JP3305058B2 - Exposure method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus used for manufacturing, for example, a semiconductor element or a liquid crystal display element in a photolithography process, and more particularly to a projection exposure apparatus having an off-axis type alignment system. It is suitable to be applied to.

[0002]

2. Description of the Related Art Conventionally, in a photolithography process, a step-and-repeat method is used as an apparatus for transferring a fine pattern onto a photosensitive substrate (a semiconductor wafer or a glass plate coated with a photoresist, etc.) at a high resolution. The so-called stepper is widely used. Such a stepper includes a focus position detection system that measures the height of an exposure surface of a shot area to be exposed on a photosensitive substrate, and a stage that adjusts the height of the substrate to the image plane of the projection optical system. And an autofocus mechanism comprising:

One example of a conventional focus position detection system is to project a measurement pattern image on a substrate at a measurement point near the center of an exposure field of a projection optical system, and re-measure a measurement pattern image by reflected light from the substrate. The focus position (height), which is the position in the optical axis direction of the projection optical system at the measurement point, is detected from the position of the pattern image for use. In this case, the focus position of the one measurement point is the object to be focused. Another example of the conventional focus position detection system is a multi-point detection system that projects a measurement pattern image at a plurality of points near and at the center of an exposure field of a projection optical system. When such a multi-point detection system is used, the focus position of the surface obtained by processing the measurement results of the focus positions at a plurality of points in the exposure field is determined by the height of the imaging plane of the projection optical system. Focused on.

In a stepper, a projection image of a circuit pattern conventionally formed on a photomask or a reticle (hereinafter, simply referred to as a “mask”) and a circuit pattern already formed on a photosensitive substrate are used. , Ie, an alignment system is provided.
The conventional alignment system includes an alignment optical system that detects the position of an alignment mark formed on a photosensitive substrate (and, in some cases, an alignment mark on a mask), and an alignment optical system that detects the position of the alignment mark. It comprises a stage system for positioning the substrate in accordance with the position. And
The alignment optical system and the focus position detecting system are completely separated from each other.

[0005]

In recent years, as the pattern of a semiconductor element or the like has become finer, the numerical aperture of a projection optical system tends to increase in order to improve the resolution of a stepper. However, as is well known, by increasing the numerical aperture of the projection optical system, the depth of focus, which is the margin for defocus from the image plane, decreases in inverse proportion to the square of the numerical aperture. In other words, when a stepper equipped with a projection optical system having a high numerical aperture is used, even if a slight defocus occurs, the resolution of the fine pattern is significantly reduced.

[0006] In this regard, if a conventional method of detecting a focus position only near the center of an exposure field is adopted as a focus position detection system, there is an inconvenience that a defocus easily occurs at an outer peripheral portion of the exposure field. On the other hand, when a conventional multi-point detection system is used as the focus position detection system, there is a disadvantage that the entire mechanism is complicated. Also, with the recent expansion of the exposure field and the enlargement of the photosensitive substrate, the necessity of finding the exact shape of the exposed surface of the substrate in the exposure field has increased. It is desired that the mechanism of the system be simplified as much as possible.

[0007] The present invention has been made in consideration of the point mow斯, and an object thereof is to allow accurate measurement of the state of the unevenness of the region of large area on a photosensitive substrate with a simple arrangement.

[0008]

An exposure apparatus according to the present invention holds a photosensitive substrate (2) and positions the substrate (2) in a two-dimensional plane as shown in FIGS. 1 and 2, for example. A substrate stage (3), an illumination optical system for illuminating a mask (1) on which a transfer pattern is formed on a substrate (2) side with exposure light (IL), and a positioning mark on the substrate (2) An alignment system (31, 32, 33) for detecting the coordinates of (8) via the objective lens (9), and positioning the substrate (2) based on the coordinates of the alignment mark (8). In the apparatus for exposing the pattern of the mask (1) on the substrate (2), the coherent measurement light beam (L
5) a light beam source for generating a reference light beam (L6) and an irradiation optical system (21) for irradiating the measurement light beam (L5) onto the substrate (2) via the objective lens (9) of the alignment system. , 22, 23), the measurement light beam (L5) and the reference light beam (L5) returned via the objective lens (9).
6) a signal processing means (25) for calculating the height of the irradiation point of the measurement light beam (L5) on the substrate (2) from a signal obtained by photoelectrically converting the interference light with (6), and the signal processing means Height adjusting means (3, 6) for adjusting the height of the substrate (2) based on the determined height.

In this case, it is desirable to provide an interferometer (4X) for measuring the coordinates of the substrate stage (3) in a two-dimensional plane, and to use the light source (12) of the interferometer as the light source for the light beam. . Another exposure apparatus according to the present invention
Holds the photosensitive substrate (2) and flattens the substrate two-dimensionally.
A substrate stage (3) to be positioned in the plane and the substrate stage
An interferometer (4) that measures the coordinates of a cottage in a two-dimensional plane
X) and a mask (1) on which a transfer pattern is formed.
An illumination optical system for illuminating the substrate side with exposure light, and the substrate
The coordinates of the alignment mark (8) above are
Alignment system (31, 32,
33), and based on the coordinates of the alignment mark.
Then, position the board and place it on the board.
Coherence in an exposure system that exposes mask patterns
Beam for generating the measurement light beam and the reference light beam
Light source (12) and the light source (12)
A moving mirror (11X) for reflecting a measurement light beam,
A fixed mirror (5X) for reflecting the reference light beam;
Using the measurement light beam from the light beam source
The height of the substrate in the Z direction perpendicular to its two-dimensional plane
Things. Next, the exposure method according to the present invention uses a mask
(1) The transfer pattern formed on the photosensitive substrate
In the exposure method for exposing (2), the substrate is two-dimensionally exposed.
Its two dimensions of the substrate stage (3) positioned in the plane
Measuring the coordinates in the plane and the two dimensions of the substrate
Measuring the height in the Z direction perpendicular to the plane, and the substrate
The coordinates of the alignment mark (8) above are
(9) a step of detecting the position and a mark for aligning the position.
Position the board based on the coordinates of the
Exposing the pattern of the mask on the substrate.
And the height of the substrate in the Z direction perpendicular to the two-dimensional plane.
The measuring step is the coherence from the light source (12) for the light beam.
Auxiliary work that generates a measurement light beam and a reference light beam
And a movable mirror (11X) provided on the substrate stage
An auxiliary process to reflect the measuring light beam with a fixed mirror
(5X) an auxiliary process of reflecting the reference light beam.
In the step of measuring the height in the Z direction,
Using the measuring light beam from the light source for the
The height of the direction is measured.

[0010]

According to the present invention, the objective lens (9)
Scans the exposure surface of the substrate (2) two-dimensionally below the substrate, and performs signal processing means (2
By plotting the height obtained in 5), the state of the unevenness on the entire exposed surface of the substrate (2) is detected. At this time, since the height of the exposure surface of the substrate (2) is detected by an interferometer method, the detection accuracy is extremely high. Further, since the objective lens (9) is shared with the alignment system, the configuration is simple. Then, the focus position of the average surface of the predetermined shot area determined by the state of the unevenness of the entire exposure surface of the substrate (2) is adjusted by the height adjustment means (3,
By adjusting the height to a predetermined reference plane (for example, in the case of a projection exposure apparatus, the image forming plane of a projection optical system) according to 6), the pattern of the mask is exposed on the substrate (2) with high resolution.

Further, by using the light source (12) of the interferometer (4X) for measuring the coordinates of the substrate stage (3) in the two-dimensional plane as the light source for the light beam, the overall structure is further simplified. Is done.

[0012]

An embodiment of the present invention will be described below with reference to the drawings. In this embodiment, the present invention is applied to a projection exposure apparatus having an off-axis type alignment sensor. FIG. 1 shows a simplified configuration of a main part of the projection exposure apparatus of this embodiment. In FIG. 1, exposure light IL from an illumination optical system (not shown) Is illuminated with substantially uniform illuminance. The image of the circuit pattern in the pattern area PA is
Through a projection optical system PL, a predetermined shot area SA on a plate 2 as a substrate on which a photosensitive material such as a photoresist is applied is projected and exposed. The plate 2 is held on a substrate stage 3 that is movable in an XY plane perpendicular to the optical axis of the projection optical system PL. The substrate stage 3 also includes a Z stage for adjusting the position of the plate 2 in the Z direction which is the optical axis direction of the projection optical system PL, a leveling stage for adjusting the inclination angle of the exposure surface of the plate 2, and the like. I have.

In the lateral direction of the substrate stage 3 in the X direction, X
Laser interferometer for shaft (hereinafter referred to as "interferometer")
4X and reference mirror 5X are arranged. The reference mirror 5X is actually fixed to a side surface of the projection optical system PL in the X direction, but for convenience of explanation, the reference mirror 5X is connected to the projection optical system P in FIG.
L is displayed apart from L. Similarly, the Y-axis interferometer 4Y and the reference mirror 5
Y is arranged. The reference mirror 5Y is actually fixed to a side surface of the projection optical system PL in the Y direction. In addition, the reference mirror 5
Since X and 5Y only need to be fixed, they need not necessarily be fixed to the projection optical system PL. In this case, the coordinate positions of the substrate stage 3 in the X and Y directions are measured by the interferometers 4X and 4Y, respectively. Information on the coordinate position in the X direction and the coordinate position in the Y direction is supplied to the control unit 6 in parallel, and the control unit 6 moves the substrate stage 3 in the X direction via the stage driving unit 7 based on the supplied coordinate positions. And in the Y direction.

In FIG. 1, an objective lens 9 is disposed on a side surface of the projection optical system PL, and an alignment / focus unit 10 is disposed above the objective lens 9. The alignment / focus unit 10 is a unit that executes two mechanisms of detecting the position of an alignment mark on the plate 2 and detecting the position (focus position) of the plate 2 in the Z direction, as described later. Actually, a plurality of sets of the objective lens 9 and the alignment / focus unit 10 are provided, but FIG. 1 shows only one set for simplicity. However, if the throughput of the focus position measurement may be reduced, only one alignment / focus unit 10 is required, and a unit provided above another objective lens (not shown) performs only normal alignment. Alignment optical system may be used.

On the plate 2 below the objective lens 9, Y
An alignment mark 8 composed of a dot pattern of concavities and convexities arranged at a predetermined pitch in the direction is formed. The alignment / focus unit 10 of this embodiment can detect the position of the alignment mark 8 in the X direction.
An alignment mark (not shown) formed of a dot pattern arranged at a predetermined pitch in the X direction is also formed on the plate 2. The position of such an alignment mark in the Y direction is also determined by the alignment / focus unit 1.
0 (or simply an alignment optical system). In addition, as the alignment mark, a two-dimensional mark formed of a concavo-convex pattern such as a cross, an L-shape, or a two-dimensional lattice may be used. In this case, those crosses or L
The character-shaped pattern may be macroscopically a cross shape or an L-shape, and may be formed of a set of dots or the like.

FIG. 2 shows a detailed configuration of the interferometer 4X and the alignment / focus unit 10 in FIG.
In FIG. 2, a polarization component perpendicular to the plane of FIG. 2 is called S-polarized light, and a polarization component parallel to the plane of FIG. 2 is called P-polarized light. In the interferometer 4X in FIG. 2, a laser beam L in which an S-polarized laser beam and a P-polarized laser beam are mixed at a ratio of 1: 1 is emitted from the laser light source 12 to the half prism 13. The wavelength of the laser beam L is, for example, the wavelength of a He—Ne laser (633).
nm), which is a wavelength band insensitive to the photoresist on the plate 2. Further, S in the laser beam L
The polarization component and the P-polarization component have slightly different frequencies. As the laser light source 12, a Zeeman laser light source or the like is used.

The laser beam L1 transmitted through the half prism 13 has an S-polarized component and a P-polarized component mixed at a ratio of 1: 1.
4 separates into an S-polarized reference beam and a P-polarized measurement beam. P transmitted through the polarizing beam splitter 14
The measurement beam of polarized light is directed to the movable mirror 11X fixed to the substrate stage 3 via the quarter-wave plate 15A, and the measurement beam reflected by the movable mirror 11X passes through the quarter-wave plate 15 to have the S-polarized component. Is reflected by the polarization beam splitter 14. On the other hand, of the laser beam L1, the S-polarized reference beam reflected by the polarization beam splitter 14 is 1
Projection optical system P via 波長 wavelength plate 15B and mirror 16
L (see FIG. 1), the reference beam 5X is fixed to the reference mirror 5X.
The light passes through the polarization beam splitter 14 through the four-wavelength plate 15B as a P-polarized light component.

The measurement beam and the reference beam emitted from the polarizing beam splitter 14 are mixed in a coherent state by the analyzer 17 and photoelectrically converted by the photoelectric detector 18A. The reference mirror 5X and the moving mirror are transmitted from the photoelectric detector 18A. 11
Beat signal SX frequency-modulated by relative displacement with X
Is output, and the beat signal SX is supplied to the integrating circuit 18B. A reference beat signal (not shown) obtained by photoelectrically converting interference light between a P-polarized component and an S-polarized component of the laser beam separated from the laser beam L is also supplied to the integrating circuit 18B. By integrating the difference between the frequency of the beat signal SX and the frequency of the reference beat signal at a predetermined cycle, the coordinates of the substrate stage 3 in the X direction are obtained and supplied to the control unit 6 in FIG.

That is, the interferometer 4X of FIG. 2 is a heterodyne type interferometer. In this heterodyne type, the frequency of the measurement beam reflected by the movable mirror 11X changes in proportion to the moving speed due to the Doppler effect. Is used. The most distinctive feature of the heterodyne interferometer is that the displacement can be measured stably regardless of the average value of the interference light intensity and the change in contrast. The typical measurement resolution is said to be λ / 2. Of course, by using the interpolation circuit, a measurement resolution of λ / 2 or less can be obtained.

Next, the half prism 13 in the interferometer 4X
The P-polarized light component and the S-polarized light component are also included in the laser beam L2 reflected at 1: 1. The laser beam L2 enters the polarization beam splitter 19 in the alignment / focus unit 10. In the alignment / focus unit 10, the S-polarized laser beam L3 reflected by the polarization beam splitter 19 in the laser beam L2 is reflected by a mirror (or a triangular prism) 20 and enters the half prism 21.

The reference beam L6 transmitted through the half prism 21 is reflected by the reference fixed mirror 24 and
The reference beam L6 further reflected by the half prism 21 enters the interferometer unit 25. On the other hand, the measurement beam L5 (S-polarized light) reflected by the half prism 21
Is a polarization beam splitter 23 via a relay lens 22
Are reflected at the target lens 9 toward the objective lens 9, and the measurement beam L5 emitted from the objective lens 9 is irradiated on the plate 2 as a spot of a predetermined size.

The measurement beam L5 reflected from the plate 2
Is a polarizing beam splitter 23 via the objective lens 9.
However, since the measurement beam L5 remains S-polarized light, the entire measurement beam L5 is reflected by the polarization beam splitter 23. The measurement beam L5 reflected and returned by the polarization beam splitter 23 returns to the half prism 21 via the relay lens 22, and a portion transmitted through the half prism 21 enters the interferometer unit 25.

The interference light of the reference beam L6 and the measurement beam L5 incident on the interferometer unit 25 is
The photoelectric conversion is performed by the photoelectric detector in 5. At this time, for example, two photoelectric detectors are provided and output photoelectric conversion signals whose phases are different from each other by 90 °. The two-phase photoelectric conversion signals are integrated and counted by an up / down counter, so that the height (focus position) of the irradiation point of the measurement beam L5 on the plate 2 in the Z direction is, for example, λ / m (m is a predetermined integer). It is measured with the resolution, and this measured value is
Supplied to That is, the interferometer in the alignment / focus unit 10 detects the focus position of the plate 2 by the homodyne method.

In FIG. 2, of the incident laser beam L2, the P-polarized laser beam L4 transmitted through the polarization beam splitter 19
After being reflected by the mirror 7 and the mirror 28, the beam is condensed by the cylindrical lens 29 to form a beam extending in the direction perpendicular to the plane of FIG. Then, the diverged laser beam L4 is reflected by the half mirror 30 and enters the polarization beam splitter 23 via the relay lens 31. Since the laser beam L4 is P-polarized light, it passes through the polarization beam splitter 23 and is focused on the plate 2 by the objective lens 9 as a linear beam spot.

FIG. 3 shows the relationship between the alignment mark 8 and the laser beams L4 and L5. The laser beam L4 is irradiated as a linear beam spot near the alignment mark 8 composed of dot patterns arranged in the Y direction. The laser beam L5 for height measurement is irradiated as a circular beam spot. In this state, when the control unit 6 in FIG. 1 finely moves the substrate stage 3 in the X direction via the stage driving unit 7, the linear beam spot of the laser beam L4 crosses over the alignment mark 8 in FIG. Sometimes, along with the zero-order diffracted light (reflected light), diffracted light of each order in the Y direction is generated. Therefore, for example, the X coordinate of the substrate stage 3 when the intensity of the ± 1st-order diffracted light is maximized is detected as the X coordinate of the alignment mark 8.

Returning to FIG. 2, the diffracted light and the scattered light generated from the alignment mark 8 by the irradiation of the laser beam L 4 are transmitted through the objective lens 9 to the polarization beam splitter 2.
Returning to No. 3, since the polarization state is P-polarized light, all the light passes through the polarization beam splitter 23. The light transmitted through the polarization beam splitter 23 is incident on the half mirror 30 via the relay lens 31, and the light transmitted through the half mirror 30 is collected on the light receiving surface of the photoelectric detector 33 by the relay lens 32. . On the light receiving surface of the photoelectric detector 33,
For example, a spatial filter is provided to block direct reflected light (0th-order diffracted light) from the plate 2. The relay lenses 31 and 32 change the pupil plane (Fourier transform plane) of the objective lens 9 into a photoelectric detector 33. Is relayed to the light-receiving surface.

The photoelectric conversion signal of the photoelectric detector 33 is also shown in FIG.
Of the alignment mark 8 in the X direction by detecting the peak value of the output signal from the photoelectric detector 33. In order to detect the coordinates in the Y direction of an alignment mark formed of a dot pattern extending in the X direction, the cylindrical lens 29 is rotated by approximately 90 ° in the alignment / focus unit 10 in FIG. The extension direction of the linear beam spot of the laser beam L4 is approximately 90 °
What is necessary is just to detect while rotating the substrate stage 3 in the Y direction in the rotated state. Alternatively, the coordinates of the alignment mark may be detected by irradiating the substrate 2 with the laser beam L4 as a cross-shaped beam spot on the plate 2 so as to sequentially finely move the substrate stage 3 in the X and Y directions.

Next, an example of the entire operation of this embodiment will be described. In this case, in FIG. 1, it is assumed that a large number of alignment marks are regularly formed on the plate 2 corresponding to the shot areas. At this time, the plate 2 is subdivided at a predetermined pitch in the Y direction while the plate 2 is suction-held on the substrate stage 3 in the same manner as when the pattern image of the reticle 1 is exposed, and the substrate stage 3 is driven. The subdivided portions are sequentially placed below the objective lens 9 by X
Scan in the direction. At this time, the interferometer unit 25 of FIG.
1 and the photoelectric conversion signal of the photoelectric detector 33 are processed by the control unit 6 in FIG. 1 to obtain the distribution of the position in the Z direction over the entire exposed surface of the plate 2 and the plate 2 The X coordinate of each upper alignment mark is measured.

Thereafter, for example, the alignment / focus unit 10 in which the cylindrical lens 29 of FIG. 2 is rotated by 90 ° is used, or another alignment optical system for detecting coordinates in the normal Y direction is used. Are sequentially scanned in the Y direction, the Y coordinate of each alignment mark on the plate 2 is measured. Based on the coordinates of the alignment mark measured in this way,
Exposure is performed by sequentially setting each shot area on the plate 2 to an exposure position in an exposure field of the projection optical system PL.

In this embodiment, the distribution of the height of the entire surface of the plate 2 in the Z direction (the distribution of the focus position) is obtained. FIG. 4 shows an example of the distribution of the height of the surface of the plate 2 in the Z direction measured by the alignment / focus unit 10 of the present embodiment, and FIG. 5 shows the distribution of the height of the surface of the plate 2 which is completely flat in the Z direction. Shows the height distribution of For example, in FIG. 4, an average plane of each shot area is obtained by approximating the distribution of focus positions of each shot area of the plate 2 with a plane. Then, when performing exposure to each shot area, by adjusting the average plane of each shot area to the imaging plane of the projection optical system PL, that is, by adjusting the focus position and the inclination angle to the imaging plane, The resolution of the projected image on each shot area is improved over the entire surface. Further, even when the area of each shot area is enlarged and large area exposure is performed, the distribution of focus positions over the entire area of the large area shot area is measured, so that the average plane can be easily formed. It can be adjusted to the image plane.

As described above, according to this embodiment, the focus position of the entire surface of the plate 2 is measured at the time of measuring the coordinates of the alignment mark, and at the time of exposure to each shot area on the plate 2, Since it is not necessary to measure the focal position by the AF sensor, the throughput is improved.
Further, as shown in FIG. 2, the objective lens 9 is shared by the alignment optical system and the focus position detection system of the plate 2, so that the optical system is simplified. A part of the laser beam generated by the laser light source 12 in the interferometer 4X is changed to a laser beam L4 for the alignment optical system and a laser beam L3 for the focus position detection system of the plate 2.
, The number of light sources is small, and the overall configuration is further simplified.

In the embodiment described above, the laser beam L3 reflected by the polarization beam splitter 19 shown in FIG. 2 is used for measuring the displacement of the plate 2 in the Z direction. Although it is used for the system, various modifications are possible according to the polarization state of the laser beam. For example, the interferometer unit 25 in the alignment / focus unit 10
Is a homodyne system, but the interferometer unit 25 may be a heterodyne system.

In FIG. 1, the distribution of the focus position on the entire surface of the plate 2 is measured by one alignment / focus unit 10. However, an alignment / focus unit (not shown) combined with an objective lens other than the objective lens 9 is used. By measuring the distribution of the focus position on the plate 2 in parallel by using a plurality of sets, the measurement time is shortened and the throughput is improved.

In FIG. 2, a photoelectric detector 33 is used as a means for detecting diffracted light or scattered light. However, an image of the alignment mark 8 is picked up by an image pickup device such as a CCD camera and aligned by an image processing method. The position of the mark 8 may be detected. The present invention is also applied to a proximity type exposure apparatus that does not use a projection optical system and adjusts the surface state of a photosensitive substrate. 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.

[0035]

According to the present invention, the objective lens of the alignment system is shared with the objective lens of the interferometer for measuring the height distribution of the photosensitive substrate. There is an advantage that the state of unevenness of a large area region on the substrate can be accurately measured only by scanning below the lens. Then, by changing the height of the substrate surface via the height adjusting means in accordance with the detected state of unevenness (defocus), an area where defocus is large due to a difference in flatness of the substrate in the exposure area. Can be minimized, and transfer accuracy can be improved. In particular, the present invention is particularly effective when a large area pattern is exposed using a plate for a liquid crystal display device or the like.

Further, by sharing the light source with the coordinate measuring interferometer, the overall configuration can be further simplified.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of an embodiment of an exposure apparatus according to the present invention.

FIG. 2 is a partially cutaway side view showing the configurations of an interferometer 4X and an alignment / focus unit 10 in FIG.

FIG. 3 is an enlarged plan view showing a relationship between an alignment mark 8 and a beam spot of a laser beam irradiated near the alignment mark 8 in the embodiment.

FIG. 4 is a perspective view showing an example of a height distribution of the surface of the plate 2 measured in the embodiment.

FIG. 5 is a perspective view showing an ideal (non-deformed) surface state of the surface of the plate 2;

[Explanation of symbols]

 Reference Signs List 1 reticle PL projection optical system 2 plate 3 substrate stage 4X, 4Y interferometer 6 control unit 8 alignment mark 9 objective lens 10 alignment / focus unit 12 laser light source 13, 21, half prism 14, 19, 23 polarization beam splitter 24 reference fixed mirror 25 Interferometer unit 29 Cylindrical lens 33 Photoelectric detector

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-86430 (JP, A) JP-A-1-161183 (JP, A) JP-A-4-328407 (JP, A) JP-A-5- JP-A-6-260393 (JP, A) JP-A-4-53220 (JP, A) JP-A-3-4103 (JP, A) JP-A-62-150721 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/027 G03F 9/00

Claims (5)

(57) [Claims] 1. A substrate stage for holding a photosensitive substrate and positioning the substrate in a two-dimensional plane, and an illumination optical system for illuminating a mask on which a transfer pattern is formed with exposure light on the substrate side. An alignment system that detects the coordinates of the alignment marks on the substrate via an objective lens, and performs positioning of the substrate based on the coordinates of the alignment marks, and An exposure apparatus for exposing a pattern of a mask, comprising: a light beam light source for generating a coherent measurement light beam and a reference light beam; and the measurement light beam on the substrate via an objective lens of the alignment system. An irradiation optical system for irradiation; and the measurement of the substrate based on a signal obtained by photoelectrically converting interference light between the measurement light beam and the reference light beam returned via the objective lens. Signal processing means for calculating the height of the irradiation point of the light beam, and height adjustment means for adjusting the height of the substrate based on the height calculated by the signal processing means, Exposure equipment. 2. An exposure apparatus according to claim 1, wherein an interferometer for measuring coordinates of the substrate stage in a two-dimensional plane is provided, and a light source of the interferometer is also used as the light beam light source. . 3. A substrate stage for holding a photosensitive substrate and positioning the substrate in a two-dimensional plane, an interferometer for measuring coordinates of the substrate stage in a two-dimensional plane, and a transfer pattern. An illumination optical system that illuminates the formed mask on the substrate side with exposure light, and an alignment system that detects the coordinates of alignment marks on the substrate via an objective lens, and includes an alignment system for the alignment. An exposure apparatus that positions the substrate based on the coordinates of a mark to expose the pattern of the mask on the substrate; a light beam light source that generates a coherent measurement light beam and a reference light beam; A movable mirror provided on the substrate stage and reflecting the measurement light beam; and a fixed mirror reflecting the reference light beam, and using the measurement light beam from the light beam light source. An exposure apparatus for measuring a height of the substrate in a Z direction perpendicular to the two-dimensional plane. 4. An exposure method for exposing a transfer pattern formed on a mask to a photosensitive substrate, wherein coordinates in the two-dimensional plane of a substrate stage for positioning the substrate in the two-dimensional plane are measured. A step of measuring a height of the substrate in a Z direction perpendicular to the two-dimensional plane; a step of detecting a coordinate of an alignment mark on the substrate via an objective lens; Positioning the substrate based on the coordinates of the mark to expose the pattern of the mask on the substrate, and measuring the height of the substrate in the Z direction perpendicular to the two-dimensional plane. An auxiliary step of generating a coherent measurement light beam and a reference light beam from a light beam light source; and an auxiliary step of reflecting the measurement light beam by a movable mirror provided on the substrate stage. And an auxiliary step of reflecting the reference light beam with a constant mirror. In the step of measuring the height in the Z direction, the height in the Z direction is measured using the measurement light beam from the light beam light source. An exposure method characterized by measuring. Step of measuring 5. A height of the Z direction, the exposure according to claim 4, characterized in that it is performed in performing the step of measuring the coordinates of said two-dimensional plane of the substrate stage Method.