG.
The following formula is obtained from the imaging formula for No. 4.

[0040]

(Equation 7)

Similarly, from the relationship shown by the two-dot chain line in FIG. 2C, the following equation is obtained from the imaging formula for the convex lens 14 in the sagittal direction.

[0042]

(Equation 8)

Accordingly, the astigmatic difference δ _RP , which is the difference between the imaging position in the meridional direction and the imaging position in the sagittal direction by the cylindrical lenses 8, 9 and the convex lens 14, is as follows. This astigmatic difference δ _RP quantitatively indicates astigmatism in the parallel system of FIG. 2C.

[0044]

(Equation 9)

Here, a configuration when the above-mentioned relationship (Equation 9) is established will be described with reference to the embodiment of FIG. In the embodiment shown in FIG. 1, an imaging lens 14 as shown in FIG. 2C is arranged between the two cylindrical lenses 8 and 9 and the focusing screen 10, and the alignment light reflected from the wafer mark WM is passed through the objective lens 7. Is converted into a substantially parallel light beam and guided to two cylindrical lenses 8 and 9, and the parallel light beams passing through the two cylindrical lenses 8 and 9 are condensed to form an image of the wafer mark WM on the focusing screen 10. When the configuration is adopted, the relationship of the above (Equation 9) is established. At this time, the two cylindrical lenses 8 and 9 disposed between the objective lens 7 and the imaging lens 14 have a configuration in which a negative cylindrical lens 8 and a positive cylindrical lens 9 are disposed in this order from the objective lens 7 side. However, conversely, the positive cylindrical lens 9 and the negative cylindrical lens 8 are arranged in this order from the objective lens 7 side, and when the two cylindrical lenses are relatively rotated, the above (Equation 9) is obtained. ) Holds.

A-2. In the case of the imaging system In the case of the imaging system, the difference between the distance b _M to the imaging position in the meridional direction and the distance b _S to the imaging position in the sagittal direction in FIG. It becomes a difference. That is, the distance b _M is as follows from (Equation 1) and (Equation 2).

[0047]

(Equation 10)

Further, the distance b _{S is obtained} from (Equation 3) and (Equation 4).
Is as follows.

[0049]

[Equation 11]

[0050] Therefore, astigmatism [delta] _RC which is the difference between the imaging position in the meridional direction of the imaging position and the sagittal direction by the cylindrical lens 8 and 9 is as follows.

[0051]

(Equation 12)

Here, the above (Equation 12) corresponds to the embodiment of FIG. 1. In the convergent light beam condensed by the objective lens 7, the negative cylindrical lens is sequentially arranged from the objective lens 7 side. 8, the result obtained in the case where the positive cylindrical lens 9 is disposed is reversed. Conversely, the positive cylindrical lens 9 and the negative cylindrical lens 8 are disposed in order from the objective lens 7 side, and both the cylindrical lenses are disposed. Even when relatively rotated,
The relationship of 2) is established.

B. Change in astigmatism when the distance is changed As shown in FIG. 3A, a positive (focal length f _C ) cylindrical lens 9 and a negative (focal length −f _C ) cylindrical lens around the optical axis AX3. The amount of astigmatism in the case where the distance to 8 is set to d is determined. When the refractive powers of the cylindrical lenses 9 and 8 are both 0, that is, when the generatrix direction of the first cylindrical lens 8 and the generatrix direction of the second cylindrical lens 9 match each other, the two cylindrical lenses 8 and 9 have the same refractive index. The meridional direction (M direction) is defined as the meridional direction, and the direction perpendicular to the M direction is defined as the sagittal direction (S direction). Therefore, the imaging position in the meridional direction is not affected by the cylindrical lenses 9 and 8 at all.

In the case where the incident light beam is a parallel light beam, the emitted light beam in the meridional direction does not converge. Will be explained.

B-1. In the case of a parallel system FIG. 3 (b) shows an optical path diagram of the parallel system. As shown in FIG. 3 (b), in the parallel system, a convex lens 14 (focal length f) having a focal length f is provided behind two cylindrical lenses 9 and 8. Image lens)
Are arranged, and an image forming position by the convex lens 14 is considered. Then, the light beam incident on the cylindrical 9 is the optical axis A.
Assuming a parallel light flux parallel to X3, the image formation position in the meridional direction by the cylindrical lenses 9, 8 and the convex lens 14 is, as shown by the two-dot chain line in FIG.
4 is a position at a distance f. Further, as shown by the solid line in FIG. 3 (b), with respect to the positive sagittal imaging by the cylindrical lens 9, and the distance from the principal point of the cylindrical lens 9 to the image point and b _A, the following relation is satisfied I do.

[0056]

(Equation 13)

Since the interval between the cylindrical lenses 9 and 8 is d, as shown by the solid line in FIG. 3B, the image of the negative cylindrical lens 8 in the sagittal direction is shifted from the principal point of the cylindrical lens 8. Assuming that the distance to the image point is c _A , the following relationship is established from the imaging formula.

[0058]

[Equation 14]

When this equation is solved for the distance c _A , the following is obtained.

[0060]

(Equation 15)

As shown by the solid line in FIG. 3B, the distance from the principal point of the convex lens 14 to the object point is x with respect to the sagittal imaging of the convex lens 14 (imaging lens).
_S, and the distance from the principal point to the image point and y _S, the following relationship is established from the imaging formula.

[0062]

(Equation 16)

[0063] Further, from the positive cylindrical lens 9 intervals up to the convex lens 14 and x _1, the following relation is established.

[0064]

[Equation 17]

By substituting (Equation 17) for (Equation 16) and solving for the distance y _S , the following is obtained.

[0066]

(Equation 18)

[0067] Therefore, astigmatism [delta] _GP which is a difference between the cylindrical lenses 9,8 and the image forming position of the imaging position and sagittal meridional direction by the convex lens 14 is as follows.

[0068]

[Equation 19]

Here, a configuration when the above-mentioned relationship (Equation 19) is established will be described with reference to the embodiment of FIG. In the embodiment of FIG. 1, an imaging lens 14 as shown in FIG. 3B is arranged between the two cylindrical lenses 8 and 9 and the focusing screen 10, and the alignment light reflected from the wafer mark WM is passed through the objective lens 7 Is converted into a substantially parallel light beam and guided to two cylindrical lenses 8 and 9, and the parallel light beams passing through the two cylindrical lenses 8 and 9 are condensed to form an image of the wafer mark WM on the focusing screen 10. When the above configuration is adopted, the relationship of (Equation 19) is established. At this time, the two cylindrical lenses 8 and 9 disposed between the objective lens 7 and the imaging lens 14 are a positive cylindrical lens 9 and a negative cylindrical lens 8 in this order from the objective lens 7 side.
Is arranged, but conversely, the objective lens 7
A negative cylindrical lens 8 and a positive cylindrical lens 9 are arranged in this order from the side. When the two cylindrical lenses are relatively rotated, the following relationship (Equation 20) is established.

[0070]

(Equation 20)

B-2. In the case of an imaging system FIG. 3C shows an imaging system.
When the distance between the principal point and the object point of the cylindrical lens 9 and a _A, the distance a _A is the distance from the principal point of the cylindrical lens 9 to the image forming position in the meridional direction by the cylindrical lens 9 and 8.

As shown by the solid line in FIG. 3C, with respect to the image formation in the sagittal direction by the positive cylindrical lens 9, if the distance from the principal point of the cylindrical lens 9 to the image point is b _A , the following relationship is obtained. Holds.

[0073]

(Equation 21)

Since the interval between the cylindrical lenses 9 and 8 is d, the image of the negative cylindrical lens 8 in the sagittal direction is determined from the principal point of the cylindrical lens 8 based on the relationship shown by the solid line in FIG. Assuming that the distance to the image point is c _A , the following relationship is established from the imaging formula.

[0075]

(Equation 22)

When the distance b _A is deleted from (Equation 20) and (Equation 21), the distance c _A becomes as follows.

[0077]

(Equation 23)

Therefore, the astigmatic difference δ _GC , which is the difference between the imaging position in the meridional direction and the imaging position in the sagittal direction by the cylindrical lenses 9 and 8, is as follows.

[0079]

(Equation 24)

Here, the above (Equation 24) corresponds to the embodiment of FIG. 1. In the convergent light beam condensed by the objective lens 7, the positive cylindrical lens is sequentially arranged from the objective lens 7 side. 9, the result obtained in the case where the negative cylindrical lens 8 is disposed is reversed. Conversely, the negative cylindrical lens 8 and the positive cylindrical lens 9 are disposed in order from the objective lens 7 side, and both the cylindrical lenses are disposed. When rotated relatively, the following (Equation 2)
The relationship of 5) is established.

[0081]

(Equation 25)

As described above, in this example, desired astigmatism can be given to the alignment light by changing the relative rotation angle or interval between the two cylindrical lenses 8 and 9 as toric lenses. . Next, in the embodiment of FIG.
An example of an operation when correcting astigmatism generated in the objective lens 7 and the beam splitter 6 will be described with reference to FIG. First, as shown in FIG. 4A, the reticle 10 of FIG. 1 is assumed to have an index mark IM formed by a pair of L-shaped marks, and the wafer W on the wafer W of FIG. The mark for detecting the position in the meridional direction among the marks WM is, as shown in FIG. 4B, a mark WM1 composed of a line and space pattern arranged at a predetermined pitch in the meridional direction. In this case, FIG.
As shown in FIG. 4C, an index mark image IM 'and a mark image WM1' are superimposed and formed on a screen 13Ma of the monitor receiver connected to the first image sensor 13M.

FIGS. 5A to 5C show image pickup signals obtained when the image shown in FIG. 4C is scanned along a certain horizontal scanning line LX. FIGS. 5A to 5C are also imaging signals obtained when the height (position in the Z direction) of the exposure surface of the wafer W is changed via the wafer stage 1 in FIG. Signals 51 and 52 are signals corresponding to the index mark image IM ', respectively.
53C is a signal corresponding to each mark image WM1 '. As can be seen from FIGS. 5A to 5C, when the height of the exposure surface of the wafer W is changed, the contrast between the peak and the bottom of the index mark image IM 'is always constant, but the contrast of the mark image WM1' is constant. The contrast between the peak and the bottom changes gradually. Then, as shown in FIG. 5B, when the contrast of the imaging signal 53B becomes the best, the wafer mark WM of the wafer W is positioned in the meridional direction.
It is considered that it is time to focus on.

Therefore, in FIG.
Is scanned in the Z direction, and the wafer mark WM is moved in the meridional direction based on the image signal of the first image sensor 13M.
Height Z in the Z direction of wafer stage 1 when focusing on
_{Find M.} Similarly, in FIG.
Is scanned in the Z direction, and the height Z _S of the wafer stage 1 in the Z direction when the wafer mark WM is focused on the reticle 10 in the sagittal direction is obtained from the image signal of the second image sensor 13S. In order to detect the focus in the sagittal direction, for example, as shown in FIG. 6, a mark WM2 formed of a line and space pattern formed at a predetermined pitch in the sagittal direction among the wafer marks WM is used. This result would represent the height Z _M when focused at the meridional direction, the amount difference of astigmatism between the height Z _S when focused at the sagittal direction. Therefore, by adjusting the relative rotation angle or the interval between the cylindrical lenses 8 and 9 by the setting device 50 of FIG. 1 so that the height Z _M and the height Z _S coincide with each other, the objective lens 7 and the beam splitter 6 can be adjusted.
Is completely corrected.

Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, the present invention is applied to a TTL (through the lens) type alignment system. FIG. 7 shows a main part of the projection exposure apparatus of this embodiment.
In, the pattern of the reticle R is exposed on the wafer W via the projection optical system PL by exposure light from an illumination optical system not shown. A wafer mark WM is formed near each shot area on the wafer W. Above the side surface of the projection optical system PL of this example, a TTL alignment system 15 is disposed. In the alignment system 15, the alignment light emitted from the light source 16 is transmitted to the first relay lens 17 by the light of a predetermined wavelength. Then, the light enters the beam splitter 20 through the filter plate 18 and the second relay lens 19 for selecting. Beam splitter 2
The alignment light transmitted through 1 is incident on the projection optical system PL via the objective lens 21 and the mirror 22 for bending the optical path, and the alignment light emitted from the projection optical system PL is irradiated on the wafer mark WM. The wavelength of the alignment light in this example is different from the wavelength of the exposure light so that the photosensitive material on the wafer W is not exposed.

The alignment light reflected from wafer mark WM passes through projection optical system PL and bending mirror 22, and forms an image of wafer mark WM on conjugate plane R 'with the exposure surface of wafer W. The conjugate plane R ′ is separated from the plane conjugate with the exposure plane of the wafer W by the distance ΔL under the exposure light. The interval ΔL is an amount caused by chromatic aberration in the projection optical system PL with respect to the exposure light and the alignment light.
The alignment light from the conjugate plane R 'is
1 and returns to the beam splitter 20, and the alignment light reflected by the beam splitter 20 passes through the prism 23 for correcting chromatic aberration of magnification, the positive cylindrical lens 9,
The image of the wafer mark WM is formed on the imaging surface of the two-dimensional imaging device 25 formed of a two-dimensional CCD or the like via the negative cylindrical lens 8 and the imaging lens 24.

From the two-dimensional position of the image of the wafer mark WM on the imaging surface of the two-dimensional imaging device 25, the amount of displacement of the wafer mark WM from a predetermined reference position can be detected. In the first and second elliptical zone plates 8 and 9 in the present example, the alignment light reflecting the wafer mark WM receives the projection optical system PL, the mirror 22 and the objective lens 2.
Objective lens 21 which becomes a substantially parallel light beam condensed through 1
And the imaging lens 24, the first elliptic zone plate 8 is set so as to satisfy the above (Equation 9).
And the second elliptical zone plate 9 are relatively rotated, or the distance between the first elliptic zone plate 8 and the second elliptic zone plate 9 is relatively changed so as to satisfy the above (Equation 19). Preferably. . Thereby, astigmatism generated in the alignment system 15 can be corrected.

In particular, in this example, since alignment is performed with light having a wavelength different from that of the exposure light by the TTL method, astigmatism mainly occurs in the projection optical system PL. By adjusting the relative rotation angles or intervals of 8, 9 astigmatism can be made zero as a whole. Moreover, when astigmatism is generated not only by the projection optical system PL but also by the bending mirror 22, the objective lens 21, the beam splitter 20, the imaging lens 24, and the like for the alignment light, the two elliptic zone plates 8 , 9, the astigmatism can be made zero as a whole. Thus, the two-dimensional position of the wafer mark WM can be accurately detected.

Also, during normal exposure, the bending mirror 2
2 is an obstacle, it is desirable to retract the bending mirror 22 during exposure in order to widen the exposure field of the projection optical system PL. However, when the bending mirror 22 is retracted, the position of the wafer mark WM is detected again.
Position reproducibility at the time of setting between the projection optical system PL becomes a problem. That is, depending on the position of the bending mirror 22,
This is because the amount of astigmatism generated with respect to the alignment light differs, and accurate position detection of the wafer mark WM cannot be performed.

Therefore, a sensor for measuring the set position of the folding mirror 22 is provided, and the folding mirror 2 is set in advance.
In the case where the amount of astigmatism is measured at the setting position 2 and the bending mirror 22 is set thereafter, the bending angle is changed by changing the relative rotation angle or interval of the cylindrical lenses 9 and 8 according to the position. It is preferable to correct the amount of change in astigmatism due to the position of the mirror 22. In addition, since the amount of astigmatism also changes due to room temperature or pressure around the projection optical system PL, the amount of change in astigmatism due to room temperature and pressure is measured in advance, and when the projection exposure apparatus is used,
It is preferable to adjust the amount of astigmatism generated by the cylindrical lenses 9 and 8 according to the measurement results of the temperature sensor and the atmospheric pressure sensor.

Next, a third embodiment of the present invention will be described with reference to FIG. In this example, the present invention is applied to an alignment system of a TTR (through-the-reticle) system. FIG. 8 shows a main part of the projection exposure apparatus of this embodiment.
In, the pattern of the reticle R is exposed on the wafer W via the projection optical system PL by exposure light from an illumination optical system not shown. A wafer mark WM is formed near each shot area on the wafer W. A TTR type alignment system 26 is arranged above the reticle R of the present embodiment. In this alignment system 26, the alignment light emitted from the light source 16 is used as a first relay lens 17, a filter for selecting light of a predetermined wavelength. The light enters the beam splitter 27 via the plate 18 and the second relay lens 19. The alignment light reflected by the beam splitter 27 is applied to the objective lens 28 and the reticle R
, And is incident on the projection optical system PL, and the alignment light emitted from the projection optical system PL is irradiated on the wafer mark WM. The wavelength of the alignment light in this example is different from the wavelength of the exposure light so that the photosensitive material on the wafer W is not exposed.

A reticle mark RM for position detection is formed on the reticle R, and the alignment light emitted from the objective lens 28 is also applied to the reticle mark RM. The reflected light from the reticle mark RM returns to the objective lens 18 as it is. On the other hand, the alignment light reflected from wafer mark WM is projected onto projection optical system PL and reticle R
, An image of the wafer mark WM is formed on the conjugate plane R ′ with the exposure plane of the wafer W. The conjugate plane R ′ is separated from the pattern forming surface of the reticle R by the distance ΔL. The interval ΔL is an amount caused by chromatic aberration in the projection optical system PL with respect to the exposure light and the alignment light. Therefore, the common optical system cannot observe the image of the wafer mark WM and the image of the reticle mark RM at the same time.

That is, the alignment light from the wafer mark WM and the alignment light from the reticle mark RM are
The beam returns to the beam splitter 27 via the objective lens 28.
Of the alignment light transmitted through the beam splitter 27, the light reflected by the beam splitter 29 and the mirror 30 further forms a parallel plate glass 31 and an imaging lens 32.
And a beam splitter 34 via a mirror 33.
The light reflected by the beam splitter 34 forms an image of the reticle mark RM on an imaging surface of a two-dimensional imaging device 35 composed of a two-dimensional CCD or the like.

On the other hand, after passing through the beam splitter 27, the alignment light transmitted through the beam splitter 29 passes through the parallel plate glass 54, the positive cylindrical lens 9, the negative cylindrical lens 8, and the imaging lens 36, and is transmitted to the beam splitter 34. The light that has reached and transmitted through the beam splitter 34 forms an image of the wafer mark WM on the imaging surface of the two-dimensional imaging device 35. At this time, light from the wafer mark WM is mixed in the light beam by the imaging lens 32, but the image of the wafer mark WM is defocused on the imaging surface of the two-dimensional imaging device 35. Similarly, the reticle mark R
Although the light from M is mixed in, the image of the reticle mark RM is defocused on the imaging surface of the two-dimensional imaging device 35. Therefore, on the imaging surface of the two-dimensional imaging device 35,
The image of the reticle mark RM and the image of the wafer mark WM overlap and are clearly formed. The imaging signal of the two-dimensional imaging device 35 is supplied to the signal processing device 41, and the position information of the wafer mark WM and the reticle mark RM obtained by the signal processing device 41 is supplied to the main control system 38 that controls the operation of the entire device. Have been.

In the signal processing device 41, the two-dimensional displacement between the image of the wafer mark WM and the image of the reticle mark RM on the imaging surface of the two-dimensional imaging device 35 determines The amount of displacement from the region is detected. The first and second elliptical zone plates 8 and 9 in the present example are composed of an objective lens 28 that is formed by collecting the alignment light that reflects the wafer mark WM through the projection optical system PL and the objective lens 28 into a substantially parallel light flux. Since the first elliptic zone plate 8 and the second elliptic zone plate 9 are relatively rotated so as to satisfy the above (Equation 9) because they are arranged between the imaging lens 36 and the above-described (Equation 9), (Equation 1
It is preferable that the distance between the first elliptic zone plate 8 and the second elliptic zone plate 9 is relatively changed so as to satisfy 9). Thereby, astigmatism generated in the alignment system 15 can be corrected.

In particular, in this example, since alignment is performed with light having a different wavelength from the exposure light by the TTR method, astigmatism mainly occurs in the projection optical system PL. By adjusting the relative rotation angles or intervals of 8, 9 astigmatism can be made zero as a whole. Moreover, when astigmatism is generated not only by the projection optical system PL but also by the objective lens 28, the beam splitters 27 and 29, the imaging lens 36, the beam splitter 34, and the like, the two elliptical zones for the alignment light. By adjusting the relative rotation angle or interval between the plates 8 and 9,
Astigmatism can be made zero as a whole.

Thus, the two-dimensional displacement of the wafer mark WM with respect to the reticle mark RM can be accurately detected. In this example, a drive device 37 for adjusting the relative rotation angle or interval between the two cylindrical lenses 9 and 8 is provided, and the drive device 37 is controlled based on a command from a main control system 38 that controls the operation of the entire device. Operate. By the way, when the reticle size changes or the position of the alignment mark is changed, the alignment system 26 is moved in a direction orthogonal to the optical axis Ax1 of the projection optical system PL,
Alignment must be performed. However,
Each time the position of the alignment mark (reticle mark RM, wafer mark WM) with respect to the optical axis Ax1 of the projection optical system PL changes, the amount of astigmatism generated in the projection optical system PL changes.

Therefore, in this example, the alignment system driving device 50 provides the alignment system 26 so as to be movable in a direction orthogonal to the optical axis Ax1 of the projection optical system PL (a direction parallel to the reticle R). Device 50
Are controlled by the main control system 38. The memory section inside the main control system 38 stores the astigmatism amount corresponding to the position of the alignment mark (reticle mark RM, wafer mark WM) with respect to the optical axis Ax1 of the projection optical system PL.
In other words, information on the amount of astigmatism according to the image height of the projection optical system PL with respect to the optical axis Ax1 is stored in advance.

Here, when the reticle size is changed or the position of the alignment mark is changed,
The main control system 38 sets the alignment system 26 at a predetermined position by moving the alignment system 26 in a direction orthogonal to the optical axis Ax1 of the projection optical system PL by the alignment system driving device 50, and then aligns the projection optical system PL with the optical axis Ax1. System 26
The amount of astigmatism according to the optical axis position is determined based on the information in the memory unit. Then, the main control system 38 drives the driving device 37 based on the obtained amount of astigmatism to adjust the relative rotation angle or the interval between the two elliptical zone plates 8 and 9, thereby obtaining the astigmatism. It can be corrected so that the astigmatism becomes zero as a whole.

As described above, according to this embodiment, the astigmatism generated in the projection optical system PL can be corrected even when the reticle size is changed or when the position of the alignment mark is changed, and the wafer mark WM can be corrected. 2 with reticle mark RM
A dimensional position can be accurately detected. It should be noted that if the configuration like this example is added to the apparatus of the second embodiment of the TTL system shown in FIG. 7, the projection optical system P can be used even when the reticle size changes or the position of the wafer mark WM is changed.
It goes without saying that the astigmatism generated at L can be corrected.

It is known that the imaging characteristics such as the projection magnification and distortion of the projection optical system PL change depending on the room temperature, the atmospheric pressure, and the like around the projection optical system PL. Therefore, in order to expose the pattern image of the reticle R onto the wafer W with higher accuracy, a mechanism for correcting the imaging characteristics of the projection optical system PL is required. Therefore, the projection optical system PL of this example is provided with an imaging characteristic correction device 39 for adjusting the imaging characteristics such as a magnification error of the projection optical system PL within a predetermined range.
The imaging characteristic correction device 39 is, for example, a projection optical system PL
The pressure of the gas in a predetermined lens chamber is variable in the space (lens chamber) between a large number of lenses constituting the lens system, and by changing the gas pressure in the lens chamber, the magnification error of the projection optical system PL is changed. Can be changed within a predetermined range.

An environment sensor 40 for measuring room temperature and atmospheric pressure is connected to the main control system 38.
Corrects the imaging characteristic of the projection optical system PL via the imaging characteristic correction device 39 according to the measurement result of the environment sensor 40. It is also conceivable that the amount of astigmatism in the projection optical system PL and other optical members changes depending on the room temperature or the atmospheric pressure. Therefore, the relationship between the measurement result by the environment sensor 40 and the amount of change in astigmatism in the optical members is measured in advance, and the main control system 38 forms the image of the projection optical system PL via the imaging characteristic correction device 39. In parallel with the correction of the image characteristics, the relative rotation angle or interval between the two cylindrical lenses 9 and 8 is adjusted via the driving device 37. As a result, the astigmatism that has changed due to the environment can be offset by the amount of change of the astigmatism in the two cylindrical lenses 9 and 8.

At the time of normal exposure, the alignment system 2
6 is an obstacle, so that the alignment system 26 can be retracted during exposure. However, when retracting the alignment system 26, the wafer mark WM is
In addition, since the position of the reticle mark RM is detected, the position reproducibility when the alignment system 26 is set on the reticle R becomes a problem. That is, the amount of astigmatism generated with respect to the alignment light varies depending on the position of the alignment system 26, so that accurate position detection of the wafer mark WM cannot be performed.

Therefore, a sensor for measuring the set position of alignment system 26 is provided, and alignment system 2 is provided in advance.
When the amount of astigmatism with respect to the set position 6 is measured, and the alignment system 26 is set thereafter, the relative rotation angle or the interval between the cylindrical lenses 9 and 8 is changed according to the position to adjust the alignment. The amount of change in astigmatism due to the position of the system 26 is corrected.

In the above-described embodiment, at least one of the two cylindrical lenses 8 and 9 is rotated to move the relative rotation angle or at least one of the two cylindrical lenses 8 and 9 to move. The amount of astigmatism is adjusted by changing the interval. However, even if the two cylindrical lenses 8 and 9 are integrally rotated around the optical axis, the state of astigmatism can be changed to some extent. it can. Therefore, the astigmatism generated in the position detecting optical system can be corrected by changing the rotation angle (hereinafter, referred to as “absolute rotation angle”) of the two cylindrical lenses 8 and 9 as one body. good. The positions of the cylindrical lenses 8 and 9 are arbitrary. For example, in the example shown in FIG. 1, the cylindrical lenses 8 and 9 may be disposed anywhere between the wafer W and the reticle 10.

In the above embodiment, a cylindrical lens is used as the toric lens. However, two general toric lenses having different focal lengths in two orthogonal directions are used, and these two toric lenses are used. It is apparent that astigmatism generated in the position detecting optical system can be corrected by changing the absolute rotation angle, the relative rotation angle, the interval, and the like of the lens.

The present invention is applicable not only to image processing of an image of the wafer mark WM but also to photoelectric conversion of light from the wafer mark WM as a whole, as in an alignment system of a laser step alignment method. By correcting astigmatism using a toric lens as described above, the position of the wafer mark WM can be detected more accurately.

Further, it goes without saying that the present invention can be applied not only to an exposure apparatus for manufacturing a semiconductor element or the like but also to a microscope or the like. As described above, the present invention is not limited to the above-described embodiment, and can take various configurations without departing from the gist of the present invention.

[0109]

According to the embodiments of the present invention, the astigmatism generated in the position detecting optical system (for example, the objective lens, the optical path bending mirror, etc.) or the projection optical system can be changed by replacing the optical member. There is an advantage that the correction can be performed without performing, and the two-dimensional position detection of the test object can be performed with higher accuracy. Another advantage is that two toric lenses can cope with a change in the working distance of the optical system for position detection when warpage or undulation is present on a substrate or the like as a test object due to chemical treatment or the like, even if the working distance of the optical system for position detection changes. is there.

Further, for example , when a driving device for changing the rotation angle or position of at least one of the two toric lenses is provided as in the third embodiment of the present invention , for example, room temperature or atmospheric pressure Even when the astigmatism of the position detecting optical system changes due to the change, the astigmatism can be easily corrected.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a main part of a projection exposure apparatus to which a first embodiment of the present invention is applied.

FIG. 2A is a perspective view showing a case where the rotation angles of two cylindrical lenses are changed in the first embodiment, and FIG.
Is an optical path diagram showing an image forming system, and (c) is an optical path diagram showing a parallel system.

3A is a perspective view showing a case where the interval between two cylindrical lenses is changed in the first embodiment, FIG. 3B is an optical path diagram showing a parallel system, and FIG. 3C is an optical path diagram showing an imaging system. It is.

FIG. 4A is an enlarged view showing an index mark IM, and FIG.
Is an enlarged view showing the wafer mark for the meridional direction,
(C) is a diagram showing an image captured by the image sensor.

FIG. 5 is a waveform diagram showing a change in an imaging signal when the height of an exposure surface of a wafer W is gradually changed in the first embodiment.

FIG. 6 is an enlarged view showing a sagittal direction wafer mark in the first embodiment.

FIG. 7 is a configuration diagram showing a main part of a projection exposure apparatus to which a second embodiment of the present invention is applied.

FIG. 8 is a configuration diagram showing a main part of a projection exposure apparatus to which a third embodiment of the present invention is applied.

[Explanation of symbols]

 R Reticle PL Projection optical system W Wafer WM Wafer mark IM Index mark 1 Wafer stage 4 Alignment system 6 Beam splitter 7 Objective lens 8 Negative cylindrical lens 9 Positive cylindrical lens 10 Focusing plate 11 Imaging lens 13M, 13S Image sensor

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Ayako Sugaya 3-2-3 Marunouchi, Chiyoda-ku, Tokyo Nikon Corporation (56) References JP-A 1-227431 (JP, A) JP-A 2- 28311 (JP, A) JP-A-2-90512 (JP, A) JP-A-3-61802 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027 G01B 11 / 00 G03F 9/00

Claims (19)

(57) [Claims] 1. A position detection light from a measurement mark on a test object is guided to an observation surface via a position detection optical system, and the position detection light is positioned on the observation surface from the position of the position detection light. In a position detection device that detects the position of the test object, a first toric lens and a second toric lens are arranged along an optical path of the position detection light between the test object and the observation surface, At least one of the two toric lenses is provided so as to be rotatable about the optical axis of the lens or to be movable along the optical axis, and at least one of the two toric lenses is rotated. Alternatively, the position detecting device is configured to correct astigmatism generated in the position detecting optical system with respect to the position detecting light by moving the position detecting light. 2. A position detection optical system for condensing position detection light from a measurement mark on a test object and forming an image of the measurement mark on a reference mark plate on which a reference mark is formed. Measuring means for detecting a two-dimensional displacement amount of the reference mark and the image of the measurement mark, and measuring the displacement of the test object from the displacement amount of the reference mark and the image of the measurement mark. In a position detecting device for detecting a position, a first toric lens and a second toric lens are arranged along an optical path of the position detection light between the test object and the reference mark plate, and the two torics are provided. Driving means for rotating at least one of the toric lenses around the optical axis of the lens or moving the lens along the optical axis; and at least one toric lens of the two toric lenses. By rotating or moving the position detecting device being characterized in that so as to correct the astigmatism generated by the position detecting optical system with respect to the light for the position detection. 3. An exposure apparatus for projecting an image of a pattern formed on a mask onto a photosensitive substrate via a projection optical system, wherein the image is obtained from a measurement mark on the photosensitive substrate via the projection optical system. A position detection optical system that collects position detection light to be formed and forms an image of the measurement mark on an observation surface,
Measuring means for detecting a two-dimensional displacement amount of the image of the measurement mark on the observation surface, and detecting the position of the photosensitive substrate from the displacement amount of the image of the measurement mark. In the apparatus, a first toric lens and a second toric lens are arranged along an optical path of the position detection light between the projection optical system and the observation surface, and at least one of the two toric lenses is arranged. The toric lens is provided so as to be rotatable about the optical axis of the lens or to be movable along the optical axis, and by rotating or moving at least one of the two toric lenses, the position detection is performed. A position detecting device for correcting astigmatism generated in the projection optical system with respect to the light beam. 4. A means for obtaining an astigmatism amount from a focused image of the measurement mark in the meridional direction and a focused image of the measurement mark in the sagittal direction formed on the observation surface, wherein the astigmatism is further provided. 2. The position detecting device according to claim 1, wherein at least one of the two toric lenses is rotated or moved so as to correct the astigmatism obtained by the means for calculating the amount. 5. A driving device, further comprising: means for calculating an astigmatism amount from a focused image of the measurement mark in the meridional direction and a focused image of the measurement mark in the sagittal direction formed on the observation surface; The method according to claim 2, wherein at least one of the two toric lenses is rotated or moved so as to correct the astigmatism obtained by the means for determining the amount of astigmatism. The position detecting device as described in the above. 6. The position detecting device according to claim 1, wherein at least one of the two toric lenses includes a cylindrical lens. 7. An illumination optical system for illuminating a reticle, a projection optical system for projecting a pattern image of the reticle onto a photosensitive substrate as the test object, and detecting a position of the photosensitive substrate. A projection exposure apparatus, comprising: the position detection device according to claim 6. 8. A device manufacturing method for manufacturing a semiconductor device using the projection exposure apparatus according to claim 7, wherein the reticle is illuminated using the illumination optical system, and the reticle is illuminated using the projection optical system. An element manufacturing method, comprising projecting and exposing a pattern image of a reticle onto the photosensitive substrate. 9. An element manufacturing method for manufacturing a liquid crystal display element using the projection exposure apparatus according to claim 7, wherein the reticle is illuminated using the illumination optical system, and the reticle is illuminated using the projection optical system. An element manufacturing method, comprising projecting and exposing a pattern image of the reticle onto the photosensitive substrate. 10. An exposure method using the projection exposure apparatus according to claim 7, wherein the reticle is illuminated using the illumination optical system, and the pattern image of the reticle is formed using the projection optical system. An exposure method comprising projecting and exposing a photosensitive substrate. 11. A step of guiding position detection light from a measurement mark on a test object to an observation surface via a position detection optical system; and detecting the position detection light on the observation surface from the position detection light. Detecting the position of the specimen, and correcting the astigmatism generated in the position detection optical system, along the optical path of the position detection light between the specimen and the observation surface. Rotating or moving at least one of the two toric lenses arranged. 12. further have a step of obtaining the astigmatism generated by the position detecting optical system, at least one of the bets of said two toric lenses
In the step of rotating or moving the lens,
2 based on the result obtained in the step of obtaining the astigmatism.
At least one of the two toric lenses
The position detecting method according to claim 11, wherein the cleanse is rotated or moved . 13. The step of obtaining the astigmatism includes the steps of: moving a surface of the object to be measured to obtain a focused image of the measurement mark in the meridional direction formed on the observation surface; 13. The method according to claim 12, further comprising the step of: moving a test surface to obtain a focused image of the measurement mark in the sagittal direction formed on the observation surface. 14. The optical system according to claim 11, wherein at least one of the two toric lenses includes a cylindrical lens.
3. The position detection method according to 3. 15. A step of guiding position detection light from a measurement mark on a test object to an observation surface via a position detection optical system; and detecting the position detection light on the observation surface from the position detection light. and detecting the position of the test object, a step of determining the astigmatism generated by the position detecting optical system, for correcting the astigmatism generated by the position detecting optical system
Disposed in an optical path between the test object and the observation surface
At least one of the two toric lenses
Rotating or moving the lick lens . 16. The position detecting method according to claim 15 , wherein at least one of the two toric lenses includes a cylindrical lens. 17. A step of detecting a position of a photosensitive substrate as the test object using the position detection method according to claim 11 , and illuminating a reticle using an illumination optical system. And a step of projecting and exposing the pattern image of the reticle to the photosensitive substrate using a projection optical system. 18. A step of detecting the position of a photosensitive substrate as the object using the position detection method according to claim 11 , and illuminating a reticle using an illumination optical system. And a step of projecting and exposing the pattern image of the reticle onto the photosensitive substrate using a projection optical system. 19. A step of detecting a position of a photosensitive substrate as the test object by using the position detection method according to claim 11 , and illuminating a reticle using an illumination optical system. And a step of projecting and exposing a pattern image of the reticle onto the photosensitive substrate using a projection optical system.