TWI643029B - Evaluation method, exposure method, and article manufacturing method - Google Patents

Abstract

An evaluation method for evaluating aberrations of a projection optical system in an exposure device includes a transfer program that transfers a plurality of pattern elements covering a mask to a substrate through the projection optical system of the exposure device; a first program that transfers information according to the transfer program; As a result, the first characteristic value related to the projection positions of the plurality of pattern elements based on the projection optical system is obtained, and the average value of the first characteristic values of the plurality of pattern elements is used as the first information indicating the aberration of the projection optical system. A detection program that detects a plurality of pattern element images projected by the projection optical system; a second program that determines a second characteristic regarding the projection positions of the plurality of pattern elements based on the projection optical system based on the detection results in the detection program; Value, the average value of the second characteristic value of the plurality of pattern elements and the difference between the second characteristic value of each of the plurality of pattern elements and the average value of the second characteristic value are obtained as the second information representing the aberration of the projection optical system; An evaluation program evaluates aberrations of the projection optical system based on the first information and the second information.

Description

Evaluation method, exposure method, and article manufacturing method

The present invention relates to an evaluation method for evaluating aberrations of a projection optical system in an exposure device, an exposure method, and a method for manufacturing an article.

As an apparatus used in a manufacturing process (lithography process) of a semiconductor device or the like, there is an exposure apparatus that transfers a pattern of a mask to a substrate. In the exposure apparatus, with the recent miniaturization of circuit patterns, it is required to evaluate aberrations of the projection optical system with high accuracy. Patent Documents 1 and 2 describe the evaluation of the performance of the projection optical system based on only one of the transfer result of actually transferring the pattern of the mask to the substrate and the result of aerial image measurement using an imaging element. Aberration.

In the case where the aberration of the projection optical system is evaluated based only on the transfer result, in order to accurately evaluate the aberration of the projection optical system, it is preferable to use a result obtained by transferring a pattern of a mask on a plurality of substrates. However, it is troublesome to transfer the mask pattern on a plurality of substrates and measure the pattern transferred to each substrate, and it will take a corresponding time. On the other hand, in the case where the aberration of the projection optical system is evaluated only based on the result of aerial image measurement, there may be an error in the result of aerial image measurement relative to the transfer result, so It may be difficult to evaluate aberrations of the projection optical system with high accuracy.

[Previous Technical Literature]

Patent Document 1: Japanese Patent Application Laid-Open No. 2003-215423

Patent Document 2: Japanese Patent Laid-Open No. 2001-166497

The present invention provides, for example, a technique advantageous for easily and accurately evaluating aberrations of a projection optical system in an exposure device.

In order to achieve the above object, as an aspect of the present invention, an aberration of a projection optical system in an exposure device is evaluated, and the method includes a transfer process for passing a plurality of pattern elements of a mask through the exposure device. The projection optical system is transferred to a substrate. The first program is to obtain a first characteristic value related to the projection position of each of the plurality of pattern elements based on the projection optical system based on the transfer result in the transfer program. To obtain an average value of the first characteristic values of the plurality of pattern elements as first information indicating aberrations of the projection optical system; and a detection program to detect the projection by the projection optical system Images of a plurality of pattern elements; a second program, based on a detection result in the detection program, obtaining a second characteristic value related to a projection position of each of the plurality of pattern elements by the projection optical system, and obtaining An average value of the second characteristic value of the plurality of pattern elements, and an average value of the second characteristic value of each of the plurality of pattern elements and the average value of the second characteristic value. As an aberration of the projection optical system of the second information; and evaluation procedures, based on the first information and the second information, evaluating the image projection optical system difference.

Further features of the present invention will be made clear by the preferred embodiments described below with reference to the drawings.

100‧‧‧ exposure device

1‧‧‧lighting optical system

1a‧‧‧ Narrow light profile

2‧‧‧Mask

2 ’, 2” ‧‧‧Evaluation mask

2b‧‧‧ pattern elements

2b _H ‧‧‧H line elements

2b _V ‧‧‧V Line Elements

2b _S ‧‧‧S Line Elements

2b _T ‧‧‧T line elements

3‧‧‧Mask

4‧‧‧ projection optical system

41‧‧‧The first plane mirror

42‧‧‧ 2nd plane mirror

43‧‧‧ concave mirror

44‧‧‧ convex mirror

5‧‧‧ substrate

5 ’, 5” ‧‧‧test substrate

6‧‧‧ Substrate

8‧‧‧ the first detection department

8a‧‧‧irradiation system

8b‧‧‧Light receiving system

9‧‧‧The second detection section

10‧‧‧Exposure device

11‧‧‧ axis

P1 ~ P5‧‧‧X position

1A and 1B are schematic views showing an exposure apparatus.

FIG. 2 is a flowchart illustrating an aberration evaluation method and an exposure method of the projection optical system.

3A and 3B are diagrams showing an evaluation mask.

FIG. 4 is a diagram showing a relationship between a line width and a height of a substrate.

5A to 5G are diagrams showing characteristics obtained in order to evaluate aberrations of the projection optical system.

6A to 6J are diagrams showing characteristics obtained in order to evaluate aberrations of the projection optical system.

FIG. 7 is a flowchart showing an aberration evaluation method and an exposure method of a projection optical system accompanying changes in lighting conditions.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In each figure, the same reference numerals are assigned to the same components or elements, and redundant descriptions are omitted.

<First Embodiment>

In this embodiment, a method for evaluating aberrations of the projection optical system in the exposure apparatus 100 will be described. First, the exposure will be described with reference to FIG. 1A. 装置 100。 The device 100. FIG. 1A is a schematic view showing an exposure apparatus 100 according to the first embodiment. The exposure device 100 can include, for example, an illumination optical system for illuminating the mask 2, a mask stage 3 that can move while holding the mask 2, a projection optical system 4 that projects a pattern of the mask 2 onto the substrate 5, and can hold the substrate. 5 and the substrate stage 6 and the control unit 7 that move. The control unit 7 includes, for example, a CPU, a memory, and the like, and controls each part of the exposure apparatus 100 (controls exposure processing).

The illumination optical system 1 shapes the light emitted from the light source into, for example, an arc-shaped slit light that is long in the X direction, by using a light-shielding member (slit predetermined member) such as a light-shielding sheet contained therein, and uses the slit light A part of the mask 2 is illuminated. As shown in FIG. 1B, a cross section 1 a (XY cross section) of the slit light emitted from the illumination optical system 1 has a shape defined by a curvature R, a slit length L, and a slit width d about the axis 11.

The projection optical system 4 may be configured as one of an equal magnification imaging optical system, a magnification imaging optical system, and a reduction imaging optical system. In this embodiment, an example in which the projection optical system 4 is configured as a constant-magnification imaging optical system will be described. The projection optical system 4 includes, for example, a first plane mirror 41, a second plane mirror 42, a concave mirror 43, and a convex mirror 44. The light emitted from the illumination optical system 1 and transmitted through the mask 2 is reflected at the upper portions of the first plane mirror 41 and the concave mirror 43 and enters the convex mirror 44. Then, the light reflected by the convex reflecting mirror 44 is reflected by the lower portion of the concave reflecting mirror 43 and the second plane reflecting mirror 42 and is incident on the substrate 5. As a result, the pattern of the mask 2 is projected onto the substrate 5. That is, the image of the pattern of the mask 2 is formed on the substrate 5.

The mask 2 and the substrate 5 are held by the mask stage 3 and the substrate stage 6, respectively, and are disposed at positions of optically conjugated positions (object surface and image plane of the projection optical system 4) via the projection optical system 4. The mask stage 3 and the substrate stage 6 are relatively synchronized with each other at a speed ratio corresponding to the projection magnification of the projection optical system 4 in a direction (for example, the Y direction) perpendicular to at least the optical axis 10 of the projection optical system 4. scanning. This allows the pattern of the mask 2 to be transferred onto the substrate while scanning the slit light in the Y direction on the substrate. The mask stage 3 and the substrate stage 6 can be configured so that the mask 2 and the substrate 5 can move in the height direction (Z direction), respectively.

Here, the exposure apparatus 100 may include a first detection unit 8 that detects the height of the substrate 5 and a second detection unit 9 that detects an image of the pattern of the mask 2 projected by the projection optical system 4 (so-called aerial image measurement is performed). . The first detection unit 8 is an oblique incidence type that irradiates light obliquely to the substrate 5 and can include an irradiation system 8 a that irradiates light to the surface of the substrate 5 and a light receiving system 8 b that receives light reflected from the substrate 5. The second detection unit 9 includes an imaging element (image sensor) such as a CCD sensor or a CMOS sensor, and can be installed on the imaging element such that the imaging surface of the imaging element has the same height as the surface of the substrate 5. Substrate platform 6. When the second detection unit 9 detects the image of the pattern of the mask 2, the second detection unit 9 moves through the substrate stage 6 so that light emitted from the projection optical system 4 enters the second detection unit 9.

In the exposure apparatus 100 configured as described above, with the recent miniaturization of circuit patterns, it is required to evaluate the aberrations of the projection optical system 4 with high accuracy. Conventionally, only the result of the transfer of the pattern of the mask 2 to the substrate 5 and the air One of the results of the image measurement was evaluated for aberrations of the projection optical system 4. In the case where the aberration of the projection optical system 4 is evaluated based only on the transfer result, in order to accurately evaluate the aberration of the projection optical system 4, it is preferable to use a pattern obtained by transferring the pattern of the mask 2 on a plurality of substrates 5 respectively. result. However, it is troublesome to transfer the pattern of the mask 2 on each of the plurality of substrates 5 and measure the pattern transferred to each of the substrates 5, and it will take a corresponding time. In particular, a procedure for measuring the line width and the like of a pattern transferred to the substrate 5 takes more evaluation time than other procedures, so it is not preferable to increase the number of substrates in the evaluation time. On the other hand, in the case where the aberration of the projection optical system 4 is evaluated only based on the results of the aerial image measurement, an error in the relative transfer result may occur in the results of the aerial image measurement, so it is difficult to evaluate the projection optical system 4 with high accuracy. Aberration.

Therefore, in the method for evaluating aberrations of the projection optical system of the present embodiment, information indicating aberrations of the projection optical system 4 is obtained based on the transfer result, and is also obtained from each of the results of aerial image measurement. Information indicating aberrations of the projection optical system 4. Then, using the information obtained from the transfer result, the information obtained from the aerial image measurement result is corrected, and the aberration of the projection optical system 4 is evaluated based on the corrected result. As a result, the number of substrates 5 to which the pattern of the mask 2 is transferred (the number of times the pattern of the mask 2 is transferred to the substrate 5) can be reduced, and aberrations of the projection optical system 4 can be easily and accurately evaluated. Hereinafter, a method of evaluating the aberrations of the projection optical system 4 based on both the transfer result and the result of aerial image measurement will be described.

[Example 1]

In Example 1, a method of evaluating the curvature of field and the astigmatism of the aberration of the projection optical system 4 in the exposure apparatus 100 will be described with reference to FIG. 2. Here, along with the evaluation method of the aberrations of the projection optical system 4, an exposure method will be described in which the exposure device 100 is corrected based on the evaluation result of the aberrations of the projection optical system 4, and the substrate is corrected using the corrected exposure device 100. exposure. FIG. 2 is a flowchart illustrating an aberration evaluation method and an exposure method of the projection optical system 4. Here, in Embodiment 1, as the characteristic value related to the projection position of the pattern of the mask 2 in the projection optical system 4, a focus value (hereinafter simply referred to as a “focus value”) of the projection optical system 4 may be used.

First, in S11, the characteristic value (focus value) of the projection optical system 4 is determined as the first characteristic value based on the transfer result obtained by transferring the pattern of the evaluation mask 2 'to the substrate. The first characteristic value is obtained by using information indicating aberrations of the projection optical system 4 as the first information. In the procedure of S11, as the mask 2, an evaluation mask 2 'can be used, and as the substrate 5, a test substrate 5' (also referred to as an evaluation substrate or a dummy substrate) can be used. In addition, the procedure of S11 is sufficient only once, but it may be repeated many times.

Here, the evaluation mask 2 'will be described. For example, the evaluation mask 2 ′ used in this embodiment is arranged, for example, as shown in FIG. 3A, at a plurality of positions (X positions P1 to P5) in a direction different from the scanning direction (for example, the X direction). In each place, two or more patterns 2a are arranged in the scanning direction. X positions P1 to P5 in the evaluation mask 2 'and emitted from the projection optical system 4 The positions P1 to P5 (see FIG. 5A) in the X direction in the section 1 a of the slit light correspond to each other. FIG. 5A is a diagram showing a section 1a of the slit light. In addition, each of the plurality of patterns 2 a may include a plurality of line elements that are different from each other in the direction in which the line extends, as the plurality of pattern elements 2 b.

As shown in FIG. 3B, each pattern 2a in this embodiment can include four types of line elements that are shifted from each other by 45 degrees in the direction in which the line extends, as a plurality of pattern elements 2b. FIG 3B feature row lines H _H 2B row line elements is shown extending in a direction perpendicular to the scanning direction of the slit of light (X direction), V 2b _V element row lines are relatively element row lines H 2B _H about Inverse Line elements rotated 90 degrees clockwise. The S line element 2b _S is a line element rotated 45 degrees counterclockwise relative to the H line element 2b _H , and the T line element 2b _T is a line element rotated 45 degrees counterclockwise with respect to the V pattern.

Hereinafter, the procedure of S11 will be described in detail. The program of S11 can include, for example, programs of S11a to S11d. In S11a, a plurality of patterns 2a (a plurality of pattern elements 2b) in the evaluation mask 2 'are transferred to the test by scanning exposure of the test substrate 5' using the exposure device 100 using the evaluation mask 2 '. On the substrate. For example, in the procedure of S11a, scanning exposure of the test substrate 5 is performed while changing the height (position in the Z direction) of the test substrate 5 'by the substrate stage 6 using the evaluation mask 2'. That is, scanning exposure of the test substrate 5 'is performed while changing the defocus amount. As a result, on the test substrate 5 ′, a plurality of patterns 2 a (a plurality of pattern elements 2 b) can be formed in a line along the scanning direction with respect to each of the X positions P1 to P5 to be transferred so that the defocus amounts are different from each other. . Here, in the procedure of S11a, in addition to the exposure for scanning exposure of the test substrate 5 ' In addition to the program, for example, a coating process for coating a photosensitive material (resist layer) on a substrate, a development process for developing a test substrate 5 'subjected to scan exposure, and the like can be performed.

In S11b, the line width of each pattern element 2b transferred to the test substrate 5 'is measured by, for example, a measurement device external to the exposure device 100. In S11c, based on the measurement results in S11b, the relationship between the line width of the pattern element 2b and the height of the test substrate 5 'at the time of exposure is obtained for each pattern position 2b for each X position. Then, based on the relationship obtained for each pattern element 2b for each X position, the focus value for each X position is obtained as a first characteristic value for each pattern element 2b. For example, if the line element of interest Row H X _H 2B at the position P1, then these measurements, shown in Figure 4 can be H when _H 2B row line elements of the line width H of each row of the exposure line features determined 2B _H The relationship of the height of the test substrate 5 '. Then, the height of the test substrate 5 'when the line width becomes the maximum corresponds to the focus value. Therefore, the line about the H line at the X position P1 can be obtained from the relationship between the line width shown in FIG. 4 and the height of the test substrate 5'. Focus value of element 2b _H. By performing the procedure for determining the focus value in this way with respect to each X position P1 to P5 and each pattern element 2b, as shown in FIG. 5B, the relationship between the X position and the focus value can be obtained for each pattern element 2b.

In S11d, the average value of the focus values (first characteristic values) for the plurality of pattern elements 2b obtained in S11c is calculated as the aberration of the projection optical system 4 by formula (1) for each X position. To find the first information. Thereby, as shown in FIG. 5C, the relationship between the X position and the average value of the focus value can be obtained. In formula (1), the focus value of the H line line element 2b _H , the V line line element 2b _V , the S line line element 2b _S , and the T line line element 2b _T at the X position Pn (n = 1 to 5). They are represented by F _nH , F _nV , F _nS , and F _nT , respectively, and their average values are represented by Fn. In addition, weights added to the optimal focus values in each pattern element are represented as w _nH , w _nV , w _nS , and w _{nT, respectively} . Here, in this embodiment, an example in which a weighted average value of the focus values of each pattern element 2b is obtained as an average value of the focus values has been described. In a case where an error corresponding to the direction in which the line and line of each pattern element 2b extends is caused by, for example, aberration in a measurement device that measures the line width of the pattern element 2b, a weighted average is preferably used. . Therefore, when this error does not occur, a simple average value of the focus value of each pattern element 2b may be obtained as the average value of the focus values, for example.

Next, in S12, based on a result obtained by detecting the image of each pattern 2a of the evaluation mask 2 'projected by the projection optical system 4 by the second detection unit 9 (result of aerial image measurement), the projection optical The characteristic value (focus value) of the system 4 is obtained as the second characteristic value. Then, based on the second characteristic value, information indicating aberrations of the projection optical system 4 is obtained as the second information. For example, the procedure of S12 may be performed automatically by the exposure apparatus 100 (control part 7). In addition, the program of S12 may be performed a plurality of times, and the second characteristic value may be obtained from a result obtained by averaging a plurality of detection results obtained in the program of S12 a plurality of times. Here, in the flowchart shown in FIG. 2, the procedure of S12 is performed after the procedure of S11, However, the procedure of S12 may be performed before the procedure of S11.

Hereinafter, the procedure of S12 will be described in detail. The program of S12 can include the programs of S12a to S12c. In S12a, while the height of the substrate 5 is changed by the substrate stage 6, the image of each pattern element 2b of the evaluation mask projected by the projection optical system 4 is detected by the second detection unit 9 for each X position. In S12b, the focus value of each pattern element 2b of the evaluation mask 2 'is obtained as the second characteristic value for each X position. As a result, as shown in FIG. 5D, the relationship between the X position and the focus value can be obtained for each pattern element 2 b.

In S12c, for example, the above formula (1) is used, and for each X position, the average value of the focus values (second characteristic values) for the plurality of pattern elements 2b obtained in the program of S12b is used as the projection optical system 4 The second information of the aberration is calculated. Thereby, as shown in FIG. 5E, the relationship between the X position and the average value of the focus value can be obtained. In S12c, for each X position, the difference between the focus value (second characteristic value) and the average value of the focus value (second characteristic value) of each pattern element 2b (i.e., the characteristic and graph shown in FIG. 5D) The difference in characteristics shown by 5E (hereinafter also referred to as a deviation value) is also calculated as the second information. For example, if the row lines concerned H _H 2B elements, it is possible to obtain a deviation value for the elements of the row lines H _H 2B by Formula (2). In formula (2), the focus value of the H-line line element 2bH at the X position Pn (n = 1 to 5) is represented as f _nH , and the average value of the focus values of the plurality of pattern elements 2 b is represented as f _n The deviation value of the H-line element 2b _H is represented by fb _nH . Thereby, as shown in FIG. 5F, the relationship between the X position and the deviation value can be obtained for each pattern element 2b.

fb _nH = f _nH -f _n ‧‧‧ (2)

Returning to the flowchart of FIG. 2, in S13, for example, the average value of the second characteristic value in the second information is made close to the average value of the first characteristic value in the first information. 1 information, correct the 2nd information obtained in S12. Thereby, information (evaluation information) used to evaluate the aberrations of the projection optical system 4 is obtained.

As a specific method of correcting the second information, there is a method of correcting the second information by applying the average value of the first characteristic value in the first information as the average value of the second characteristic value in the second information. That is, in this method, the result of combining the average value (characteristic shown in FIG. 5C) in the first information and the deviation value (characteristic shown in FIG. 5F) in the second information is used as the corrected second information. Get the method. For example, if attention is paid to the H-line element 2b _H , the average value in the first information and the deviation value in the second information can be combined by Equation (3). In formula (3), the result of combining the average value in the first information about the H-line line element 2b _H at the X position Pn (n = 1 to 5) and the deviation value in the second information is expressed as F _0nH , and the _weight in the H-line element 2b _H is represented by W _nH . By performing the process of combining the average value in the first information and the deviation value in the second information with respect to each pattern element 2b and each X position, the evaluation information can be obtained as shown in FIG. 5G. Here, similar to the reason for using the above-mentioned weighted average, when an error occurs in the detection result obtained by the second detection unit 9 depending on the direction in which the line and line of each pattern element 2b extends, it is preferable to add a deviation value. the weight of.

F _0nH = F _n + W _nH × fb _1H . ． ． (3)

In S14, the aberrations (image plane curvature and astigmatism) of the projection optical system 4 are evaluated based on the evaluation information (FIG. 5G) obtained in S13. For example, as shown in FIG. 5G, the curvature of the image plane can be evaluated based on the difference between the maximum value and the minimum value of the focus value. In addition, astigmatism can be evaluated for each X position based on the difference in focus values among the plurality of pattern elements 2b. In S15, the exposure device 100 is corrected based on the evaluation result in S14. For example, by adjusting the position of the optical element of the projection optical system 4, or by processing or replacing the optical element of the projection optical system 4, the exposure device 100 can be calibrated. In S16, the exposure apparatus 100 corrected in S15 is used to expose the substrate 5 using the mask 2 having a circuit pattern transferred to the substrate 5 on which a circuit is to be formed.

[Example 2]

In Example 2, a method of evaluating distortion aberration as the aberration of the projection optical system 4 in the exposure apparatus 100 will be described. In Example 2, as in Example 1, the aberration evaluation of the projection optical system 4, the correction of the exposure device 100, and the exposure of the substrate 5 can be performed in accordance with the flowchart shown in FIG. 2. Here, in Embodiment 2, as a characteristic value of the projection optical system 4, a pattern of the mask 2 can be projected by the projection optical system 4 in a direction (XY direction) perpendicular to the optical axis 10 of the projection optical system 4. The offset between the position of the target position and the target position (hereinafter referred to as "offset"). In addition, in the second embodiment, it is possible to use a position where a plurality of positions (X positions P0 to P30) in a direction different from the scanning direction has, for example, a plurality of cross marks as a plurality of pattern elements 2b along the slit light. Evaluation mask 2 "for the patterns 2a arranged in the scanning direction.

First, in S11, based on a transfer result obtained by transferring the pattern of the evaluation mask 2 "onto a substrate, a characteristic value (offset amount) of the projection optical system 4 is determined as the first characteristic value. Based on the first characteristic value, information indicating aberrations of the projection optical system 4 is obtained as the first information.

In S11a, a plurality of patterns 2a (a plurality of pattern elements 2b) of the evaluation mask 2 "are transferred to the test substrate by scanning and exposing the test substrate 5" with the exposure mask 100 using the evaluation mask 2 ". on.

In S11b, the position (XY direction) of each pattern element 2b transferred to the test substrate 5 "is measured by, for example, a measuring device external to the exposure device 100. Thus, for example, as shown in FIG. 6A, the display rotation can be obtained. A grid-like distribution 61 printed on the position of each pattern element 2b of the test substrate 5 ". Then, in S11c, based on the measurement results in S11b (distribution shown in FIG. 6A), the positions and target positions (distribution of target positions) of each pattern element 2b of the evaluation mask 2 "are projected by the projection optical system 4 62). The first direction (X direction in the present embodiment) perpendicular to the optical axis 10 of the projection optical system 4 and the first direction perpendicular to the optical axis 10 of the projection optical system 4 and different from the first direction The offset amount is obtained in each of two directions (the Y direction in this embodiment). Hereinafter, the offset amount in the first direction (X direction) is represented as Dx, and The amount of shift in the second direction (Y direction) is represented as Dy. Here, the target position is a position in the XY direction of each pattern element 2 b of the evaluation mask 2 ″ to be projected by the projection optical system 4.

In S11d, for each X position, the average value of each of the offset amounts Dx and Dy (first characteristic value) of each pattern element 2b is obtained as the first information indicating the aberration of the projection optical system 4. Thereby, as shown in FIG. 6B, the relationship between the X position and the average value of the offset amounts can be obtained for each of the offset amounts Dx and Dy.

Next, in S12, based on a result obtained by detecting the image of each of the patterns 2b of the evaluation mask 2 "projected by the projection optical system 4 using the second detection unit 9 (the result of aerial image measurement), the projection optical The characteristic value (offset) of the system 4 is obtained as the second characteristic value. Then, based on the second characteristic value, information indicating the aberration of the projection optical system 4 is obtained as the second information.

In S12a, the image of each pattern element 2b is detected by the second detection unit 9 with respect to each detection point of the plurality of detection points in the cross section 1a of the slit light. The plurality of detection points are arranged, for example, as shown in FIG. 6E, 11 detection points (Y0 to Y10) are arranged in the Y direction at each X position (P0 to P30). FIG. 6E is a diagram showing a plurality of detection points in a cross section of the slit light. When a plurality of detection points are arranged in this manner, the evaluation mask 2 "is repeatedly moved in the Y direction by, for example, an amount corresponding to the pitch of the detection points in the Y direction, and the detection of the pattern element 2b by the second detection unit 9 is performed. The program of the image. Thus, the image of the pattern element 2b can be detected at each of a plurality of detection points. Then, in S12b, based on the detection result in the second detection unit 9, for each The X position is obtained by using the offsets Dx and Dy as the second characteristic values. Thereby, as shown in FIG. 6C and FIG. 6D, the relationship between the X position and the offset (Dx, Dy) can be obtained for each detection point in the Y direction. FIG. 6C is a diagram showing the relationship between the X position and the shift amount Dx, and FIG. 6D is a diagram showing the relationship between the X position and the shift amount Dy.

In S12c, for each X position, an average value of the shift amounts Dx at a plurality of measurement points (Y0 to Y10) in the Y direction is obtained as the second information indicating the aberration of the projection optical system. As a result, as shown in FIG. 6F, the relationship between the X position and the average value of the shift amount Dx can be obtained. Then, using Equation (4), for each X position, the difference between the offset Dx (second characteristic value) and the average value of the offset Dx (second characteristic value) at each detection point in the Y direction. (That is, the difference (deviation value) between the characteristic shown in FIG. 6C and the characteristic shown in FIG. 6F) is also obtained as the second information. In Equation (4), the offset Dx at the X position Pi (i = 0 ~ 30) and the detection point Yj (j = 0 ~ 10) is set to dX _ij , and the offset Dx at the X position Pi The average value of is set to dX _i , and the deviation value of the offset Dx is set to dXb _ij . Thereby, as shown in FIG. 6G, the relationship between the X position and the deviation value of the offset Dx can be obtained for each detection point in the Y direction.

dXb _ij = dX _ij -dX _i ‧‧‧ (4)

In the same manner as the shift amount Dx, in S12c, for each X position, an average value of the shift amounts Dy at a plurality of detection points (Y0 to Y10) in the Y direction is used as the aberration of the projection optical system. The second information is obtained. As a result, as shown in FIG. 6F, the relationship between the X position and the average value of the shift amount Dy can be obtained. Then, the difference between the offset Dy (second characteristic value) and the average value of the offset Dy (second characteristic value) at each detection point in the Y direction is calculated for each X position by using Equation (5). (That is, the difference (deviation value) between the characteristic shown in FIG. 6D and the characteristic shown in FIG. 6F) is also obtained as the second information. In Equation (5), the offset Dy at the X position Pi (i = 0 ~ 30) and the detection point Yj (j = 0 ~ 10) is set to dy _ij , and the offset Dy at the X position Pi The average value of is set to dY _i , and the deviation value of the offset Dy is set to dYb _ij . As a result, as shown in FIG. 6H, the relationship between the X position and the deviation value of the offset Dy can be obtained for each detection point in the Y direction.

dYb _ij = dY _ij -dY _i . ． ． (5)

Returning to the flowchart of FIG. 2, in S13, the second information obtained in S12 is corrected by using the first information obtained in S11 to obtain evaluation information. For example, the average value of the offset amount Dx (characteristic shown in FIG. 6B) in the first information and the offset value (characteristic shown in FIG. 6G) of the offset Dx in the second information can be combined to obtain Information for evaluation in the X direction. The average value of the offset amount Dx in the first information and the deviation value of the offset amount Dx in the second information can be combined by Equation (6). In Equation (6), the average value of the offset amount Dx in the first information at the X position Pi (i = 0 to 30) is set to DX _i , and the average value of the offset amount Dx in the first information is set to DX _i . The value and the deviation value of the offset amount Dy in the second information are combined to be DX _0ij . By performing the process of combining the average value of the offset amount Dx in the first information and the offset value of the offset amount Dx in the second information with respect to each X position, the evaluation in the X direction can be obtained as shown in FIG. 6I Use information. Here, in a case where an error occurs in the detection result obtained by the second detection section 9 according to the position X and the detection point position Pi Yj using the offset value added to the weights Wx _ij.

_{DX 0ij = DX i + Wx ij} × dXb ij. ． ． (6)

Similarly, by combining the average value of the offset amount Dy (the characteristic shown in FIG. 6B) in the first information and the offset value of the offset amount Dy (the characteristic shown in FIG. 6H), it is possible to combine Get evaluation information about the Y direction. The average value of the offset amount Dy in the first information and the deviation value of the offset amount Dy in the second information can be combined by Equation (7). In Equation (7), the average value of the offset amount Dy in the first information at the X position Pi (i = 0 to 30) is set to DY _i , and the average of the offset amount Dy in the first information is set to DY _i . The value and the deviation value of the offset amount Dy in the second information are combined to be DY _0ij . By performing the process of combining the average value of the offset amount Dy in the first information and the deviation value of the offset amount Dy in the second information with respect to each X position, the evaluation in the Y direction can be obtained as shown in FIG. 6J. Use information. Here, when an error occurs in the detection result obtained by the second detection unit based on the X position Pi and the position of the detection point Yj, the weight Wy _ij added to the deviation value may be used.

DY _0ij = DY _i + Wy _ij × dYb _ij . ． ． (7)

In S14, the aberration (distortion aberration) of the projection optical system 4 is evaluated based on the evaluation information (FIGS. 6I and 6J) obtained in S13. In S15, the exposure device 100 is corrected based on the evaluation result in S14. In S16, the exposure apparatus 100 corrected in S15 is used to expose the substrate 5 using the mask 2 having a circuit pattern transferred to the substrate 5 on which a circuit is to be formed.

<Second Embodiment>

In the exposure apparatus 100, for example, the lighting conditions such as the shape of an effective light source such as a conventional, belt, and dipole, NA of the illumination optical system 1, and belt ratio and transmittance may be changed. However, each time the lighting conditions are changed, it takes time and time to transfer the pattern of the evaluation mask to the test substrate under the changed lighting conditions and obtain the characteristic values of the projection optical system 4 based on the transfer results. . Therefore, after changing the lighting conditions, it is preferable not to perform each program of S11 in the flowchart shown in FIG. 2 and to evaluate the aberrations of the projection optical system 4 under the changed lighting conditions. Therefore, in this embodiment, the programs of S11 in the flowchart shown in FIG. 2 are not performed under the changed lighting conditions, and only the programs of S12 are newly performed, and the projection optical system under the changed lighting conditions is performed. 4 aberration evaluation. Hereinafter, a method of evaluating aberrations of the projection optical system 4 in this embodiment will be described with reference to FIG. 7. FIG. 7 illustrates an aberration evaluation method and exposure method of the projection optical system 4 under two different lighting conditions, respectively. Process flow chart.

In S21, the lighting condition of the exposure device 100 is set to the first lighting condition. The first lighting condition refers to a lighting condition before the lighting condition of the exposure device 100 is changed. In S22, each program of S11 in the flowchart shown in FIG. 2 is performed to find the average value of the first characteristic value (first information). Hereinafter, the average value of the first characteristic value obtained in S22 is referred to as "average value A1". In S23, each program of S12 in the flowchart shown in FIG. 2 is performed to obtain the average value of the second characteristic value and the deviation value of the second characteristic value (second information). Hereinafter, the average value of the second characteristic value obtained in S23 will be referred to as "average value A2", and the deviation value of the second characteristic value obtained in S23 will be referred to as "deviation value A2". In the flowchart shown in FIG. 7, the procedure of S23 is performed after the procedure of S22, but it may be performed before the procedure of S22.

In S24, the aberration of the projection optical system 4 is evaluated based on a result obtained by correcting the second information obtained in S23 using the first information obtained in S22, and the exposure apparatus 100 is corrected based on the evaluation result. The program of S24 corresponds to each of the programs of S13 to S15 in the flowchart shown in FIG. 2. In S25, the mask 5 having a circuit pattern transferred to a substrate 5 on which a circuit is to be formed is exposed to the substrate 5 under the first lighting condition. The procedure of S25 corresponds to the procedure of S16 of the flowchart shown in FIG. 2, and is repeated several times according to the number of substrates 5 on which circuits are to be formed.

In S26, the lighting condition of the exposure apparatus 100 is changed from a 1st lighting condition to a 2nd lighting condition. In S27, each of the programs in S12 of the flowchart shown in FIG. 2 is performed to newly obtain the average value of the second characteristic value and The second characteristic value of the deviation value of the second characteristic value (third information). Hereinafter, the average value of the second characteristic obtained in S27 is referred to as “average value B”, and the deviation value of the second characteristic obtained in S27 is referred to as “deviation value B”. In S28, based on the difference between the second information (average value A2) obtained in S23 and the third information (average value B) obtained in S27, the first information (under the lighting conditions before the change) is corrected ( Mean A1). Specifically, the first information is corrected by adding the difference between the second information (average value A2) and the third information (average value B) to the first information (average value A1).

In S29, based on the result obtained by correcting the third information obtained in S27 with the first information corrected in S28, the aberration of the projection optical system under the changed lighting condition (second lighting condition) is evaluated. Based on the evaluation results, the exposure device 100 is corrected. The program of S29 corresponds to each of the programs of S13 to S15 in the flowchart shown in FIG. 2. In S30, the mask 5 having the circuit pattern transferred to the substrate 5 on which the circuit is to be formed is used, and the substrate 5 is exposed under the second lighting condition. The procedure of S30 corresponds to the procedure of S16 of the flowchart shown in FIG. 2, and is repeated several times according to the number of substrates 5 on which circuits are to be formed. In this way, in the second embodiment, the procedure of transferring the pattern of the evaluation mask to the test substrate under the lighting conditions after the change (S11 in the flowchart of FIG. 2) is not performed, and the change after the change can be easily evaluated. Aberrations of the projection optical system 4 under the lighting conditions.

<Embodiment of Article Manufacturing Method>

The manufacturing method of the article of embodiment of this invention is suitable for manufacture, for example Microdevices such as semiconductor devices, and components with fine structures. The method for manufacturing an article according to this embodiment includes a process of forming a latent image pattern (the process of exposing the substrate) to the photosensitive agent applied on the substrate using the above-mentioned exposure method, and a substrate on which the latent image pattern is formed in the process. Development process. Furthermore, the above-mentioned manufacturing method includes other well-known procedures (oxidation, film formation, vapor deposition, doping, planarization, etching, resist peeling, dicing, bonding, packaging, etc.). The manufacturing method of the article of this embodiment is advantageous compared with the conventional method in at least one of the performance, quality, productivity, and production cost of an article.

(Other embodiments)

The present invention can also be implemented in a process in which a program that realizes one or more functions of the above-mentioned embodiment is supplied to a system or device through a network or a storage medium, and one of the computers of the system or device is supplied. The above processor reads and executes the program. It can also be realized by a circuit (for example, an ASIC) that realizes one or more functions.

Although the present invention has been described in connection with exemplary embodiments, it should be understood that the present invention is not limited to the exemplary embodiments disclosed. Regarding the scope of patent application, the widest interpretation should be given to include all modifications and equivalents of the structure and function.

Claims (14)

An evaluation method for evaluating aberrations of a projection optical system in an exposure device, comprising: a transfer program that transfers a plurality of pattern elements of a mask to a substrate through the projection optical system of the exposure device; A program for obtaining a first characteristic value related to a projection position of each of the plurality of pattern elements by the projection optical system based on a transfer result in the transfer program, and obtaining the plurality of pattern elements The average value of the first characteristic value is used as the first information. The detection program detects a plurality of pattern elements projected by the projection optical system using a sensor that receives light from the projection optical system. A second program, based on a detection result in the detection program, obtaining a second characteristic value related to a projection position of each of the plurality of pattern elements based on the projection optical system, and obtaining the plurality of An average value of the second characteristic value of the pattern element and a difference between the second characteristic value of each of the plurality of pattern elements and the average value of the second characteristic value as the second information; And an evaluation program that uses a characteristic value related to a projection position of each of the plurality of pattern elements based on the projection optical system, an item of an average value of the first characteristic value as the first information, and The sum of the difference terms of the second information is obtained as evaluation information, and aberrations of the projection optical system are evaluated based on the evaluation information. The evaluation method according to item 1 of the scope of patent application, wherein, in the evaluation program, an average value and a weighted value of the first characteristic value as the first information are used as the second information according to a pattern element. The difference is added up to obtain the evaluation information. According to the evaluation method of claim 1, in the mask, a plurality of line elements that are different from each other in a direction in which the line extends are formed as the plurality of pattern elements. The evaluation method according to item 3 of the scope of patent application, wherein the directions in which the line lines of the plurality of line line elements extend are shifted from each other by 45 degrees. The evaluation method according to item 3 of the scope of patent application, wherein in the first program, the first characteristic value of each pattern element is weighted according to the direction in which the line extends, and the plurality of patterns are obtained. An average value of the first characteristic value obtained by element weighting is used as the first information. The evaluation method according to item 1 of the scope of patent application, wherein the first characteristic value and the second characteristic value each include a focus value of the projection optical system, and in the evaluation program, the projection optical system is evaluated At least one of the curved image surface and astigmatism. The evaluation method according to item 1 of the scope of patent application, wherein the first characteristic value and the second characteristic value are respectively included in a direction perpendicular to the optical axis of the projection optical system by the projection optical system. The shift amount between the position where the pattern is imaged and the target position, and in the evaluation program, the distortion aberration of the projection optical system is evaluated. The evaluation method according to item 7 of the scope of patent application, wherein the first characteristic value and the second characteristic value include the offset in a first direction perpendicular to the optical axis, and the first characteristic value and the second characteristic value, respectively. The shift amount in a second direction that is perpendicular to the optical axis and different from the first direction. The evaluation method according to item 1 of the scope of patent application, wherein the transfer procedure is performed only once. The evaluation method according to item 9 of the scope of patent application, wherein the detection procedure is performed a plurality of times, and in the second procedure, the plurality of detection results obtained in the plurality of detection procedures are averaged to As a result, the second information is obtained. The evaluation method according to item 1 of the scope of patent application, wherein when the lighting conditions of the exposure device are changed, performing: performing the detection procedure and the second procedure again under the changed lighting conditions, Recalculate the second information under the lighting condition after the change; based on the second information obtained under the lighting condition before the change and the second information obtained under the lighting condition after the change A program for correcting the evaluation information; and a program for evaluating aberrations of the projection optical system under changed lighting conditions based on the corrected evaluation information. An exposure method for exposing a substrate, comprising: a program for evaluating aberrations of a projection optical system using the evaluation method of the first patent application scope; and correcting an office based on an evaluation result of the aberrations of the projection optical system. A program of the exposure device; and a program of exposing the substrate using the corrected exposure device. An article manufacturing method for manufacturing an article, the manufacturing method comprising: a procedure for exposing a substrate using an exposure method according to item 12 of a patent application; and the substrate subjected to the exposure in the exposure procedure Procedure for development; an article is manufactured from the aforementioned substrate. An evaluation method for evaluating aberrations of a projection optical system in an exposure device, comprising: a first program, obtained by transferring a plurality of pattern elements to a substrate using the projection optical system of the exposure device; The transfer result is used to obtain a first characteristic value related to the projection position of each of the plurality of pattern elements of the mask based on the projection optical system, and an average value of the first characteristic values of the plurality of pattern elements is obtained. As the first information; the second program is based on a detection result obtained by detecting images of the plurality of pattern elements projected by the projection optical system using a sensor that receives light from the projection optical system, Obtaining a second characteristic value related to the projection position of each of the plurality of pattern elements based on the projection optical system, obtaining an average value of the second characteristic value of the plurality of pattern elements, and determining the second characteristic value The difference between the second characteristic value of each of the plurality of pattern elements and the average value of the second characteristic value is used as the second information; and the evaluation program compares the difference between the second characteristic value and the value based on the projection optical system. A characteristic value related to the projection position of each of the plurality of pattern elements is summed as a term with an average value of the first characteristic value as the first information and a term with the difference as the second information. The evaluation information is obtained, and aberrations of the projection optical system are evaluated based on the evaluation information.