KR102126232B1 - Evaluation method, exposure method, and method of manufacturing article - Google Patents

Abstract

The evaluation method for evaluating the aberration of the projection optical system in the exposure apparatus includes a transfer step of transferring a plurality of pattern elements of the mask to the substrate by the projection optical system of the exposure apparatus, and the plurality of pattern elements by the projection optical system A first characteristic value for each of the projection positions is obtained based on a transfer result in the transfer step, and an average value of the first characteristic values of the plurality of pattern elements is obtained as first information indicating aberration of the projection optical system The first process, a detection process for detecting an image of the plurality of pattern elements projected by the projection optical system, and a second characteristic value for each projection position of the plurality of pattern elements by the projection optical system are detected Based on the detection result in the process, the difference between the average value of the second characteristic values of the plurality of pattern elements and the average value of the second characteristic value and the second characteristic value of each of the plurality of pattern elements are determined. And a second step of obtaining as second information indicating the aberration of the projection optical system, and an evaluation step of evaluating the aberration of the projection optical system based on the first information and the second information.

Description

Evaluation method, exposure method, and manufacturing method of article{EVALUATION METHOD, EXPOSURE METHOD, AND METHOD OF MANUFACTURING ARTICLE}

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

One of the apparatuses used in a manufacturing process (lithography process) such as a semiconductor device is an exposure apparatus that transfers a pattern of a mask onto a substrate. In the exposure apparatus, it is required to evaluate the aberration of the projection optical system with high precision with the recent miniaturization of circuit patterns. Patent Documents 1 and 2 describe evaluating the aberration of the projection optical system based on only one of a result of transfer of a pattern of a mask actually transferred to a substrate and a result of aerial image measurement using an imaging element.

Japanese Patent Publication No. 2003-215423 Japanese Patent Publication No. 2001-166497

When evaluating the aberration of the projection optical system based only on the transfer result, it is preferable to use the result of transferring the pattern of the mask to a plurality of substrates, respectively, in evaluating the aberration of the projection optical system with high accuracy. However, it is cumbersome to transfer the patterns of the masks to a plurality of substrates, and to measure the patterns transferred to each substrate, and it may take a corresponding time. On the other hand, when evaluating the aberration of the projection optical system based only on the results of aerial image measurement, it may be difficult to accurately evaluate the aberration of the projection optical system because errors may occur in the results of aerial image measurement on the transfer result. .

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

In order to achieve the above object, an evaluation method as an aspect of the present invention is an evaluation method for evaluating aberration of a projection optical system in an exposure apparatus, and a plurality of pattern elements of a mask are substrated by the projection optical system of the exposure apparatus. The transfer process to be transferred to and a first characteristic value for each projection position of the plurality of pattern elements by the projection optical system are obtained based on the transfer result in the transfer process, and the first of the plurality of pattern elements is obtained. A first step of obtaining an average value of the characteristic values as first information indicating aberration of the projection optical system, a detection step of detecting an image of the plurality of pattern elements projected by the projection optical system, and the plurality of projections by the projection optical system The second characteristic value for each projection position of the pattern element of is obtained based on the detection result in the detection step, and the average value of the second characteristic value of the plurality of pattern elements and each of the plurality of pattern elements A second step of obtaining a difference between the second characteristic value relating to the average value of the second characteristic value as second information indicating aberration of the projection optical system; and the projection optical system based on the first information and the second information. Characterized in that it comprises an evaluation process for evaluating the aberration.

Another object or other aspect of the present invention will be revealed by preferred embodiments described below with reference to the accompanying drawings.

1A and 1B are schematic views showing an exposure apparatus.
2 is a flowchart showing an aberration evaluation method and an exposure method of the projection optical system.
3A and 3B are views showing an evaluation mask.
4 is a diagram showing the relationship between the line width and the height of the substrate.
5A to 5G are diagrams showing characteristics obtained to evaluate aberration of the projection optical system.
6A to 6J are diagrams showing characteristics obtained to evaluate the aberration of the projection optical system.
7 is a flowchart showing an aberration evaluation method and an exposure method of the projection optical system with changing lighting conditions.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In addition, in each drawing, the same reference numerals are assigned to the same members or elements, and overlapping descriptions are omitted.

<First Embodiment>

In the present embodiment, an evaluation method for evaluating the aberration of the projection optical system in the exposure apparatus 100 will be described. First, the exposure apparatus 100 will be described with reference to Fig. 1A. 1A is a schematic diagram showing the exposure apparatus 100 of the first embodiment. The exposure apparatus 100 includes, for example, an illumination optical system 1 that illuminates the mask 2, a mask stage 3 that can hold and move the mask 2, and a pattern of the mask 2 on a substrate ( It may include a projection optical system 4 projected on 5), a substrate stage 6 that can hold and move the substrate 5, and a control unit 7. The control unit 7 includes, for example, a CPU or a memory, and controls each unit of the exposure apparatus 100 (controls exposure processing).

The illumination optical system 1 shapes light emitted from the light source by a light blocking member (slit defining member) such as a masking blade included therein, for example, to shape the slit light into a circular arc shape long in the X direction. A part of the mask 2 is illuminated. The cross-section 1a (XY cross-section) of the slit light emitted from the illumination optical system 1 is a shape defined by the curvature R around the axis 11, the slit length L and the slit width d as shown in FIG. 1B. Can have

The projection optical system 4 may be configured as any one of an equal magnification imaging optical system, an enlarged imaging optical system and a reduced imaging optical system. In the present embodiment, an example in which the projection optical system 4 is constituted by an equal magnification imaging optical system will be described. The projection optical system 4 may include, 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 by the first planar mirror 41 and the concave mirror 43, respectively, and enters the convex mirror 44. Then, the light reflected from the convex mirror 44 is reflected by the lower portion of the concave mirror 43 and the second planar mirror 42, respectively, and enters the substrate 5. Thereby, the pattern of the mask 2 is projected on the substrate 5. That is, the image of the pattern of the mask 2 is imaged 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 optically conjugated through the projection optical system 4 (object surface of the projection optical system 4) And a top surface). The mask stage 3 and the substrate stage 6 are at least at a speed ratio according to the projection magnification of the projection optical system 4 while synchronizing with each other in a direction perpendicular to the optical axis 10 of the projection optical system 4 (for example, the Y direction). It is relatively injected. Thus, the pattern of the mask 2 can be transferred onto the substrate while scanning the slit light on the substrate in the Y direction. In addition, the mask stage 3 and the substrate stage 6 may be configured to move the mask 2 and the substrate 5 in the height direction (Z direction), respectively.

Here, the exposure apparatus 100 detects the image of the pattern of the mask 2 projected by the projection optical system 4 and the 1st detection part 8 which detects the height of the board|substrate 5 (so-called aerial image) And a second detector 9 (which performs measurement). The first detection unit 8 is an incidence-radiation type that irradiates light to the substrate 5 at an angle, an irradiation system 8a that irradiates light on the surface of the substrate 5, and a number that receives light reflected from the substrate 5 It may include a light system (8b). Further, the second detection unit 9 includes, for example, an imaging element (image sensor) such as a CCD sensor or a CMOS sensor, and the substrate stage 6 such that the imaging surface of the imaging element is flush with the surface of the substrate 5 ). Then, when detecting the image of the pattern of the mask 2, the second detection unit 9 is moved by 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, it is required to evaluate the aberration of the projection optical system 4 with high precision with the recent miniaturization of circuit patterns. Conventionally, aberration evaluation of the projection optical system 4 has been performed based on only one of a result of transfer of the mask 2 to the pattern substrate 5 and a result of aerial image measurement. When evaluating the aberration of the projection optical system 4 based only on the transfer result, using the result of transferring the patterns of the masks 2 to the plurality of substrates 5, respectively, makes the aberration of the projection optical system 4 highly accurate. It is preferable for evaluation. However, transferring the patterns of the mask 2 to the plurality of substrates 5 respectively, and measuring the patterns transferred to the respective substrates 5 is complicated and may take a corresponding time. In particular, since the process of measuring the line width or the like of the pattern transferred to the substrate 5 may take a lot of evaluation time compared to other processes, increasing the number of substrates is not preferable in terms of evaluation time. On the other hand, when evaluating the aberration of the projection optical system 4 based only on the result of aerial image measurement, since an error of the transfer result may occur in the result of the aerial image measurement, the aberration of the projection optical system 4 is evaluated with high precision. It can be difficult to do.

Therefore, the method for evaluating the aberration of the projection optical system according to the present embodiment obtains information indicating the aberration of the projection optical system 4 based on the transfer result, and also projects the projection optical system 4 based on each of the results of aerial image measurement. ) To obtain information indicating aberration. Then, the information obtained based on the result of aerial image measurement is corrected by the information obtained based on the transfer result, and the aberration of the projection optical system 4 is evaluated based on the corrected result. Thereby, the number of the substrates 5 for transferring the pattern of the mask 2 (that is, the number of times the pattern of the mask 2 is transferred to the substrate 5) can be reduced, and the projection optical system 4 The aberration can be evaluated easily and with high precision. The method of evaluating the aberration of the projection optical system 4 based on both the transfer result and the result of aerial image measurement will be described below.

[Example 1]

In Example 1, a method of evaluating image curvature and astigmatism as an aberration of the projection optical system 4 in the exposure apparatus 100 will be described with reference to FIG. 2. Here, the exposure apparatus 100 is corrected based on the evaluation method of the aberration of the projection optical system 4, and the exposure apparatus 100 is corrected based on the evaluation result of the aberration of the projection optical system 4, and the substrate is used by using the corrected exposure apparatus 100. The exposure method to be exposed is also described. 2 is a flowchart showing an aberration evaluation method and an exposure method of the projection optical system 4. Here, in Example 1, as a characteristic value relating to the projection position of the pattern of the mask 2 in the projection optical system 4, the focus value of the projection optical system 4 (hereinafter simply referred to as "focus value") Can be used.

First, in S11, the characteristic value (focus value) of the projection optical system 4 is obtained as the first characteristic value based on the transfer result of transferring the pattern of the evaluation mask 2'onto the substrate, and the projection optical system 4 Information indicating aberration of is obtained as first information from the first characteristic value. In the process of S11, an evaluation mask 2'is used as the mask 2, and a test substrate 5'(also referred to as an evaluation substrate or a dummy substrate) can be used as the substrate 5. In addition, although it is enough to perform the process of S11 only once, you may repeat it several times.

Here, the evaluation mask 2'will be described. For example, the evaluation mask 2'used in the present embodiment is, for example, as shown in Fig. 3A, a plurality of positions in a direction different from the scanning direction (for example, the X direction) ( In each of the X positions P1 to P5), two or more patterns 2a are arranged to be arranged in the scanning direction. The X positions P1 to P5 in the evaluation mask 2'correspond to the positions P1 to P5 in the X direction in the cross section 1a of the slit light emitted from the projection optical system 4 (see A in Fig. 5). do. 5A is a view showing a cross section 1a of the slit light. In addition, each of the plurality of patterns 2a may include a plurality of line elements having different directions in which the lines extend, as the plurality of pattern elements 2b.

As shown in Fig. 3B, each pattern 2a in this embodiment may include four types of line elements in which directions in which the lines extend are different by 45 degrees from each other, as a plurality of pattern elements 2b. The H line element 2b _H shown in FIG. 3B is a line element extending in a direction (X direction) perpendicular to the scanning direction of the slit light, and the V line element 2b _{V is} connected to the H line element 2b _H. It is a line element rotated 90 degrees counterclockwise. Further, the S line element 2b _S is a line element that is rotated 45 degrees counterclockwise with respect to the H line element 2b _H , and the T line element 2b _T is 45 counterclockwise with respect to the V pattern. It is also a rotated line element.

The process details of S11 will be described below. The process of S11 can include the process of S11a-S11d, for example. In S11a, a plurality of patterns 2a (a plurality of patterns) in the evaluation mask 2'is obtained by scanning exposure of the test substrate 5'by the exposure apparatus 100 using the evaluation mask 2'. The pattern element 2b) is transferred onto the test substrate. For example, in the process of S11a, while using the evaluation mask 2', the height of the test substrate 5'(position in the Z direction) is changed by the substrate stage 6, while the test substrate 5 is Scanning exposure is performed. That is, scanning exposure of the test substrate 5'is performed while changing the defocus amount. Thereby, in the test substrate 5', a plurality of patterns 2a (a plurality of pattern elements 2b) transferred with different defocus amounts to each of the X positions P1 to P5 are arranged in the scanning direction, Can be formed. Here, in the process of S11a, in addition to the exposure process of scanning and exposing the test substrate 5', for example, a coating process of applying a photosensitive material (resist) on the substrate, or a test substrate 5'where scanning exposure has been performed A developing process for developing) may also be performed.

In S11b, the line width of each pattern element 2b transferred to the test substrate 5'is measured, for example, by a measuring device external to the exposure apparatus 100 or the like. In S11c, based on the measurement result in S11b, the relationship between the line width of the pattern element 2b and the height of the test substrate 5'during exposure is obtained for each pattern element 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 the first characteristic value for each pattern element 2b. For example, paying attention to the H line element 2b _H at the X position P1, from their measurement results, as shown in Fig. 4, the line width of the H line element 2b _H and each H line element ( the relationship between the height of the test substrate (5 ') at the time of exposure of the _H 2b) can be obtained. Then, based on the relationship between the line width shown in Fig. 4 and the height of the test substrate 5', since the height of the test board 5'when the line width becomes maximum corresponds to the focus value, X The focus value for the H line element 2b _H at the position P1 can be obtained. By performing the process of obtaining the focus value in this way for 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 is determined for each pattern element 2b. ).

In S11d, the average value of the focus value (first characteristic value) for the plurality of pattern elements 2b obtained in S11c is obtained for each X position by Equation 1 as first information indicating aberration of the projection optical system 4. . Thereby, as shown in FIG. 5C, the relationship between the X position and the average value of the focus values can be obtained. In Equation 1, the H line elements 2b _H , V line elements 2b _V , S line elements 2b _S and T line elements 2b _{T at the} X position Pn (n=1 to 5) The focus values are denoted by F _nH , F _nV , F _nS , and F _nT , respectively, and their average values are denoted by Fn. In addition, the weights added to the best focus values in each pattern element are shown as w _nH , w _nV , w _nS , and w _nT , respectively. Here, in this embodiment, an example of obtaining a weighted average value of the focus values of each pattern element 2b as the average value of the focus values has been described. The weighted average value is, for example, an error in the direction in which the line of each pattern element 2b extends due to aberration in the measurement device measuring the line width of the pattern element 2b occurs in the measurement result It is preferably used for. Therefore, when the error does not occur, as the average value of the focus values, for example, a simple average value of the focus values of each pattern element 2b may be obtained.

Subsequently, in S12, the image of each pattern 2a of the evaluation mask 2'projected by the projection optical system 4 is detected by the second detection unit 9 (a result of aerial image measurement). Then, the characteristic value (focus value) of the projection optical system 4 is obtained as the second characteristic value. Then, information indicating the aberration of the projection optical system 4 is obtained as second information from the second characteristic value. The process of S12 may be performed automatically by, for example, the exposure apparatus 100 (control unit 7). In addition, the process of S12 may be performed multiple times, and you may obtain a 2nd characteristic value based on the result of averaging the detection results obtained in the process of S12 multiple times. Here, in the flowchart shown in FIG. 2, the process of S12 is performed after the process of S11, but the process of S12 may be performed before the process of S11.

The details of the process in S12 will be described below. Step S12 may include steps S12a to S12c. In S12a, the image of each pattern element 2b of the evaluation mask projected by the projection optical system 4 is changed by the second detection unit 9 while changing the height of the substrate 5 by the substrate stage 6 It detects every position. Then, in S12b, the focus value for each pattern element 2b of the evaluation mask 2'is determined as the second characteristic value for each X position. Thereby, as shown in D of FIG. 5, the relationship between the X position and the focus value can be obtained for each pattern element 2b.

In S12c, the average value of the focus value (second characteristic value) of the plurality of pattern elements 2b obtained in the process of S12b is used as second information indicating the aberration of the projection optical system 4, for example, Equation 1 above. Use to find for each X position. As a result, as shown in Fig. 5E, the relationship between the X position and the average value of the focus values can be obtained. In addition, in S12c, the difference between the average value of the focus value (second characteristic value) and the focus value (second characteristic value) of each pattern element 2b (that is, the characteristic shown in D in Fig. 5 and the E in Fig. 5). The difference in the characteristics shown (hereinafter referred to as a variation value) is also determined for each X position as second information. For example, paying attention to the H line element _(H 2b), it can be determined by the variation value H of the line element _(H 2b) in equation (2). In Equation 2, the focus value of the H line element 2b _{H at the} X position Pn (n=1 to 5) is f _nH , and the average value of the focus values for the plurality of pattern elements 2b is f _n , H The fluctuation values relating to the line elements 2b _H are denoted by fb _nH , respectively. Thereby, as shown in F of FIG. 5, the relationship between the X position and the fluctuation value can be obtained for each pattern element 2b.

Returning to the flowchart of Fig. 2, in S13, for example, the second information obtained in S12 is S11 such that the average value of the second characteristic values in the second information is close to the average value of the first characteristic values in the first information. It is corrected by the first information obtained from. Thereby, information (evaluation information) used to evaluate the aberration of the projection optical system 4 is obtained.

One specific method of correcting the second information is a method of correcting the second information by applying the average value of the first characteristic values in the first information as the average value of the second characteristic values in the second information. That is, this method is a method after correcting the result of adding up the average value in the first information (characteristic shown in C in FIG. 5) and the variation value in the second information (characteristic shown in F in FIG. 5). 2 This is a method that can be obtained as information. For example, paying attention to the H line element 2b _H , the sum of the average value in the first information and the fluctuation value in the second information can be performed by Equation (3). In Equation 3, the result of adding up the average value in the first information about the H line element 2b _H at the X position Pn (n=1 to 5) and the fluctuation value in the second information is F _0nH , The weight in the H line element 2b _H is represented by W _nH , respectively. In this way, evaluation information is shown in FIG. 5G by performing a process of summing the average value in the first information and the fluctuation value in the second information for each pattern element 2b and each X position. Can be obtained as Here, the weight added to the fluctuation value is similar to the reason for using the weighted average described above, in the case where an error occurs in the detection result by the second detector 9 according to the direction in which the line of each pattern element 2b is extended. It is preferred to be used.

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

[Example 2]

In Example 2, a method of evaluating distortion aberration as aberration of the projection optical system 4 in the exposure apparatus 100 will be described. Also in Example 2, as in Example 1, aberration evaluation of the projection optical system 4, calibration of the exposure apparatus 100, and exposure of the substrate 5 can be performed according to the flowchart shown in FIG. . Here, in Example 2, as a characteristic value of the projection optical system 4, the pattern of the mask 2 by the projection optical system 4 in the direction perpendicular to the optical axis 10 of the projection optical system 4 (XY direction) The amount of shift between the projected position and the target position (hereinafter simply referred to as "shift amount") can be used. Further, in Example 2, for example, a plurality of positions (X position P0) in a direction different from the scanning direction in a pattern 2a in which a plurality of cross marks are arranged in the scanning direction of slit light as a plurality of pattern elements 2b. To P30), an evaluation mask 2" for each can be used.

First, in S11, the characteristic value (displacement amount) of the projection optical system 4 is obtained as a first characteristic value based on the transfer result of transferring the pattern of the evaluation mask 2" onto the substrate, and the projection optical system 4 Information indicating aberration of is obtained as first information from the first characteristic value.

In S11a, a plurality of patterns 2a (a plurality of pattern elements) of the evaluation mask 2" is obtained by scanning exposure of the test substrate 5" by the exposure apparatus 100 using the evaluation mask 2". (2b)) is transferred onto the test substrate.

In S11b, the position (XY direction) of each pattern element 2b transferred to the test substrate 5" is measured, for example, by a measuring device external to the exposure apparatus 100. Thereby, for example, As shown in Fig. 6A, a grid-like distribution 61 indicating the position of each pattern element 2b transferred to the test substrate 5" can be obtained. And in S11c, based on the measurement result in S11b (distribution shown in Fig. 6A), the position where each pattern element 2b of the evaluation mask 2" is projected by the projection optical system 4 and The amount of misalignment of the target position (distribution 62 of the target position) is determined. The amount of misalignment is the first direction perpendicular to the optical axis 10 of the projection optical system 4 (X direction in this embodiment), and the projection optical system. It can be obtained for each of the second direction (Y direction in this embodiment) perpendicular to the optical axis of (4) and different from the first direction. In the following, the displacement amount in the first direction (X direction) is Dx, And the amount of displacement in the second direction (Y direction) is represented by Dy, where the target position is XY to which each pattern element 2b of the evaluation mask 2" is to be projected by the projection optical system 4. It is the location of the direction.

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

Subsequently, in S12, the image of each pattern 2b of the evaluation mask 2" projected by the projection optical system 4 is detected by the second detection unit 9 (a result of aerial image measurement). Then, the characteristic value (shift amount) of the projection optical system 4 is obtained as the second characteristic value, and the information indicating the aberration of the projection optical system 4 is obtained as the second information from the second characteristic value.

In S12a, the image of each pattern element 2b is detected by the second detection unit 9 for each of the plurality of detection points in the cross section 1a of the slit light. The plurality of detection points are arranged such that eleven detection points Y0 to Y10 are arranged in the Y direction at each X position P0 to P30, for example, as shown in E of FIG. 6. 6E is a diagram showing a plurality of detection points in the cross section of the slit light. When a plurality of detection points are arranged in this way, for example, the image of the pattern element 2b is moved by moving the evaluation mask 2" in the Y direction by an amount corresponding to the pitch of the detection points in the Y direction. The process of detecting by the second detection unit 9 is repeated, whereby the image of the pattern element 2b can be detected at each of the plurality of detection points, and in S12b, the second detection unit 9 Based on the detection result of, the displacement amounts Dx and Dy are respectively determined for each X position as the second characteristic value, whereby the position X and the displacement amounts Dx and Dy are shown in Figs. ) Can be obtained for each detection point in the Y direction. C in Fig. 6 is a diagram showing the relationship between the X position and the displacement amount Dx, and D in Fig. 6 is the X location and the displacement amount Dy It is a diagram showing the relationship of.

In S12c, the average value of the displacement amount Dx at a plurality of measurement points Y0 to Y10 in the Y direction is determined for each X position as second information indicating aberration of the projection optical system. Thereby, as shown in F of FIG. 6, the relationship between the X position and the average value of the displacement amount Dx can be obtained. Then, the difference between the average value of the amount of displacement Dx (the second characteristic value) and the amount of displacement Dx (the second characteristic value) at each detection point in the Y direction (that is, the characteristic shown in FIG. 6C and FIG. 6) The difference (variation value) of the characteristic shown in F is also obtained for each X position by equation (4) as the second information. In Equation 4, the displacement amount Dx at the X position Pi (i=0 to 30)) and the detection point Yj (j=0 to 10)) is dX _ij , and the average value of the displacement amount Dx at the X position Pi is dX _i and the variation value of the displacement Dx are called dXb _ij . Thereby, as shown in G of FIG. 6, the relationship between the X position and the fluctuation value of the deviation amount Dx can be obtained for each detection point in the Y direction.

Similar to the shift amount Dx, in S12c, the average value of the shift amount Dy at a plurality of detection points Y0 to Y10 in the Y direction is determined for each X position as second information indicating the aberration of the projection optical system. Thereby, as shown in F of FIG. 6, the relationship between the X position and the average value of the deviation amount Dy can be obtained. Then, the difference between the average value of the amount of displacement Dy (the second characteristic value) and the amount of displacement Dy (the second characteristic value) at each detection point in the Y direction (that is, the characteristic shown in D in FIG. 6 and that in FIG. 6) The difference (variation value) of the characteristic shown in F is also obtained for each X position by equation (5) as the second information. In Equation 5, the displacement amount Dy at the X position Pi (i=0 to 30)) and the detection point Yj (j=0 to 10)) is dY _ij , and the average value of the displacement amount Dy at the X position Pi is dY _i and the variation value of the shift amount Dy are called dYb _ij . Thereby, as shown in H of FIG. 6, the relationship between the X position and the fluctuation value of the shift amount Dy can be obtained for each detection point in the Y direction.

Returning to the flowchart of Fig. 2, in S13, information for evaluation is obtained by correcting the second information obtained in S12 by the first information obtained in S11. For example, the average value of the deviation amount Dx in the first information (the characteristic shown in B in FIG. 6) and the variation value of the deviation amount Dx in the second information (the characteristic shown in G in FIG. 6) are added up. By doing so, it is possible to obtain information for evaluation in the X direction. The sum of the average value of the deviation amount Dx in the first information and the variation value of the deviation amount Dx in the second information can be performed by Equation (6). In Equation (6), the average value of the displacement amount Dx in the first information at the X position Pi (i=0 to 30) is DX _i , the average value of the displacement amount Dx in the first information and the second information The result of summing the fluctuation values of the deviation amount Dy of is called DX0 _ij . Fig. 6 shows information for evaluation in the X direction by performing a process of summing the average value of the deviation amount Dx in the first information and the variation value of the deviation amount Dx in the second information for each X position. It can be obtained as shown in I. Here, the weight Wx _ij added to the fluctuation value may be used when an error occurs in the detection result by the second detection unit 9 according to the X position Pi and the position of the detection point Yj.

Similarly, by summing the average value of the displacement amount Dy in the first information (the characteristic shown in B in FIG. 6) and the variation value of the displacement amount Dy in the second information (the characteristic shown in H in FIG. 6), Information for evaluation in the Y direction can be obtained. The sum of the average value of the deviation amount Dy in the first information and the variation value of the deviation amount Dy in the second information can be performed by Equation (7). In equation (7), the average value of the displacement amount Dy in the first information at the X position Pi (i=0 to 30) is DY _i , the average value of the displacement amount Dy in the first information and the second information The result of summing the variation values of the deviation amount Dy of is DY _0ij . Fig. 6 shows information for evaluating the Y direction by performing a process of summing the average value of the amount of displacement Dy in the first information and the variation value of the amount of displacement Dy in the second information for each X position. It can be obtained as shown in J. Here, the weight Wy _ij added to the fluctuation value may be used when an error occurs in the detection result by the second detection unit according to the X position Pi and the position of the detection point Yj.

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

<Second Embodiment>

In the exposure apparatus 100, for example, the shape of an effective light source such as conventional, leased, dipole, or illumination conditions such as NA, leap contrast, and transmittance of the illumination optical system 1 may be changed. However, whenever the lighting conditions are changed, it is necessary to transfer the pattern of the evaluation mask to the test substrate in the lighting conditions after the change, and to obtain the characteristic values of the projection optical system 4 based on the transfer result, corresponding effort and time are required. Can take. Therefore, after changing the lighting condition, it is preferable to evaluate the aberration of the projection optical system 4 in the lighting condition after the change, without performing each step of S11 in the flowchart shown in FIG. 2. Therefore, in the present embodiment, the projection optical system in the lighting condition after the change is performed only by newly performing the respective steps in S12 without performing the respective steps of S11 in the flowchart shown in FIG. 2 in the lighting conditions after the change. Is evaluated. The method for evaluating the aberration of the projection optical system 4 in the present embodiment will be described below with reference to FIG. 7. 7 is a flowchart showing an aberration evaluation method and an exposure method of the projection optical system 4 under each of two different lighting conditions.

In S21, the lighting conditions of the exposure apparatus 100 are set as the first lighting conditions. The first lighting condition corresponds to the lighting condition before changing the lighting condition of the exposure apparatus 100. In S22, the average value (first information) of the first characteristic value is obtained by performing each step of S11 in the flowchart shown in FIG. 2. Hereinafter, the average value of the first characteristic values obtained in S22 is referred to as "average value A1". In S23, the average value of the second characteristic value and the variation value (second information) of the second characteristic value are obtained by performing each step of S12 in the flowchart shown in FIG. Hereinafter, the average value of the second characteristic value obtained in S23 is referred to as "average value A2", and the variation value of the second characteristic value obtained in S23 is referred to as "variation value A2". In addition, in the flowchart shown in FIG. 7, although the process of S23 is performed after the process of S22, you may perform before the process of S22.

In S24, the aberration of the projection optical system 4 is evaluated based on the result of correcting the second information obtained in S23 with the first information obtained in S22, and the exposure apparatus 100 is corrected based on the evaluation result. The process of S24 corresponds to each process of S13 to S15 of the flowchart shown in FIG. In S25, the substrate 5 is exposed under the first lighting condition using the mask 2 having the circuit pattern transferred to the substrate 5 to be formed. The process of S25 corresponds to the process of S16 in the flow chart shown in FIG. 2, and can be repeated a plurality of times depending on the number of substrates 5 to form a circuit.

In S26, the lighting conditions of the exposure apparatus 100 are changed from the first lighting conditions to the second lighting conditions. In S27, the second characteristic value of the average value of the second characteristic value and the second characteristic value of the fluctuation value (third information) of the second characteristic value is newly obtained by performing each step of S12 in the flowchart shown in FIG. 2. Hereinafter, the average value of the second characteristic obtained in S27 is referred to as "average value B", and the variation value of the second characteristic obtained in S27 is referred to as "variation 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 (average value A1) obtained under the lighting conditions before the change is corrected. 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, the aberration of the projection optical system under the changed lighting condition (second lighting condition) is evaluated based on the result of correcting the third information obtained in S27 by the first information corrected in S28, and based on the evaluation result To calibrate the exposure apparatus 100. The process of S29 corresponds to each process of S13 to S15 of the flowchart shown in FIG. In S30, the substrate 5 is exposed under the second lighting condition using the mask 2 having the circuit pattern transferred to the substrate 5 to be formed. The process of S30 corresponds to the process of S16 in the flow chart shown in FIG. 2, and can be repeated a plurality of times depending on the number of substrates 5 to form a circuit. In this way, in the second embodiment, the process of transferring the pattern of the evaluation mask to the test substrate under the changed lighting conditions (S11 in the flowchart of Fig. 2) is not performed, and the projection optical system under the changed lighting conditions (4) ) Can be easily evaluated.

<Embodiment of the manufacturing method of the article>

The method for manufacturing an article according to the embodiment of the present invention is suitable for manufacturing an article such as a micro device such as a semiconductor device or an element having a fine structure. The article manufacturing method of the present embodiment includes a step of forming a latent image pattern using the exposure method on a photosensitive agent applied to the substrate (step of exposing the substrate), and a step of developing the substrate on which the latent image pattern is formed in such a step. do. In addition, these manufacturing methods include other well-known processes (oxidation, film formation, deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The article manufacturing method of the present embodiment is advantageous in at least one of performance, quality, productivity, and production cost of the article, compared to the conventional method.

<Other embodiments>

Embodiment(s) of the present invention are recorded on a storage medium (sometimes referred to as a more completely'non-transitory computer-readable storage medium') to perform one or more functions of the above embodiment(s). One or more circuits (eg, application specific integrated circuits (ASICs)) for reading and executing computer executable instructions (eg, one or more programs) and/or executing one or more functions of the embodiment(s) above Reading and executing computer-executable instructions from a storage medium by a computer of a system or device comprising and for example to execute one or more functions of the embodiment(s) and/or the embodiment(s) ) May be realized by a method executed by a computer of the system or apparatus by controlling one or more circuits to execute one or more functions. The computer may include one or more processors (eg, central processing unit (CPU), micro processing unit (MPU)) and a separate computer or network of separate processors to read and execute computer-executable instructions. can do. Computer-executable instructions may be provided to a computer, for example, from a network or storage medium. Storage media include, for example, hard disks, random-access memory (RAM), read-only memory (ROM), storage in distributed computing systems, optical disks (eg, compact disks (CD), digital versatile disks (DVD)) , Or Blu-ray Disc (BD) ^TM , a flash memory device, a memory card, or the like.

(Other examples)

The present invention provides a program for realizing one or more functions of the above-described embodiments to a system or device via a network or storage medium, and one or more processors read and execute the program in the computer of the system or device. It is also possible to realize the processing. In addition, it can be implemented by a circuit (eg, ASIC) that realizes one or more functions.

Although preferred embodiments of the present invention have been described above, the present invention is of course not limited to these embodiments, and various modifications and changes can be made within the scope of the gist.

Claims (16)

It is an evaluation method for evaluating the aberration of the projection optical system in the exposure apparatus,
A transfer step of transferring a plurality of pattern elements of the mask to the substrate by the projection optical system of the exposure apparatus,
For each of the plurality of pattern elements, the projection position of the projection optical system obtained from the transfer result in the transfer step is obtained as a first value, and the average value of the first values in the plurality of pattern elements is first information. The first process to obtain as
A detection step of detecting an image of the plurality of pattern elements projected by the projection optical system;
For each of the plurality of pattern elements, the projection position of the projection optical system obtained from the detection result in the detection step is determined as a second value, and the average value of the second values in the plurality of pattern elements and the plurality of A second step of obtaining a difference from said second value for each of said pattern elements as second information,
And an evaluation step of evaluating the aberration of the projection optical system based on the evaluation information obtained from the first information and the second information. According to claim 1,
In the evaluation step, the evaluation information is obtained by summing the difference between the average value of the first value as the first information and the difference as the second information. According to claim 2,
In the evaluation step, the evaluation information is obtained by summing the average value of the first value as the first information and the difference as the weighted second information for each pattern element. According to claim 1,
In the detection step, an evaluation method characterized by detecting an image of the plurality of pattern elements projected by the projection optical system using a sensor that receives light from the projection optical system. According to claim 1,
The plurality of pattern elements, each of the line extending direction, characterized in that each comprises a plurality of line elements, evaluation method. The method of claim 5,
The plurality of line elements are characterized in that the direction in which the lines extend is different from each other by 45 degrees. The method of claim 5,
In the first step, weighting the first value of each pattern element according to a direction in which the line extends and obtaining an average value of the first value weighted with respect to the plurality of pattern elements as the first information Characterized, evaluation method. According to claim 1,
The projection position of the projection optical system, respectively obtained as the first value and the second value, includes a focus value of the projection optical system,
In the evaluation step, at least one of image curvature and astigmatism of the projection optical system is evaluated. According to claim 1,
The projection position of the projection optical system obtained as the first value and the second value, respectively, is a position and a target position where each of the plurality of pattern elements is imaged by the projection optical system in a direction perpendicular to the optical axis of the projection optical system. Including the amount of misalignment of
In the evaluation step, an evaluation method characterized in that distortion aberration of the projection optical system is evaluated. The method of claim 9,
The projection position of the projection optical system obtained as the first value and the second value, respectively, is the amount of displacement in the first direction perpendicular to the optical axis, and a second direction perpendicular to the optical axis and different from the first direction. The evaluation method characterized by including the said amount of shift in said. According to claim 1,
The transfer method is characterized in that it is performed only once, the evaluation method. The method of claim 11,
The detection process is performed multiple times,
In said 2nd process, the said 2nd information is calculated|required based on the result which averaged the multiple detection result obtained by the said detection process multiple times. According to claim 1,
When the lighting conditions of the exposure device is changed,
A step of newly obtaining the second information in the lighting condition after the change by newly performing the detection step and the second step in the lighting condition after the change,
A step of correcting the evaluation information based on a difference between the second information obtained in the lighting condition before the change and the second information obtained in the lighting condition after the change,
The evaluation method characterized by performing the process of evaluating the aberration of the said projection optical system in the lighting condition after change based on the said correction information for correction. It is an exposure method to expose a substrate,
A process of evaluating the aberration of the projection optical system using the evaluation method according to any one of claims 1 to 13,
A step of correcting the exposure apparatus based on the evaluation result of aberration of the projection optical system,
And exposing the substrate using the calibrated exposure apparatus. A step of exposing the substrate using the exposure method according to claim 14,
And a step of developing the substrate subjected to exposure in the step,
A method for manufacturing an article, characterized in that the article is obtained from a developed substrate. It is an evaluation method for evaluating the aberration of the projection optical system in the exposure apparatus,
For each of the plurality of pattern elements of the mask, the projection position of the projection optical system obtained from the transfer result of transferring the plurality of pattern elements to the substrate by the projection optical system of the exposure apparatus is determined as a first value, and the plurality of pattern elements are obtained. A first step of obtaining an average value of the first values in the pattern elements as first information;
For each of the plurality of pattern elements, a projection position of the projection optical system obtained from a detection result of detecting an image of the plurality of pattern elements projected by the projection optical system is obtained as a second value, and the plurality of pattern elements are A second step of obtaining, as second information, a difference between the average value of the second values and the average value of the second value and the second value of each of the plurality of pattern elements,
And an evaluation step of evaluating the aberration of the projection optical system based on the evaluation information obtained from the first information and the second information.

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