Exposure apparatus and method of manufacturing article

Abstract

To reduce the positional deviation of a pattern transferred to a substrate.SOLUTION: An exposure apparatus including a projection optical system, comprising: a first driving unit for driving at least one optical element constituting the projection optical system in a first direction along an optical axis to change a magnification of the projection optical system; a second driving unit for driving a stage holding an original or a substrate in the first direction; a control unit for performing control of positioning the stage in the first direction by the second driving unit in accordance with driving of the at least one optical element by the first driving unit; and an adjustment unit for adjusting at least one of a first condition set for driving the at least one optical element and a second condition set for driving the stage when a difference between an index indicating a correlation between a control deviation of the projection optical system obtained in the control from results of measuring the position of each of the at least one optical element and the stage and a control deviation of the stage, and a predetermined reference index of the index exceeds a threshold.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an exposure apparatus and a method for manufacturing an article. [Background technology]

[0002] An exposure apparatus used in a manufacturing process for semiconductor devices and the like has an original stage that holds an original, a substrate stage that holds a substrate, a projection optical system that projects the pattern of the original onto the substrate, and a drive mechanism that drives the projection lens (projection optical system) (see Patent Documents 1 and 2). Patent Document 1 discloses a technique relating to scanning exposure in which the substrate is exposed while scanning the original and substrate, and Patent Document 2 discloses a technique in scanning exposure in which the substrate is exposed while driving the projection lens.

[0003] In scanning exposure, errors caused by the exposure apparatus, such as control deviations of the original stage and substrate stage, and control deviations and vibrations of the projection lens, may cause a positional deviation in the pattern (image) transferred to the substrate. In order to reduce such positional deviations, a technique has been proposed in which a correction amount for correcting such positional deviations is obtained in advance for each exposure position. Also, a technique has been proposed in which a correction drive based on the correction amount is added to the drive of the projection optical system during scanning exposure to drive the projection lens, thereby reducing distortion of the pattern (image) transferred to the substrate (see Patent Document 3).

[0004] In recent years, as semiconductor manufacturing processes have become more sophisticated and complicated, not only misalignment caused by exposure equipment occurs, but also misalignment caused by the process (called "base distortion"). In the semiconductor manufacturing process, a process of exposing a substrate to light, a process of developing the exposed substrate, and a process of performing other well-known processes (etching, resist stripping, planarization, etc.) on the developed substrate are repeated multiple times. When these processes are repeated, base distortion occurs mainly due to the effects of heat treatment, and it is therefore necessary to correct the base distortion using an exposure device. The shape of the base distortion is also becoming more complicated every year.

[0005] The positional deviation caused by the exposure device and the substrate distortion caused by the process can be corrected by driving the projection lens in the optical axis direction to change the magnification of the pattern (image) transferred to the substrate. However, when the projection lens is driven in the optical axis direction, the imaging position changes, and if the imaging position does not match the optimal imaging position on the substrate, for example, the exposure amount is insufficient, which causes poor resolution. Therefore, the imaging position is matched with the optimal imaging position on the substrate by driving the substrate stage or the original stage in the optical axis direction according to the driving of the projection lens (change in the position of the projection lens). At this time, the projection lens, the substrate stage, and the original stage can be positioned with high accuracy by using PID (Proportional-Integral-Differential) control or the like. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4261810 [Patent Document 2] JP 2020-148865 A [Patent Document 3] Japanese Patent Application Publication No. 4-225213 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in an exposure apparatus, temperature changes in the air conditioning system, heat from the exposure light, heat from driving each stage and projection lens, etc., can cause deformation of the structure of each stage and projection lens, and errors in the measurement system that measures the position of each stage and projection lens. Such deformation and errors cause changes in the control characteristics related to the driving of each stage and projection lens, and if such changes are large, each stage and projection lens will be driven to a position shifted from the target position, resulting in a decrease in positioning accuracy. The decrease in positioning accuracy of each stage and projection lens leads to over- or under-correction of substrate distortion caused by the process, which increases the positional deviation of the pattern (image) transferred to the substrate, and is one of the causes of defects in the manufactured semiconductor elements.

[0008] The present invention has been made in consideration of the problems with the conventional techniques, and has an exemplary object to provide a technique that is advantageous for reducing the positional deviation of a pattern transferred onto a substrate. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, an exposure apparatus as one aspect of the present invention is an exposure apparatus that projects a pattern of an original onto a substrate via a projection optical system to expose the substrate, and is characterized in having: a first drive unit that drives at least one optical element that constitutes the projection optical system in a first direction along the optical axis of the projection optical system to change the magnification of the projection optical system; a second drive unit that drives a stage that holds the original or the substrate in the first direction; a control unit that controls the second drive unit to position the stage in the first direction in accordance with the driving of the at least one optical element by the first drive unit; and an index that indicates the interrelationship between a control deviation of the projection optical system and a control deviation of the stage, obtained from the results of measuring the respective positions of the at least one optical element and the stage in the control; and an adjustment unit that adjusts at least one of a first condition set for driving the at least one optical element and a second condition set for driving the stage when a difference between the index and a predetermined reference index exceeds a threshold value.

[0010] Further objects or other aspects of the present invention will become apparent from the following description of the embodiments with reference to the accompanying drawings. Effect of the Invention

[0011] According to the present invention, for example, it is possible to provide a technique that is advantageous for reducing the positional deviation of a pattern transferred onto a substrate. [Brief description of the drawings]

[0012] [Figure 1] 1 is a diagram showing a configuration of an exposure apparatus according to one aspect of the present invention. [Diagram 2] FIG. 4 is a block diagram of a control system related to driving of the substrate stage. [Diagram 3] FIG. 4 is a diagram showing the configuration of a calculator for calculating a synchronization error between the projection optical system and the substrate stage. [Figure 4] FIG. 11 is a block diagram of a control system to which a correction amount for correcting background distortion is added. [Diagram 5] 11A and 11B are diagrams illustrating an example of a correction amount for correcting a positional deviation caused by an exposure apparatus and a correction amount for correcting a positional deviation caused by a process. [Figure 6] FIG. 2 is a diagram showing one shot area on a substrate. [Figure 7] 2 is a diagram showing the correction amount and synchronization error shown in FIG. 1; [Figure 8] 8 is a diagram showing the correction amount and synchronization error in a state in which the control characteristic of the substrate stage has changed from the state shown in FIG. 7. [Figure 9] FIG. 9 is a diagram showing the synchronization errors shown in FIGS. 7 and 8, and the difference between them. [Figure 10] 2 is a flowchart for explaining an exposure operation in the exposure apparatus shown in FIG. [Figure 11] FIG. 2 is a diagram showing a shot area on a substrate, the shot area being the target for measuring the surface position; [Figure 12] FIG. 2 is a diagram showing a shot area on a substrate for which a synchronization error is calculated. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0014] 1 is a diagram showing the configuration of an exposure apparatus EX according to one aspect of the present invention. The exposure apparatus EX is a lithography apparatus that is used in a lithography process, which is a manufacturing process for devices such as semiconductor elements, and forms a pattern on a substrate using an original (reticle or mask).

[0015] In this specification and the accompanying drawings, directions are shown in an XYZ coordinate system in which the direction along the optical axis AX of the projection optical system 101 is defined as the Z axis, and two directions parallel to a plane perpendicular to the Z axis and perpendicular to each other are defined as the X axis and the Y axis. Also, directions parallel to the X axis, Y axis, and Z axis in the XYZ coordinate system are defined as the X direction, Y direction, and Z direction, respectively. Hereinafter, the Z direction may be referred to as the height direction.

[0016] The exposure apparatus EX is a scanning exposure apparatus (scanner) that employs a step-and-scan method in which the original 102 and the substrate 104 are scanned relatively to each other while exposing the substrate (scanning exposure) to light, thereby transferring the pattern of the original 102 to the substrate 104. In this embodiment, the exposure apparatus EX uses a rectangular or arc-shaped slit (exposure slit) as an exposure area, and scans the original 102 and the substrate 104 relatively at high speed to expose a large screen on the substrate with high precision. In this embodiment, the direction in which the original 102 and the substrate 104 are scanned relatively (scanning direction) is the Y direction (+Y direction or -Y direction).

[0017] The exposure apparatus EX, as shown in FIG. 1, has a projection optical system 101, an original stage 103, a substrate stage 105, interferometers 108, 111, and 116, driving units DU1, DU2, and 117, and a control unit 113.

[0018] The projection optical system 101 projects a pattern of an original 102 arranged on an object plane onto a substrate 104 arranged on an image plane. The projection optical system 101 includes multiple optical elements, and is configured, for example, as a reduction optical system (reduction projection lens system). The optical axis AX of the projection optical system 101 is indicated by a dashed line parallel to the Z direction in Fig. 1, and the object plane and image plane of the projection optical system 101 are in a relationship perpendicular to the Z direction.

[0019] The original 102 is held by an original stage 103. The pattern of the original 102 is projected according to the magnification (1 / 4, 1 / 2, 1 / 5, etc.) of the projection optical system 101, and forms an image (pattern image) on the image plane of the projection optical system 101.

[0020] The substrate 104 has a resist (photosensitive agent) disposed (coated) on its surface. A plurality of shot areas having the same pattern structure formed in a previous exposure process are arranged on the substrate 104.

[0021] The substrate stage 105 holds (fixes) the substrate 104 by vacuum suction or electrostatic suction via a chuck. The substrate stage 105 also includes an XY stage that can be driven in the X and Y directions, and can also be driven in the Z direction that is parallel to the optical axis AX of the projection optical system 101. The substrate stage 105 also includes a leveling stage that can be rotated in the θX and θY directions, and a rotation stage that can be rotated in the θZ direction. In other words, the substrate stage 105 includes a drive unit DU1 (second drive unit) that drives the substrate stage 105 in the X, Y, Z, θX, θY, and θZ directions. In this way, the substrate stage 105 constitutes a six-axis drive system (correction system) for matching the pattern image of the original 102 with the shot area on the substrate. The X position, Y position, Z position, θX position, θY position, and θZ position (position information) of the substrate stage 105 are constantly measured by a mirror 110 and an interferometer 111 provided on the substrate stage 105.

[0022] In this embodiment, the projection optical system 101 is provided with a driving unit 117 (first driving unit) that drives at least one optical element constituting the projection optical system 101, for example, a projection lens, in the Z direction, which is a direction (first direction) along the optical axis AX of the projection optical system 101. The driving unit 117 may drive all the projection lenses constituting the projection optical system 101, i.e., the entire projection optical system 101, or may drive each individual projection lens constituting the projection optical system 101. Hereinafter, the entire projection optical system 101, i.e., all the projection lenses and each individual projection lens of the projection optical system 101 will be collectively referred to as the projection optical system 101. By adjusting the position of the projection optical system 101 in the Z direction by the driving unit 117, it is possible to improve the magnification and correct distortion errors while reducing various aberrations of the projection optical system 101. In this way, the driving unit 117 has a function of changing the magnification of the projection optical system 101 by driving the projection optical system 101. The Z position (position information) of the projection optical system 101 (or the projection lens) is constantly measured by a mirror 115 and an interferometer 116 provided in the projection optical system 101.

[0023] The original stage 103 scans (drives) the original 102, for example, at a constant speed along the Y direction (arrow 103a) in a plane perpendicular to the optical axis AX of the projection optical system 101. Note that with respect to the X direction, the original 102 is scanned so as to always maintain a target position. In this manner, the original stage 103 includes a driver DU2 (second driver) that drives the original stage 103 in the Y direction. Note that the driver DU2 is configured to drive the original stage 103 not only in the Y direction, but also in the X direction, Z direction, θX direction, θY direction, and θZ direction. The X position, Y position, and Z position (position information) of the original stage 103 are constantly measured by a mirror 107 and an interferometer 108 provided on the original stage 103.

[0024] The illumination optical system 106 illuminates the original 102 with pulsed light emitted from a light source such as an excimer laser. The illumination optical system 106 includes a beam shaping optical system, an optical integrator, a collimator, a mirror, and the like, and is configured to efficiently transmit or reflect pulsed light in the far ultraviolet region. For example, the beam shaping optical system shapes the cross-sectional shape (dimensions) of the incident light into a desired shape. The optical integrator uniformizes the light distribution characteristics of the light beam, and illuminates the original 102 with uniform illuminance. The illumination optical system 106 sets a rectangular illumination area by a masking blade in accordance with the size (shot size) of the shot area of ​​the substrate. The pattern of the original 102 partially illuminated by the illumination area is projected onto the substrate 104 via the projection optical system 101.

[0025] The control unit 113 is configured, for example, by a computer (information processing device) including a CPU, a memory, etc. The control unit 113 generally controls each unit of the exposure apparatus EX in accordance with a program stored in a storage unit or the like to operate the exposure apparatus EX. In addition, as described below, the control unit 113 also functions as an adjustment unit that adjusts at least one of a setting (first condition) related to driving the projection optical system 101 in the Z direction and a setting (second condition) related to driving the substrate stage 105 (original stage 103) in the Z direction.

[0026] In this embodiment, the control unit 113 controls the entire operation system described below in order to form a pattern image of the original 102 on a predetermined area of ​​the substrate 104. For example, the control unit 113 adjusts the position in the XY plane (X position, Y position, and θZ position) and the position in the Z direction (θX position, θY position, and Z position). The control unit 113 also controls the driving of the original stage 103 and the substrate stage 105 so that the original 102 and the substrate 104 are scanned synchronously with respect to the projection optical system 101. In this way, the control unit 113 performs scanning exposure in which the pattern of the original 102 is projected onto the substrate 104 via the projection optical system 101 to expose the substrate 104. The control unit 113 may also be composed of a sub-control unit (e.g., a projection optical system control unit, an original stage control unit, and a substrate stage control unit) that controls each unit constituting the exposure apparatus EX, and a main control unit that controls each sub-control unit.

[0027] When the original stage 103 is scanned in the direction of the arrow 103a (+Y direction), the substrate 104 is scanned in the direction of the arrow 105a (-Y direction) at a speed corrected according to the magnification of the projection optical system 101. The scanning speed of the original stage 103 is determined based on the width in the scanning direction of the masking blade in the illumination optical system 106 and the sensitivity of the resist arranged on the substrate 104 so as to be advantageous for productivity.

[0028] In aligning the pattern of the original 102 in the XY plane, the control unit 113 generates (calculates) control data based on position information obtained from each of the interferometers 108 and 111 and position information of the substrate 104 obtained from an alignment scope (not shown). The control unit 113 controls the original stage 103 and the substrate stage 105 based on this control data.

[0029] FIG. 2 is a block diagram of a control system related to driving the substrate stage 105. In this embodiment, an example in which PID (Proportional-Integral-Differential) control is applied will be described. The control unit 113 includes a calculator 30, a PID compensator 31, and a filter 31. Note that, although FIG. 2 assumes a control system block diagram for the Z-direction position of the substrate stage 105, similar block diagrams are also used for the control systems for the X-direction position, the Y-direction position, and the θZ-direction position. Also, although a control system block diagram related to driving the substrate stage 105 is shown here, the same is true for a control system block diagram related to driving the projection optical system 101.

[0030] 2, the substrate stage control target value is specified (set) by the control unit 113, and is a value indicating the position (Z position) where the substrate stage 105 should be located next. The current position of the substrate stage 105 is measured by the interferometer 111 and acquired as position information. The calculator 30 calculates the difference between the substrate stage control target value and the position information obtained by the interferometer 111 as a deviation amount (control deviation or position deviation) from the substrate stage control target value. The PID compensator 31 applies P gain (proportional gain), I gain (integral gain), and D gain (differential gain), which are control parameters of PID control, to the deviation amount calculated by the calculator 30, and calculates a drive command value for the substrate stage 105 (drive unit DU1). For example, a filter 32 such as a low-pass filter may be applied to the drive command value calculated by the PID compensator 31. The substrate stage 105 is driven and positioned toward the substrate stage control target value by the drive command value that has passed through the filter 32. In this manner, the substrate stage 105 is feedback-controlled by the control system shown in FIG.

[0031] 3 is a diagram showing the configuration of a calculator for calculating a synchronization error between the projection optical system 101 and the substrate stage 105. The synchronization error means a relative driving deviation amount between the projection optical system 101 and the substrate stage 105 in control of positioning the substrate stage 105 in the Z direction by the driver DU1 in response to driving of the projection optical system 101 by the driver 117. The controller 113 calculates the synchronization error between the projection optical system 101 and the substrate stage 105 based on the control deviation of the projection optical system 101 and the control deviation of the substrate stage 105.

[0032] The control target value of the projection optical system 101 and position information obtained by the interferometer 116 (projection optical system interferometer measurement value) are input to a projection optical system difference calculator 41, which serves as a functional block of the control unit 113. The projection optical system difference calculator 41 calculates the difference between the control target value of the projection optical system 101 and the projection optical system interferometer measurement value, i.e., the control deviation of the projection optical system 101.

[0033] Similarly, the control target value of the substrate stage 105 and position information obtained by the interferometer 111 (substrate stage interferometer measurement value) are input to a substrate stage difference calculator 42 which serves as a functional block of the control unit 113. The substrate stage difference calculator 42 calculates the difference between the control target value of the substrate stage 105 and the substrate stage interferometer measurement value, i.e., the control deviation of the substrate stage 105.

[0034] The control deviation of the projection optical system 101 obtained by the projection optical system difference calculator 41 and the control deviation of the substrate stage 105 obtained by the substrate stage difference calculator 42 are input to a synchronization error calculator 43 as a functional block of the control unit 113. The synchronization error calculator 43 calculates the difference between a value (control deviation) obtained by correcting the control deviation of the projection optical system 101 with a magnification according to the characteristics of the projection optical system 101 and the control deviation of the substrate stage 105, that is, a synchronization error. The synchronization error is equivalent to a positional deviation of a pattern image when the pattern of the original 102 is projected onto the substrate 104, that is, when the substrate 104 is exposed. The magnification according to the characteristics of the projection optical system 101 is a known value for converting the control deviation of the projection optical system 101 into a positional deviation amount of a pattern image when the substrate 104 is exposed. The magnification according to the characteristics of the projection optical system 101 can be determined by a design value of the projection optical system 101, but may also be determined by an actual measurement value obtained by measuring the control deviation of the projection optical system 101 and the positional deviation amount of the pattern image transferred onto the substrate 104, for example. In the following, the control deviation corrected with the magnification according to the characteristics of the projection optical system 101 will be referred to as the control deviation of the projection optical system 101.

[0035] The exposure apparatus EX in this embodiment employs a master-slave control method in which the projection optical system 101 is used as a master and the substrate stage 105 and the original stage 103 are used as slaves. Specifically, the control deviation of the projection optical system 101 is added to a control target value in the Z direction of the substrate stage 105. Note that there is a magnification according to the characteristics of the projection optical system 101 between the change in the image position on the substrate with respect to the drive of the projection optical system 101 and the change in the image position on the substrate with respect to the drive of the substrate stage 105. Therefore, a magnification (gain) according to the characteristics of the projection optical system 101 is multiplied to the control deviation of the projection optical system 101 so that the change in the image position on the substrate with respect to the drive of the projection optical system 101 coincides. In this way, PID control is performed using the control deviation corrected with the magnification according to the characteristics of the projection optical system 101, thereby correcting the difference between the control deviation of the projection optical system 101 and the control deviation of the substrate stage 105, i.e., the synchronization error.

[0036] In this embodiment, the synchronization error is calculated based on the control deviation of the projection optical system 101 and the control deviation of the substrate stage 105, but the synchronization error may be calculated based on the control deviation of the projection optical system 101 and the control deviation of the original stage 103. In this case, the control target value of the original stage 103 and position information (original stage interferometer measurement value) obtained by the interferometer 116 are input to an original stage difference calculator (control unit 113). The original stage difference calculator calculates the difference between the control target value of the original stage 103 and the original stage interferometer measurement value, i.e., the control deviation of the original stage 103. Then, the control deviation of the projection optical system 101 obtained by the projection optical system difference calculator 41 and the control deviation of the original stage 103 obtained by the original stage difference calculator are input to a synchronization error calculator (control unit 113). The synchronization error calculator calculates the difference between the control deviation of the projection optical system 101 and the control deviation of the original stage 103, i.e., the synchronization error.

[0037] 4(a) and 4(b) are control system block diagrams in which a correction amount (substrate distortion correction amount) for correcting the above-mentioned substrate distortion is added to the control system block diagram regarding the driving of each of the projection optical system 101 and the substrate stage 105. The projection optical system 101 is feedback-controlled by the control system shown in FIG. 4(a), and the substrate stage 105 is feedback-controlled by the control system shown in FIG. 4(b). Before explaining the control system block diagrams shown in FIG. 4(a) and FIG. 4(b), the substrate distortion will be explained. As described above, the substrate distortion is a process-induced positional deviation, which is distinguished from the exposure device-induced positional deviation. FIG. 5 is a diagram showing an example of a correction amount for correcting the exposure device-induced positional deviation and a correction amount for correcting the process-induced positional deviation. In FIG. 5, the horizontal axis (Y) indicates the position in the scanning direction with the center of the shot area of ​​the substrate 104 set to 0, and the unit is mm. The vertical axis (Comp) indicates the correction amount for correcting the exposure device-induced positional deviation and the process-induced substrate distortion. The correction amount is, for example, a correction amount for correcting a deviation relative to a position in the scanning direction within a shot area. The unit of the vertical axis is nm, and for example, when the vertical axis is a positive value, the drive target value of the projection optical system 101 is set (changed) taking into consideration a value for correcting a deviation of +Comp. Note that in Fig. 5, the graph shown by the solid line indicates the correction amount of the complicated process-induced base distortion, and the graph shown by the dashed dotted line indicates the correction amount of the exposure apparatus-induced position deviation and the conventional process-induced base distortion.

[0038] 4(a) is a block diagram of a control system related to driving the projection optical system 101 in the Z direction. In order to correct the above-mentioned base distortion, a correction amount is added to the control target value (projection optical system control target value) of the projection optical system 101. By adding the correction amount to the projection optical system control target value, the magnification of the pattern image projected onto the substrate 104 changes, making it possible to correct the base distortion.

[0039] FIG. 4B is a block diagram of a control system related to driving the substrate stage 105 in the Z direction. In order to drive (correctively drive) the substrate stage 105 in the Z direction in response to a change in the control target value of the projection optical system 101, a correction amount is added to the control target value of the substrate stage 105 (substrate stage control target value). By adding the correction amount to the substrate stage control target value, it becomes possible to match the imaging position with the optimal imaging position on the substrate. As described above, there is a magnification according to the characteristics of the projection optical system 101 between the change in the imaging position on the substrate with respect to the driving of the projection optical system 101 and the change in the imaging position on the substrate with respect to the driving of the substrate stage 105. Therefore, the correction amount added to the substrate stage control target value is multiplied by a magnification (gain) according to the characteristics of the projection optical system 101 so that the change in the imaging position on the substrate with respect to the driving of the projection optical system 101 matches.

[0040] The correction amount varies with respect to the position in the scanning direction in the shot area, for example, as shown by a solid line in FIG. 5, and is set (specified) for each position in the scanning direction by the control unit 113. FIG. 6 is a diagram showing one shot area 601 on a substrate. Six chips are formed in the shot area 601 along the Y direction, which is the scanning direction. In FIG. 6, the size of the shot area 601 in the Y direction is, for example, 20 mm, and periodic base distortion occurs for each chip. Therefore, the correction amount shown in FIG. 5 has a periodic tendency according to the chip size. Note that the correction amount may be obtained in consideration of the control characteristics of the stage, including the dynamic characteristics of the actuator of the stage, as disclosed in Patent Document 1. In addition, the correction amount is set so that the base distortion is corrected by a combination of the correction amount to be added to the projection optical system control target value and the correction amount to be added to the substrate stage control target value.

[0041] Fig. 7 is a diagram showing the correction amount shown in Fig. 5 and the synchronization error between the projection optical system 101 and the substrate stage 105. Referring to Fig. 7, exposure starts from a position of -10 mm in the Y direction and ends at a position of +10 mm. In Fig. 7, the graph shown by the solid line is the correction amount, and the graph shown by the dashed line is the synchronization error between the projection optical system 101 and the substrate stage 105. The synchronization error tends to increase and decrease as the correction amount increases and decreases.

[0042] As described above, the synchronization error between the projection optical system 101 and the substrate stage 105 results in a positional deviation of the pattern image when the pattern of the original 102 is projected onto the substrate 104, i.e., when the substrate 104 is exposed to light. Whether or not the positional deviation of the pattern image will cause a defect in the semiconductor element depends on the positioning accuracy required for the semiconductor element. The amount of correction varies depending on which step of the semiconductor manufacturing process is exposed. As described above, the tolerance for the positional deviation of the pattern image and the amount of correction are not unique, so it is difficult to judge (decide) whether or not the semiconductor element will be defective based only on the magnitude (amount of error) of the synchronization error between the projection optical system 101 and the substrate stage 105.

[0043] FIG. 8 is a diagram showing the correction amount in a state where the control characteristics of the substrate stage 105 have changed from the state shown in FIG. 7, and the synchronization error between the projection optical system 101 and the substrate stage 105. The correction amount shown in FIG. 8 is shown by a solid line and is the same as the correction amount shown in FIG. 7. By repeating the exposure operation, the structure of each stage is deformed and errors occur in the interferometers 108 and 111 due to heat caused by the light (pulsed light) from the illumination optical system 106 and heat caused by driving the original stage 103 and the substrate stage 105. Such deformation and error cause a change in the control characteristics of the original stage 103 and the substrate stage 105. When the change in the control characteristics of each stage is large, each stage is driven to a position having an error with respect to the position to which it should be driven, that is, a position shifted from the target position, and the positioning accuracy is reduced. Referring to FIG. 8, the control deviation of the substrate stage 105 in the Y direction is increased in the range from -10 mm to 0 mm, which is the position where exposure starts, and as shown by the dashed line, the synchronization error between the projection optical system 101 and the substrate stage 105 is increased.

[0044] 8 also occurs when the control characteristics of the projection optical system 101 change. Repeated exposure operations cause an error in the interferometer 116 due to heat from the light from the illumination optical system 106, heat from driving the projection optical system 101 and the projection lens, etc. Such an error causes a change in the control characteristics of the projection optical system 101, and as described above, the projection optical system 101 and the projection lens are driven to a position that has an error with respect to the position to which they should be driven, that is, a position shifted from the target position, resulting in a decrease in positioning accuracy.

[0045] 9 is a diagram showing the synchronization error between the projection optical system 101 and the substrate stage 105 shown in each of FIGS. 7 and 8, and the difference therebetween. In FIG. 9, 701 is the synchronization error shown in FIG. 7, that is, the synchronization error before the control characteristic of the substrate stage 105 changes, and 801 is the synchronization error shown in FIG. 8, that is, the synchronization error after the control characteristic of the substrate stage 105 changes. 901 is the difference between the synchronization error 701 and the synchronization error 801. For example, even if the synchronization error 701 occurs, the manufactured semiconductor element is a good product, and if the synchronization error 801 occurs, the manufactured semiconductor element is a defective product. In this case, when manufacturing semiconductor elements having the same characteristics, if the difference between the synchronization error generated by exposure and the synchronization error 701 (a synchronization error that is a predetermined reference) is smaller than the difference 901, the manufactured semiconductor element is more likely to be a good product. In this way, by monitoring the difference (fluctuation) between the synchronization error and the reference synchronization error, it is possible to determine whether an unacceptable position shift of the pattern image will occur when the control characteristics of the substrate stage 105 (original stage 103) change.

[0046] In this embodiment, when the difference between the synchronization error between the projection optical system 101 and the substrate stage 105 and the reference synchronization error exceeds a threshold, the control unit 113 adjusts the control parameters of the PID compensator 31 of the control system of the substrate stage 105 so that the difference is equal to or smaller than the threshold. Also, instead of the control system of the substrate stage 105, the control parameters of the PID compensator of the control system of the projection optical system 101 may be adjusted. As described above, the control parameters of the PID compensator of the control system of the substrate stage 105 and the projection optical system 101 include the P gain, the I gain, and the D gain. For example, by adjusting the P gain, it is possible to shorten the rise time, by adjusting the I gain, it is possible to reduce the steady-state deviation, and by adjusting the D gain, it is possible to suppress the vibration component. Therefore, by adjusting the control parameters of the PID compensator, it is possible to reduce the synchronization error between the projection optical system 101 and the substrate stage 105 and to reduce the difference from the reference synchronization error.

[0047] Furthermore, when the difference between the synchronization error between the projection optical system 101 and the substrate stage 105 and the reference synchronization error exceeds a threshold, the control unit 113 may adjust the driving conditions set for driving the substrate stage 105 (drive unit DU1) so that the difference is equal to or smaller than the threshold. Similarly, instead of the driving conditions set for driving the substrate stage 105, the control unit 113 may adjust the driving conditions set for driving the projection optical system 101 (drive unit DU2). The driving conditions include, for example, at least one of the driving speed, acceleration, jerk, and driving trajectory. Specifically, the control unit 113 reduces the scanning speed of the original stage 103 and the substrate stage 105, and reduces the driving speed of the projection optical system 101 in the Z direction and the driving speed of the substrate stage 105 in the Z direction. By reducing the scanning speed of the original stage 103 and the substrate stage 105, the time required to expose one shot area on the substrate (exposure time) increases. When the exposure time increases, the driving time in the Z direction of the projection optical system 101 and the substrate stage 105 also increases during the exposure of one shot area. Therefore, it is possible to reduce the driving speed of the projection optical system 101 and the substrate stage 105. By reducing the driving speed of the projection optical system 101 and the substrate stage 105, the control deviation that occurs depending on the driving speed is reduced, and therefore it is possible to reduce the difference between the synchronization error between the projection optical system 101 and the substrate stage 105 and the reference synchronization error.

[0048] Furthermore, the control unit 113 may stop the exposure (exposure operation) of the substrate 104 when the difference between the synchronization error between the projection optical system 101 and the substrate stage 105 and the reference synchronization error exceeds a threshold value. As described above, even if the control parameters of the PID compensator and the drive conditions set for driving the projection optical system 101 and the substrate stage 105 are adjusted, the difference between the synchronization error between the projection optical system 101 and the substrate stage 105 and the reference synchronization error may exceed the threshold value. In such a case, since a failure or poor adjustment of hardware including the projection optical system 101 and the substrate stage 105 is considered, it is advisable to stop the exposure of the substrate 104 and inspect the abnormal portion.

[0049] In this manner, in this embodiment, when the difference between the index (difference 901) indicating the interrelationship between the control deviation of the projection optical system 101 and the control deviation of the substrate stage 105 and the reference index (synchronization error 701) exceeds a threshold value, the driving of the projection optical system 101 and the substrate stage 105 is adjusted. Specifically, at least one of the first condition set for driving the projection optical system 101 in the Z direction and the second condition set for driving the substrate stage 105 is adjusted. Note that, as described above, the first condition and the second condition include the control parameters of the PID compensator and the driving conditions of each driving unit. This allows the process-induced base distortion to be corrected appropriately and without excess or deficiency even when the control characteristics of the projection optical system 101 and the substrate stage 105 (original stage 103) change. Therefore, the exposure apparatus EX is advantageous in reducing the positional deviation of the pattern (image) transferred to the substrate 104.

[0050] Next, the operation of the exposure apparatus EX, that is, the exposure operation (exposure process), will be described with reference to Fig. 10. As described above, the exposure operation is performed by the control unit 113 comprehensively controlling each part of the exposure apparatus EX.

[0051] In S1, the substrate 104 is carried into the exposure apparatus EX. Specifically, the substrate 104 is carried by a carrying hand (not shown), and the substrate 104 is held by the substrate stage 105.

[0052] In S2, pre-alignment (pre-measurement and correction) for global alignment is performed. Specifically, a low-magnification field alignment optical system (not shown) is used to measure and correct the amount of deviation such as a rotation error of the substrate 104 so that the alignment mark on the substrate falls within the measurement range of a high-magnification field alignment optical system (not shown) used in global alignment.

[0053] In S3, a global tilt is performed. Specifically, a surface position measuring instrument (not shown) is used to measure the surface heights (surface positions) of a plurality of measurement points on the substrate 104 for a plurality of shot regions 1101 of the substrate 104, as shown in Fig. 11. Then, based on the surface positions measured by the surface position measuring instrument, the overall tilt of the substrate 104 is calculated and corrected.

[0054] In S4, a pre-adjustment is performed (pre-scan) for measuring the surface position of the substrate 104 during exposure (while the original stage 103 and the substrate stage 105 are being driven). The pre-adjustment includes, for example, adjustment of the amount of light from the light source of a surface position measuring instrument as disclosed in Japanese Patent Application Laid-Open No. 10-64980, detection of a correction value as disclosed in Japanese Patent Application Laid-Open No. 9-45608, and the like.

[0055] Also, in S4, as described above, a synchronization error between the control deviation of the projection optical system 101 and the control deviation of the substrate stage 105 is obtained and evaluated. Specifically, as shown in FIG. 12, the projection optical system 101 and the substrate stage 105 are driven in synchronization with each other with respect to a plurality of shot regions 1201 of the substrate 104, and a synchronization error between the projection optical system 101 and the substrate stage 105 is calculated as described above. Then, the synchronization error between the projection optical system 101 and the substrate stage 105 is associated with a first condition related to the driving of the projection optical system 101 and a second condition related to the driving of the substrate stage 105, and stored in a storage unit of the exposure apparatus EX, for example, a non-volatile memory of the control unit 113. Here, it is determined whether or not a synchronization error corresponding to (the same as) the first condition and the second condition is stored in the storage unit. If a synchronization error corresponding to the first condition and the second condition is stored in the storage unit, a difference between the synchronization error stored in the storage unit and the synchronization error calculated in S4 is calculated. If the difference is equal to or smaller than a threshold value, the process proceeds to S5. On the other hand, if the difference exceeds the threshold, the control parameters of the PID compensator of the control system of the projection optical system 101 or the substrate stage 105 are adjusted as described above. After adjusting the control parameters of the PID compensator, the projection optical system 101 and the substrate stage 105 are driven again in synchronization with each other for the multiple shot regions 1201 of the substrate 104, and a synchronization error between the projection optical system 101 and the substrate stage 105 is calculated. The difference between the synchronization error and the synchronization error stored in the storage unit is calculated and compared with the threshold. If the difference is equal to or smaller than the threshold, the process proceeds to S5. In this manner, the adjustment of the control parameters of the PID compensator of the control system of the projection optical system 101 or the substrate stage 105 is repeated so that the difference between the synchronization error calculated in S4 and the synchronization error stored in the storage unit is equal to or smaller than the threshold. Note that if the number of times the control parameters of the PID compensator of the control system of the projection optical system 101 or the substrate stage 105 are adjusted exceeds the upper limit number of times, the substrate 104 is unloaded from the exposure apparatus EX without going through the subsequent steps (i.e., the exposure is stopped).

[0056] In S5, the projection optical system 101 is corrected (adjusted). Specifically, the inclination, field curvature, and the like of the projection optical system 101 are obtained using a light amount sensor and a reference mark (not shown) arranged on the substrate stage 105 and a reference plate (not shown) arranged on the original stage 103. For example, a change in the amount of exposure light when the substrate stage 105 is driven in the X direction, Y direction, and Z direction is measured by a light amount sensor arranged on the substrate stage 105. Then, based on the change in the amount of exposure light, the amount of deviation of the reference mark with respect to the reference plate is obtained, and the projection optical system 101 is corrected.

[0057] In S6, global alignment is performed. Specifically, the alignment mark of the substrate 104 is detected using a high-magnification field alignment optical system, and the overall amount of misalignment of the substrate 104 and the amount of misalignment common to each shot area are obtained. In order to detect the alignment mark with high accuracy, the alignment mark must be located at a position (best contrast position) where the contrast of the alignment mark is the best contrast. The best contrast position can be measured using a surface position measurement device and a high-magnification field alignment optical system. For example, the substrate stage 105 is driven to a predetermined height (position in the Z direction), the contrast is measured using the high-magnification field alignment optical system, and the position of the substrate 104 in the Z direction is measured using the surface position measurement device. At this time, the measurement results of the contrast corresponding to each position in the Z direction of the substrate stage 105 and the measurement results of the position in the Z direction of the substrate 104 are stored in association with each other. Then, based on the measurement results of the contrasts, the position in the Z direction of the substrate stage 105 where the contrast is the highest is obtained and set as the best contrast position.

[0058] In S7, exposure (scanning exposure) is performed on each shot area of ​​the substrate 104. Specifically, a surface position measuring device measures the surface position of each shot area of ​​the substrate 104, a drive target value to an optimal exposure position is calculated based on the measurement result, and each shot area of ​​the substrate 104 is exposed while driving the substrate stage 105 to the optimal exposure position.

[0059] In S8, the substrate 104 is carried out from the exposure apparatus EX. Specifically, the substrate 104, on which each shot area has been exposed, is received from the substrate stage 105 by a transport hand (not shown) and transported to the outside of the exposure apparatus EX.

[0060] In S4, the synchronization error between the projection optical system 101 and the substrate stage 105 needs to be stored in advance in a storage unit of the exposure apparatus EX. The synchronization error to be stored in the storage unit may be, for example, a synchronization error calculated for a substrate that was previously manufactured under the same conditions and turned out to be a good product. Alternatively, a synchronization error calculated immediately after the exposure apparatus EX is installed or immediately after the substrate stage 105 is adjusted may be selected.

[0061] In addition, in S4, a first condition regarding the driving of the projection optical system 101 and a second condition regarding the driving of the substrate stage 105 may be adjusted by setting a plurality of thresholds. For example, consider a case where a first threshold, a second threshold greater than the first threshold, and a third threshold greater than the second threshold are set as thresholds. Then, if the difference between the synchronization error calculated in S4 and the synchronization error stored in the storage unit exceeds the first threshold and is equal to or smaller than the second threshold, the control parameters of the PID compensator of the control system of the projection optical system 101 or the substrate stage 105 are adjusted as described above. Also, if the difference between the synchronization error calculated in S4 and the synchronization error stored in the storage unit exceeds the second threshold and is equal to or smaller than the third threshold, the scanning speed of the original stage 103 and the substrate stage 105 and the driving speed in the Z direction of the projection optical system 101 and the substrate stage 105 are reduced. Furthermore, if the difference between the synchronization error calculated in S4 and the synchronization error stored in the storage unit exceeds the third threshold, the substrate 104 is unloaded from the exposure apparatus EX without going through the subsequent steps (by stopping the exposure).

[0062] In addition, in S4, a plurality of thresholds (first threshold<second threshold<third threshold) may be set to adjust the first condition for driving the projection optical system 101 and the second condition for driving the substrate stage 105 stepwise. In this case, if the difference between the synchronization error calculated in S4 and the synchronization error stored in the storage unit exceeds the first threshold, the control parameters of the PID compensator of the control system of the projection optical system 101 or the substrate stage 105 are adjusted as described above. If the difference between the synchronization error calculated again and the synchronization error stored in the storage unit after adjusting the control parameters of the PID compensator exceeds the first threshold, the drive speed in the Z direction of the projection optical system 101 and the substrate stage 105 is reduced (the drive conditions are adjusted). If the difference between the synchronization error calculated again and the synchronization error stored in the storage unit exceeds the second threshold after reducing the drive speed in the Z direction of the projection optical system 101 and the substrate stage 105, the drive speed in the Z direction of the projection optical system 101 and the substrate stage 105 is further reduced. After the drive speed in the Z direction of the projection optical system 101 and the substrate stage 105 is further reduced, if the difference between the recalculated synchronization error and the synchronization error stored in the storage unit exceeds a third threshold value, the substrate 104 is unloaded from the exposure apparatus EX without going through the subsequent steps (exposure is stopped). In this way, by gradually adjusting the first condition related to the drive of the projection optical system 101 and the second condition related to the drive of the substrate stage 105, it is possible to suppress a decrease in productivity due to a decrease in drive speed or a stop of exposure.

[0063] In this embodiment, in S4, the projection optical system 101 and the substrate stage 105 are driven in synchronization with each other for a plurality of shot areas 1201 on the substrate 104, and a synchronization error between the projection optical system 101 and the substrate stage 105 is calculated, but this is not limited to the above. The projection optical system 101 and the substrate stage 105 may be driven in synchronization with each other for shot areas at a predetermined fixed interval among the plurality of shot areas 1201, and a synchronization error between the projection optical system 101 and the substrate stage 105 may be calculated. Also, a synchronization error between the projection optical system 101 and the substrate stage 105 may be calculated only for the leading substrate among a plurality of substrates (including a lot) in the same manufacturing process, or after a fixed time has elapsed.

[0064] In this embodiment, the synchronization error based on the control deviation of the projection optical system 101 and the control deviation of the substrate stage 105 has been described as an example, but the same applies to the synchronization error based on the control deviation of the projection optical system 101 and the control deviation of the original stage 103. In other words, the substrate stage 105 can be replaced with the original stage 103.

[0065] The method for manufacturing an article according to the embodiment of the present invention is suitable for manufacturing articles such as semiconductor elements, liquid crystal display elements, flat panel displays, and MEMS. The manufacturing method includes a step of exposing a substrate coated with a photosensitive agent using the above-mentioned exposure apparatus EX, and a step of developing the exposed photosensitive agent. In addition, an etching step, an ion implantation step, and the like are performed on the substrate using the developed pattern of the photosensitive agent as a mask, and a circuit pattern is formed on the substrate. These steps of exposure, development, etching, and the like are repeated to form a circuit pattern consisting of multiple layers on the substrate. In a post-process, dicing (processing) is performed on the substrate on which the circuit pattern is formed, and chip mounting, bonding, and inspection steps are performed. In addition, the manufacturing method may include other well-known steps (oxidation, film formation, deposition, doping, planarization, resist peeling, and the like). The method for manufacturing an article according to the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article compared to the conventional methods.

[0066] The disclosure of this specification includes the following exposure apparatus and method for manufacturing an article.

[0067] (Item 1) 1. An exposure apparatus that projects a pattern of an original onto a substrate via a projection optical system to expose the substrate, comprising: a first drive unit that drives at least one optical element that constitutes the projection optical system in a first direction along an optical axis of the projection optical system to change a magnification of the projection optical system; a second drive unit that drives a stage that holds the original or the substrate in the first direction; a control unit that performs control to position the stage in the first direction by the second driving unit in response to driving of the at least one optical element by the first driving unit; an adjustment unit that adjusts at least one of a first condition set for driving the at least one optical element and a second condition set for driving the stage when a difference between an index indicating a correlation between a control deviation of the projection optical system and a control deviation of the stage, which is obtained from a result of measuring the positions of the at least one optical element and the stage in the control, and a predetermined reference index of the index, exceeds a threshold value; An exposure apparatus comprising:

[0068] (Item 2) 2. The exposure apparatus according to item 1, wherein the index is a difference between a value obtained by correcting a control deviation of the projection optical system with a magnification of the projection optical system and a control deviation of the stage.

[0069] (Item 3) 2. The exposure apparatus according to item 1, wherein the index is a difference between a value obtained by multiplying the control deviation of the projection optical system by a magnification of the projection optical system and the control deviation of the stage.

[0070] (Item 4) the control unit includes a first compensator for feedback-controlling the projection optical system based on a control deviation of the projection optical system, and a second compensator for feedback-controlling the stage based on a control deviation of the stage, the first condition includes a control parameter of the first compensator; the second condition includes a control parameter of the second compensator. 4. The exposure apparatus according to claim 1, wherein:

[0071] (Item 5) the first compensator and the second compensator include a PID compensator; The control parameters include a P gain, an I gain, and a D gain of the PID compensator. 5. The exposure apparatus according to item 4,

[0072] (Item 6) the first condition includes a drive condition set in the first drive unit, the second condition includes a drive condition set in the second drive unit; 5. The exposure apparatus according to item 4,

[0073] (Item 7) 7. The exposure apparatus according to item 6, wherein the drive conditions include at least one of a drive speed, an acceleration, a jerk, and a drive trajectory.

[0074] (Item 8) The threshold values ​​include a first threshold value and a second threshold value that is greater than the first threshold value; When the difference exceeds the first threshold, the adjustment unit adjusts the control parameter; If the difference exceeds the first threshold value after adjusting the control parameter, the adjustment unit adjusts the drive condition; If the difference exceeds the second threshold value after adjusting the driving condition, the adjustment unit further adjusts the driving condition. 7. The exposure apparatus according to item 6,

[0075] (Item 9) the thresholds include a third threshold greater than the second threshold, after further adjusting the driving conditions, stopping exposure of the substrate if the difference exceeds the third threshold value; 9. The exposure apparatus according to item 8,

[0076] (Item 10) 10. The exposure apparatus according to any one of items 1 to 9, wherein the adjustment unit adjusts the at least one of the conditions so that the difference is equal to or less than the threshold value.

[0077] (Item 11) Exposing a substrate using the exposure apparatus according to any one of items 1 to 10; developing the exposed substrate; A method for producing an article, comprising the steps of:

[0078] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0079] 101: Projection optical system 102: Original 103: Original stage 104: Substrate 105: Substrate stage 113: Control unit 117, DU1, DU2: Drive unit EX: Exposure device

Claims

1. 1. An exposure apparatus that projects a pattern of an original onto a substrate via a projection optical system to expose the substrate, comprising: a first drive unit that drives at least one optical element that constitutes the projection optical system in a first direction along an optical axis of the projection optical system to change a magnification of the projection optical system; a second drive unit that drives a stage that holds the original or the substrate in the first direction; a control unit that performs control to position the stage in the first direction by the second driving unit in response to driving of the at least one optical element by the first driving unit; an adjustment unit that adjusts at least one of a first condition set for driving the at least one optical element and a second condition set for driving the stage when an index indicating a correlation between a control deviation of the projection optical system and a control deviation of the stage, the control deviation being obtained from a result of measuring the positions of the at least one optical element and the stage in the control, and a difference between the index and a predetermined reference index exceeds a threshold value; An exposure apparatus comprising:

2. 2. The exposure apparatus according to claim 1, wherein the index is a difference between a value obtained by correcting a control deviation of the projection optical system with a magnification of the projection optical system and a control deviation of the stage.

3. 2. The exposure apparatus according to claim 1, wherein the index is a difference between a value obtained by multiplying a control deviation of the projection optical system by a magnification of the projection optical system, and a control deviation of the stage.

4. the control unit includes a first compensator for feedback-controlling the projection optical system based on a control deviation of the projection optical system, and a second compensator for feedback-controlling the stage based on a control deviation of the stage, the first condition includes a control parameter of the first compensator; the second condition includes a control parameter of the second compensator.

2. The exposure apparatus according to claim 1.

5. the first compensator and the second compensator include a PID compensator; The control parameters include a P gain, an I gain, and a D gain of the PID compensator.

5. The exposure apparatus according to claim 4.

6. the first condition includes a drive condition set in the first drive unit, the second condition includes a drive condition set in the second drive unit; 5. The exposure apparatus according to claim 4.

7. 7. The exposure apparatus according to claim 6, wherein the drive conditions include at least one of a drive speed, an acceleration, a jerk, and a drive trajectory.

8. The threshold value includes a first threshold value and a second threshold value that is greater than the first threshold value, When the difference exceeds the first threshold, the adjustment unit adjusts the control parameter; If the difference exceeds the first threshold value after adjusting the control parameter, the adjustment unit adjusts the drive condition; If the difference exceeds the second threshold value after adjusting the driving condition, the adjustment unit further adjusts the driving condition.

7. An exposure apparatus according to claim 6.

9. the threshold value includes a third threshold value that is greater than the second threshold value; after further adjusting the driving conditions, if the difference exceeds the third threshold, stopping exposure of the substrate; 9. An exposure apparatus according to claim 8.

10. 2. The exposure apparatus according to claim 1, wherein the adjustment unit adjusts the at least one of the conditions so that the difference is equal to or smaller than the threshold value.

11. exposing a substrate using an exposure apparatus according to any one of claims 1 to 10; developing the exposed substrate; A method for producing an article, comprising the steps of:

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