JPH09219354A - Position sensing apparatus, and aligner with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the variation of a base line in the alignment sensor of an off-axis system or the like. SOLUTION: An index plate 35 with a formed index mark 34 thereon is interposed between a first objective lens 33 and a down-projection prism 36 to provide these optical systems in an index objective portion 11c separated from a sensor main body 11b provided with an illumination optical system including an infrared light source 26. A visible illumination light AL1 and an infrared illumination light AL2 are projected respectively on a wafer mark 38 and an index mark 34. Conjugating nearly the index and wafer marks 34, 38 with each other under the infrared illumination light AL2 by making a cold mirror 37 present just below the down-projection prism 36 reflect the infrared illumination light AL2, a visible sensed light LB1 from the wafer mark 38 and an infrared sensed light LB2 from the index mark 34 are respectively received by image sensors 41, 42 to sense the relative position of the wafer mark 38 to the index mark 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a photolithography process for manufacturing a semiconductor element, a liquid crystal display element, an image pickup element (CCD or the like), a thin film magnetic head or the like, and a mask pattern on a photosensitive substrate. The present invention relates to a position detection device suitable for application to an alignment sensor of an exposure device used for exposure to light, and an exposure device equipped with this position detection device.

[0002]

2. Description of the Related Art For example, in a projection exposure apparatus such as a stepper used in a photolithography process for manufacturing a semiconductor element or the like, or an exposure apparatus such as a proximity type exposure apparatus, it is formed on a reticle as a mask. In order to transfer the formed circuit pattern to a photoresist layer on a wafer (or a glass plate etc.) as a photosensitive substrate with high overlay accuracy, the reticle and each shot area of the wafer are aligned with high accuracy. Is required. Therefore, an alignment mark (wafer mark) for alignment is attached to each shot area of the wafer. Then, as an alignment sensor for detecting the positions of those alignment marks, a dot row-shaped alignment mark on the wafer is irradiated with laser light, and the position of the mark is diffracted or scattered by the mark. LSA (Lase
r Step Alignment) method, FIA (Fi) that measures the image data of the alignment mark imaged by illuminating it with light with a wide wavelength band using a halogen lamp as the light source.
(eld Image Alignment) method or a diffraction grating-like alignment mark on the wafer is irradiated with laser light of the same frequency or slightly changed frequency from two directions, and the two diffracted lights generated are caused to interfere with each other, and alignment is performed from the phase. LIA (Laser Interferometric) that measures the position of the mark
Alignment) method.

Further, as a conventional alignment method,
A TTL (through-the-lens) method for measuring the position of an alignment mark on a wafer via a projection optical system,
An off-axis method that directly measures the position of the alignment mark on the wafer without using the projection optical system, and a TTR (through) that simultaneously observes the wafer and reticle through the projection optical system and detects the relative positional relationship between them.・ The reticle) method is available. When performing alignment between a reticle and a wafer using these alignment sensors, a baseline amount, which is the distance between the measurement center of the alignment sensor and the center (exposure center) of the projected image of the reticle pattern, is obtained in advance. There is. Then, the alignment sensor detects the amount of deviation of the alignment mark from the measurement center, and the center of the shot area is accurately aligned with the exposure center by moving the wafer by a distance corrected by the baseline amount. It However, the baseline amount may gradually change during the process of maintaining and using the exposure apparatus. When a so-called baseline variation, which is a variation in the baseline amount, occurs,
Alignment accuracy (superposition accuracy) decreases. Therefore, conventionally, for example, a baseline check is regularly performed to accurately measure the interval between the measurement center of the alignment sensor and the exposure center.

[0004]

However, even if such a baseline check is performed, if the baseline amount fluctuates in a short period of time, there is a disadvantage that the alignment accuracy decreases. One of the factors of such a short-term baseline fluctuation that reduces the alignment accuracy is the measurement of the alignment sensor due to the thermal deformation due to the irradiation of the illumination light for exposure, mechanical vibration, or the change of the environment such as the atmosphere. It is the drift (displacement) of the center position. As described above, when the measurement center of the alignment sensor drifts, even if the alignment sensor and the wafer are relatively stationary, the amount of misalignment between the measurement center and the alignment mark changes, which causes an alignment error. Becomes Hereinafter, the fact that the amount of positional deviation between the measurement center of the alignment sensor and the alignment mark to be measured is unlikely to change is referred to as "drift stability" of the alignment sensor. In particular, since the off-axis type alignment sensor does not go through the projection optical system when detecting the alignment mark on the wafer, the drift stability of the alignment sensor itself is maximized as compared with the alignment sensor such as the TTL type through the projection optical system. It is important to raise.

Further, in recent years, along with the miniaturization of line widths of semiconductor elements and the like, ultraviolet light capable of obtaining high resolution as illumination light for exposure, and further far ultraviolet light such as KrF excimer laser light and ArF excimer laser light. Illumination light having a short wavelength such as light has been used. For example, in a projection exposure apparatus that uses excimer laser light as illumination light for exposure, T
Since various technical difficulties are involved when adopting the TL type alignment sensor, the degree of importance of the off-axis type alignment sensor, which has a high degree of freedom in design and high potential, is increasing. However, in the case of performing the alignment by such an off-axis method, if the drift stability of the alignment sensor itself is not high as described above, there is a disadvantage that the alignment accuracy is reduced as compared with the case of performing the alignment by the TTL method or the like. is there.

In view of the above problems, an object of the present invention is to provide a position detecting device which is excellent in drift stability and can detect the position of an object (position detecting mark) with high accuracy. Another object of the present invention is to provide an exposure apparatus equipped with such a position detection device.

[0007]

A position detecting device according to the present invention comprises a position detecting mark (3) formed on an object (2) to be inspected.
8) Condensing optical system (3) for condensing the light flux (LB1)
3, 39) and photoelectric detection means (41) for photoelectrically converting the light beam condensed by this condensing optical system, and its position detection mark (38) based on the detection signal from this photoelectric detection means. In the position detecting device for detecting the position of the reference body (35), the reference body (35) is arranged between the object (2) and the condensing optical system (33, 39) and has a predetermined index mark (34). ) And the photoelectric detection means (41) as the first photoelectric detection means, the light beam (LB2) from the index mark (34) is received via the condensing optical system (33, 39). Second photoelectric detection means (42) for photoelectric conversion,
And the first and second photoelectric detection means (41, 4).
Based on the detection signal from (2), the index mark (3
The position of the position detection mark (38) relative to 4) is detected.

According to the position detecting device of the present invention, the luminous flux (LB1) (hereinafter,
Both the "inspection object detection light" and the light flux (LB2) from the index mark (34) (hereinafter referred to as "reference detection light") are detected via the same focusing optical system (33, 39). Therefore, the object detection light and the reference detection light are similarly affected by the drift due to the heat or the mechanical vibration to the condensing optical system, and the drift stability is improved,
The detection accuracy (detection reproducibility) of the relative position of the position detection mark (38) with respect to the index mark (34) is improved.

In this case, an illumination optical system (21) for illuminating the position detection mark (38) and the index mark (34).
˜30), the illumination optical system irradiates the index mark (34) with a light flux (AL2) directed toward the object (2) side through the index mark (34). And a reflecting member (37) that makes the index mark (34) forming surface and the position detecting mark (38) forming surface substantially conjugate by reflecting the light to the side. The light beam (LB2) that has passed through the condensing optical system (33, 39) after being reflected is preferably received by the second photoelectric detection means (42).
As a result, the optical path lengths of the object detection light (LB1) and the reference detection light (LB2) become substantially the same, and the condensing optical system can be easily used in common and the first and second The light receiving surface of the photoelectric detecting means can be arranged at substantially the same distance from the condensing optical system.

Further, the surface on which the index mark (34) is formed is arranged close to the surface on which the position detection mark (38) is formed, and the position detection mark (38) and the index mark (34) are illuminated. It has an optical system (21-30),
The index mark (34) is irradiated from the illumination optical system, passes through the index mark (34), and then the light beam (LB2) condensed by the condensing optical system (33, 39) is used as the second light beam.
Light is preferably received by the photoelectric detection means (42). As a result, the index mark (34) and the position detection mark (3
Since 8) and 8) are arranged close to each other, drift stability is further improved.

An example of the condensing optical system is an image forming optical system (33, 39) that forms an image of the position detection mark (38) and the index mark (34). An example of the second photoelectric detection means is an image pickup device (41, 42) for picking up an image of the position detection mark (38) and an image of the index mark (34). Further, in the case where the first and second photoelectric detection means are image pickup elements (41B) for picking up the image of the position detection mark (38) and the image of the index mark (34) at the same time, for example, FIG. As shown in (a), the illumination light (AL) for the index mark (34) is located at a position conjugate with the index mark (34) through the reflection member (37) in the illumination optical system.
It is preferable to dispose a light shielding member (46C) for partially shielding 2). As a result, the reference detection light (LB
2) It is possible to prevent unnecessary stray light that is mixed in, and to prevent the contrast of the index mark image of the index mark (34) on the image pickup element (41B) from decreasing, so that the SN ratio of the detection signal corresponding thereto can be reduced. improves. A similar method is effective for the detection signal of the wafer mark (38).

Further, the index mark (34) is in the optical axis (AX1) direction (Z direction) of the focusing optical system (33, 39).
Height adjusting means (43) for adjusting the position of the and environmental condition measuring means (PG, TG1, TG) for measuring the environmental condition of the surroundings.
2, 6a) and the light flux (LB2) from the index mark (34) by the condensing optical system (33, 39) according to the detection result of the amount of change in the environmental condition measured by the environmental condition measuring means. Offset calculating means (6) for obtaining an offset amount between the light condensing position and a predetermined target value, and based on the offset amount obtained by the offset calculating means, the height adjusting means (43) is provided. It is preferable to independently adjust the position of the index mark via the. As a result, the offset of the focus position of the reference detection light due to environmental changes is eliminated, and the detection position of the index mark (34) is stabilized,
As a result, the detection accuracy of the position detection mark (38) is improved.

Further, according to the environmental condition measuring means (PG, TG1, TG2, 6a) for measuring the environmental condition of the surroundings and the detection result of the change amount of the environmental condition measured by the environmental condition measuring means, the collection thereof is performed. An offset calculating means (6) for obtaining an offset amount between a light beam condensing position from the index mark (34) by the optical optical system (33, 39) and a predetermined target value, and an offset obtained by this offset calculating means. It is preferable to correct the relative position of the position detection mark (38) with respect to the index mark (34) based on the amount. As a result, the offset of the index mark (34) from the target focus position is corrected, and the detection accuracy of the position detection mark (38) is improved.

Next, a first exposure apparatus according to the present invention is an exposure apparatus including the position detection apparatus of the present invention, which transfers and exposes a transfer pattern on a mask (R) onto a photosensitive substrate (2). Then, using the alignment mark (38) on the photosensitive substrate (2) as the position detection mark, the position of the alignment mark (38) on the photosensitive substrate (2) is detected through the position detection device. The mask (R) is detected and the photosensitive substrate (2) is aligned based on the detection result.

According to the first exposure apparatus of the present invention,
Since the position detecting device of the present invention having the above-described operation is provided, the relative position of the alignment mark (38) with respect to the index mark (34) can be detected with high accuracy, and the position on the reticle (R) can be improved. The pattern can be exposed on the photosensitive substrate (2) with high precision. Further, a second exposure apparatus according to the present invention includes the position detection apparatus of the present invention, and transfers the transfer pattern on the mask (R) to the first holding member (1
An exposure apparatus for transferring and exposing onto a photosensitive substrate (2) through a projection optical system (1) supported by 6), a reference body (35) having an index mark (34) formed thereon, and a collection body thereof. A second holding member (14) for supporting at least one optical member (33) in the optical optical system (33, 39) independently of the remaining optical members in the condensing optical system (33, 39). )
And the second holding member includes a first holding member (1
6) fixed to the surface of the photosensitive substrate (2) side, and the alignment mark (38) on the photosensitive substrate (2) is used as the position detection mark, and the photosensitive substrate (2) is passed through the position detection device. ), The position of the alignment mark (38) is detected, and the mask (R) is detected based on the detection result.
And the photosensitive substrate (2) are aligned with each other.

According to the second exposure apparatus of the present invention,
The same effect as that of the first exposure apparatus can be obtained, and the reference body having the index mark (34) formed thereon and the condensing optical system (3
Since at least one optical member (33) in (3, 39) is supported by the second holding member (14) that independently supports the remaining optical members of the condensing optical system, the index mark ( The influence of, for example, thermal deformation or mechanical vibration of the projection optical system (1) or the first holding member (16) on the component 34) is reduced. Therefore, the drift stability of the position detection device is improved.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The first embodiment of the present invention will be described below.
An example will be described with reference to FIGS. In this example, the present invention is applied to an off-axis type FIA type alignment sensor provided in a stepper type projection exposure apparatus that collectively exposes a reticle pattern to each shot area on a wafer.

FIG. 1 shows a partial cross-section of the configuration of the alignment sensor of this example, and FIG. 2 shows the overall configuration of the projection exposure apparatus of this example. In FIG. 1, at the time of exposure, the pattern of the reticle R (see FIG. 2) is transferred to each shot area on the wafer 2 via the projection optical system 1. In the following description, the Z axis is taken parallel to the optical axis AX of the projection optical system 1, the Y axis is taken parallel to the plane of FIG. 1 and the X axis is taken perpendicular to the plane of FIG. 1 on a plane perpendicular to this Z axis. . First, FIG. 2 is a side view of FIG. 1 viewed in the Y direction. As shown in FIG. 2, the wafer 2 is placed on the Z tilt stage 3Z via a wafer holder (not shown). The Z tilt stage 3Z can move the wafer 2 in the optical axis AX direction (Z direction), incline the wafer 2, and rotate the wafer 2 around the optical axis AX by an internal drive system. The Z tilt stage 3Z is mounted on an XY stage 3XY that is movable in the X and Y directions with respect to the projection optical system 1 by the wafer stage drive system 5 in FIG. The wafer stage 3 is composed of the XY stage 3XY and the Z tilt stage 3Z.

Returning to FIG. 1, a movable mirror 4b for reflecting a laser beam from an external laser interferometer 4a is fixed to an end portion of the wafer stage 3, and the wafer stage 3 is fixed by the laser interferometer 4a and the movable mirror 4b. The X-direction and Y-direction positions and rotation angles of are measured. The position information of the laser interferometer 4a is supplied to a central control system 6 that centrally controls the entire apparatus. Based on this position information, the central control system 6 transmits the wafer stage 3 via a wafer stage drive system 5.
Control the positioning operation.

Further, as shown in FIG. 2, an irradiation optical system 9a for supplying detection light for forming a pinhole image or a slit image toward the surface of the wafer 2 in an oblique direction with respect to the optical axis AX, A light receiving optical system 9 which re-images a pinhole image or the like on the vibration slit from the reflected light beam of the detection light on the surface of the wafer 2 and receives the light beam transmitted through the vibration slit.
and an oblique incidence type focus position detection system (hereinafter, referred to as “focus position detection systems 9a and 9b”).
The focus position detection systems 9a and 9b supply a focus signal corresponding to the position deviation of the surface of the wafer 2 in the Z direction with respect to the best image plane of the projection optical system 1 to the central control system 6, and the central control system 6
Drives the Z tilt stage 3Z in the Z direction by the autofocus system based on this focus signal. In this example, the light-receiving optical system 9 is preliminarily set so that the image plane becomes the zero point reference.
The angle of a parallel plate glass (plane parallel) (not shown) provided inside b is adjusted, and autofocus is performed so that the focus signal from the light receiving optical system 9b becomes zero.

Next, the off-axis method of this example and F
The configuration of the IA type alignment sensor will be described. As shown in FIG. 1, the alignment sensor 11 of this example
Is configured by arranging the first light source 21 and the like in the casing 12, and the lamp house portion 11a installed outside the chamber in which the projection exposure apparatus of this example is housed, and the second light source 2
6 and the image pickup elements 41, 42, etc. are arranged in the casing 13, and are fixed to the lower side surface of the projection optical system 1, the sensor main body 11b, the first objective lens 33, the index plate 34.
The projection prism 36 and the like are disposed in the casing 14, and the index objective unit 11c is fixed to the lower portion of the end of the projection optical system 1 in the -Y direction. The lens barrel 15 of the projection optical system 1 is fixed to a projection optical system holder 16 fixed to a predetermined column (not shown). The projection optical system holding unit 16 is made of a low thermal expansion material such as an alloy having a low thermal expansion coefficient such as Invar, and is designed so that the temperature variation inside the chamber does not affect the projection optical system 1 and the alignment sensor 11 as much as possible.

The casing 13 of the sensor main body portion 11b includes a plurality of support frames (in FIG. 1, the inner support frame 17 thereof).
a and 17b), and is fixed to the side surface portion 16a of the projection optical system holding portion 16. In addition, the index objective unit 11
The casing 14 of c is formed of a low thermal expansion material such as an alloy having a low thermal expansion coefficient like the projection optical system holding portion 16,
A plurality of support frames (in FIG. 1, the inner support frame 18
a, 18b), and is fixed to the back surface portion 16b near the outer periphery of the projection optical system holding portion 16. in this case,
The measurement position of the alignment sensor 11 is brought as close as possible to the optical axis AX of the projection optical system 1, and the index objective unit 11c
It is important to arrange the plurality of support frames of symmetry with respect to the Y axis. Hereinafter, the side surface portion 16 of the projection optical system holding portion 16
a is the "D surface", the back surface portion 16b of the projection optical system holding unit 16
Will be described as “C plane”. Similarly, the projection optical system 1
The rear inclined portion 15a of the lens barrel 15 will be described as "B surface", and the central rear surface portion 1a of the projection optical system 1 will be described as "A surface".

First, the illumination light of a wide band wavelength emitted from the first light source 21 formed of a halogen lamp or the like installed in the lamp house portion 11a constituting the alignment sensor 11 is appropriately operated by the action of the wavelength limiting optical filter 22. It becomes visible illumination light having a wavelength width. The illumination light AL1 formed of the visible illumination light is then condensed by the condenser lens 23 on the incident end surface of the light guide 24 formed of an optical fiber or the like. The other end of the light guide 24 is taken out from the casing 12 to the outside of the casing 1 of the sensor body 11b.
It is installed inside the casing 13 through the outer surface of the casing 3. The illumination light AL1 emitted in the + Y direction from the exit end surface of the light guide 24 is condensed by the condenser lens 25 and is incident on the dichroic mirror 28 that is obliquely installed at an inclination angle of 45 ° with respect to the optical path of the illumination light AL1. .

The dichroic mirror 28 has a wavelength selectivity of reflecting visible light and transmitting infrared light, and the illumination light AL1 which is visible light is reflected downward by the dichroic mirror 28 with almost no dimming. Then, the field stop 29 is uniformly illuminated. Note that, as will be described later, the dichroic mirror 28 includes a second body installed in the sensor body 11b.
Illumination light AL2 consisting of infrared light emitted from the light source 26 of
Is incident from a direction orthogonal to the illumination light AL1. The illumination light AL1 that has passed through the field stop 29 is transmitted to the relay lens 3
The light is condensed at 0 and enters the half prism 31 arranged at an inclination angle of 45 ° with respect to the optical path of the illumination light AL1. The illumination light AL1 reflected in the + Y direction on the half mirror surface of the half prism 31 then passes through the window 13a provided on the lower side surface of the casing 13, and then passes through the window 14a on the side surface of the casing 14 of the index objective portion 11c. Through casing 1
It is incident on the inside of 4.

Next, the illumination light AL1 is emitted from the first objective lens 3
After forming a projection image of the exit end surface of the light guide 24 on the entrance pupil plane 32 of No. 3, the index plate 3 made of a transparent glass plate on which the index mark 34 is formed through the first objective lens 33.
5 is incident. The illumination light AL1 that has passed through the index plate 35 is
The light is deflected downward by the incident light prism 36 and enters a cold mirror 37 made of a transparent glass plate. A cold mirror film (hereinafter referred to as “CM film”) 37a that transmits visible light but reflects infrared light is vapor-deposited on the surface of the cold mirror 37. The illumination light AL is visible light.
1 passes through the cold mirror 37 with almost no dimming. In this case, the first objective lens 33 and the relay lens 3
0, and the optical axis of the optical system including the reflecting prism 36 and the like is defined as the optical axis AX1.

The cold mirror 37 is the index objective unit 11c.
The cold mirror drive element 43, which is provided inside the device and is composed of a piezoelectric element or the like, is configured to be capable of fine movement in the optical axis AX1 direction (Z direction).
3 is controlled by a central control system 6. As will be described later, the optical axis AX1 direction (Z direction) of the cold mirror 37 is controlled by the central control system 6 via the cold mirror drive element 43.
The position of may be adjusted. After passing through the cold mirror 37, the illumination light AL1 has a predetermined shape and is a wafer mark (alignment mark on the wafer) arranged on the surface of the wafer 2 corresponding to the focal plane of the first objective lens 33.
38 is irradiated almost vertically. The illumination area on the wafer 2 is set to a desired size by the field stop 29.
The wafer mark 38 is formed in a size of about 100 μm square and has a two-dimensional lattice-like pattern structure formed at a pitch of several μm in each of the X direction and the Y direction. However, a one-dimensional grid pattern or the like may be used as the wafer mark 38.

The illumination light AL1 applied to the wafer mark 38 is reflected and diffracted by the wafer mark 38 and returns upward from the wafer 2 along the optical axis AX1 as wafer mark detection light LB1. The wafer mark detection light LB1 is
The light enters the cold mirror 37 again, passes through the cold mirror 37 with almost no dimming by the CM film 37a, is then deflected in the -Y direction by the incident prism 36, passes through the index plate 35, and then reaches the first objective lens 33. Incident. Due to the wafer mark detection light LB1, a Fraunhofer diffraction image by the wafer mark 38 is formed on the entrance pupil plane 32 of the first objective lens 33. On the index plate 35, the index mark 34 having a pattern structure of a two-dimensional (one-dimensional also possible) phase grating shape having the same size as the wafer mark 38 is formed,
The index plate 35 is placed near the first objective lens 33. Therefore, the illumination light AL1 that illuminates the wafer mark 38
And wafer mark detection light LB1 from the wafer mark 38
The spread on the index plate 35 is approximately the effective diameter of the first objective lens 33, that is, about a dozen mm. On the other hand, the size of the index mark 34 on the index plate 35 is 100 μm.
It is very small around m-square, and it is about 10 ^-4 in terms of area ratio. Therefore, the illumination light AL1 passing through the index plate 35 can be uniformly irradiated on the wafer mark 38 without being substantially affected by the light shielding or diffraction by the index mark 34. Similarly, the wafer mark detection light LB1 returning from the wafer mark 38 is hardly affected by light blocking or diffraction by the index mark 34 when passing through the index plate 35, and thus the entrance pupil plane of the first objective lens 33. Index mark 34 for the wafer mark image of 32 wafer marks 38
Has almost no effect.

The wafer mark detection light LB1 emitted from the entrance pupil surface 32 of the first objective lens 33 is the half prism 3
After passing through 1, the light enters the second objective lens 39. The wafer mark detection light LB1 collected by the second objective lens 39 enters the dichroic mirror 40. The dichroic mirror 40 has wavelength selectivity that reflects visible light and transmits infrared light, like the dichroic mirror 28 described above.
The wafer mark detection light LB1 is emitted from the dichroic mirror 4
At 0, the light is reflected with almost no dimming, and a wafer mark image of the wafer mark 38 is formed on the image pickup surface of the two-dimensional image pickup device 41 including a two-dimensional CCD. If the wafer mark 38 is a one-dimensional mark, the image pickup device 41 may be a one-dimensional CCD or the like. The wafer mark image of the wafer mark 38 is hardly affected by the “vignetting” by the index mark 34 and can be regarded as an ideal image formation. Therefore, the position of the wafer mark 38 is accurately detected from the wafer mark image. The light intensity of the wafer mark image of the wafer mark 38 is converted into an electric signal by the image pickup element 41 and supplied to the central control system 6.

On the other hand, the illumination light AL2, which is infrared light emitted from the second light source 26 in the sensor body 11b, is condensed by the condenser lens 27, and the dichroic mirror 2 is used.
The light passes through the field diaphragm 29 with little dimming, passes through the field stop 29, is condensed by the relay lens 30, and enters the half prism 31. The light source 26 uses the light source 26 as the optical axis AX1.
It is supported so that it can be finely moved in a direction perpendicular to the direction (Z direction). As will be described later, the telecentricity of the illumination light AL2 is adjusted by changing the position of the light source 26 in the direction perpendicular to the optical axis AX1.

The light source 26 is also the sensor main body 11b.
Alternatively, the illumination light AL2 of infrared light may be introduced into the sensor main body portion 11b via a light guide or the like similarly to the illumination light AL1 which is visible light. Disposing a heat source such as a halogen lamp outside the sensor body 11b is an essential method for highly accurate positioning.

FIG. 3 is an optical path diagram for explaining the optical path of the illumination light AL2 in detail. As shown in FIG. 3, the illumination light AL2 incident on the half prism 31 is reflected by the half prism 31, Entrance pupil plane 3 of the first objective lens 33
2 forms a projected image of the light source 26 of FIG. The diameter of the luminous flux of the illumination light AL2 emitted from the first objective lens 33 is approximately several tens of millimeters, which is almost equal to the effective diameter of the first objective lens 33, and the index plate 35 arranged immediately after the first objective lens 33.
It is sufficiently possible to irradiate the index mark 34 with a size of about 100 μm above uniformly. The pattern structure of the index mark 34 is a two-dimensional (one-dimensional) phase pattern in which the phase of the transmitted light is different by 180 ° between the concave portion and the convex portion having the same degree of periodicity as the wafer mark 38. Therefore, of the illumination light AL2, the light flux irradiating this index mark 34 is transmitted and diffracted, and most of them are converted into only ± 1st order four (two in the case of a one-dimensional mark) diffracted light flux. It becomes the detection light LB2.

After passing through the index plate 35, the index mark detection light LB2 made of infrared light is deflected downward by the epi-illumination prism 36 and irradiated on the cold mirror 37. The CM film 37a deposited on the surface of the cold mirror 37 has an optical property of transmitting visible light and reflecting infrared light as described above. Therefore, the CM film 37a of the cold mirror 37
The index mark detection light LB2 reflected by the index plate 3 is returned to the epi-illumination prism 36 again and is deflected in the −Y direction, and is not affected by the index mark 34.
After passing through 5, the light enters the first objective lens 33 again. A Fraunhofer diffraction image by the index mark 34 is formed on the entrance pupil plane 32 of the first objective lens 33 by the index mark detection light LB2. The cold mirror 37 on which the CM film 37a is formed is configured such that the position in the optical axis AX1 direction (Z direction) can be adjusted by the cold mirror drive element 43, and the optical axis AX1 of the cold mirror 37 is adjusted.
By changing the position in the direction, the position of the index mark 34 in the optical axis AX1 direction is substantially adjusted.

In this case, the optical path length from the index mark 34 to the reflecting surface of the epi prism 36 is D ₂ , and the epi prism 36 is
If the optical path length from the reflecting surface of the CM film to the CM film 37a of the cold mirror 37 is D ₁ , the index mark 34 to the CM film 37 can be
Optical path length L ₁ (= D ₁ + along optical axis AX1 up to a
The positions of the cold mirror 37 and the index plate 35 are set so that D ₂ ) and the optical path length L ₂ along the optical axis AX1 from the wafer surface to the CM film 37a surface of the cold mirror 37 are substantially equal. Therefore, when viewed from the first objective lens 33, it seems that the index mark 34 exists on the surface of the wafer. That is, for the first objective lens 33, the index mark 34 is equivalent to being on the focal plane of the first objective lens 33.

The index mark detection light LB2 emitted from the first objective lens 33 passes through the half prism 31 and
It is incident on the objective lens 39. The index mark detection light LB2 collected by the second objective lens 39 passes through the dichroic mirror 40 with almost no dimming, and the two-dimensional image pickup element 42 including a two-dimensional CCD for the index mark 34.
An index mark image of the index mark 34 is formed on the image pickup surface of. If the index mark 34 is a one-dimensional mark, the image sensor 42 may be a one-dimensional CCD or the like. The light intensity of the index mark image of the index mark 34 is converted into an electric signal by the image pickup element 42 and supplied to the central control system 6. The image sensor 42 is arranged as close to the dichroic mirror 40 as possible. The focusing of the index mark image of the index mark 34 on the image sensor 42 is performed by the index plate 35 and the cold mirror 3.
7 and the arrangement of the image sensor 42 and the like are changed.

The index mark image of the index mark 34 is hardly affected by the eclipse by the index mark 34 itself, and accurately has the position information of the index mark 34. However, the index mark detection light LB2 is reflected by the incident prism 36.
The image contrast is slightly lowered due to the influence of spherical aberration that is insufficiently corrected due to the passing of the beam. Therefore, as a method for coping with spherical aberration, spherical aberration correcting means using an aspherical lens or the like for correcting spherical aberration may be provided on the optical path between the dichroic mirror 40 and the image sensor 42. Further, for example, the configuration shown in FIG. 4A can suppress the spherical aberration of the index mark detection light LB2.

FIG. 4A shows an example of the structure for correcting spherical aberration. In the example of FIG. 4A, a deflecting mirror 36A is adopted instead of the incident prism 36, and an index plate 35 is used.
And the glass plate of the cold mirror 37 are made substantially equal in thickness. As a result, the index mark detection light LB2 has the same aberration condition as the wafer mark detection light LB1, and both the wafer mark image of the wafer mark 38 and the index mark image of the index mark 34 on the image pickup surfaces of the image pickup devices 41 and 42 are substantially the same. An ideal image is formed. In this case, the optical path length from the index mark 34 to the reflection surface of the polarization mirror 36A is D ₄ , and from the reflection surface of the polarization mirror 36A to the cold mirror 3.
If the optical path length of up to 7 of CM film 37a and D _3, the optical path length _{L 5 (= D 3 + D} 4) along the optical axis AX1 to the CM film 37a from the index mark 34, the cold mirror 37 from the wafer surface Of the cold mirror 3 so that the optical path length L ₃ along the optical axis AX1 up to the surface of the CM film 37a becomes substantially equal.
7 and the position of the index plate 35 are set.

Further, in the example of FIGS. 1 and 4 (a), the index plate 35 and the cold mirror 37 are used.
Instead of the incident light prism 36 of FIG. 1 as shown in FIG.
An index mark 34A similar to the index mark 34 of FIG. 1 is formed on the surface facing the first objective lens 33, and a CM film 3a similar to the CM film 37a is formed on the surface facing the wafer mark 38.
An epi prism 36B having 7b deposited may be used. In this case, the index mark 34A of the epi-illumination prism 36B
If the optical path length from the reflecting surface to the reflecting surface is D ₆ and the optical path length from the reflecting surface to the CM film 37b is D ₅ , the index mark 34A
To CM film 37b from the optical path length L ₆ along the optical axis AX1
The size and position of the epi-illumination prism 36B are set so that (= D ₅ + D ₆ ) and the optical path length L ₄ along the optical axis AX1 from the wafer surface to the CM film 37b are substantially equal.
According to this method, optical components such as an index plate and a cold mirror are reduced, the manufacturing cost is reduced, and flare can be expected to be reduced by reducing the boundary surface in the optical path. In addition, the number of parts affected by thermal and mechanical fluctuations is reduced,
The effect of shifting parts is reduced. In the example of FIGS. 1 and 4A and 4B, the index marks 34, 34
In the pattern structure A, the phase of transmitted light at the convex portion and the concave portion is 18
Although the phase pattern is different by 0 °, bright and dark lines
It may be an and space pattern or the like.

Returning to FIG. 1, the central control system 6 includes the image pickup device 4
1 and 42 respectively supply electric signals of the wafer mark image of the wafer mark 38 and the index mark image of the index mark 34, and the position information of the wafer stage 3 from the laser interferometer 4a. Mark 34
The two-dimensional displacement of the center of the wafer mark image of the wafer mark 38 with respect to the center of the index mark image is detected. Further, since the magnification between the images on the image pickup surfaces of the image pickup elements 41 and 42 and the surface of the wafer 2 is known in advance, the positional shift amount is converted into the positional shift amount on the wafer 2. And
By adding the measured value of the laser interferometer 4a at the time of the measurement to the converted positional deviation amount, the two-dimensional position of the wafer mark 38 in the stage coordinate system (coordinate system indicating the position of the wafer stage 3) can be obtained. The position is calculated. In this case, when the center of the wafer mark image of the wafer mark 38 matches the center of the index mark image of the index mark 34,
The position of the center of the wafer mark 38 can be regarded as the measurement center of the alignment sensor 11.

A plurality of shot areas are formed on the wafer 2, and a wafer mark similar to the wafer mark 38 is formed at a predetermined position in each of these shot areas. The wafer stage 3 is moved so that the wafer marks in those shot areas sequentially enter the detection area of the alignment sensor 11, and the position shift amount with respect to the index mark 34 is detected, and the position of the wafer stage 3 is detected by the laser interferometer 4a. By doing so, the position of the wafer mark in the shot area in the stage coordinate system can be detected.

Further, the projection exposure apparatus of this example is provided with an environment sensor for measuring the environment temperature and atmospheric pressure around the apparatus as shown in FIG. For example, a temperature sensor such as a temperature sensor TG2 that measures the temperature around the casing 14 of the index objective unit 11c of the FIA type alignment sensor 11 or a temperature sensor TG1 that measures the ambient temperature on the wafer 2,
Also, an atmospheric pressure sensor PG for measuring the atmospheric pressure around the apparatus is installed, and output signals of the temperature sensor, the atmospheric pressure sensor, etc. are constantly supplied to the signal processing device 6a. The signal processing device 6a obtains the temperature and atmospheric pressure from these output signals and supplies them to the central control system 6.

In this example, as an example, the wafer 2
The coordinate positions of the wafer marks attached to a predetermined number of shot areas (sample shots) selected from the above are measured using the alignment sensor 11, and the measurement results are statistically processed to arrange the shot areas on the wafer 2. Enhanced Global Alignment (EG
Alignment of each shot area is performed by the method A). Further, for example, by using a reference mark member (not shown) on the wafer stage 3, the center of the projected image of the pattern of the reticle R through the projection optical system 1 (exposure center).
And the measurement center of the alignment sensor 11 (index mark 3
Since the baseline amount, which is the amount of positional deviation from the image center of 4), is measured, the central control system 6 determines the wafer stage 3 based on the coordinates obtained by correcting the array coordinates of each shot area with the baseline amount. To position. With the above operation, each shot area of the wafer 2 can be accurately positioned with respect to the projected image of the pattern of the reticle R. By performing exposure in this state, high overlay accuracy can be obtained for each shot area. To be

Next, the operation of the alignment sensor 11 of this example will be described. Alignment sensor 11 of this example
Has the following features as compared with the conventional FIA type alignment sensor. First, the sensor body 11b and the index objective unit 11c are separated. FIG.
FIG. 5A shows the configuration of the alignment sensor 11 of FIG. 1 of this example viewed from the back side, and FIG. 5B shows the configuration of the conventional FIA type alignment sensor viewed from the back side. As shown in FIG. 5B, in the conventional alignment sensor, the sensor main body and the objective are not separated, and the sensor main body 51 in which the sensor main body and the index objective are integrated holds the projection optical system. The support frames 52a and 52b are provided on the D surface of the portion 16.
Has been fixed through. In this case, since the thermal deformation of the sensor body 51 has a great influence on the baseline fluctuation,
The casing of the sensor body 51 is made of a low thermal expansion material.

On the other hand, the alignment sensor 1 of this example
1, the index objective unit 11c is separated from the sensor body 11b as shown in FIG. 5 (a). The sensor body 11b is fixed to the D surface of the projection optical system holder 16 via the support frames 17a and 17c. On the other hand, the index objective section 11c is arranged toward the optical axis AX of the projection optical system 1 from a position slightly apart from the + Y direction end of the sensor main body section 11b, and is parallel to the Y axis and passes through the optical axis AX. It is fixed to the C surface of the projection optical system holding unit 16 via symmetrically arranged support frames 18a to 18d.

As a second feature, as shown in FIG. 1, the index mark 34 is the first objective lens 33 and the wafer mark 38.
It is located between and. And as the third feature,
The index mark detection light LB2 from the index mark 34 and the wafer mark detection light LB1 from the wafer mark 38 are separated immediately before entering the image pickup devices 41 and 42. With the above three features, the following operational effects can be obtained.

First, the D surface 1 of the ordinary projection optical system holder 16
When 6a expands and contracts and moves, or when the sensor body 11b moves and deforms, it causes a so-called baseline fluctuation, which causes a fluctuation in the baseline amount. However, in this example, the wafer mark detection light LB1 and the index mark detection light L
B2 is a dichroic mirror 40 of the sensor body 11b
Except for the subsequent optical paths, they pass through almost the same optical path. Therefore, the index mark image of the index mark 34 on the image pickup surface of the image pickup element 42 and the wafer mark 3 on the image pickup surface of the image pickup element 41.
The wafer mark image of No. 8 is displaced by a substantially equal drift amount, and the expansion and contraction of the D surface and the movement and deformation of the sensor main body portion 11b do not cause the baseline variation. In other words, as long as the index objective portion 11c and the wafer mark 38 are stationary, the amount of positional deviation between the image of the index mark and the image of the wafer mark 38 hardly changes, and the "drift stability" becomes extremely high. .

Further, since the wafer mark detection light LB1 and the index mark detection light LB2 travel in substantially the same optical path, they are equally affected by mechanical vibrations and air fluctuations in the optical path, so that the index mark 34 The detection positions of the index mark image and the wafer mark image of the wafer mark 38 on the imaging surface also fluctuate equally. Therefore, the index mark 3
When the position of the wafer mark 38 is detected on the basis of 4, the so-called difference between the two is measured, this is advantageous in terms of measurement reproducibility. Furthermore, the casing 13 of the sensor body 11b
Since it does not have to be composed of a low thermal expansion material such as a low thermal expansion alloy which is generally expensive and difficult to process, the cost can be kept low.

Further, the source of the baseline fluctuation caused by the sensor main body 11b is greatly reduced, and a factor causing the baseline fluctuation is, for example, the horizontal of the C plane (16b) to which the index objective section 11c is fixed. The drift of the position of the index mark 34 with respect to the wafer mark 38 due to the expansion and contraction in the direction and the drift of the index mark 34 with respect to the wafer mark 38 due to the internal deformation of the index objective portion 11c are the main ones. In this case, since the index objective portion 11c itself is originally small, the internal deformation of the index objective portion 11c is also small. Therefore, the drift of the index mark 34 is also extremely small. In addition, in the index objective portion 11c, the optical member that is greatly affected by the thermal fluctuation and has a great influence on the drift is the casing 14 that supports the epi-illumination prism 36, and the thermal deformation of the casing 14 causes the epi-illumination prism 36 to pitch. The baseline fluctuations due to displacement due to rolling, rolling, yawing, etc. are reduced as described below. For this reason, the incident light prism 36B of FIG.
The operation in the case of using will be described as an example.

FIG. 6 is an epi-illumination prism 36B of FIG. 4 (b).
6A is a perspective view showing the positional relationship between the index objective unit 11c and the wafer 2, and FIG. 6B to FIG. ) Is
Pitching, rolling, yawing, vertical movement (movement in the Z direction), lateral movement (movement in the X direction), and forward / backward movement (movement in the Y direction) of the epi-illumination prism 36B, respectively.
Shows the state of. In FIG. 6A, the index objective portion 11 c including the first objective lens 33, the episcopic prism 36 B having the index mark 34 A and the CM film 37 b formed in the casing 14 is located on the wafer 2 on which the wafer mark 38 is formed. It is installed in. The illumination light AL1 for illuminating the wafer mark 38 and the wafer mark detection light LB1 (see FIG. 1) pass through the opening 14a provided in the casing 14 corresponding to the center of the bottom of the epi-illumination prism 36B. Here, the casing 1 is attached to the incident-light prism 36B.
When pressure due to thermal deformation of No. 4 is applied, arrows 45
As shown in 45E, phenomena such as pitching, rolling, yawing, vertical movement, lateral movement, and forward / backward movement occur,
Image drift of the index mark 34A and the wafer mark 38 occurs. Hereinafter, the drift amounts of the image of the index mark 34A and the wafer mark 38 caused by pitching, rolling, etc. will be referred to as ΔX _TM and ΔX _WM , respectively, and the drift amount ΔX _WM of the image of the wafer mark 38 and the drift amount ΔX _{TM of the} index mark 34A will be described. The difference will be described as ΔD.

Conventionally, the index mark is the first objective lens 33.
Between the wafer mark 38 and the wafer mark 38 and the incident prism is displaced due to pitching, rolling, or the like, except for lateral movement, the wafer mark image drift amount ΔX.
_{The WM} was directly the drift amount ΔD between the wafer mark and the index mark, but in the case of this example, the index mark 3
Since 4A is installed between the first objective lens 33 and the wafer mark 38, the amount of drift Δ between the image of the wafer mark 38 and the index mark 34A will be described below.
D is reduced as compared with the conventional one.

As shown by the dotted line in FIG. 6B, when the epi-illumination prism 36B is displaced by pitching, the drift amount ΔX _WM of the image of the wafer mark 38 and the index mark 34A.
The following relational expression holds true with the drift amount ΔX _{WM of} ΔX _WM = 2ΔX _TM , ΔD = ΔX _WM −ΔX _TM = ΔX _WM / 2 Therefore, the drift amount ΔD is halved compared to the conventional one.

[0051] Further, as shown in FIG. 6 (c), between incident prism 36B is the drift amount [Delta] X _WM of the drift amount [Delta] X _WM, the index mark 34A of the wafer mark 38 when displaced by rolling the next The relational expression holds. ΔX _TM = 0, ΔD = ΔX _WM −ΔX _TM = ΔX _{WM In} this case, the drift amount ΔD does not change.

[0052] Further, as shown in FIG. 6 (d), if the incident prism 36B is displaced by yawing, between the drift amount [Delta] X _WM of the wafer mark 38, and the drift amount [Delta] X _WM of the index mark 34A follows The relational expression holds. ΔX _WM = ΔX _TM , ΔD = ΔX _WM −ΔX _TM = 0 Therefore, the drift amount ΔD is almost zero.

Further, as shown in FIG. 6 (e), when the epi-illumination prism 36B moves up and down, the drift amount ΔX _WM of the wafer mark 38 and the drift amount ΔX of the index mark 34A.
_The following relational expression holds with _WM . ΔX _WM = ΔX _TM , ΔD = ΔX _WM −ΔX _TM = 0 In this case, no drift occurs.

[0054] Further, as shown in FIG. 6 (f), if the incident prism 36B is moved laterally, the drift amount [Delta] X _WM of the drift amount [Delta] X _WM of the wafer mark 38, the index mark 34A
The following relational expression holds between and. _{ΔX WM = 0, ΔD = ΔX} WM -ΔX TM = -ΔX TM this case, conventionally, does not occur drift, drift occurs in this example. However, in the normal case, the epi-illumination prism 3
The lateral movement of 6B hardly occurs, and thus the effect of this example is not diminished.

Further, as shown in FIG. 6G, when the epi-illumination prism 36B moves back and forth, the drift amount ΔX _WM of the wafer mark 38 and the drift amount ΔX of the index mark 34A.
_The following relational expression holds with _WM . ΔX _TM = 0 ΔD = ΔX _WM −ΔX _TM = ΔX _{WM In} this case, there is no difference from the conventional case.

As described above, it can be seen that the structural superiority of arranging the index mark 34A between the first objective lens 33 and the wafer mark 38 also appears here. In addition,
In the above, for convenience of explanation, the incident light prism 36 of FIG.
Although B has been described as an example, similar results can be obtained with the configuration of FIG. That is, since the index plate 35 on which the index mark 34 is formed is arranged in the very vicinity of the epi-illumination prism 36, the influence of the heat deformation pressure of the casing 14 on the index plate 35 and the epi-illumination prism 36 becomes almost the same, and the index The plate 35 makes the same displacement as the epi-illumination prism 36. Therefore, it can be considered that the amount of drift between the index mark 34 and the wafer mark 38 is similar to that in the case of FIG.

As described above, the casing 14 of the index objective portion 11c
Even if it is not made of low thermal expansion material, the baseline fluctuation is greatly reduced. However, in the case of this example, since the casing 14 of the index objective portion 11c is made of the low thermal expansion material, the baseline variation due to the thermal deformation of the casing 14 hardly occurs. However, if necessary, only the index objective section 11c may be provided with measures such as wind shielding, heat insulation, and air conditioning. The only problem with expansion and contraction of the C surface on the back surface of the projection optical system 1 is the drift in the Y direction. Considering the symmetry of the fixing method of the index objective section 11c, the index objective section 11c hardly drifts in the X direction. Therefore, it is also effective to intensively control the temperature on the back surface side of the projection optical system holding unit 16, especially around the C surface (16b). Further, in this example, as described with reference to FIG. 2, the temperature sensor TG2 is installed in the vicinity of the index objective unit 11c, and the temperature sensor TG2 measures the temperature around the C plane. Therefore, from the temperature change, the index objective unit 11
The drift amount of c can be predicted.

As described above, since the locations of the drifts due to the heat generation in the alignment sensor 11 can be significantly reduced and limited, the use of the low thermal expansion material, the partial temperature control and the predictive control by the temperature monitor are wasteful. Therefore, in the alignment sensor 11, the amount of baseline fluctuation due to thermal fluctuation can be made extremely small, and the alignment accuracy can be greatly improved. Further, since it is not necessary to frequently repeat the baseline check, there is an advantage that throughput (productivity) is improved.

Illumination light AL for the index mark 34
It is necessary to adjust the telecentricity of 2 (hereinafter, simply referred to as “telecentricity”) very strictly. Important environmental changes around the alignment sensor 11 include changes in atmospheric pressure in addition to thermal changes. If there is a significant change in atmospheric pressure, the wafer mark 38 on the image pickup devices 41 and 42
The wafer mark image and the index mark image of the index mark 34 are defocused on the image pickup surfaces of the image pickup devices 41 and 42.
In this case, the image shift does not occur unless the telecentricity of the wafer mark image of the wafer mark 38 and the index mark image of the index mark 34 with respect to the imaging surface is destroyed, but the image shift occurs if the telecentric shift occurs. Regarding the wafer mark 38, the illumination light AL1 for the wafer mark 38
Even if the telecentricity of the
2 and the like so that the wafer mark image of the wafer mark 38 is always focused on the image pickup element 41, the vertical position of the wafer mark 38 is set to the focus position detection system 9a, 9b in FIG. Then, the central control system 6 drives and adjusts the Z tilt stage 3Z, so that the wafer mark 38 can be corrected so that the image does not shift with respect to a change in atmospheric pressure.

On the other hand, regarding the index mark 34, the telecentric adjustment of the illumination light AL2 is strictly performed as described below to prevent the image shift. First, the Z tilt stage 3Z is moved with respect to the wafer mark 38 that can be moved up and down along the optical axis AX1.
To adjust the telecentricity of the illumination light AL1. next,
The telecentric adjustment for the index mark 34 that cannot be moved up and down is performed as follows. First, a light source image of the illumination light AL1 for which the telecentric adjustment has been completed for the wafer mark 38,
The illumination light AL2, which is infrared light with respect to the light source image of the illumination light AL1, is observed on the entrance pupil plane 32 of the first objective lens 33.
Position of the light source 26 so that the light source images of
Fine tune on a plane perpendicular to X1. By doing so, since the telecentricity of the illumination light AL2 with respect to the index mark 34 is completely adjusted, the index mark image of the index mark 34 on the image pickup element 42 serving as the detection reference drifts even if the atmospheric pressure changes. The position of the wafer mark 38 can be detected with high accuracy. The light source images may be observed at the conjugate position of the entrance pupil plane 32.

Further, by using the atmospheric pressure sensor PG of FIG. 2 and the cold mirror drive element 43 of FIG. 1 and the like, the index mark 34 on the image pickup element 41 with respect to the atmospheric pressure variation is the same as the case of the wafer mark 38. If the focus of the index mark image is automatically adjusted, it is possible to prevent the occurrence of a telecentric offset due to a change in atmospheric pressure. Based on the focus change amount of the index mark image due to the atmospheric pressure change obtained by the design value and the atmospheric pressure variation amount obtained by the atmospheric pressure sensor PG, a cold film in which, for example, a CM film 37a is formed by a command from the central control system 6 By adjusting the height position (position in the direction along the optical axis) of the CM film 37a via the cold mirror drive element 43 that drives the mirror 37, the index mark image of the index mark 34 is always kept at the best focus position. You can In addition, the index mark 34 on the image sensor 41 due to atmospheric pressure fluctuation
The rate of change in the position shift of the index mark image is previously measured and stored in the central control system 6, and the offset to be given to the detected position of the image of the index mark 34 is calculated from the atmospheric pressure fluctuation amount obtained by the atmospheric pressure sensor PG. Thus, the position of the image of the index mark 34 serving as the detection reference can always be corrected for the atmospheric pressure change and stably measured.

Next, a second example of the embodiment of the present invention will be described with reference to FIG. In this example, the wafer mark 3
The wafer mark image of No. 8 and the index mark image of the index mark 34 are not spatially separated but are separated temporally and detected. The basic configuration is similar to that of the first example of FIG. 1, and in FIG. 7, parts corresponding to those of FIG.
The detailed description is omitted.

In the alignment sensor 61 of this example, the illumination light AL which is visible light for detecting the wafer mark 38 is used.
Lamp house 61 for supplying 1 to the sensor body 11b
A rotary shutter 53 and a drive mechanism 53 for driving the rotary shutter 53 are arranged in front of the light guide 14 in a.
a is provided. Further, an image pickup device for receiving the wafer mark detection light LB1 from the wafer mark 38 and an image pickup device for receiving the index mark detection light from the index mark 34 are not separately provided, but one image pickup device 41A receives the light. It is supposed to do. Other configurations are similar to those of the first example of FIG. The rotary shutter 53 is controlled to be opened / closed by the central control system 6 via the drive mechanism 53a, and the wafer mark 38 is detected intermittently. On the other hand, the index mark 34
The light source 26 installed in the sensor main body 11b for supplying the illumination light AL2 composed of infrared light for detecting is controlled by the central control system 6 to be turned on / off, and the index mark 3
4 is intermittently detected. Less than,
The operation of the alignment sensor 61 of this example will be described.

When the wafer mark 38 reaches the measurement area of the alignment sensor 61 due to the stepping of the wafer stage 3, the central control system 6 turns off the infrared light source 26. The central control system 6 simultaneously operates the lamp house 61
The rotary shutter 53 is opened via the drive mechanism 53a of a, the wafer mark 38 is irradiated with the illumination light AL1, and the wafer mark detection light LB1 is received by the imaging element 41A. An electric signal corresponding to the position of the wafer mark 38 is supplied to the central control system 6 from the image pickup element 41A. Next, as the wafer stage 3 starts stepping to move to another wafer mark position, the central control system 6 turns on the light source 26 and at the same time closes the rotary shutter 53 to illuminate the index mark 34. The light AL2 is emitted, and the index mark detection light LB2 is received by the image sensor 41A. Image sensor 41A
From, an electric signal corresponding to the position of the index mark 34 is supplied to the central control system 6. By repeating this series of operations in the EGA type alignment, each shot area (sample shot) with respect to the index mark 34
The coordinate position of can be measured.

The position of the index mark 34 need not be detected every time the wafer stage 3 is stepped.
For example, the index mark 34 may be detected only twice at the time of the first sample shot measurement and at the time of the last sample shot measurement, and the average value of the two measurement values may be taken. Furthermore, the position of the index mark 34 may be determined by a single measurement value during stepping between appropriate shot areas.

According to the present example, in addition to the advantages of the first example of FIG. 1, there is an advantage that the number of optical components such as the image pickup device and other optical devices is reduced and the cost is reduced. Next, a third example of the embodiment according to the present invention will be described with reference to FIG. In this example, an index mark 34B similar to the index mark 34 of FIG. To CM
The film 37b is formed. Other configurations are similar to those of the example of FIG. 1, and in FIG. 8A, portions corresponding to FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 8A shows a schematic structure of the present example. In FIG. 8A, the index mark 34B is formed on the upper surface of the cold mirror 37 arranged right above the wafer 2. The CM film 3 is provided on the wafer 2 side of the cold mirror 37.
7b is formed, and the illumination light AL2, which is the infrared light irradiating the index mark 34B, is reflected by the CM film 37b,
The index mark detection light LB2 is returned to the image sensor 42 side. Further, a field stop 29B for the index mark 34B is provided between the condenser lens 27 and the dichroic mirror 28 in the optical path of the illumination light AL2 to provide the illumination light AL.
A field stop 29A for the wafer mark 38 is provided between the condenser lens 25 and the dichroic mirror 28 in the optical path of 1.
Is provided. As described above, by separately providing the field stop 29B for the index mark 34B and the field stop 29A for the wafer mark 38, only the index mark 34B and the wafer mark 38 are illumination light AL2 and visible light, which are infrared light, respectively. Irradiation light AL1 which is light can be used for limited irradiation.

The optical path length L ₅ from the CM film 37b formed on the back side of the cold mirror 37 to the index mark 34B and the CM film 37b of the cold mirror 37 to the wafer mark 3
The optical path length L ₆ up to 8 is set to the same length, and the index mark 34B is on the focal plane of the first objective lens 33. The traveling direction of the index mark detection light LB2 is set to the image pickup element 42.
The function of deflecting (reflecting) to the side is the same as in the example of FIG.
7b has. Index mark 34B and CM in this case
The optical distance from the film 37b is determined by the index mark detection light LB2.
All you have to do is to secure a small space so that you can keep it.

In the present example, the index mark 34B is arranged immediately above the wafer mark 38 as close as possible, and the optical paths of the index mark detection light LB2 and the wafer mark detection light LB1 are combined early to be shared. The influences of air fluctuations and mechanical vibrations on the index mark detection light LB2 and the wafer mark detection light LB1 are made as close as possible. As a result, the drift stability of the alignment sensor is further improved, and the measurement reproducibility of the position detection of the wafer mark 38 is improved. In addition, the wafer mark 38 and the index mark 34 are simultaneously affected by the displacement of the epi-illumination prism 36, which is greatly affected by the heat fluctuation, and the index mark detection light LB2 and the wafer mark detection light LB1 are caused by the displacement of the epi-illumination prism 36. No baseline drift occurs.
Therefore, the effects of pitching, rolling, yawing, etc. described in the first example can be eliminated.

Next, as in the third example, the incident light prism 36
Two modified examples in which the index mark is arranged closer to the wafer 2 side will be described with reference to FIGS. 8B and 8C. The basic configuration is similar to that of the example of FIG. FIG.
FIG. 8B shows a schematic configuration of a first modified example with respect to the third example. As shown in FIG. 8B, in the present example,
The dedicated light source 26 that emits infrared light to illuminate the index mark 34B is not provided, and the index mark 34B and the wafer mark 38 are illuminated only by the light source that emits visible light. FIG. 8B shows a light guide 24 that supplies visible light from a visible light source (not shown). The illumination light from the light guide 24 enters the field stop 29C via the condenser lens 25. The field stop 29C is provided with two openings, and the illumination light from the condenser lens 25 is illumination light AL for illuminating the index mark 34B.
3 and the illumination light AL1 for irradiating the wafer mark 38. This illumination light AL3 corresponds to the illumination light AL2 in FIG. The following illumination light AL1 and illumination light A
The optical path of L3 is the illumination light AL1 and the illumination light AL of FIG.
It is similar to the case of 2.

Further, in this example, the means for deflecting (reflecting) the index mark detection light LB3 toward the image pickup element 42 is different from the CM film 37b in FIG.
4B is a reflection member 37c such as an aluminum (Al) film partially vapor-deposited on the wafer mark 38 side of the transparent flat plate glass 37K on which 4B is formed. Also in this case, the optical path length L ₇ from the reflecting member 37c to the index mark 34B and the flat glass 37
The optical path length L ₈ from the K reflection member 37c to the wafer mark 38 is set to the same length, and the index mark 34B is set.
Is on the focal plane of the first objective lens 33. According to the present example, the cost can be reduced as compared with the example of FIG. 8A because the light source that emits infrared light is not provided.

FIG. 8C shows a schematic configuration of the second modification of the third example. As shown in FIG. 8C,
In this example, as a means for deflecting the index mark detection light LB2 toward the image pickup element 42, a CM film or a reflecting member such as aluminum is not used. In this example, the index mark 34C having light reflectivity is used as the index mark, and the index mark 34C is formed on the wafer 2 side of the transparent flat plate glass 37K, and the surface of the wafer 2 is protected from chrome oxide or the like. A light shielding member 37d made of a light absorbing material is vapor-deposited so as to overlap the index mark 34C. In this case, the index mark 34C itself may be made light-absorbing, and the light shielding member 37d may be made of a reflecting member such as aluminum.

In this example, the index mark 34C is substantially deviated from the focal plane of the first objective lens 33 and defocused toward the first objective lens 33 side. Therefore, the image pickup element for detecting the index mark 34C is used. It is necessary to dispose 42 at a position rearward of the image pickup element 41 for detecting the wafer mark 38. The example of FIG. 8C is the simplest in which the index mark is arranged from the first objective lens 33 to the wafer mark 38 side without using the index mark detection light deflecting means (reflecting means) such as the CM film 37a in FIG. It is an example.

In addition, all of the above-described illumination methods for the wafer mark 38 are based on the epi-illumination method. However, even when the wafer mark 38 is transmitted and illuminated, the index mark is applied from the first objective lens 33 to the wafer mark 38. A method of arranging on the side can be applied. Further, the wafer mark 38
Alternatively, the index mark itself may be composed of a light-emitting body that spontaneously emits light. In this case, there is an advantage that no illumination means for the wafer mark 38 and the index mark is required.

As described above, as in the examples of FIGS. 8 (a) to 8 (c), it is used as a detection reference for almost all situations in which an object whose position is to be detected, such as the wafer mark 38, is imaged and detected. It is possible to apply a position detection method in which the index mark is arranged closer to the position detection target such as the wafer mark 38 than the light condensing means such as the first objective lens 33. Furthermore, the synergistic effect produced by using the method such as the independent holding of the first objective lens 33 and the index mark 34 described in the first example can be expected as well.

Next, a fourth example of the embodiment according to the present invention will be described with reference to FIGS. 9 and 10. In the above example, except for the example of FIG. 7, the image pickup element for detecting the wafer mark 38 and the image pickup element for detecting the index mark are separately provided, but it is not always necessary to provide two image pickup elements, and the index plate is not necessarily provided. By properly setting the arrangement of the above-mentioned index marks and appropriately setting a light-shielding plate for preventing stray light in the optical path of the illumination optical system on the light source side from the half prism 31, the index marks and the wafer can be formed by one imaging device. The position of the mark 38 can be detected simultaneously and with high accuracy. In this example, 1
An example of detecting the position of the wafer mark 38 based on the position of the index mark by the image pickup device of the table will be shown. The basic configuration except for the image sensor is the same as that of the example of FIG. 1, and in FIGS. 9 and 10, the portions corresponding to FIG.

FIG. 9A shows a schematic configuration of this example. As shown in FIG. 9A, the detection lights LB1 and LB2 from the index mark 34 and the wafer mark 38 are generated by one image pickup element 41B. Received light. In this case, the image sensor 41B
Stray light from the infrared light source 26 may be mixed in the area of the upper wafer mark 38 in the wafer mark image to reduce the contrast of the wafer mark image.

Therefore, the wafer mark 38 is generated by the stray light.
In order to prevent the S / N ratio of the electrical signal corresponding to the above from deteriorating, in the optical path before the illumination light AL2, which is infrared light, enters the dichroic mirror 28, and also the index mark 34.
In the vicinity of the position conjugate with (in FIG. 9A, the infrared light source 26
(Between the condenser lens 27 and the condenser lens 27) is provided with a light shielding plate 46B for shielding the outside of the pattern area of the index mark 34, and this light shielding plate 46B is used for the index plate 34 and the lens system (27, 30,
It is preferable to have a substantially conjugate relationship via 33).

FIG. 9C shows the state of the pattern on the light shielding plate 46B, and FIG. 9E shows the state of the index mark 34 formed on the index plate 35. FIG. 9 described below
9 (b) and FIG. 9 (d) also show the state of the pattern on each light shielding plate. As shown in FIG. 9 (e), the index mark 34 has two grid patterns for measuring in the X direction, which are formed at predetermined intervals along a straight line parallel to the X axis passing through the center of the index plate 35. The pattern 34X and two grid patterns 34Y for Y-direction measurement, which are formed at predetermined intervals along a straight line parallel to the Y-axis passing through the center of the index plate 35, are configured. On the other hand, the light-shielding plate 46B shown in FIG. 9C has a grid pattern 34 of the index marks 34.
At positions corresponding to X and 34Y, the grid pattern 34X,
A transmissive portion 48T including two transmissive portions 48X for the X axis and two transmissive portions 48Y for the Y axis having a width slightly larger than 34Y is provided, and the transmissive portion 48T is surrounded by a light shielding portion 48D. Has been. Most of the infrared illumination light AL2 from the light source 26 is shielded by the light shield 48D, so that the wafer mark 38 on the image sensor 41B.
Stray light from the infrared light source can be reduced from being mixed with the wafer mark image, and the SN ratio of the electric signal corresponding to the wafer mark image can be improved.

Next, considering the prevention of stray light with respect to the index mark image, the stray light caused by the illumination light AL1 of the visible light illuminating the wafer mark 38 is present in the detection area of the index mark image of the index mark 34 on the image pickup element 41B. In order to reduce the stray light, there is a position in the optical path of the illumination light AL1 incident on the dichroic mirror 28 and at a position conjugate with the surface of the wafer 2 or in the vicinity thereof (in the dichroic mirror 28 in FIG. 9A). In the optical path between the condenser lens 25 and the condenser lens 25), it is preferable to provide a light shielding plate 46A that shields a light beam passing through a position conjugate with the pattern area of the index mark 34.

FIG. 9B shows a pattern on the light-shielding plate 46A. As shown in FIG. 9B, the light-shielding plate 46A has conjugates corresponding to the grid patterns 34X and 34Y of the index mark 34. At the position, two light shielding parts 47X for the X axis having a width slightly larger than the grid patterns 34X, 34Y,
And a light-shielding portion 47 composed of two light-shielding portions 47Y for the Y-axis. Since the portion of the illumination light AL1 for wafer mark detection that passes through the index mark 34 is shielded, the wafer mark which is the reflected light from the wafer mark 38 in the detection area of the index mark image of the index mark 34 on the image sensor 41B. The detection light LB1 is reduced, and the SN ratio of the electric signal corresponding to the index mark image is improved.

Further, the illumination light AL2 that does not contribute to the image formation of the index mark 34 may become stray light with respect to the index mark detection light. In order to prevent the SN ratio of the output signal of the index mark image of the image sensor 41B from being deteriorated by this stray light,
In the optical path until the illumination light AL2 enters the dichroic mirror 28, and at a position conjugate with the index mark 34 via the cold mirror 37 or in the vicinity thereof (FIG. 9 (a),
By providing a light shielding plate 46C between the dichroic mirror 28 and the condenser lens 27),
The SN ratio of the electric signal corresponding to the index mark image on B can be improved.

FIG. 9D shows a pattern on the light shielding plate 46C. As shown in FIG. 9D, the light shielding plate 46C has conjugates corresponding to the grid patterns 34X and 34Y of the index mark 34. 2 for the X axis having a width slightly larger than the grid patterns 34X and 34Y similar to those in FIG. 9B.
A light-shielding portion 49 including one light-shielding portion 49X and two Y-axis light-shielding portions 49Y is provided. By doing this,
Stray light due to the illumination light AL2 is reduced, and it can be expected that the SN ratio of the electric signal corresponding to the image of the index mark 34 of the image pickup element 41B is improved.

As described above, the provision of the light shielding plate reduces stray light, and it is not necessary to separately provide an image pickup device for detecting the index mark and an image pickup device for detecting the wafer mark. It is possible to receive the image formation light from the mark at the same time and obtain an image pickup signal with good contrast. The present invention is not limited to the FIA type alignment sensor, but may be an off-axis type LI.
The same can be applied to the A-type alignment sensor and the LSA-type alignment sensor.

Further, the present invention is not limited to the stepper type projection exposure apparatus, but the reticle and the wafer are synchronously scanned while a part of the reticle pattern is projected on the wafer through the projection optical system. The same can be applied to a scanning exposure type projection exposure apparatus that sequentially transfers a pattern to each shot area of a wafer. 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.

[0086]

According to the position detecting device of the present invention, the luminous flux from the position detecting mark (hereinafter referred to as "inspection object detecting light")
Also, the light flux from the index mark (hereinafter referred to as “reference detection light”) is detected via the same focusing optical system. Therefore, the object detection light and the reference detection light are similarly affected by the drift due to heat or mechanical vibration to the condensing optical system, so that the drift stability is improved and the position detection mark position detection accuracy is improved. Has the advantage of improving. Especially,
INDUSTRIAL APPLICABILITY The position detecting device of the present invention is effective for an off-axis type alignment sensor that requires high drift stability.

Further, an illumination optical system for illuminating the position detection mark and the index mark, and a light beam irradiated to the index mark by this illumination optical system and traveling toward the object side through the index mark is reflected to the index mark side. A reflecting member that substantially conjugates the formation surface of the index mark and the formation surface of the position detection mark with each other, and transmits the light flux that has passed through the condensing optical system after being reflected by the reflection member to the second In the case of receiving light by the photoelectric detection means, the optical path lengths of the object detection light and the reference detection light are substantially equal to each other, so that the position detection mark and the index mark can be easily detected by the common focusing optical system. Become.

Further, the index mark forming surface is arranged close to the position detecting mark forming surface and has an illumination optical system for illuminating the position detecting mark and the index mark. The illumination optical system illuminates the index mark. When the second photoelectric detection means receives the light beam that has been condensed by the condensing optical system after passing through the index mark, the index mark and the position detection mark are arranged close to each other, so that drift stability is improved. There is an advantage of further improvement.

Further, the condensing optical system is an image forming optical system for forming the images of the position detection mark and the index mark, and the first and second photoelectric detecting means respectively form the image of the position detection mark and the index mark. If it is an image sensor that captures an image,
It is possible to detect the relative position of the position detection mark by detecting the image of the position detection mark and the image of the index mark formed by the condensing optical system with each image pickup device.

Further, the first and second photoelectric detecting means are image pickup devices for picking up the image of the position detection mark and the image of the index mark, respectively, and are conjugated with the index mark or the position detection mark in the illumination optical system. When a light blocking member for partially blocking the illumination light is arranged at a different position, unnecessary light flux in the reference detection light can be blocked, and the SN ratio of the detection signal in the second photoelectric detection unit can be increased. Has the advantage of improving.

Further, the height adjusting means for adjusting the position of the index mark or the image of the index mark in the optical axis direction of the converging optical system, the environmental condition measuring means for measuring the surrounding environmental condition, and the environmental condition measuring device. An offset calculation means for obtaining an offset amount between the light-condensing position of the light beam from the index mark by the light-converging optical system and a predetermined target value according to the detection result of the measured change amount of the environmental condition, When the position of the index mark or the image of the index mark is independently adjusted via the height adjusting means based on the offset amount obtained by the calculating means, there is no offset of the focus position of the reference detection light due to environmental changes. There is an advantage that the detection accuracy of the position detection mark is improved.

Further, in accordance with the environmental condition measuring means for measuring the surrounding environmental condition and the detection result of the change amount of the environmental condition measured by the environmental condition measuring means, the light flux from the index mark by the condensing optical system is detected. When correcting the relative position of the position detection mark with respect to the index mark on the basis of the offset calculation means for obtaining the offset amount between the focus position and the predetermined target value and the offset amount obtained by this offset calculation means, There is an advantage that the offset of the mark from the target focus position is corrected and the detection accuracy of the position detection mark is improved.

According to the first exposure apparatus of the present invention,
Since the position detecting device of the present invention having the above-described action is provided, the relative position of the alignment mark with respect to the index mark can be detected with high accuracy, and the pattern on the reticle can be accurately detected on the photosensitive substrate. Can be exposed to light. Further, according to the second exposure apparatus of the present invention,
The effect similar to that of the exposure apparatus can be obtained, and the influence of, for example, thermal deformation or mechanical vibration of the projection optical system and the first holding member on the index mark and the position detection mark can be made common. Therefore, the drift stability of the position detection device is further improved.

[Brief description of drawings]

FIG. 1 is a first embodiment of a position detecting device according to the present invention.
It is the schematic block diagram which notched one part which shows the example of.

FIG. 2 is a schematic configuration diagram showing a main part of a projection exposure apparatus including the position detection device of FIG.

3 is a diagram showing an optical path of detection illumination light of an index mark 34 in FIG.

4A and 4B are configuration diagrams showing two modified examples of a portion including the epi-illumination prism and the like of FIG.

5A is a view of the FIA alignment sensor of FIG. 1 viewed from the back side, and FIG. 5B is a view of a conventional FIA alignment sensor viewed from the back side.

FIG. 6 is an explanatory diagram of various positional deviation amounts when the epi-illumination prism 36B of FIG. 4 is displaced.

FIG. 7 is a schematic configuration diagram showing a second example of the embodiment according to the present invention.

8A is a schematic configuration diagram showing a third example of the embodiment according to the present invention, and FIGS. 8B and 8C are respectively FIG.
It is a schematic block diagram which shows the modification of (a).

FIG. 9 is an explanatory diagram showing a fourth example of the embodiment according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Projection optical system 2 Wafer 3 Wafer stage 6 Central control system 11 FIA type alignment sensor 11a Lamp house part 11b Sensor main body part 11c Index objective part 12 Casing (lamp house part) 13 Casing (sensor main part) 14 Casing (index objective) 15) Lens barrel 16 Projection optical system holder 17a, 17b, 18a, 18b Support frame 21 Light source (visible light) 26 Light source (infrared light) 33 First objective lens 34, 34A to 34C Index mark 35 Index plate 36, 36B Epi-illumination prism 37 Cold mirror 37a CM film 39 Second objective lens 41, 42, 41A, 41B Imaging element 46A, 46B, 46C Light-shielding plate

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/30 525W 525X

Claims (9)

[Claims] 1. A condensing optical system for condensing a luminous flux from a position detection mark formed on an object to be inspected, and a photoelectric detecting means for photoelectrically converting the luminous flux condensed by the condensing optical system. Then
In a position detection device that detects the position of the position detection mark based on a detection signal from the photoelectric detection means, the position detection device is arranged between the test object and the condensing optical system, and a predetermined index mark is formed. A reference body; and a second photoelectric detection unit that receives the light beam from the index mark through the condensing optical system and photoelectrically converts the light beam when the photoelectric detection unit is the first photoelectric detection unit. A position detecting device which detects a relative position of the position detecting mark with respect to the index mark based on detection signals from the first and second photoelectric detecting means. 2. The position detecting device according to claim 1, wherein an illumination optical system that illuminates the position detection mark and the index mark, the illumination mark is irradiated to the index mark by the illumination optical system, and the illumination mark passes through the index mark. By reflecting a light beam directed toward the object side toward the index mark side, a reflecting member that substantially conjugates the formation surface of the index mark and the formation surface of the position detection mark, A position detecting device characterized in that, after being reflected by the reflecting member, the light flux that has passed through the condensing optical system is received by the second photoelectric detecting means. 3. The position detecting device according to claim 1, wherein a surface on which the index mark is formed is arranged in proximity to a surface on which the position detection mark is formed, and illumination for illuminating the position detection mark and the index mark. An optical system is provided, and the light flux emitted from the illumination optical system to the index mark and passed through the index mark and then condensed by the condensing optical system is received by the second photoelectric detection means. Position detection device. 4. The position detecting device according to claim 1, 2, or 3, wherein the focusing optical system is an imaging optical system that forms an image of the position detection mark and the index mark, The position detecting device, wherein the first and second photoelectric detecting means are image pickup devices for picking up the image of the position detection mark and the image of the index mark, respectively. 5. The position detection device according to claim 1, 2, 3, or 4, wherein the first and second photoelectric detection means respectively form an image of the position detection mark and an image of the index mark. An image pickup device for picking up an image, and a position detection characterized by disposing a light shielding member for partially shielding illumination light in a position conjugate with the index mark or the position detection mark in the illumination optical system. apparatus. 6. The position detecting device according to claim 1, wherein the height adjustment for adjusting the position of the index mark or the image of the index mark in the optical axis direction of the focusing optical system. Means, an environmental condition measuring means for measuring the surrounding environmental condition, and, in accordance with a detection result of the amount of change in the environmental condition measured by the environmental condition measuring means, An offset calculation means for obtaining an offset amount between the light-condensing position and a predetermined target value, and based on the offset amount obtained by the offset calculation means, the index mark or the indicator through the height adjusting means. A position detection device characterized in that the position of the image of the mark is adjusted independently. 7. The position detecting device according to claim 1, wherein an environmental condition measuring means for measuring an environmental condition of the surroundings, and a change of the environmental condition measured by the environmental condition measuring means. An offset calculating means for obtaining an offset amount between the light collecting position of the light beam from the index mark by the light collecting optical system and a predetermined target value according to the amount detection result; and an offset amount obtained by the offset calculating means. A position detecting device for correcting the relative position of the position detecting mark with respect to the index mark based on the above. 8. An exposure device comprising the position detection device according to claim 1, which transfers and exposes a transfer pattern on a mask onto a photosensitive substrate, the position on the photosensitive substrate. The position of the alignment mark on the photosensitive substrate is detected via the position detection device using the alignment mark as the position detection mark, and the alignment of the mask and the photosensitive substrate is performed based on the detection result. An exposure apparatus characterized by being performed. 9. The position detecting device according to claim 1, wherein the transfer pattern on the mask is transferred onto a photosensitive substrate via a projection optical system supported by a first holding member. An exposure apparatus for transferring and exposing the reference mark on which the index mark is formed and at least one optical member in the condensing optical system independently of the remaining optical members in the condensing optical system. A second holding member that is supported by the second holding member is fixed to the surface of the first holding member on the side of the photosensitive substrate, and the alignment mark on the photosensitive substrate is used as the position detection mark. An exposure apparatus, wherein the position of the alignment mark on the photosensitive substrate is detected via the position detecting device, and the mask and the photosensitive substrate are aligned based on the detection result. .