JPH11162841A - Method apparatus for measuring exposure conditions and aberration, and device manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase measuring accuracy without increasing the apparatus manufacturing cost. SOLUTION: A pattern of an original plate is exposed and transferred to a plurality of exposure positions on a photosensitive substrate W, under changing exposure conditions to form a plurality of exposure patterns, the patterns are photographed by an image-pickup means 105 at two or more positions mutually shifted by a distance smaller than the distance corresponding to a pixel pitch in an image-pickup plane to obtain two or more image signals for the patterns, the image signals are combined to obtain image signals for the patterns, the image signals are used by a projection accumulation device 107 and a fast Fourier transform(FFT) operating device 108 to find the frequency components for each photosensitive patterns. On the basis of the frequency components of the patterns, optimum exposure conditions are determined at transferring of the original plate patterns to the photosensitive substrate. Or on the basis of the frequency components of the patterns, aberration of a projection optical system is determined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring an optimum exposure condition and an aberration of an exposure apparatus used in a lithography process for manufacturing an LSI or the like, and a device manufacturing method using the method. About.

[0002]

2. Description of the Related Art In an exposure apparatus used in a lithography process for manufacturing an LSI or the like, the degree of integration of a circuit pattern is increased, and the line width of a pattern to be transferred is also in a submicron region. It is important to accurately set the exposure condition and the focus condition in order to stably maintain the resolution.

Conventionally, printing is performed on a photosensitive substrate while changing exposure conditions, that is, at least one of a focus position and an exposure amount (shutter time) for each shot.
The optimum exposure condition is determined by developing the photosensitive substrate and measuring the line width of the linear pattern with an optical microscope or a line width measuring device.

Alternatively, as proposed in Japanese Patent Laid-Open No. 8-78307, a pattern having a periodicity such as L &
Using an exposure condition measuring reticle having an S (line and space) pattern, a resist image of this pattern is captured by a photoelectric conversion device such as a CCD, and the image signal is subjected to an FFT operation. The exposure condition is measured by detecting the frequency component.

[0005]

However, when the resist pattern is imaged by a photoelectric conversion device such as a CCD and the exposure conditions are measured, the resist changes due to the effect of bleaching due to the illumination of the exposure light. In this case, there is a problem that the intensity distribution is lowered and the measurement accuracy is deteriorated. Further, with the improvement in the resolution of the projection lens, the measurement pattern to be transferred is also in a sub-micron region, so that there is a problem that sufficient accuracy cannot be obtained with the current pixel resolution.

As a method of reducing the above problem, there is a method of increasing the pixel resolution. Improving the pixel resolution can be achieved by a method of improving the optical magnification or by using an A / D
This can be achieved by improving the resolution of the converter.
However, in this case, the change scale of the apparatus becomes large, and the manufacturing cost becomes high.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and apparatus for measuring exposure conditions and aberrations of an exposure apparatus and a method for manufacturing an apparatus and a device manufacturing method without increasing the manufacturing cost of the apparatus. To improve it.

[0008]

According to the present invention, in order to achieve this object, a plurality of photosensitive patterns are formed by exposing and transferring a pattern of an original plate to a plurality of exposure positions on a photosensitive substrate while changing exposure conditions. Each photosensitive pattern is imaged at two or more positions shifted from each other by a distance smaller than the distance corresponding to the pixel pitch on the surface, and two or more image signals for each photosensitive pattern obtained thereby are synthesized to form each photosensitive pattern. And the frequency component of each photosensitive pattern is obtained based on the image signal of each photosensitive pattern. Then, an optimal exposure condition for exposing and transferring the pattern of the original plate onto the photosensitive substrate is determined based on the frequency components of the respective photosensitive patterns, or the aberration of the projection optical system is determined based on the frequency components of the respective photosensitive patterns. The measurement accuracy is improved without increasing the manufacturing cost of the device.

[0009]

In a preferred embodiment of the present invention, the photosensitive substrate is a wafer coated with a resist, and the photosensitive pattern is a resist pattern formed through a development step after exposure, or It is a latent image formed on the resist layer. Further, the pattern of the original plate is a pattern having a periodicity, and when determining the optimum exposure condition, the power of a fundamental frequency determined by the pattern having the periodicity among the frequency components of the photosensitive patterns is used. The optimum exposure condition is determined based on the above. The exposure condition is an exposure amount or a vertical position of the substrate.

When measuring the aberration of the projection optical system,
The pattern of the original plate is arranged at a plurality of positions on the original plate, and determines the aberration of the projection optical system based on the phase of the frequency component of each photosensitive pattern. Alternatively, the image plane position of the projection optical system is determined based on the power of a fundamental frequency determined by the pattern having the periodicity among the frequency components of the photosensitive patterns, and the aberration of the projection optical system is determined based on the determined image plane position. I do.

In the above-mentioned prior art, for example, a mask having an L & S exposure condition measurement reference pattern having a periodicity in one direction and a duty of 1: 1 is used, and an image of the reference pattern is exposed. When the L & S pattern is transferred by exposing sequentially on the wafer while changing at least one of the conditions of the amount and the focus position, when the optimal focus position and the optimal exposure amount are obtained, the resist pattern duty (line and space lengths) Ratio) is 1: 1.

Therefore, in a more specific embodiment of the present invention, when a similar L & S pattern is transferred and developed, and each resist pattern is imaged with a CCD camera, the resist pattern (1) is located at the first position of the resist pattern. A first image signal obtained by integrating the image signal in one direction, and moving the stage on which the photosensitive substrate is mounted from the first position by half the pixel resolution. At the second position, the resist pattern is imaged again and the same integration is performed to obtain a second image signal. Then, the image signal obtained by synthesizing the first and second image signals is converted into a spatial frequency domain, and the duty of the L & S resist image is detected by calculating the intensity of the spatial frequency generated from the pattern in that domain. And the aberration of the projection optical system are determined. Hereinafter, embodiments of the present invention will be described more specifically through examples.

[0013]

FIG. 1 is a block diagram showing the configuration of an apparatus for measuring exposure conditions in an exposure apparatus according to one embodiment of the present invention. FIG. 2 is a schematic view of a portion for detecting a focus position and controlling an exposure amount in the exposure apparatus.

First, focus detection will be described. In FIG. 2, reference numeral 203 denotes a high-intensity light source such as a semiconductor laser, and reference numeral 204 denotes an illumination optical system. The light emitted from the light source 203 passes through the pinhole via the illumination optical system 204, and the light flux is changed in direction by the bending mirror 205.
The light enters the surface of the wafer W. The light beam reflected at the measurement point on the wafer W is changed in direction by the bending mirror 206 and is incident on the two-dimensional position detecting element 208 via the position detecting optical system 207. The two-dimensional position detecting element 208 is composed of a CCD or the like, and can detect an incident position. Since a change in the position of the wafer W in the direction of the optical axis AX of the projection lens 101 can be detected as a shift in the incident position of the light beam on the two-dimensional position detecting element 208, the position of the wafer W in the direction of the optical axis AX is 2
It can be detected based on the output signal from the dimensional position detection element 208.

Next, the exposure amount control will be described. 215
Is a light source such as a mercury lamp, 214 is a shutter that can be opened and closed, and 213 is a sensor for detecting illuminance. Exposure light from the light source 215 illuminates the reticle R via the shutter 214, the half mirror 212, and the mirror 211, and transfers the pattern of the reticle R onto the wafer via the projection lens 101. The sensor 213 is a half mirror 2
Part of the exposure light from No. 12 is received. The integrated exposure control device 209 measures the illuminance of the exposure light based on the output of the sensor 213, and controls the shutter 214 so that the exposure amount is constant.
Control the opening and closing time of the

Next, formation of a pattern image for measuring exposure conditions will be described. FIG. 4 shows a line and space pattern M for exposure condition measurement used in this exposure apparatus. The measurement pattern M has rectangular patterns Mx and My which are formed of chrome, have the same line width, and extend in the X and Y directions and are arranged in parallel. To form this pattern image on the wafer, the reticle R on which the pattern M has been formed is set in an exposure apparatus, the wafer W coated with a positive resist is set, and the pattern M is sequentially exposed by a step-and-repeat method. I will do it. At this time, the exposure is performed while changing the exposure amount according to the shot position in the X direction and changing the focus offset by a fixed amount at a time in accordance with the shot position in the Y direction. FIG. 3 is a sectional view of the resist pattern after development of the wafer W exposed in this manner. In the figure, (A) ~
(C) shows the case where the exposure amount is changed at the best focus position, and (D) to (F) shows the case where the exposure amount is changed at the defocused position.

Next, a configuration and a method for measuring exposure conditions using the resist pattern of the pattern M formed on the wafer will be described. As shown in FIG. 1, the optical axis AX of the reduction projection lens 101 that projects the circuit pattern on the reticle R surface onto the wafer W is parallel to the Z direction in the figure. In FIG. 1, a wafer W is a developed wafer on which an image of a pattern M is formed. 3 is wafer W
Is a wafer stage that adsorbs and moves in the X, Y, and Z directions. An illumination system 103 illuminates the resist pattern of the pattern M, and a half mirror 102 is arranged on the optical path. Reference numeral 104 denotes a detection optical system, and a pattern M is formed at a predetermined magnification based on light from the half mirror 102.
The image of the resist pattern is formed on the imaging surface of the imaging device 105. The imaging device 105 is configured by a photoelectric conversion device such as an ITV or a two-dimensional image sensor, and converts a captured image into a two-dimensional electric signal. Reference numeral 106 denotes an AD converter for AD-converting the output of the imaging device 105;
7 is a projection integration device, 108 is an FFT operation device, 109 is a frequency intensity detection device, and 110 is a control device.

Next, the operation in this configuration will be described with reference to FIG. First, in step 701, the image of the resist pattern of the pattern M converted into a two-dimensional electric signal by the imaging device 105 is converted by the AD conversion device 106 into the optical magnifications of the projection optical system 101 and the detection optical system 104 and the imaging plane. Is converted into a two-dimensional discrete electric signal sequence corresponding to the addresses of the pixels on the two-dimensional device in the X and Y directions by the sampling pitch λs determined by the pixel pitch of.

Next, in step 702, a predetermined two-dimensional window Wx including the resist pattern Mx 'of the pattern Mx shown in FIG. 5 is set by the projection integrating device 107, and in step 703, a window is set in the Y direction. Pixel integration is performed within Wx, and a discrete electric signal sequence s1 (x) is output in the x direction shown in FIG.

Next, in step 704, the stage 100 on which the wafer W is mounted is moved in the X direction by one pixel pitch.
Move by / 2. In steps 705 to 707, a two-dimensional discrete electric signal sequence is obtained in the same manner as in steps 701 to 703, a window Wx including the pattern Mx is set, and pixel integration is performed in the window Wx in the Y direction. Thus, a discrete electric signal sequence s2 (x) in the x direction shown in FIG. 6 is output.

Next, in step 708, based on the discrete electric signal sequences s1 (x) and s2 (x), a combined signal sequence s (x2) as shown in FIG.

[0022]

(Equation 1) Next, in step 709, the FFT operation device 108
Is calculated by The FFT operation unit 108 performs a discrete Fourier transform on the input electric signal sequence s (x) to obtain s (x)
Is converted to the spatial frequency domain, and its Fourier coefficient is calculated at high speed. The method is a known N point (N = 2)
And the frequency fk = k when the sampling frequency is fs = 1.
/ N of the complex Fourier coefficient Xk can be obtained by the following equation.

[0023]

(Equation 2) Next, in step 710, the frequency intensity detecting device 1
From 09, the power spectrum pk of the spatial frequency fk is obtained by the following equation.

[0024]

(Equation 3) Here, if the pattern pitch of the pattern M is λp, the intensity at the spatial frequency f1p = λs / λp becomes large.
n-th harmonic of f1p fnp = n · f1p (n = 2, 3,
4,...).

FIG. 8 shows a transfer image Mx 'at each exposure position of the pattern M when the focus (the position in the optical axis direction of the wafer W) is changed, and the transfer image Mx' is taken by the CCD camera 105 as described above, and projected and integrated. FIG. 9 shows an example of the obtained signal.
FIG. 11 to FIG. 11 show power spectra obtained by subjecting the signal to discrete Fourier transform by the FFT operation device 108. It can be seen that the intensity at the fundamental frequencies f1p and f2p determined by the ratio between the pattern pitch λp and the sampling pitch λs increases at any of the focus positions in FIGS. At the optimum focus position shown in FIG. 10, if the ratio of the line and the space, that is, the duty of the L & S pattern M formed on the reticle R is 1: 1, the power of the fundamental frequency g1p = 2λs / λp is obtained even in the resist pattern M ′. And the power of gnp = n · g1p (n = 2, 3, 4,...) Also increases. However, in the defocused state,
Since the line-and-space duty in the pattern M 'is no longer 1: 1, n times the fundamental frequency f1p,
In this case, the power at the frequency f3p is as shown in FIG. 9 and FIG.
As shown in FIG. 1, it becomes large and becomes minimum as shown in FIG. 10 at the optimum focus position.

Therefore, the optimum focus position can be detected by arbitrarily selecting from the frequencies n times the fundamental frequency f1p and detecting the focus position at which the power at that frequency is minimized. That is, as shown in FIG. 16, the intensity (frequency intensity) of the frequency f3p is obtained for various focus positions, and the focus position corresponding to the minimum value of the frequency intensity at this time is the optimum focus position.

For each focus position, the ratio of the power of the selected frequency f3p to the power of another fundamental frequency (eg, g1p or g2p) is determined, and the focus position that minimizes this ratio is determined as the optimum focus position. Is also good. In this way, by normalizing with the power of another fundamental frequency in the measurement of each shot, it is possible to reduce an error due to a difference between shots, for example, a difference in reflected light amount due to a difference in illumination light amount or a difference in resist thickness. .

FIG. 12 shows that each resist pattern Mx ′ of the pattern M exposed while changing the exposure amount is
The projection integrated signal obtained by imaging at 05 and projecting and integrating is shown,
13 to 15 show power spectra obtained by performing a discrete Fourier transform on the signal by the FFT operation device 108. It can be seen that the intensity of the fundamental frequencies f1p and f2p increases irrespective of the exposure amount, similarly to the case where the exposure is performed while changing the focus. As for the optimal exposure amount, similarly to the optimal focus position, the line and space duty is 1:
It can be defined as the amount of exposure that is closest to 1, that is, the power at which the power in the frequency component f3p is minimum. FIG. 17 shows a change in the frequency intensity f3p when the exposure amount is changed, and the exposure amount corresponding to the minimum value of the frequency intensity is the optimum exposure amount. Of course, as described above, each shot may be standardized with power of another fundamental frequency.

In the case of the optimum focus position or the optimum exposure amount, the duty ratio of the line and space in the resist pattern Mx 'is 1: 1.
The frequency intensity at 1p and g2p becomes maximum. Therefore, the focus position or the exposure amount at which the frequency intensity at g1p or g2p becomes the maximum may be defined as the optimum focus position or the exposure amount. Further, the powers of the fundamental frequencies, for example, the powers at g1p and g2p may be compared, and the focus position or the exposure amount when a certain desired relationship is obtained may be defined as the optimal focus position or the optimal exposure amount.

By feeding back the calculated optimum focus position to the focus control device 210 in FIG. 2, the wafer W can always be set to the best focus position. The exposure amount can also be set to the optimum exposure amount by feeding back the integrated exposure control device 209 in FIG.

The optimum focus position and the optimum exposure amount are calculated as described above. The optimum exposure condition is always set by repeatedly performing this processing and feeding back in accordance with the change in the resist type and the film thickness. Can be.

In the above description, the resist pattern Mx 'after development is detected. However, even if a latent image before development is detected, the optimum focus position and the optimum exposure amount can be determined. According to this, since the development step can be omitted, the exposure condition can be automatically measured on the projection exposure apparatus, and the setup time can be greatly reduced.

Although the above description has been made using only the pattern Mx arranged in the X direction, the pattern My arranged in the Y direction is also used to detect the optimum focus position in the X direction and the Y direction. Thereby, the astigmatism of the projection optical system can be measured. That is, in the Y direction, similarly to the case of the X direction, a predetermined two-dimensional window Wy including the resist pattern My ′ of the pattern My is set as shown in FIG. Pixel integration is performed to obtain a discrete electric signal sequence s (y) in the Y direction. This is similarly converted to a spatial frequency domain by a discrete Fourier transform, and the Fourier coefficient is calculated, whereby an optimum focus position in the Y direction can be obtained. In this way, by detecting the optimum focus position in each direction using patterns having different directions, it is possible to measure the actual astigmatism when the projection lens 101 goes through the resist process.

Further, a measurement pattern is provided at a plurality of positions at the center and the outer peripheral position in the exposure area, and the optimum focus position at each position is detected, so that the actual image plane when the projection lens 101 goes through the resist process is detected. Curvature and image plane tilt can be detected. However, in terms of improving accuracy, L & S
It is desirable that the number of lines in the pattern be large in performing the FFT processing, and at least 10 or more lines are required.

In the above-described processing, the power after the Fourier transform is evaluated. If the phase is detected, the asymmetry of the resist pattern can be detected, and the coma at each position within the exposure amount range of the projection lens 101 is also measured. When detecting the aberration of the projection lens in this way, instead of using a resist for actually exposing the circuit pattern, another material that is well-sensitized may be used. For example, a magneto-optical material or a photochromic material may be used.

In the above-described embodiment, a reduction projection lens or an exposure device is used for exposing a measurement pattern on a wafer and for detecting a resist pattern. May be performed with the observation optical system described above. Thereby, the influence of the aberration of the projection lens itself on the measurement result can be reduced.

In the above-described embodiment, the exposure condition when the projection optical system is used is determined. However, the exposure condition for the promixity exposure without using the projection optical system may be used. Instead, the distance between the mask and the wafer may be changed.

Next, an example of manufacturing a device that can use the above-described exposure apparatus will be described. FIG. 18 shows a micro device (a semiconductor chip such as an IC or an LSI, a liquid crystal panel,
2 shows a flow of manufacturing a CCD, a thin-film magnetic head, a micromachine, and the like. In step 1 (circuit design), a device pattern is designed. Step 2 is a process for making a mask on the basis of the designed pattern. on the other hand,
In step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon or glass. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer. The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer produced in step 4, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). including. In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 19 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. In step 12 (CVD), a green film is formed on the wafer surface. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. Step 1
In step 5 (resist processing), a resist is applied to the wafer.
Step 16 (exposure) uses the above-described exposure apparatus or exposure method to align and print the circuit pattern of the mask on a plurality of shot areas of the wafer. Step 17
In (development), the exposed wafer is developed. Step 18
In (etching), portions other than the developed resist image are scraped off. In step 19 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer. According to this, it is possible to manufacture a large-sized device which was conventionally difficult to manufacture at low cost.

[0040]

As described above, according to the present invention, it is possible to measure the exposure condition and the aberration of the projection optical system with high accuracy without increasing the cost as compared with the conventional one. For example, conventionally, it was necessary to change hardware such as increasing the resolution of an A / D converter in order to improve the detection resolution. However, according to the present invention, such hardware change is not required. Therefore, it is possible to improve the optimal exposure conditions and the accuracy of aberration measurement without increasing the cost.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an exposure condition measuring apparatus of an exposure apparatus according to one embodiment of the present invention.

FIG. 2 is a partial schematic diagram of a configuration for focus detection and exposure amount control in the exposure apparatus of FIG. 1;

FIG. 3 is a sectional view of a pattern formed on a resist in the apparatus of FIG. 1;

FIG. 4 is a view showing a pattern formed on a mask for measuring exposure conditions used in the apparatus of FIG. 1;

FIG. 5 is a diagram showing a relationship between a pattern formed on a wafer and a two-dimensional window in the apparatus of FIG. 1;

FIG. 6 shows a first image signal sequence s1 (x) imaged by the apparatus of FIG. 1, and a second image signal sequence s2 (x) imaged by shifting the pattern position by a pixel resolution or less.
FIG. 7 is a diagram illustrating a third image signal sequence s (x2) obtained by combining a first image signal sequence and a second image signal.

7 is a flowchart illustrating a process of creating a first image signal sequence, a second image signal sequence, and a third image signal sequence in FIG. 6, and calculating a power spectrum.

8 is a diagram showing an example of a projection integrated signal obtained by capturing a pattern obtained by changing the focus and exposing the image in the apparatus shown in FIG. 1 with a CCD camera.

9 is a diagram in which the projection integrated signal of the pattern transferred at the defocused (-) position in the apparatus of FIG. 1 is subjected to discrete Fourier transform by an FFT arithmetic unit, and the frequency intensity is plotted on the vertical axis and the spatial frequency is plotted on the horizontal axis. It is.

10 is a diagram in which a projection integrated signal of a pattern transferred at an optimum focus position in the apparatus of FIG. 1 is subjected to discrete Fourier transform by an FFT arithmetic unit, and frequency intensity is plotted on a vertical axis and spatial frequency is plotted on a horizontal axis.

11 is a diagram in which the projection integrated signal of the pattern transferred at the defocused (+) position in the apparatus of FIG. 1 is subjected to discrete Fourier transform by an FFT arithmetic unit, and the frequency intensity is plotted on the vertical axis, and the spatial frequency is plotted on the horizontal axis. It is.

12 is a diagram illustrating an example of a projection integrated signal obtained by capturing a pattern transferred by changing the exposure amount in the apparatus of FIG. 1 with a CCD camera.

13 is a diagram in which the projection integrated signal of the pattern when the exposure amount is small in the apparatus of FIG. 1 is subjected to discrete Fourier transform by an FFT arithmetic unit, and the frequency intensity is plotted on the vertical axis and the spatial frequency is plotted on the horizontal axis.

FIG. 14 is a diagram in which a projection integrated signal is subjected to discrete Fourier transform by an FFT arithmetic unit at an optimum exposure amount in the apparatus of FIG. 1, and a frequency axis is plotted on a vertical axis, and a spatial frequency is plotted on a horizontal axis.

15 is a diagram in which a projection integrated signal of a pattern when the exposure amount is large in the apparatus of FIG. 1 is subjected to discrete Fourier transform by an FFT operation apparatus, and a vertical axis represents a frequency intensity and a horizontal axis represents a spatial frequency.

FIG. 16 is a diagram plotting frequency intensity on a vertical axis and a focus position on a horizontal axis.

FIG. 17 is a diagram plotting frequency intensity on the vertical axis and exposure amount on the horizontal axis.

FIG. 18 is a flowchart showing an example of manufacturing a device that can use the apparatus or method of the present invention.

FIG. 19 is a detailed flowchart of the wafer process of FIG. 18.

[Explanation of symbols]

101: projection lens, 102: half mirror, 103:
Illumination system, 104: detection optical system, 105: imaging device, 10
6: AD conversion device, 107: projection integration device, 108: F
FT calculation device, 109: frequency intensity detection device, 110:
Control device, 203: high brightness light source, 204: illumination optical system,
205, 206: folding mirror, W: wafer, 207:
Position detection optical system, 208: two-dimensional position detection element, 20
9: integrated exposure control device, 211: mirror, 212: half mirror, 213: sensor, 214: shutter, 21
5: light source, AX: optical axis, M: line and space pattern, Mx, My: rectangular pattern, M ′ (Mx ′,
My '): resist pattern, R: reticle, Wx, W
y: window.

Claims (20)

[Claims] A step of exposing and transferring a pattern of an original plate to a plurality of exposure positions on a photosensitive substrate while changing exposure conditions to form a plurality of photosensitive patterns, and a distance smaller than a distance corresponding to a pixel pitch on an imaging surface. Imaging each photosensitive pattern at two or more positions shifted from each other only by combining the two or more image signals for each photosensitive pattern obtained thereby to obtain an image signal of each photosensitive pattern; Determining a frequency component for each photosensitive pattern based on the image signal of, and determining an optimal exposure condition when exposing and transferring the pattern of the original plate to the photosensitive substrate based on the frequency component of each photosensitive pattern, A method for measuring exposure conditions, comprising: 2. The method according to claim 1, wherein the photosensitive substrate is a wafer coated with a resist. 3. The exposure condition measuring method according to claim 2, wherein the photosensitive pattern is a resist pattern formed through a development step after exposure. 4. The exposure condition measuring method according to claim 2, wherein the photosensitive pattern is a latent image formed on the resist layer. 5. The exposure condition measuring method according to claim 1, wherein the pattern of the original plate is a pattern having periodicity. 6. The step of determining the optimum exposure condition includes determining the optimum exposure condition based on power of a fundamental frequency determined by the pattern having the periodicity among the frequency components of the photosensitive patterns. The exposure condition measuring method according to claim 5, wherein: 7. The exposure condition measuring method according to claim 1, wherein the exposure condition is an exposure amount or a vertical position of the substrate. 8. A process of forming a plurality of photosensitive patterns by exposing and transferring a pattern of an original plate to a plurality of exposure positions on a photosensitive substrate via a projection optical system while changing exposure conditions, and corresponding to a pixel pitch on an imaging surface. Capturing each photosensitive pattern at two or more positions shifted from each other by a distance smaller than the distance to be obtained, and synthesizing two or more image signals of each photosensitive pattern obtained thereby to obtain an image signal of each photosensitive pattern Determining a frequency component for each photosensitive pattern based on an image signal of each photosensitive pattern; and determining an aberration of the projection optical system based on a frequency component of each photosensitive pattern. Aberration measurement method. 9. The aberration measuring method according to claim 8, wherein the photosensitive substrate is a wafer coated with a resist. 10. The aberration measuring method according to claim 9, wherein said photosensitive pattern is a resist pattern formed through a developing step after exposure. 11. The aberration measurement method according to claim 9, wherein the photosensitive pattern is a latent image formed on the resist layer. 12. The pattern of the original plate is arranged at a plurality of positions on the original plate.
The method for measuring aberration according to any one of the preceding claims. 13. The projection optical system according to claim 8, wherein in the step of determining the aberration of the projection optical system, the aberration of the projection optical system is determined based on a phase of a frequency component of each of the photosensitive patterns. Aberration measurement method. 14. The aberration measuring method according to claim 8, wherein the exposure condition is a position of the photosensitive substrate in an optical axis direction of the projection optical system. 15. The aberration measuring method according to claim 8, wherein the pattern of the original plate is a pattern having a periodicity. 16. In the step of determining the aberration of the projection optical system, an image plane position of the projection optical system is determined based on a power of a fundamental frequency determined by the periodic pattern among the frequency components of the photosensitive patterns. 16. The aberration measuring method according to claim 15, wherein the method is characterized by determining the aberration of the projection optical system based on the above. 17. A device manufacturing method, comprising: exposing a pattern on an original plate to a photosensitive substrate in consideration of an optimum exposure condition determined by the exposure condition measuring method according to claim 1. 18. A pattern on an original plate is exposed on a photosensitive substrate via the projection optical system in consideration of the aberration of the projection optical system determined by the aberration measurement method according to claim 8. Device manufacturing method. 19. An exposure condition measuring apparatus for an exposure apparatus for exposing a pattern on an original plate to a photosensitive substrate, wherein the pattern on the original plate is exposed and transferred to a plurality of exposure positions on the photosensitive substrate while changing exposure conditions. Means for forming a pattern, means for imaging each photosensitive pattern at two or more positions mutually shifted by a distance smaller than the distance corresponding to the pixel pitch on the imaging surface, and two or more for each photosensitive pattern obtained by this Means for obtaining an image signal of each photosensitive pattern by synthesizing the image signals of the photosensitive patterns, means for determining a frequency component for each photosensitive pattern based on the image signal of each photosensitive pattern, and Means for determining an optimum exposure condition when exposing and transferring the pattern of the original plate to the photosensitive substrate. measuring device. 20. An aberration measuring device for the projection optical system of an exposure apparatus for exposing a pattern of an original onto a photosensitive substrate via a projection optical system, wherein the pattern of the original is exposed on the photosensitive substrate via the projection optical system. Means for forming a plurality of photosensitive patterns by exposure and transfer while changing exposure conditions to a plurality of exposure positions,
Means for imaging each photosensitive pattern at two or more positions mutually shifted by a distance smaller than the distance corresponding to the pixel pitch on the imaging surface, and combining two or more image signals for each photosensitive pattern obtained by the means; Means for obtaining an image signal of each photosensitive pattern, means for obtaining a frequency component for each photosensitive pattern based on the image signal of each photosensitive pattern, and determining the aberration of the projection optical system based on the frequency component of each photosensitive pattern An aberration measuring device comprising: