Measurement method, lithography method, article manufacturing method, program, information processing device, measuring device, and lithography device.

Abstract

This technology provides advantages for accurately measuring the positions of multiple marks on a circuit board using multiple scopes. [Solution] A measurement method for measuring the position of each of several marks provided on a substrate using multiple scopes includes: an acquisition step of acquiring mark images captured by each of the multiple scopes; an identification step of identifying one or more defocus amount candidates for each scope based on first information showing the relationship between the defocus amount and the contrast value; a selection step of selecting a combination from among several combinations obtained by extracting one defocus amount candidate for each scope in which the difference between the maximum and minimum values ​​of the defocus amount candidates is less than a specified value; a setting step of setting a correction value for the measurement error of the mark position for each scope based on the defocus amount candidates in the selected combination; and a determination step of determining the position of each of the multiple marks based on the mark images and the correction value.

Description

Technical Field

[0001] The present invention relates to a measurement method, a lithography method, an article manufacturing method, a program, an information processing apparatus, a measurement apparatus, and a lithography apparatus.

Background Art

[0002] As one of lithography apparatuses used in manufacturing processes of semiconductor devices, liquid crystal displays, etc., an exposure apparatus that exposes a substrate by transferring a pattern of a reticle (mask) onto the substrate through a projection optical system is known. In the exposure apparatus, an off-axis scope for detecting a mark on the substrate without passing through the reticle and the projection optical system is provided, and the position of the mark on the substrate is measured based on the mark image obtained by the off-axis scope. However, measurement errors may occur in the measurement results of the mark positions obtained using the off-axis scope depending on the defocus amount of the off-axis scope. Patent Document 1 describes correcting the alignment measurement value by the influence of the defocus characteristics.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to achieve both overlay accuracy and throughput in an exposure apparatus, a plurality of off-axis scopes for detecting different marks among a plurality of marks on a substrate may be provided. In the plurality of off-axis scopes, the best focus positions may be different from each other due to mounting errors or mechanical differences in the exposure apparatus. In this case, in order to accurately measure the positions of a plurality of marks on the substrate, it is important to consider the mark detection results among the off-axis scopes.

[0005] Therefore, the present invention aims to provide a technique that is advantageous for accurately measuring the positions of multiple marks on a substrate using multiple scopes. [Means for solving the problem]

[0006] To achieve the above objective, a measurement method as one aspect of the present invention is a measurement method for measuring the position of each of a plurality of marks provided on a substrate using a plurality of scopes that image different marks from each other, and is characterized by including: an acquisition step of acquiring a mark image captured by each of the plurality of scopes; an identification step of identifying one or more defocus amount candidates corresponding to the contrast value of the mark image for each scope based on first information that shows the relationship between the defocus amount and the contrast value, which has been generated in advance for each scope; a selection step of selecting a combination from a plurality of defocus amount candidates obtained by extracting one defocus amount candidate from each scope such that the difference between the maximum and minimum values ​​of the defocus amount candidates is less than a specified value; a setting step of setting a correction value for each scope to correct the measurement error of the mark position caused by the defocus amount based on the defocus amount candidate of each scope in the combination selected in the selection step; and a determination step of determining the position of each of the plurality of marks based on the mark image and the correction value.

[0007] Further objects or other aspects of the present invention will be revealed by preferred embodiments described below with reference to the accompanying drawings. [Effects of the Invention]

[0008] According to the present invention, for example, it is possible to provide an advantageous technique for accurately measuring the positions of multiple marks on a substrate using multiple scopes. [Brief explanation of the drawing]

[0009] [Figure 1]A schematic diagram showing an example configuration of the exposure apparatus of the first embodiment. [Figure 2] Flowchart showing the method for generating the first and second pieces of information. [Figure 3] Diagram showing the first information generated for each scope. [Figure 4] Diagram showing the second piece of information generated for each scope. [Figure 5] In the first embodiment, a flowchart showing a measurement method for measuring the positions of multiple marks on a substrate is provided. [Figure 6] A diagram illustrating an example of identifying candidate defocus amounts corresponding to the contrast values ​​of a marked image based on the first piece of information. [Figure 7] This figure illustrates an example of selecting the combination that minimizes the difference ZR from among multiple defocus amount candidate combinations based on the first piece of information. [Figure 8] A diagram illustrating combinations of multiple defocus amount candidates. [Figure 9] A diagram illustrating an example of identifying the measurement error of the mark position corresponding to the defocus amount candidate based on the second piece of information. [Figure 10] In the second embodiment, a flowchart showing a measurement method for measuring the positions of multiple marks on a substrate is provided. [Modes for carrying out the invention]

[0010] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0011] In this specification and the accompanying drawings, directions are indicated in an XYZ coordinate system with the substrate surface as the XY plane. The directions parallel to the X, Y, and Z axes in the XYZ coordinate system are defined as the X direction, Y direction, and Z direction, respectively, and the rotations around the X, Y, and Z axes are defined as θX, θY, and θZ, respectively. Control and driving (movement) related to the X, Y, and Z axes refer to control or driving (movement) related to the direction parallel to the X, Y, and Z axes, respectively. Furthermore, control or driving related to the θX, θY, and θZ axes refer to control or driving related to rotation around the axis parallel to the X, Y, and Z axes, respectively.

[0012] The lithography apparatus according to the present invention is an apparatus for forming a pattern on a substrate. Examples of lithography apparatuses include an exposure apparatus that exposes a substrate to transfer a pattern from a master plate (mask) onto the substrate, and an imprint apparatus that uses a master plate (mold) to form a pattern on an imprint material on a substrate. In the following, an exposure apparatus will be used as an example to explain the lithography apparatus.

[0013] <First Embodiment> A first embodiment of the exposure apparatus EPX according to the present invention will be described. The exposure apparatus EPX is a lithography apparatus that forms patterns on a substrate (wafer, plate) and is used to manufacture semiconductor devices, flat panel displays (FPDs), and the like. The exposure apparatus EXP can transfer the pattern of a master plate (mask, reticle) onto a substrate by performing an exposure process that projects the pattern of a master plate onto the substrate via a projection optical system and exposes the substrate. The exposure process is performed for each of a plurality of shot regions on the substrate, and the pattern of the master plate can be transferred to each shot region.

[0014] The exposure apparatus EXP of this embodiment is an exposure apparatus for manufacturing flat panel displays, and is a step-and-scan type exposure apparatus (so-called scanner) that transfers the pattern of the original plate onto the substrate while relatively scanning the original plate and the substrate. However, the exposure apparatus EXP may be a step-and-repeat type exposure apparatus (so-called stepper) that transfers the pattern of the original plate onto the substrate with the position of the original plate fixed.

[0015] FIG. 1 is a schematic diagram showing a configuration example of the exposure apparatus EXP of this embodiment. The exposure apparatus EXP may include an illumination optical system 1, an original plate stage 2, a projection optical system 4, a substrate stage 9, and a control unit 10.

[0016] The illumination optical system 1 includes lenses, mirrors, etc., and illuminates the original plate 3 held by the original plate stage 2 with light (exposure light) having a uniform illuminance distribution. The illumination optical system 1 of this embodiment shapes the light emitted from a light source (not shown) into slit light having a predetermined cross-sectional shape (for example, a rectangular shape or an arc shape), and illuminates a part (illumination area) of the original plate 3 with the slit light. The light source may include, for example, a mercury lamp and an elliptical mirror.

[0017] The original plate stage 2 is configured to hold and drive the original plate 3 on which the pattern to be transferred to the substrate 8 is formed. The original plate stage 2 of this embodiment may be configured to drive the original plate 3 in the X direction, Y direction, and rotation direction (θZ direction). The original plate 3 is disposed on the object plane of the projection optical system 4.

[0018] The projection optical system 4 projects the pattern image of the original plate 3 illuminated by the illumination optical system 1 onto the substrate 8. The projection optical system 4 of this embodiment has a plane mirror 5, a concave mirror 6, and a convex mirror 7. The light from the original plate 3 is reflected in the order of the upper part of the plane mirror 5, the upper part of the concave mirror 6, the convex mirror 7, the lower part of the concave mirror 6, and the lower part of the plane mirror 5, and forms an image on the substrate 8. The projection optical system 4 may be any of an equal magnification system, an enlargement system, and a reduction system. Further, the projection optical system 4 may be configured mainly with a projection lens using lenses, a refractive-reflective optical system, or may be configured as a plurality of imaging optical systems.

[0019] The substrate stage 9 holds and drives the substrate 8. In this embodiment, the substrate stage 9 may be configured to drive the substrate 8 in the X, Y, Z, rotation (θZ direction), and tilt (θX direction, θY direction). The substrate 8 is positioned in the image plane of the projection optical system 4. The substrate stage 9 drives the substrate 8 based on drive commands from the control unit 10.

[0020] The control unit 10 is composed of a computer (information processing device) including a processing unit (processor) such as a CPU (Central Processing Unit) and a storage unit such as memory, and comprehensively controls each part of the exposure apparatus EXP. In this embodiment, the control unit 10 controls the driving of the original plate stage 2 and the substrate stage 9 based on the position and / or angle of the original plate stage 2 and the substrate stage 9 measured by a position sensor such as an interferometer or encoder. This indirectly controls the position and / or angle of the original plate 3 and the substrate 8, and enables alignment of the original plate 3 and the substrate 8 (i.e., positioning of the substrate 8).

[0021] Furthermore, the control unit 10 controls the exposure process for each of the multiple shot regions on the substrate 8. In the exposure process, the original plate stage 2 and the substrate stage 9 are moved synchronously in a predetermined direction (for example, the Y direction) to scan the original plate 3 and the substrate 8 relatively, thereby exposing the substrate 8 via the original plate 3 and the projection optical system 4. Specifically, the illumination region illuminated by the illumination optical system 1 is moved across the original plate 3, and the pattern image of the original plate 3 in the illumination region is projected onto the substrate 8 by the projection optical system 4. This allows the entire pattern provided on the original plate 3 to be transferred onto the substrate 8. This exposure process is repeated for each of the multiple shot regions on the substrate 8.

[0022] In this embodiment, the exposure apparatus EXP is equipped with multiple off-axis scopes 21 to 23 that detect (image) different marks from each other among multiple marks (alignment marks) provided on the substrate 8 (for example, one shot area). In the exposure apparatus EXP of this embodiment, the multiple off-axis scopes 21 to 23 are provided (mounted) on the lower surface of the projection optical system 4. The multiple off-axis scopes 21 to 23 may simultaneously detect (image) different alignment marks from each other among multiple marks on the substrate 8. In this embodiment, an example in which the exposure apparatus EXP is equipped with three off-axis scopes 21 to 23 is described, but the number of off-axis scopes is not limited to three; two or more are acceptable.

[0023] Each off-axis scope 21-23 is an off-axis scope that detects marks on the substrate 8 without going through the projection optical system 4. Each off-axis scope 21-23 detects only the marks on the substrate 8 in order to measure the position of the marks on the substrate 8, and does not detect the marks on the original plate 3. Each off-axis scope 21-23 in this embodiment has an illumination system that illuminates the marks on the substrate 8 and an image sensor that captures images of the marks on the substrate 8. Each off-axis scope 21-23 may also have a processing unit (calculation unit) that acquires the mark image obtained by the image sensor and uses the mark image to determine the position of the marks or to determine the contrast value of the mark image. The contrast value of the mark image is an index that represents the difference in brightness between the mark part and the other part (background part) in the mark image.

[0024] The control unit 10 acquires the position and contrast value of the marks obtained by the processing units of each off-axis scope 21-23, as well as the position coordinates of the substrate stage 9 when the marks were detected. Based on this information, the control unit 10 controls the position of the substrate stage 9 in the XY direction to align the master plate 3 and the substrate 8. Note that the functions of the processing units of each off-axis scope 21-23 may also be provided in the control unit 10, and the following describes an example in which the control unit 10 also functions as the processing unit for each off-axis scope 21-23. Note that in the following, off-axis scopes may be simply referred to as "scopes".

[0025] Here, the exposure apparatus EXP may be provided with a drive mechanism that drives each of the scopes 21-23 to move the detection field (imaging field) of each scope 21-23 on the substrate 8. The exposure apparatus EXP may also be provided with an alignment scope 20. The alignment scope 20 is a through-the-mirror (TTM) type scope that detects marks on the substrate 8 via the projection optical system 4. The alignment scope 20 detects marks on the original plate 3 and also detects marks on the substrate 8 via the projection optical system 4 in order to measure the relative position between the marks on the original plate 3 and the marks on the substrate 8.

[0026] Incidentally, measurement errors (so-called defocus shifts) may occur in the mark position measurement results obtained using each scope 21-23 due to the amount of defocus of each scope 21-23. Also, the best focus position may differ between multiple scopes 21-23 due to mounting errors on the exposure device and machine differences. In this case, in order to accurately measure the positions of multiple marks on the substrate, it is important for the scopes to consider each other's mark detection results. It is also possible to provide each scope 21-23 with a sensor to measure the surface height of the substrate 8 and a mechanism to adjust the focus, but this method may lead to an increase in the size of each scope 21-23 and an increase in equipment costs.

[0027] Therefore, in this embodiment, the positions of multiple marks on the substrate 8 are measured based on first information showing the relationship between the amount of defocus and the contrast value, and second information showing the relationship between the amount of defocus and the measurement error of the mark position. The measurement method will be described below.

[0028] [Generation of first and second information] First, the method for generating the first and second information will be described. Figure 2 is a flowchart illustrating the method for generating the first and second information. The flowchart in Figure 2 can be performed individually for each of the multiple scopes 21 to 23, using the first substrate when production starts under arbitrary process conditions, that is, the first substrate in a lot containing multiple substrates. Furthermore, the flowchart in Figure 2 can be executed, for example, by the control unit 10. The first and second information generated individually for each scope 21 to 23 according to the flowchart in Figure 2 can be stored in the memory unit of the control unit 10.

[0029] In step S101, the control unit 10 causes each of the scopes 21-23 to detect (image) marks on the substrate 8 in each of a plurality of arrangement states in which the distance between each of the scopes 21-23 and the substrate 8 in the Z direction is different (i.e., the amount of defocus). The plurality of arrangement states can be generated, for example, by moving the substrate 8 in steps in the Z direction using the substrate stage 9 to change the height of the substrate 8 in the Z direction. This makes it possible to obtain mark images obtained for each of the plurality of arrangement states in which the amount of defocus is different for each of the scopes 21-23.

[0030] In step S102, the control unit 10 determines the contrast value of the mark image obtained for each of the multiple arrangement states for each of the scopes 21 to 23. Then, in step S103, the control unit 10 generates first information showing the relationship between the amount of defocus and the contrast value for each of the scopes 21 to 23. For example, the control unit 10 determines the relationship between the amount of defocus and the contrast value by performing a second-order or higher fitting process on the contrast value obtained for each of the multiple arrangement states for each of the scopes 21 to 23. The relationship between the amount of defocus and the contrast value can be obtained as a characteristic in which the contrast value changes in a normal distribution manner in response to changes in the amount of defocus. Furthermore, the control unit 10 determines the amount of defocus that maximizes the contrast value (i.e., the height of the substrate 8) as the position where the amount of defocus is zero, i.e., the best focus position. In this way, first information showing the relationship between the amount of defocus and the contrast value can be generated.

[0031] Figure 3 shows the first information generated for each scope 21-23. Figure 3(a) shows the first information for scope 21 having the best focus position Z1. Figure 3(b) shows the first information for scope 22 having the best focus position Z2. Figure 3(c) shows the first information for scope 23 having the best focus position Z3. As shown in Figures 3(a)-(c), the best focus positions Z1-Z3 in the first information for each scope 21-23 differ from each other due to mounting errors and machine differences for each scope 21-23 on the exposure device.

[0032] In step S104, the control unit 10 determines the measurement error of the mark position (X,Y) caused by the amount of defocus for each of the scopes 21 to 23. For example, the control unit 10 can determine the difference between the mark position (X,Y) calculated from the mark image and the target position as the measurement error for each of a plurality of arrangement states with different amounts of defocus. As the target position, for example, the position of the mark on the substrate 8 measured using the alignment scope 20 may be used.

[0033] In step S105, the control unit 10 generates second information for each of the scopes 21 to 23, showing the relationship between the amount of defocus and the measurement error of the mark position. The relationship between the amount of defocus and the measurement error of the mark position in the second information is generated for each of the X and Y directions, with the best focus positions Z1 to Z3 as the reference (origin). Figure 4 shows the second information generated for each scope. Figure 4(a) shows the second information for scope 21, Figure 4(b) shows the second information for scope 22, and Figure 4(c) shows the second information for scope 23.

[0034] In this embodiment, an example has been described in which the first and second information are generated for each process condition (i.e., for each lot), but the invention is not limited to this, and the first and second information may be generated for each substrate or for each shot area. Furthermore, in this embodiment, an example has been described in which the flowchart in Figure 2 is performed at the start of production, but the flowchart in Figure 2 may also be performed at any other time to regenerate the first and second information.

[0035] [Method for measuring the mark position] Next, a measurement method for measuring the positions of multiple marks on the substrate 8 using multiple scopes 21-23 will be described. Figure 5 is a flowchart showing the measurement method for measuring the positions of multiple marks on the substrate 8. The flowchart in Figure 5 can be performed, for example, by the control unit 10 for each substrate 8 or for each shot area.

[0036] In step S201, the control unit 10 causes the multiple scopes 21-23 to detect (image) different marks from among the multiple marks on the substrate 8. The multiple scopes 21-23 may simultaneously detect different marks. Then, in step S202, the control unit 10 acquires the mark images captured by each of the scopes 21-23.

[0037] In step S203, the control unit 10 determines the mark position (X,Y) based on the mark images acquired from each of the scopes 21 to 23. Next, in step S204, the control unit 10 determines the contrast value of the mark images acquired from each of the scopes 21 to 23. Here, the contrast value of the mark image acquired from scope 21 is "C1", the contrast value of the mark image acquired from scope 22 is "C2", and the contrast value of the mark image acquired from scope 23 is "C3".

[0038] In step S205, the control unit 10 identifies one or more defocus amount candidates corresponding to the contrast value of the mark image for each of the scopes 21 to 23, based on pre-generated first information. The first information is information showing the relationship between the defocus amount and the contrast value, and in this embodiment, as shown in Figure 3, the contrast value changes in a normal distribution manner in response to changes in the defocus amount. Therefore, one or two defocus amount candidates corresponding to the contrast value of the mark image can be identified from the first information.

[0039] The first information shown in Figure 3 is represented by an approximation function obtained by performing a second-order or higher fitting on the discretely obtained relationship between the amount of defocus and the contrast value. By applying this approximation function, one or two candidate defocus amounts corresponding to contrast values ​​C1 to C3 can be identified. For example, if the relationship between the amount of defocus and the contrast value follows a normal distribution, two candidate defocus amounts may be identified for one contrast value. In this embodiment as well, as shown in Figure 6, there may be two candidate defocus amounts for each of the contrast values ​​C1 to C3.

[0040] Figure 6 illustrates an example of identifying candidate defocus amounts corresponding to the contrast values ​​of a marked image based on the first information shown in Figure 3. For scope 21, two candidate defocus amounts Z11 to Z12 corresponding to contrast value C1 are identified based on the first information shown in Figure 6(a). For scope 22, two candidate defocus amounts Z21 to Z22 corresponding to contrast value C2 are identified based on the first information shown in Figure 6(b). For scope 23, candidate defocus amounts Z31 to Z32 corresponding to contrast value C3 are identified based on the first information shown in Figure 6(c).

[0041] In step S206, the control unit 10 selects a combination from among multiple defocus amount candidates in which the difference ZR between the maximum and minimum values ​​of the defocus amount candidates is less than a specified value. Multiple defocus amount combinations are obtained by extracting one defocus amount candidate for each of the scopes 21 to 23. In this embodiment, the control unit 10 selects the combination from among the multiple defocus amount candidate combinations in which the difference ZR is minimized.

[0042] Figure 7 illustrates an example of selecting the combination with the smallest difference ZR from among multiple defocus amount candidate combinations, based on the first information shown in Figure 6. In the example in Figure 7, a total of eight combinations are obtained, each containing one of the defocus amount candidates Z11 to Z12 from scope 21, one of the defocus amount candidates Z21 to Z22 from scope 22, and one of the defocus amount candidates Z31 to Z32 from scope 23. These eight combinations may also be understood as combinations of multiple defocus amount candidates. Of these eight combinations, the combination containing the defocus amount candidate Z11 from scope 21, the defocus amount candidate Z22 from scope 22, and the defocus amount candidate Z31 from scope 23 is selected as the combination with the smallest difference ZR.

[0043] Here, we will explain the combinations of multiple defocus amount candidates with reference to Figure 8. In Figure 8, we will illustrate and explain the defocus amount candidates Z11-Z12 identified for scope 21 and the defocus amount candidates Z21-Z22 identified for scope 22. As mentioned above, multiple defocus amount combinations can be obtained by extracting one defocus amount candidate for each scope. Focusing on the two scopes 21-22, we can obtain four types of defocus amount candidate combinations shown in Figures 8(a)-(d). Also, Figures 8(a)-(d) show the surface inclination T of the substrate 8 obtained by the combination of defocus amount candidates.

[0044] Figure 8(a) shows combinations of defocus amount candidate Z11 for scope 21 and defocus amount candidate Z21 for scope 22. Figure 8(b) shows combinations of defocus amount candidate Z11 for scope 21 and defocus amount candidate Z22 for scope 22. Figure 8(c) shows combinations of defocus amount candidate Z12 for scope 21 and defocus amount candidate Z21 for scope 22. Figure 8(d) also shows combinations of defocus amount candidate Z12 for scope 21 and defocus amount candidate Z22 for scope 22.

[0045] The surface of the substrate 8 held by the substrate stage 9 can ideally be positioned perpendicular to the optical axis of each scope 21-22. Therefore, from the viewpoint of scope alignment, the combination that minimizes the surface inclination T of the substrate 8, i.e., the combination that minimizes the difference ZR, best represents the surface of the substrate 8 actually held by the substrate stage 9. Accordingly, in this embodiment, a combination is selected from among several defocus amount candidates in which the difference ZR between the maximum and minimum values ​​of the defocus amount candidates is less than a specified value (preferably the minimum). Of the four types of defocus amount candidate combinations shown in Figures 8(a) to (d), the combination that minimizes the difference ZR between the maximum and minimum values ​​of the defocus amount candidates is the one shown in Figure 8(b).

[0046] The method for selecting a combination of candidate defocus amounts is not limited to the method using the difference ZR as described above. For example, the method may also be applicable when the substrate 8 (substrate stage 9) has a pitch or roll component. Specifically, the method may involve performing a first-order fitting on the relationship between the X or Y position of each scope 21-23 and the Z position of the substrate 8 (substrate stage 9), and selecting the combination that minimizes the residual.

[0047] In step S207, the control unit 10 identifies the measurement error of the mark position (X,Y) caused by the amount of defocus for each of the scopes 21 to 23, based on the candidate defocus amounts for each scope 21 to 23 in the combination selected in step S206. Pre-generated second information may be used to determine the measurement error. The second information is information showing the relationship between the amount of defocus and the measurement error of the mark position (X,Y), as shown in Figure 6. Based on the second information, the control unit 10 identifies the measurement error of the mark position corresponding to the candidate defocus amount for each of the scopes 21 to 23 in the combination selected in step S206.

[0048] Figure 9 illustrates an example of identifying the measurement error of the mark position corresponding to the defocus amount candidate based on the second information shown in Figure 6. For scope 21, since the defocus amount candidate Z11 is selected, the measurement errors DSX1 and DSY1 of the mark position corresponding to the defocus amount candidate Z11 are identified based on the second information shown in Figure 9(a). For scope 22, since the defocus amount candidate Z22 is selected, the measurement errors DSX2 and DSY2 of the mark position corresponding to the defocus amount candidate Z22 are identified based on the second information shown in Figure 9(b). Furthermore, for scope 23, since the defocus amount candidate Z31 is selected, the measurement errors DSX3 and DSY3 of the mark position corresponding to the defocus amount candidate Z31 are identified based on the second information shown in Figure 9(c).

[0049] In step S208, the control unit 10 sets a correction value for each of the scopes 21 to 23 to correct the measurement error of the mark position (X,Y) identified in step S207. Specifically, the control unit 10 sets a correction value for each of the scopes 21 to 23 so that the measurement error of the mark position identified in step S207 is reduced (preferably canceled out). The correction value may be set for both the X direction and the Y direction.

[0050] In step S209, the control unit 10 determines the positions of multiple marks on the substrate 8 based on the mark positions (X,Y) obtained in step S203 and the correction value set in step S208. Specifically, the control unit 10 determines the positions of multiple marks by applying the correction value to the mark positions obtained from the mark images for each of the scopes 21 to 23.

[0051] For scope 21, correction values ​​are applied to the mark position (X,Y) obtained from the mark image in step S203 to correct for measurement errors DSX1 and DSY1. This allows the position of the mark detected by scope 21 to be determined. For scope 22, correction values ​​are applied to the mark position (X,Y) obtained from the mark image in step S203 to correct for measurement errors DSX2 and DSY2. This allows the position of the mark detected by scope 22 to be determined. Furthermore, for scope 23, correction values ​​are applied to the mark position (X,Y) obtained from the mark image in step S203 to correct for measurement errors DSX3 and DSY3. This allows the position of the mark detected by scope 23 to be determined.

[0052] As described above, in this embodiment, from a combination of multiple defocus amount candidates for which one defocus amount candidate is extracted for each of the scopes 21 to 23, a combination is selected in which the difference between the maximum and minimum values ​​of the defocus amount candidates is less than a specified value. Then, based on the defocus amount candidates of each scope 21 to 23 in the selected combination, a correction value is set for each scope 21 to correct the measurement error of the mark position caused by the defocus amount, and this correction value is applied to the mark position. As a result, even without providing sensors for measuring the surface height of the substrate 8 or mechanisms for adjusting the focus in each of the scopes 21 to 23, the positions of multiple marks on the substrate 8 can be measured accurately using multiple scopes 21 to 23.

[0053] <Second Embodiment> A second embodiment of the present invention will now be described. The relationship between the amount of defocus and the contrast value in the first information may change due to changes in the attitude caused by driving each of the scopes 21 to 23, or due to changes over time due to prolonged use. Therefore, in this embodiment, an example will be described in which a step of regenerating the first information is added to a measurement method for measuring the positions of multiple marks on the substrate 8 using multiple scopes 21 to 23. This embodiment basically follows the first embodiment, and can be followed except for the matters mentioned below.

[0054] Figure 10 is a flowchart showing a measurement method for measuring the positions of multiple marks on the substrate 8 in this embodiment. The flowchart in Figure 10 can be performed, for example, by the control unit 10 for each substrate 8 or for each shot area.

[0055] In step S301, the control unit 10 causes multiple scopes 21-23 to detect (image) different marks from among multiple marks on the substrate 8. In step S302, the control unit 10 acquires the mark images captured by each scope 21-23. In step S303, the control unit 10 determines the mark position (X,Y) based on the mark images acquired from each scope 21-23. In step S304, the control unit 10 determines the contrast value of the mark images acquired from each scope 21-23. In step S305, for each scope 21-23, the control unit 10 identifies one or more defocus amount candidates corresponding to the contrast value of the mark image based on pre-generated first information. Steps S301-S305 are the same as steps S201-S205 in Figure 5 described in the first embodiment.

[0056] In step S306, the control unit 10 determines whether there is a combination among the multiple defocus amount candidates in which the difference ZR between the maximum and minimum values ​​of the defocus amount candidates is less than the specified value A, as shown in equation (1) below. The specified value A can be set to a value that can keep the measurement accuracy of multiple marks, which are affected by changes in attitude due to the driving of each scope 21-23 and changes over time due to prolonged use, within an acceptable range, based on prior experiments and simulations. For example, the specified value A can be set in advance to a value that can keep the measurement error of the mark position (X,Y) caused by the defocus amount within an acceptable range. Note that the specified value A in this embodiment may be the same as the specified value used in step S206 of the first embodiment. ZR

[0057] ​In step S306, if there is a combination among the multiple defocus amount candidate combinations in which the difference ZR is less than a specified value, the process proceeds to step S307. In step S307, the control unit 10 selects the combination from the multiple defocus amount candidate combinations that has the smallest difference ZR. Next, in step S308, the control unit 10 identifies the measurement error of the mark position (X,Y) caused by the defocus amount for each of the scopes 21 to 23 based on the defocus amount candidate for each of the scopes 21 to 23 in the combination selected in step S307. In step S309, the control unit 10 sets a correction value for each of the scopes 21 to 23 to correct the measurement error of the mark position (X,Y) identified in step S207. In step S310, the control unit 10 determines the position of the mark on the substrate 8 based on the mark position (X,Y) obtained in step S303 and the correction value set in step S309. Steps S308 to S310 are the same as steps S207 to S209 in Figure 5, which were described in the first embodiment.

[0058] On the other hand, if in step S306 there is no combination among the multiple defocus amount candidates in which the difference ZR is less than a specified value, the process proceeds to step S311. In step S311, the control unit 10 regenerates the first information for each of the scopes 21 to 23. The control unit 10 may also regenerate the second information for each of the scopes 21 to 23. The regeneration of the first and second information can be performed according to the flowchart in Figure 2 described in the first embodiment. After step S306 is performed, the process proceeds to step S301, and steps S301 to S305 are performed again using the regenerated (updated) first and second information.

[0059] As described above, in this embodiment, it is determined whether there is a combination among the multiple defocus amount candidate combinations in which the difference ZR is less than a specified value, and if there is no combination in which the difference ZR is less than a specified value, the first and second information are regenerated. With this embodiment as well, even without providing sensors for measuring the surface height of the substrate 8 or mechanisms for adjusting the focus in each of the scopes 21 to 23, the positions of multiple marks on the substrate 8 can be accurately measured using multiple scopes 21 to 23.

[0060] <Embodiment of Article Manufacturing Method> The article manufacturing method according to an embodiment of the present invention is suitable for manufacturing articles such as microdevices such as semiconductor devices and elements having a microstructure. The article manufacturing method of this embodiment includes a formation step of forming a pattern on a substrate using the above-described lithography apparatus (lithography method), a processing step of processing the substrate on which the pattern was formed in the formation step, and a manufacturing step of manufacturing an article from the substrate processed in the processing step. When the lithography apparatus is configured as an exposure apparatus, the formation step may be a step of forming a latent image pattern on a photosensitive agent coated on a substrate by exposing the substrate using the above-described exposure apparatus (exposure method). In this case, the processing step may include a step of developing the substrate on which the latent image pattern was formed. Furthermore, the article manufacturing method includes other well-known steps (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The article manufacturing method of this embodiment is advantageous compared to conventional methods in at least one of the performance, quality, productivity, and production cost of the article.

[0061] <Other examples> The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0062] <Summary of Embodiments> The disclosures herein include at least the following measurement methods, lithography methods, article manufacturing methods, programs, information processing devices, measuring devices, and lithography devices. (Item 1) A measurement method for measuring the position of each of a plurality of marks provided on a substrate, using a plurality of scopes that image different marks from each other, An acquisition step of acquiring a mark image captured by each of the aforementioned multiple scopes, A selection step in which, based on first information that shows the relationship between the amount of defocus and the contrast value generated in advance for each scope, one or more candidate defocus amounts corresponding to the contrast value of the mark image are identified for each scope, A selection process involves extracting one defocus amount candidate for each scope, and from among the multiple defocus amount candidate combinations obtained, selecting a combination in which the difference between the maximum and minimum values ​​of the defocus amount candidates is less than a specified value. A setting step in which, based on the defocus amount candidates for each scope in the combination selected in the selection step, a correction value is set for each scope to correct the measurement error of the mark position caused by the defocus amount, A measurement method characterized by including a determination step of determining the position of each of the plurality of marks based on the mark image and the correction value. (Item 2) In the relationship between the amount of defocus and the contrast value in the first information, the contrast value changes in a normal distribution manner in response to changes in the amount of defocus. The measurement method according to item 1, characterized in that in the specified step, a defocus amount of 1 or 2 which becomes the contrast value of the mark image is identified in the first information as a candidate for the defocus amount. (Item 3) The measurement method according to item 1 or 2, characterized in that the selection step involves selecting the combination that minimizes the difference from among the multiple combinations of defocus amount candidates. (Item 4) The measurement method according to any one of items 1 to 3, characterized in that if there is no combination among the plurality of defocus amount candidates in which the difference is less than the specified value, the first information is regenerated for each scope. (Item 5) The measurement method according to any one of items 1 to 4, characterized in that, in the setting step, the correction value is set based on second information that shows the relationship between the defocus amount and the measurement error of the mark position, which is generated in advance for each scope, so that the measurement error of the mark position corresponding to the candidate defocus amount for each scope is corrected. (Item 6) The measurement method according to item 5, characterized in that if there is no combination among the plurality of candidate defocus amounts in which the difference is less than the specified value, the second information is regenerated for each scope. (Item 7) The measurement method according to any one of items 1 to 6, characterized in that, in the determination step, the position of each of the multiple marks is determined by applying the correction value to the mark position obtained from the mark image for each scope. (Item 8) A lithography method for forming a pattern on a substrate, A measurement step of measuring the position of each of the multiple marks provided on the substrate using the measurement method described in any one of items 1 to 7, A positioning step in which the substrate is positioned based on the results of the measurement step, A forming step of forming a pattern on the substrate positioned in the positioning step, A lithography method characterized by including [a certain element]. (Item 9) A step of forming a pattern on a substrate using the lithography method described in item 8, A process of processing the substrate on which the pattern is formed, A process for manufacturing an article from the processed substrate, A method for manufacturing articles, characterized by including the following: (Item 10) A program to cause an information processing device to execute one of the measurement methods described in item 1 through 7. (Item 11) An information processing device that performs the measurement method described in any one of items 1 to 7. (Item 12) A measuring device for measuring the position of each of several marks provided on a circuit board, Multiple scopes that image different marks from the aforementioned multiple marks, The system includes a processing unit that determines the positions of the plurality of marks based on the mark images captured by each of the plurality of scopes, The aforementioned processing unit, Based on information showing the relationship between the amount of defocus and the contrast value, which is generated in advance for each scope, one or more candidate defocus amounts corresponding to the contrast value of the mark image are identified for each scope. From the multiple combinations of defocus amount candidates obtained by extracting one defocus amount candidate for each scope, select the combination in which the difference between the maximum and minimum values ​​of the defocus amount candidates is less than a specified value. Based on the defocus amount candidates for each scope in the selected combination, a correction value is set for each scope to compensate for the measurement error of the mark position caused by the defocus amount. A measuring device characterized by determining the position of each of the plurality of marks based on the mark image and the correction value. (Item 13) A lithography apparatus for forming patterns on a substrate, A stage for holding the substrate, The device comprises a measuring device as described in item 12, which measures the position of each of the multiple marks provided on the substrate, A lithography apparatus characterized by positioning the substrate by driving the stage based on the measurement results of the measuring device. (Item 14) The lithography apparatus is an exposure apparatus that exposes the substrate via a projection optical system, The lithography apparatus according to item 13, characterized in that the plurality of scopes in the measuring device are provided in the projection optical system.

[0063] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of symbols]

[0064] 1: Illumination optics, 2: Master plate stage, 3: Master plate, 4: Projection optics, 8: Substrate, 9: Substrate stage, 10: Control unit, 20: Alignment scope, 21-23: Off-axis scope, EXP: Exposure system (lithography system)

Claims

1. A measurement method for measuring the position of each of a plurality of marks provided on a substrate, using a plurality of scopes that image different marks from each other, An acquisition step of acquiring a mark image captured by each of the aforementioned multiple scopes, A selection step in which, based on first information that shows the relationship between the amount of defocus and the contrast value generated in advance for each scope, one or more candidate defocus amounts corresponding to the contrast value of the mark image are identified for each scope, A selection process involves extracting one defocus amount candidate for each scope, and from among multiple combinations of defocus amount candidates obtained, selecting a combination in which the difference between the maximum and minimum values ​​of the defocus amount candidates is less than a specified value. A setting step in which, based on the defocus amount candidates for each scope in the combination selected in the selection step, a correction value is set for each scope to correct the measurement error of the mark position caused by the defocus amount, A measurement method characterized by including a determination step of determining the position of each of the plurality of marks based on the mark image and the correction value.

2. In the relationship between the amount of defocus and the contrast value in the first information, the contrast value changes in a normal distribution manner in response to changes in the amount of defocus. The measurement method according to claim 1, characterized in that in the specified step, a defocus amount of 1 or 2 that becomes the contrast value of the mark image is identified in the first information as a candidate for the defocus amount.

3. The measurement method according to claim 1, characterized in that the selection step involves selecting the combination that minimizes the difference from among the plurality of defocus amount candidate combinations.

4. The measurement method according to claim 1, characterized in that if there is no combination among the plurality of candidate defocus amounts in which the difference is less than the specified value, the first information is regenerated for each scope.

5. The measurement method according to claim 1, characterized in that, in the setting step, the correction value is set based on second information that shows the relationship between the defocus amount and the measurement error of the mark position, which is generated in advance for each scope, so that the measurement error of the mark position corresponding to the defocus amount candidate for each scope is corrected.

6. The measurement method according to claim 5, characterized in that if there is no combination among the plurality of candidate defocus amounts in which the difference is less than the specified value, the second information is regenerated for each scope.

7. The measurement method according to claim 1, characterized in that the determination step involves determining the position of each of the plurality of marks by applying the correction value to the mark position obtained from the mark image for each scope.

8. A lithography method for forming a pattern on a substrate, A measurement step of measuring the position of each of the multiple marks provided on the substrate using the measurement method described in any one of claims 1 to 7, A positioning step in which the substrate is positioned based on the results of the measurement step, A forming step of forming a pattern on the substrate positioned in the positioning step, A lithography method characterized by including [a certain element].

9. A step of forming a pattern on a substrate using the lithography method described in claim 8, A process of processing the substrate on which the pattern is formed, A process for manufacturing an article from the processed substrate, A method for manufacturing articles, characterized by including the following:

10. A program for causing an information processing device to execute the measurement method described in any one of claims 1 to 7.

11. An information processing device that performs the measurement method according to any one of claims 1 to 7.

12. A measuring device for measuring the position of each of several marks provided on a circuit board, Multiple scopes that image different marks from the aforementioned multiple marks, The system includes a processing unit that determines the positions of the plurality of marks based on the mark images captured by each of the plurality of scopes, The aforementioned processing unit, Based on information indicating the relationship between the amount of defocus and the contrast value, which is generated in advance for each scope, one or more candidate defocus amounts corresponding to the contrast value of the mark image are identified for each scope. From the multiple combinations of defocus amount candidates obtained by extracting one defocus amount candidate for each scope, select the combination in which the difference between the maximum and minimum values ​​of the defocus amount candidates is less than a specified value. Based on the defocus amount candidates for each scope in the selected combination, a correction value is set for each scope to compensate for the measurement error of the mark position caused by the defocus amount. A measuring device characterized by determining the position of each of the plurality of marks based on the mark image and the correction value.

13. A lithography apparatus for forming patterns on a substrate, A stage for holding the substrate, The measuring device according to claim 12 measures the position of each of a plurality of marks provided on the substrate, A lithography apparatus characterized by positioning the substrate by driving the stage based on the measurement results of the measuring device.

14. The lithography apparatus is an exposure apparatus that exposes the substrate via a projection optical system, The lithography apparatus according to claim 13, characterized in that the plurality of scopes in the measuring device are provided in the projection optical system.

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