JP2018031980A - Measurement method, measurement device, exposure equipment and production method of article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measurement method of a distortion of image.SOLUTION: A method of measuring a distortion of an image imaged on a substrate via an optical system includes: a first step of transferring a first mark group containing a plurality of first marks arranged with a constant pitch in a first direction and an orthogonal second direction provided on an article surface of the optical system while shifting the substrate in the first direction and the second direction such that the plurality of first marks are transferred by a second transcription between marks of the plurality of first marks transferred on the substrate by the first transcription; a second step of transferring on the substrate while shifting the substrate in the first and second directions such that the second mark group containing a plurality of second marks arranged with a pitch smaller than a pitch of the first mark in the first and second directions provided on the article surface may form a pair with each of the plurality of first marks; and a third step of obtaining the distortion on the basis of a displacement amount with the first marks and second marks transferred on the substrate.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a measuring method, a measuring apparatus, an exposure apparatus, and an article manufacturing method for measuring distortion.

  A technique using a box-in-box pattern has been proposed as a measuring method for measuring distortion of a projection optical system of an exposure apparatus (a distortion component generated when a mask pattern image is projected (transferred) onto a substrate). (See Patent Document 1).

  In the prior art, for example, first, a plurality of first marks (large square marks) distributed over the entire surface in a shot area are collectively transferred to a substrate. Next, while moving the stage holding the substrate step by step so that the second mark (small square mark) is superimposed on each of the plurality of first marks projected on the substrate, the second marks are moved to the substrate one by one. Transcript to. Then, the shift amount between the first mark and the second mark projected on the substrate is measured, and the distortion is obtained based on the shift amount.

Japanese Examined Patent Publication No. 63-038697

  However, in the prior art, an error in the step movement of the stage when the second mark is transferred to the substrate affects the distortion measurement result. If the stage movement error of the stage fluctuates irregularly, it is possible to achieve high accuracy by obtaining an average value from a plurality of measurements. However, since the time required for multiple measurements becomes long, the measurement cost increases. Further, when the error of the stage step movement is a regular error, high accuracy cannot be expected by multiple measurements.

  The present invention has been made in view of such a problem of the prior art, and an object of the present invention is to provide a measurement method that is advantageous for measuring distortion.

  In order to achieve the above object, a measurement method according to one aspect of the present invention is a measurement method for measuring a distortion indicating distortion of an image projected on a substrate via an optical system, the object of the optical system being A first mark group including a plurality of first marks arranged at a constant pitch in a first direction and a second direction orthogonal to the first direction arranged on a surface is a first transfer of the first mark group. The plurality of first marks are transferred between the marks of the plurality of first marks transferred to the substrate by the second transfer of the first mark group following the first transfer. A first step of transferring to the substrate while shifting in the first direction and the second direction, and a pitch smaller than the pitch of the first marks in the first direction and the second direction disposed on the object plane Multiple second arranged in pitch A second mark group including a mark is paired with each of the plurality of first marks transferred to the substrate in the first step, each of the plurality of second marks transferred to the substrate. , Based on the second step of transferring the substrate to the substrate while shifting the substrate in the first direction and the second direction, and the shift amount between the first mark and the second mark transferred to the substrate. And a third step for obtaining distortion.

  Further objects and other aspects of the present invention will become apparent from the preferred embodiments described below with reference to the accompanying drawings.

  According to the present invention, for example, it is possible to provide a measurement method that is advantageous for measuring distortion.

It is the schematic which shows the structure of the exposure apparatus as 1 side surface of this invention. It is a figure which shows the structure of the mask used for the measurement process which measures distortion. It is a flowchart for demonstrating the measurement process which measures distortion. It is a figure for demonstrating the measurement process which measures distortion. It is a figure for demonstrating the principle of the measurement process which measures distortion. It is a figure for demonstrating the principle of the measurement process which measures distortion. It is a figure which shows the structure of the mask used for the measurement process which measures distortion. It is a figure for demonstrating the measurement process which measures distortion. It is a figure for demonstrating the typical measurement process which measures distortion. It is a figure for demonstrating a Box-in-Box pattern.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings. In addition, in each figure, the same reference number is attached | subjected about the same member and the overlapping description is abbreviate | omitted.

  First, a typical measurement process for measuring distortion indicating distortion of an image held on a stage and projected onto a substrate via an optical system such as a projection optical system will be described. In such a measurement process, for example, a mask 480 having a Box-in-Box pattern as shown in FIG. 9A is disposed on the object plane of the optical system. The mask 480 includes the first mark 10 and the second mark 11. The first marks 10 are arranged at a plurality of locations where distortion is to be measured on the mask surface. The second mark 11 is arranged at one location near the center on the mask surface.

  Next, as illustrated in FIG. 9B, the substrate 490 is exposed through a mask 480 and an optical system, and the first mark 10 is transferred to the substrate 490. At this time, the substrate 490 may be exposed while shielding the second mark 11 with a light shielding plate or the like so that only the first mark 10 is transferred to the substrate 490. Next, as shown in FIG. 9C, the substrate 490 is exposed through the mask 480 and the optical system, and the second mark 11 is transferred to the substrate 490. At this time, the second mark 11 is transferred to the substrate 490 while stepping the stage holding the substrate 490 so that the second mark 11 is superimposed on each of the first marks 10 transferred to the substrate 490. . Then, as shown in FIG. 9D, the amount of deviation between the first mark 10 and the second mark 11 transferred to the substrate 490 is measured, and the distortion is obtained based on the amount of deviation.

  In FIGS. 9A to 9D, the Box-in-Box pattern is shown in a simplified manner. Actually, each of the first mark 10 and the second mark 11 is shown in FIG. And it has a structure as shown in FIG.10 (b). In FIG. 10A and FIG. 10B, the shaded portion indicates the light shielding portion, and the white portion indicates the transmission portion. When the first mark 10 shown in FIG. 10A and the second mark 11 shown in FIG. 10B are superimposed and transferred to the substrate 490, an overlay mark as shown in FIG. 10C is formed. . In such an overlay mark, distortion can be obtained by measuring the shift amount between the first mark 10 and the second mark 11. However, in such a measurement method, for example, an error in the step movement of the stage when the second mark 11 is transferred to the substrate 490 affects the distortion measurement result. Therefore, in the present embodiment, the measurement method advantageous for measuring the distortion with high accuracy is realized by reducing the influence of the error of the step movement of the stage.

  In this embodiment, an exposure apparatus having a projection optical system that is a distortion measurement target will be described. FIG. 1 is a schematic diagram showing a configuration of an exposure apparatus 40 as one aspect of the present invention. The exposure apparatus 40 is a lithography apparatus that exposes a substrate via a projection optical system. The exposure apparatus 40 includes an illumination optical system 42, a mask stage 43, a light shielding plate 44, a projection optical system 45, a substrate stage 46, a measurement unit 47, and a control unit 50.

  The illumination optical system 42 is an optical system that illuminates the mask MS for device manufacture or the mask 48 for distortion measurement with light from the light source 41. The mask stage 43 is a stage that holds the mask MS and the mask 48. The mask MS has a pattern corresponding to a circuit pattern necessary for manufacturing a device, and the mask 48 forms a Box-in-Box pattern necessary for measuring distortion, as will be described later. Have a mark for. In the present embodiment, the mask stage 43 holds the mask MS and the mask 48 in an exchangeable manner, as shown in FIG.

  The light shielding plate 44 realizes a function of limiting light from the illumination optical system 42 so that a predetermined region (mark) in the mask 48 is taken as one shot. The light shielding plate 44 includes a plurality of light shielding plates that are movable independently of each other. In the present embodiment, the light shielding plate 44 is provided on the mask stage 43, but may be provided inside the illumination optical system 42.

  The projection optical system 45 is an optical system that projects the pattern image of the mask MS illuminated by the illumination optical system 42 or the image of the mark of the mask 48 illuminated by the illumination optical system 42 onto the substrate 49. The substrate stage 46 is a stage that holds and moves the substrate 49. In the present embodiment, the substrate for device manufacture to which the pattern of the mask MS is transferred and the substrate for distortion measurement to which the mark of the mask 48 is transferred are referred to as the substrate 49 without distinction.

  The measurement unit 47 includes, for example, a microscope and detects various marks (for example, alignment marks and overlay marks) formed on the substrate 49. In this embodiment, the measurement unit 47 is an overlay mark formed by exposing the substrate 49 through the mask 48, that is, an overlay mark composed of a pair of a first mark and a second mark described later. Is detected, and the amount of deviation between the first mark and the second mark is measured.

  The control unit 50 includes a CPU 51, a memory 52, and the like, and controls the entire exposure apparatus 40. The CPU 51 executes the distortion measurement processing program 52a stored in the memory 52, thereby controlling the substrate stage 46 and the measurement unit 47 to perform measurement processing for measuring the distortion of the projection optical system 45 (function as a processing unit). To do). Further, the CPU 51 calculates a correction value 52b for exposure control for controlling the exposure process for exposing the substrate 49 so as to reduce (correct) the distortion obtained by the measurement process, and stores it in the memory 52. The memory 52 also stores a job 52c including various parameters in measurement processing and exposure processing.

With reference to FIG. 2, the mask 48 used for the measurement process which measures a distortion is demonstrated in detail. The mask 48 has a first mark group including first marks (large square marks) 20 arranged at a constant pitch in the X direction (first direction) and the Y direction (second direction orthogonal to the first direction). . In the present embodiment, the first mark group is m ₁ row n ₁ column (m ₁ , n ₁ ) arranged with a pitch (first pitch) Px1 in the X direction and a pitch (second pitch) Py1 in the Y direction. A plurality of first marks 20). The row position represents the position in the Y direction, and the column position represents the position in the X direction. Further, the mask 48 has a second mark group including second marks (small square marks) 21 arranged in a pitch smaller than the pitch of the first marks 20 in the X direction and the Y direction. In the present embodiment, the second mark group is a pitch (third pitch) Px2 obtained by dividing the pitch Px1 in the X direction by n ₂ (an integer of 2 or more), and the pitch Py1 in the Y direction is m ₂ (an integer of 2 or more). ), A plurality of second marks 21 arranged at a pitch (fourth pitch) Py2. When m ₂ and n ₂ are 2 as in the present embodiment, three or more second marks 21 need to be arranged in the X direction and the Y direction (that is, 3 rows and 3 columns or more). . In other words, the second mark group includes the second marks 21 of m ₂ +1 rows n ₂ +1 columns. In the present embodiment, m ₁ and n ₁ are assumed to be 3, m ₂ and n ₂ are assumed to be 2, and the arrangement of the second marks 21 is assumed to be 3 rows and 3 columns. Further, the mask 48 includes light shielding portions 22 arranged from each of the first marks 20 at a pitch Px2 along the X direction and from each of the first marks 20 at a pitch Py2 along the Y direction. In the region on the mask where the first mark 20, the second mark 21, and the light shielding part 22 are not formed, other marks may be formed, or a light shielding part.

  In the present embodiment, the mask 48 in which both the first mark 20 and the second mark 21 are formed is used, but the mask in which the first mark 20 is formed and the mask in which the second mark 21 is formed. It may be used. In the present embodiment, a box-in-box pattern is described as an example of the overlay mark obtained from the first mark 20 and the second mark 21, but a bar-in-bar pattern may be used. Good.

  With reference to FIG.3 and FIG.4 (a) thru | or FIG.4 (d), the measurement process which measures the distortion in this embodiment is demonstrated. In S <b> 101, the mask 48 and the substrate 49 coated with the resist are carried into the exposure apparatus 40, the mask 48 is held on the mask stage 43, and the substrate 49 is held on the substrate stage 46.

In S < _b > 102, the first mark group (image) in 2 rows and 2 columns (m ₂ rows and n ₂ columns) is transferred to the substrate 49. Here, “row” in the first mark group represents the number of the first mark group (a plurality of first marks 20 in 3 rows and 3 columns in this embodiment) transferred along the Y direction. The “column” in the group represents the number of transfer of the first mark group along the X direction. Specifically, as shown in FIG. 4A, first, a plurality of first marks 20 in 3 rows and 3 columns (m ₁ row and n ₁ column) are set as one shot (that is, 3 rows and 3 columns). The light shielding plate 44 is moved so that the first marks 20 in (m ₁ row n ₁ column) are exposed. Next, as shown in FIG. 4B, the substrate 49 is shifted in the X direction and the Y direction by the substrate stage 46 (that is, while the substrate stage 46 is moved stepwise), the first mark 20 of 3 rows and 3 columns. The image is transferred to the substrate 49. Referring to FIG. 4B, in the present embodiment, for example, first, an image of the first mark 20 in 3 rows and 3 columns is transferred to the upper left of the substrate 49. Next, the substrate stage 46 (substrate 49) is moved stepwise in the + X direction by a pitch Px2, and the image of the first mark 20 in 3 rows and 3 columns is transferred to the upper right of the substrate 49. Next, the substrate stage 46 is stepped in the + Y direction by a pitch Py2, and the image of the first mark 20 in 3 rows and 3 columns is transferred to the lower right of the substrate 49. Then, the substrate stage 46 is stepped in the −X direction by a pitch Px2, and the image of the first mark 20 in 3 rows and 3 columns is transferred to the lower left of the substrate 49. In other words, the first mark 20 is transferred by the second transfer of the first mark group following the first transfer between the marks of the first mark 20 transferred to the substrate 49 by the first transfer of the first mark group. Thus, the step movement of the substrate stage 46 is controlled.

In S <b> 103, the second mark group (image thereof) in 2 rows and 2 columns is transferred to the substrate 49. Here, “row” in the second mark group represents the number of transfer of the second mark group (a plurality of second marks 21 in 3 rows and 3 columns in this embodiment) along the Y direction. The “column” in the group represents the number of transfer of the second mark group along the X direction. Specifically, first, as shown in FIG. 4C, the second mark 21 of 3 rows and 3 columns (m ₂ +1 row n ₂ +1 column) is set to one shot (that is, 3 rows and 3 columns). The light shielding plate 44 is moved so that the second mark 21 is exposed). Next, as shown in FIG. 4D, the substrate 49 is shifted in the X direction and the Y direction by the substrate stage 46 (that is, while the substrate stage 46 is moved stepwise), the second mark 21 in 3 rows and 3 columns. The image is transferred to the substrate 49. Referring to FIG. 4D, in this embodiment, for example, first, the image of the second mark 21 in 3 rows and 3 columns is superposed on the first mark 20 transferred to the substrate 49. Transcript to the upper left. Next, the substrate stage 46 (substrate 49) is stepped in the + X direction by a pitch Px2 × 3 so that the image of the second mark 21 in 3 rows and 3 columns is superposed on the first mark 20 transferred to the substrate 49. Then, the image is transferred to the upper right of the substrate 49. Next, the substrate stage 46 is moved stepwise in the + Y direction by a pitch Py2 × 3 so that the image of the second mark 21 in 3 rows and 3 columns overlaps the first mark 20 transferred to the substrate 49. Transfer to the lower right of 49. Then, the substrate stage 46 is moved stepwise in the −X direction by a pitch Px2 × 3 so that the image of the second mark 21 in 3 rows and 3 columns overlaps the first mark 20 transferred to the substrate 49. Transfer to the lower left of 49. As described above, the minimum necessary range in which the substrate stage 46 is moved stepwise is Px2 × 3 in the X direction and Py2 × 3 in the Y direction in this embodiment, but the arrangement of the second marks 21 and the light shielding plate 44 Varies depending on the arrangement.

  In S102 and S103, the image of the first mark group and the image of the second mark group are transferred to the substrate 49 by the exposure process, but no development process is interposed therebetween. In this embodiment, the image of the second mark group is transferred after the image of the first mark group is transferred. However, the image of the first mark group is transferred after the image of the second mark group is transferred. Also good. In other words, it is arbitrary which of S102 and S103 is performed first.

  In S104, development processing for developing the substrate 49 subjected to the exposure processing in S102 and S103 is performed. As a result, 36 superposition marks 32 composed of pairs of the first marks 20 transferred in S102 and the second marks 21 transferred in S103 are formed on the substrate 49.

  In S105, the shift amount between the first mark 20 and the second mark 21 is measured for each of the overlay marks 32 formed on the substrate 49 through the development processing in S104. In the present embodiment, the amount of deviation between the first mark 20 and the second mark 21 is measured by the measurement unit 47 of the exposure apparatus 40, but the amount of deviation between the first mark 20 and the second mark 21 is measured by an external measuring instrument. May be measured.

  In S106, distortion is obtained based on the amount of deviation between the first mark 20 and the second mark 21 measured in S105. In the present embodiment, by substituting the deviation amount between the first mark 20 and the second mark 21 measured in S105 into the equations shown in the following equations (1) to (14), the equation is solved. Ask for distortion. These calculations are performed by the control unit 50 (CPU 51) that also functions as a calculation unit.

Here, the symbols in the equations (1) to (14) are as follows.
δx (n), δy (n): measured value of the nth overlay mark (shift amount between the first mark 20 and the second mark 21)
dx1 (i), dy1 (i): distortion (distortion amount) corresponding to the in-shot coordinates of the i-th first mark
dx2 (j), dy2 (j): position error ex1 (k), ey1 (k), θ1 (k) in the mask manufacturing of the j-th second mark: array error ex2 of the k-th shot of the first mark (L), ey2 (l), θ2 (l): arrangement error X1 (i) of the l-th shot of the second mark, Y1 (i): in-shot coordinates X2 (j) of the i-th first mark, Y2 (j): In-shot coordinates εx (n), εy (n): quantization error SX (l) due to rounding, SY (l): Shot position coordinates p of the second mark p: Mask Number of second marks arranged in q: Number of shots of second mark transferred to substrate (number of second mark groups)
By solving equations (1) to (14), not only the distortions dx1 and dy1, but also the shot arrangement errors ex1, ey1, ex2, and ey2 and the mask manufacturing position errors dx2 and dy2 can be obtained. it can. Therefore, in the present embodiment, the distortion obtained in S106 does not include shot arrangement errors.

  In S107, a correction value 52b for reducing (correcting) the distortion obtained in S106 is calculated and stored in the memory 52. The correction value 52b stored in the memory 52 is used for an exposure process when manufacturing a device or used for adjusting the projection optical system 45.

In the present embodiment, m ₁ and n ₁ have been described as 3, but they may not be the same number, or may be 3 or more. Also, have been described m ₂ and n ₂ as 2, for example, may be used as the 3, it may be a different number each.

  Here, with reference to FIG. 5A to FIG. 5U, the principle of measurement processing for measuring distortion in the present embodiment will be described. First, with reference to FIGS. 5A to 5G, problems in typical measurement processes as shown in FIGS. 9A to 9D will be described.

  FIG. 5A shows an image of the first mark 10 of the mask 480 transferred to the substrate without distortion. FIG. 5B shows an image of the second mark 11 of the mask 480 transferred to the substrate without any error in the step movement of the stage holding the substrate. As described above, the substrate is exposed while stepping the stage holding the substrate so that the image of the second mark 11 is transferred to each of the positions P1, P2, and P3 on the substrate. When the image of the first mark 10 shown in FIG. 5A and the image of the second mark 11 shown in FIG. 5B are superimposed, that is, there is no distortion and there is no error in the step movement of the stage. Then, an overlay mark as shown in FIG. 5C is obtained.

  FIG. 5D shows a state in which the image of the first mark 10 to be transferred to the position P3 on the substrate is shifted and transferred due to distortion. In such a case, when there is no error in the step movement of the stage (that is, when the image of the first mark 10 shown in FIG. 5D and the image of the second mark 11 shown in FIG. 5B are superimposed) ), An overlay mark as shown in FIG. Therefore, the distortion can be obtained by measuring the shift amount between the image of the first mark 10 and the image of the second mark 11 in the overlay mark formed at the position P3 on the substrate.

  Further, in the state where there is no distortion as shown in FIG. 5A, a stage step error occurs when the image of the second mark 11 is transferred to the position P3 on the substrate as shown in FIG. 5F. In such a case, an overlay mark as shown in FIG. However, the overlay mark shown in FIG. 5G is the same as the overlay mark shown in FIG. Therefore, in a typical measurement process as shown in FIGS. 9A to 9D, when there is an error in the step movement of the stage, such an error (effect) cannot be separated from the distortion. .

  Next, a measurement process according to this embodiment will be described with reference to FIGS. 5 (h) to 5 (u). FIG. 5H shows an image of the first mark 20 (first mark group) of the mask 48 transferred to the substrate without distortion. FIG. 5I shows the first mark 20 (first mark group) by shifting the substrate by a distance half the pitch of the first mark 20 from the state shown in FIG. ) Image is transferred to the substrate. As shown in FIG. 5I, a new image of the first mark 20 is transferred to positions P1 ', P2', and P3 'on the substrate.

  FIG. 5J shows an image of the second mark 21 (second mark group) of the mask 48 transferred to the substrate without distortion. Since the second mark group includes three second marks 21 arranged at half the pitch of the first mark 20, as shown in FIG. 5 (j), positions P1, P1 ′ on the substrate. And the image of the first mark 21 is transferred to P2 at a time. FIG. 5 (k) shows a state in which the image of the second mark 21 is transferred to the positions P2 ', P3 and P3' on the substrate at a time without any error in the step movement of the substrate stage 46.

  When the image of the first mark 20 shown in FIG. 5 (i) and the image of the second mark 21 shown in FIG. 5 (k) are superposed, that is, there is no distortion and the error of the step movement of the substrate stage 46 is caused. In the absence, an overlay mark as shown in FIG. 5 (l) is obtained.

  FIG. 5M shows, for example, an image of the first mark 20 transferred to the substrate in the present embodiment in a state where distortion as shown in FIG. 5D occurs and there is no step error of the substrate stage 46. An image of the second mark 21 is shown. As shown in FIG. 5 (m), the image of the first mark 10 to be transferred to the positions P3 and P3 'on the substrate is transferred while being shifted by distortion.

  FIG. 5 (n) shows a state where there is no distortion and there is an error in the step movement of the substrate stage 46 from the positions P1, P1 ′ and P2 on the substrate to the positions P2 ′, P3 and P3 ′. The image of the 1st mark 20 and the image of the 2nd mark 21 which are transcribed in FIG.

  5 (m) and FIG. 5 (n), the image of the first mark 20 and the image of the second mark 21 (overlapping mark) transferred to the substrate are naturally different. is there. Specifically, in FIG. 5 (m), the overlay marks formed at positions P3 and P3 ′ on the substrate are displaced, but in FIG. 5 (n), the positions P2 ′, P3 and P3 on the substrate. There is a shift in the overlay mark formed on '. As described above, according to the measurement process in this embodiment, unlike the above-described typical measurement process, it is possible to separate the error of the step movement of the substrate stage 46 from the distortion.

  Further, in the measurement processing in the present embodiment, even if there is an error in the step movement of the substrate stage 46 when the first mark 20 is transferred, the error and the distortion can be separated. FIG. 5 (o) shows an image of the first mark 20 and the second mark 21 transferred to the substrate in the present embodiment when there is an error in the step movement of the substrate stage 46 when the first mark 20 is transferred. The image is shown. Here, it is assumed that there is an error in the step movement of the substrate stage 46 from the positions P1, P2 and P3 on the substrate to the positions P1'P2 'and P3'. Referring to FIG. 5 (o), the image of the first mark 20 and the image of the second mark 21 (overlapping mark) transferred to the substrate are different from those in FIG. 5 (m) and FIG. 5 (n). Accordingly, it is possible to separate the error of the step movement of the substrate stage 46 from the distortion.

  In the measurement processing according to the present embodiment, even if the image of the second mark 21 is transferred by being displaced due to distortion, the error of step movement of the substrate stage 46 and the distortion can be separated. FIG. 5 (p) shows a state in which the image of the second mark 21 to be transferred to the positions P1 'and P3 on the substrate is shifted and transferred due to distortion. In such a case, in the present embodiment, the image of the first mark 20 and the image of the second mark 21 as shown in FIG. 5 (q) are transferred to the substrate. Referring to FIG. 5 (q), the image of the first mark 20 and the image of the second mark 21 (overlapping mark) transferred to the substrate are shown in FIG. 5 (m), FIG. 5 (n) and FIG. It is also different from o). Therefore, the distortion in each of the transfer of the first mark 20 and the transfer of the second mark 21 and the error of the step movement of the substrate stage 46 in the transfer of the first mark 20 and the transfer of the second mark 21 respectively. Can be separated.

  However, in this embodiment, it is a condition that the error of the step movement of the substrate stage 46 does not include the magnification component and the orthogonality error. For example, if a magnification component is included in the step movement error, the amount of deviation between the image of the first mark 20 and the image of the second mark 21 is measured in the same manner as when there is a magnification due to distortion. Can not be separated. The condition in which the magnification component and the orthogonality error are not included in the error of the step movement of the substrate stage 46 (each is zero) is expressed by the above-described equations (8) to (11).

  For example, when the first mark 20 is transferred, a distortion as shown in FIG. 6A is generated, and further, an error of the step movement of the substrate stage 46 is generated. As shown in FIG. Consider a case where the image of the mark 20 and the image of the second mark 21 are transferred to the substrate. Further, when the second mark 21 is transferred, a distortion as shown in FIG. 6C is generated, and further, an error of the step movement of the substrate stage 46 is generated. As shown in FIG. Consider a case where the image of the mark 20 and the image of the second mark 21 are transferred to the substrate. Referring to FIGS. 6B and 6D, the amount of deviation between the image of the first mark 20 and the image of the second mark 21 is measured in the same way, so that they cannot be separated. Therefore, in this embodiment, as described above, the magnification component and the orthogonality error included in the step movement error of the substrate stage 46 are set to zero.

  As understood from the above description, when the second marks 21 are arranged at half the pitch of the first marks 20, three or more second marks 21 are required in the X direction and the Y direction. is there. For example, consider a second mark group in which two second marks 21 are arranged as shown in FIG. In this case, as shown in FIG. 5 (s), assuming that an error of the step movement of the substrate stage 46 occurs when the second mark 21 is transferred to the positions P3 and P3 ′ on the substrate, FIG. As shown, the image of the first mark 20 and the image of the second mark 21 are transferred to the substrate. Referring to FIG. 5 (t), the image of the first mark 20 and the image of the second mark 21 (overlapping mark) transferred to the substrate are the same as in FIG. It is impossible to separate the error of step movement and distortion.

The number of the second marks 21 included in the second mark group is basically set to a number obtained by adding 1 to the number of images of the first mark group to be transferred to the substrate (for example, m ₂ rows and n ₂ columns). That's fine. For example, when the number of first mark groups to be transferred to the substrate is 3, the number of second marks 21 included in the second mark group so that images of four or more second marks 21 can be simultaneously transferred. Can be determined. As shown in FIG. 5 (u), when three images (A to C) of the first mark group are transferred, the four second marks 21 can be transferred simultaneously by three step movements (I to K). Thus, the second mark group may be configured. In addition, when a remainder is generated when the number of rows or columns of the first mark 20 is divided by the number of rows or columns of the second mark 21, the distortion and the step movement error can be separated. What is necessary is just to reduce the number at the time of transferring the two marks 21.

  Thus, in the present embodiment, distortion can be measured with high accuracy without affecting the error of step movement of the substrate stage 46.

As a specific example, the distortion measurement range is 750 [mm] in the X direction, 400 [mm] in the Y direction, the measurement pitch is 187.5 [mm] in the X direction, and 200 [mm] in the Y direction. A measurement method in the case of the above will be described. Here, m ₁ is 5, n ₁ is 3, m ₂ and n ₂ are 2.

  As shown in FIG. 7, the mask 48 includes first marks 20 including 3 rows and 5 columns of first marks 20 arranged at a pitch of 187.5 [mm] in the X direction and at a pitch of 200 [mm] in the Y direction. It has a mark group. The mask 48 has a second mark group including the second marks 21 arranged in 3 rows and 3 columns at a pitch of 93.75 [mm] in the X direction and at a pitch of 100 [mm] in the Y direction. Further, the masks 48 are arranged from each of the first marks 20 at a pitch of 93.75 [mm] along the X direction and from each of the first marks 20 at a pitch of 100 [mm] along the Y direction. A light shielding part 22 is provided.

  In the measurement process, first, as shown in FIG. 8A, the first mark 20 in 3 rows and 5 columns is taken as one shot (that is, the first mark 20 in 3 rows and 5 columns is exposed). ), Moving the light shielding plate 44. Next, as shown in FIG. 8E, the substrate 49 is shifted by the substrate stage 46 at a pitch of 93.75 [mm] in the X direction and at a pitch of 100 [mm] in the Y direction (while being moved stepwise). Two rows of first mark group images are transferred to the substrate 49. As a result, in the X direction, ten images of the first mark 20 are transferred, but when the number is divided by the number of the second marks 21 arranged in the Y direction, that is, 3, a remainder is generated. In this case, for example, the number in the X direction of the image of the second mark 21 transferred at one time is divided into 3 and 2.

  In the present embodiment, the process of transferring the three second marks 21 is performed three times in the X direction, and the process of transferring the two second marks 21 is performed twice. Further, in order to reduce the bias of the image of the second mark 21 transferred to the substrate 49, some shot patterns may be provided in the process of transferring the two second marks 21. For example, in the mask 48 shown in FIG. 7, among the second marks 21 arranged in the X direction, a shot including two second marks 21 from the left side, and a shot including two second marks 21 from the right side, May be provided to reduce the deviation of the image of the second mark 21. In the present embodiment, transfer is performed twice with a shot including the two second marks 21 from the left side, and transfer is performed twice with a shot including the two second marks 21 from the right side.

  As shown in FIG. 8B, the light shielding plate 44 is arranged so that the second mark 21 in 3 rows and 3 columns is taken as one shot (that is, the second mark 21 in 3 rows and 3 columns is exposed). Move. Then, as shown in FIG. 8F, the image of the second mark group is transferred to the four corners of the substrate 49 while shifting the substrate 49 in the X direction and the Y direction by the substrate stage 46 (stepping).

  Next, as shown in FIG. 8C, the second mark 21 in 3 rows and 2 columns is taken as one shot (that is, the second mark in 3 rows and 2 columns including two second marks 21 from the left side). 21 is moved) so that the light shielding plate 44 is moved. Then, as shown in FIG. 8G, the image of the second mark group is transferred while shifting the substrate 49 in the X direction and the Y direction by the substrate stage 46 (stepping).

  Next, as shown in FIG. 8D, the second mark 21 in 3 rows and 2 columns is taken as one shot (that is, the second mark 21 in 3 rows and 2 columns including two second marks 21 from the right side). ) So that the light shielding plate 44 is moved. Then, as shown in FIG. 8H, the image of the second mark group is transferred while shifting the substrate 49 in the X direction and the Y direction by the substrate stage 46 (stepping).

  As a result, 60 overlay marks 32 composed of pairs of the image of the first mark 20 and the image of the second mark 21 formed on the substrate 49 after the development processing for developing the substrate 49 are obtained. For each of these overlay marks 32, the amount of deviation between the image of the first mark 20 and the image of the second mark 21 is measured to determine the distortion.

  According to the exposure apparatus 40 of the present embodiment, since the distortion of the projection optical system 45 can be measured with high accuracy, for example, the projection optical system 45 is adjusted with high accuracy so as to reduce such distortion. be able to. Therefore, the exposure apparatus 40 can sufficiently reduce the influence of distortion and perform highly accurate exposure processing.

  The article manufacturing method in the embodiment of the present invention is suitable for manufacturing articles such as devices (semiconductor elements, magnetic storage media, liquid crystal display elements, etc.), for example. Such a manufacturing method includes a step of exposing a substrate coated with a photosensitive agent using an exposure apparatus 40 and a step of developing the exposed substrate. Such a manufacturing method may include other well-known steps (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, and the like). The method for manufacturing an article in the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article as compared with the conventional method.

  As mentioned above, although preferable embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

40: Exposure apparatus 45: Projection optical system 48: Mask 46: Substrate stage 47: Measurement unit 49: Substrate 50: Control unit

Claims (8)

A measurement method for measuring distortion that shows distortion of an image projected on a substrate via an optical system,
A first mark group including a plurality of first marks arranged on the object plane of the optical system and arranged at a constant pitch in a first direction and a second direction orthogonal to the first direction, the first mark The plurality of first marks are transferred by the second transfer of the first mark group following the first transfer between the marks of the plurality of first marks transferred to the substrate by the first transfer of the group. And a first step of transferring the substrate to the substrate while shifting the substrate in the first direction and the second direction;
A second mark group including a plurality of second marks arranged on the object plane and arranged in a pitch smaller than the pitch of the first marks in the first direction and the second direction is transferred to the substrate. The substrate is placed in the first direction and the second direction so that each of the plurality of second marks forms a pair with each of the plurality of first marks transferred to the substrate in the first step. A second step of transferring to the substrate while shifting;
A third step of obtaining the distortion based on a shift amount between the first mark and the second mark transferred to the substrate;
A measurement method characterized by comprising: The first mark group includes the plurality of m ₁ rows and n ₁ columns (m ₁ , n ₁ : an integer of 3 or more) arranged at a first pitch in the first direction and at a second pitch in the second direction. Including the first mark
In the first step, the first mark group of m ₂ rows and n ₂ columns (m ₂ , n ₂ : integer greater than or equal to ₂ ) is divided into the first direction by a third pitch obtained by dividing the first pitch by n _2. , While transferring the substrate to the substrate while shifting the substrate in the second direction by a fourth pitch obtained by dividing the second pitch by m ₂ ,
The second mark group includes the plurality of second marks arranged at the third pitch in the first direction and at the fourth pitch in the second direction. Measurement method. The measurement method according to claim 2, wherein the second mark group includes the second marks of m ₂ +1 rows n ₂ +1 columns.   4. The measurement method according to claim 1, wherein a mask on which the first mark group and the second mark group are formed is used in the first step and the second step. 5. . In the first step and the second step, a mask on which the first mark group and the second mark group are formed is used.
The mask includes light-shielding portions arranged at the third pitch along the first direction from each of the first marks and at the fourth pitch along the second direction from each of the first marks. The measurement method according to claim 2 or 3, wherein A measurement device that measures distortion that shows distortion of an image projected onto a substrate held on a stage via an optical system,
A first mark group including a plurality of first marks arranged at a constant pitch in a first direction and a second direction orthogonal to the first direction; and the first mark in the first direction and the second direction. A second mark group including a plurality of second marks arranged at a pitch smaller than the pitch, and a mask disposed on the object plane of the optical system,
The first mark group is transferred between the marks of the plurality of first marks transferred to the substrate by the first transfer of the first mark group, by the second transfer of the first mark group following the first transfer. A process of transferring the substrate to the substrate while shifting the substrate in the first direction and the second direction by the stage so that the plurality of first marks are transferred, and transferring the second mark group to the substrate The stage is placed on the substrate in the first direction and the second by the stage so that each of the plurality of second marks to be paired with each of the plurality of first marks transferred to the substrate in the processing. A processing unit that performs a process of transferring to the substrate while shifting in a direction;
A measurement unit for measuring a shift amount between the first mark and the second mark transferred to the substrate;
A calculation unit for obtaining the distortion based on the amount of deviation measured by the measurement unit;
A measuring apparatus comprising: An exposure apparatus that exposes a substrate through a projection optical system,
A stage for holding the substrate;
The measurement apparatus according to claim 6, which measures distortion that indicates distortion of an image projected onto the substrate held on the stage via the projection optical system;
A control unit that controls an exposure process for exposing the substrate so as to reduce distortion measured by the measuring device;
An exposure apparatus comprising: A step of exposing the substrate using the exposure apparatus according to claim 7;
Developing the exposed substrate;
A method for producing an article comprising:

Images