JP7312053B2 - Exposure apparatus and article manufacturing method - Google Patents

Description

The present invention relates to an exposure apparatus and an article manufacturing method.

2. Description of the Related Art As one of the apparatuses used in the manufacturing process (lithography process) of semiconductor devices and the like, an exposure apparatus is known that performs scanning exposure of a shot area of a substrate by scanning the substrate with exposure light. In such an exposure apparatus, the surface position of the substrate is measured (focus measurement) during scanning of the substrate prior to exposure of the shot area with the exposure light, and the height and tilt of the substrate are controlled based on the measurement results. done.

In recent years, in order to improve the yield, scanning exposure is also performed in the imperfect shot area, which is located at the peripheral edge of the substrate and where only part of the pattern of the original is transferred. In such a missing shot area, a part of a plurality of measurement target locations that are the target of focus measurement is missing. It can be difficult to accurately perform depth control and tilt control. In Japanese Patent Application Laid-Open No. 2002-200020, the validity/invalidity of focus measurement is determined in advance from the layout information of the shot area, and based on the determination result, the focus measurement value is not used at the missing measurement target location. Methods have been proposed for substrate height control and tilt control.

JP-A-10-116877

For example, substrate height control can be performed using the results of focus measurement at at least one measurement target location, while substrate tilt control can be performed using focus measurement results at at least two measurement target locations. I can't do it without it. That is, in scanning exposure of the imperfect shot area, substrate tilt control is started later than substrate height control, and the time difference between the start time of substrate tilt control and the exposure start time is shortened. In this case, the vibration of the substrate that is caused by tilt control of the substrate and remains after the start of exposure may affect the accuracy of pattern formation on the substrate.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a technique that is advantageous in terms of pattern formation accuracy on a substrate in scanning exposure.

To achieve the above object, an exposure apparatus as one aspect of the present invention is an exposure apparatus that exposes a shot area of a substrate by scanning a stage holding the substrate with respect to exposure light, wherein the stage a measurement unit that measures the surface position of the shot area prior to the exposure of the shot area with the exposure light during the scanning of , and a control unit that controls the tilt of the substrate based on the measurement result of the measurement unit. and wherein the control unit starts tilt control of the substrate when the surface position is measured at a plurality of measurement points by the measurement unit, and controls the substrate at a start time of exposure of the shot area with the exposure light. The stage for tilt control of the substrate at least in a period before the exposure start time according to the time difference between the start time of the tilt control of the substrate and the exposure start time, so that the vibration of the determining a control profile for driving the

Further objects or other aspects of the present invention will be made clear by preferred embodiments described below with reference to the accompanying drawings.

According to the present invention, for example, it is possible to provide an advantageous technique in terms of pattern formation accuracy on a substrate in scanning exposure.

Schematic diagram showing the configuration of an exposure apparatus A diagram showing the positional relationship of multiple measurement points in the shot area, the irradiation area, and the measurement unit. Board height and tilt control block diagram A diagram for explaining scanning exposure for a plurality of shot areas. A diagram for explaining scanning exposure for a plurality of shot areas. A diagram for explaining scanning exposure for a plurality of shot areas. A diagram showing the control profile of the substrate and the vibration of the substrate W. A diagram showing an example of determination of the substrate tilt control profile Flowchart showing scanning exposure processing Flowchart showing inclination control profile determination processing

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. In addition, the following embodiments do not limit the invention according to the scope of claims. Although multiple features are described in the embodiments, not all of these multiple features are essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant description is omitted.

<First embodiment>
An exposure apparatus 100 of a first embodiment according to the present invention will be described. The exposure apparatus 100 of the present embodiment scans the substrate W with exposure light (slit light, pattern light) emitted from a projection optical system, for example, to perform scanning exposure of a shot area of the substrate W, that is, scanning exposure. • It is an exposure apparatus (scanning exposure apparatus) of the and-repeat system. In the following description, the axis parallel to the optical axis AX of the projection optical system is the Z-axis, and the two axes perpendicular to each other in the plane perpendicular to the Z-axis are the X-axis and the Y-axis. Also, the scanning direction of the mask M and the substrate W (that is, the scanning direction of the irradiation region on the substrate) is the Y direction.

[Configuration of exposure device]
FIG. 1 is a schematic diagram showing the configuration of an exposure apparatus 100 of this embodiment. The exposure apparatus 100 can include, for example, an illumination system 106, a mask stage 103, a projection optical system 101, a substrate stage 105, a measurement section 102, and a control section 104.

The illumination system 106 shapes light emitted from a light source (not shown) such as an excimer laser into slit light to illuminate the mask M (original). The mask M is made of quartz glass, for example, and has a pattern (for example, a circuit pattern) to be transferred onto the substrate. The mask stage 103 includes a chuck that holds the mask M, and is movable in at least the X and Y axial directions. When exposing the substrate W, the mask stage 103 scans at a constant speed in the Y-axis direction (arrow 103a), which is the planar direction perpendicular to the optical axis AX of the projection optical system 101 . Positional information of the mask stage 103 in each axial direction can be constantly measured using a bar mirror 120 installed on the mask stage 103 and a first interferometer 121 for position detection of the mask stage 103 .

The projection optical system 101 projects the light transmitted through the mask M onto the substrate at a predetermined projection magnification. The image plane (focus plane) of the projection optical system 101 is perpendicular to the Z-axis direction. The substrate W is, for example, a single crystal silicon substrate, and a resist (photosensitizer) can be applied on the surface. The substrate stage 105 includes a chuck that holds the substrate W, and can move (rotate) in the directions of the X, Y, and Z axes, and further in the directions of rotation of the axes, ie, θx, θy, and θz directions. When exposing the substrate W, the substrate stage 105 scans at a constant speed in the Y-axis direction (arrow 105a), which is the planar direction perpendicular to the optical axis AX of the projection optical system 101 . Positional information of the substrate stage 105 in each axial direction can be constantly measured using a bar mirror 123 installed on the substrate stage 105 and a second interferometer 124 for detecting the position of the substrate stage 105 .

The measurement unit 102 performs surface position measurement (focus measurement) of the substrate W held by the substrate stage 105 . The measurement unit 102 of the first embodiment is an oblique incidence type that obliquely irradiates the substrate W with light. A light-receiving unit that receives a light beam reflected by W (reflected light beam) and a processing unit 126 can be included.

The light projecting unit can include, for example, a light source 110, a collimator lens 111, a slit member 112, a light projecting optical system 113, and a mirror 114. The light source 110 has, for example, a lamp or a light-emitting diode, and emits a light beam with a wavelength that does not sensitize the resist on the substrate. The collimator lens 111 converts the light flux emitted from the light source 110 into parallel light with a substantially uniform cross-sectional light intensity distribution. The slit member 112 is composed of a pair of prisms bonded together so that their slopes face each other. etc. is provided. The projection optical system 113 is a double-side telecentric optical system, and projects a plurality of light beams (nine light beams in this embodiment) generated by passing through a plurality of apertures formed in the slit member 112 to a mirror 114. is made incident on the substrate through .

The plane having the plurality of apertures and the plane including the surface of the substrate W can be configured to satisfy the Scheimpflug condition for the projection optical system 113 . In this embodiment, the incident angle (the angle formed with the optical axis) when each light beam from the light projecting section is incident on the substrate W is 70° or more. In addition, a plurality of light beams emitted from the light projecting unit are arranged to measure θ° (for example, 22.5 °) Incident at different positions on the substrate from the rotated direction.

The light receiving section can include, for example, a mirror 115 , a light receiving optical system 116 , a correcting optical system 117 , and a photoelectric conversion section 118 . The mirror 115 guides the plurality of light fluxes reflected by the substrate W to the light receiving optical system 116 . The light-receiving optical system 116 is a double-side telecentric optical system, and a stopper diaphragm provided in common for a plurality of light beams filters out high-order diffracted light (noise light) caused by the pattern formed on the substrate. ) is cut. Correction optical system 117 has a plurality of lenses so as to correspond to a plurality of light fluxes, and converts a plurality of light fluxes having parallel optical axes that have passed through light receiving optical system 116 to photoelectric converter 118 . An image is formed on the light-receiving surface so as to form spotlights having the same size. The photoelectric conversion unit 118 can include, for example, a number of photoelectric conversion elements (nine in this embodiment) corresponding to a plurality of luminous fluxes. Each photoelectric conversion element includes a CCD line sensor or the like, detects the intensity (light intensity) of the luminous flux incident on the light receiving surface, and outputs it to the processing unit 126 (arithmetic circuit). The processing unit 126 is configured by, for example, a computer having a CPU, memory, etc., and measures (determines) the surface position of the substrate W at each measurement point based on the output from the photoelectric conversion unit 118 .

In the light receiving optical system 116, the correcting optical system 117, and the photoelectric conversion unit 118, tilt correction is performed in advance so that each measurement point on the substrate and the light receiving surface of the photoelectric conversion unit 118 are conjugate with each other. Therefore, there is no change in the position of the pinhole image on the light-receiving surface due to the local inclination of each measurement point, and the height change in the optical axis direction AX of each measurement point is responded to on the light-receiving surface. The position of the pinhole image at . Here, the photoelectric conversion unit 118 of the present embodiment is configured by a one-dimensional CCD line sensor, but a device in which a plurality of two-dimensional position measurement elements are arranged may be used.

The controller 104 includes a main controller 127 , a mask position controller 122 and a substrate position controller 125 . Each control unit can be configured by a computer including, for example, a CPU and a memory. The main control unit 127 is connected to each component of the exposure apparatus 100 via a line, and centrally controls the operation of each component according to a program or the like. The mask position control section 122 controls the operation of the mask stage 103 based on commands from the main control section 127 . The substrate position controller 125 controls the operation of the substrate stage 105 based on commands from the main controller 127 .

The main control unit 127 controls the scanning exposure of the shot area of the substrate W while controlling the height and tilt of the substrate W based on the measurement result of the measurement unit 102 . That is, the main controller 127 relatively scans the mask stage 103 and the substrate stage 105 at a speed ratio corresponding to the projection magnification of the projection optical system 101 while controlling the height and tilt of the substrate W. FIG. As a result, the irradiation area irradiated with the exposure light from the projection optical system 101 (that is, the area where the pattern image of the mask M is projected by the projection optical system 101) is moved on the substrate, and the pattern of the mask M is projected onto the substrate. It can be transferred to the shot area. By sequentially performing such scanning exposure for each of the plurality of shot areas on the substrate W while moving the substrate stage 105 in steps, the exposure processing for one substrate W can be completed.

[Scanning exposure of shot area]
Scanning exposure of the shot area of the substrate W in the exposure apparatus 100 described above will be described. FIG. 2 shows a shot region 201 to be scanned and exposed, an irradiation region 202 irradiated with exposure light from the projection optical system 101, and a plurality of measurement points (this embodiment) for measuring the surface position of the substrate W by the measurement unit 102. It is a diagram showing the positional relationship with nine measurement points in the form). In FIG. 2, an irradiation area 202 is a rectangular area surrounded by dashed lines. The measurement points 203 ( 203 a to 203 c ) are measurement points for measuring the surface position of the substrate W inside the irradiation area 202 . Measurement points 204 ( 204 a to 204 c ) and measurement points 205 ( 205 a to 205 c ) are measurement points (prefetch measurement points) for measuring the surface position of the substrate W prior to exposure in the irradiation area 202 . Each of the measurement points 204 and 205 is arranged at a position separated from the measurement point 203 in the irradiation area 202 by a distance Lp in the scanning direction. In this embodiment, each of the measurement points 203, 204, and 205 is composed of three measurement points arranged in a direction (X direction) intersecting the scanning direction (Y direction). or four or more measurement points. Also, the measurement point 203 can be used to calibrate the measurement results at the measurement points 204 and 205 .

In the measurement unit 102 configured as described above, the measurement points used for measuring the surface position of the substrate W prior to exposure in the irradiation area 202 are switched according to the scanning direction (moving direction) of the substrate W. be done. For example, when scanning and exposing the shot area 201 by moving the substrate W in the direction F, the measurement points 204 (204a to 204c) are used. In this case, the main control unit 127 drives the substrate stage 105 based on the measurement results at the measurement points 204 so that the substrate surface within the irradiation area 202 is positioned at the best focus position of the projection optical system 101. The height and tilt of the substrate W are controlled (adjusted). On the other hand, when scanning and exposing the shot area 201 by moving the substrate W in the direction R, the measurement points 205 (205a to 205c) are used. In this case, the main control unit 127 drives the substrate stage 105 based on the measurement results at the measurement points 205 so that the substrate surface within the irradiation area 202 is positioned at the best focus position of the projection optical system 101. The height and tilt of the substrate W are controlled (adjusted). The best focus position is also called the optimum exposure image plane position.

FIG. 3 is an example of a control block diagram for driving the substrate stage 105 for controlling the height and tilt of the substrate W. As shown in FIG. This control block diagram shows an example in which PID (Proportional-Integral-Differential) control is applied, and may include a subtractor 127a, a PID compensator 127b, a filter 127c and a limiter 127d. Subtractor 127 a , PID compensator 127 b , filter 127 c and limiter 127 d may be provided as components of main controller 127 . In FIG. 3, a P gain (proportional gain), a D gain (differential gain), and an I gain (integral gain) are set in the PID compensator 127b. The filter 127c is, for example, a low-pass filter, and has a filter constant (cutoff frequency) set. A drive limit value for limiting the drive amount of the substrate stage 105 is set in the limiter 127d. The main control unit 127 calculates the deviation between the surface position of the substrate W measured by the measurement unit 102 and the best focus position (target position) using the subtractor 127a, and calculates the deviation using the PID compensator 127b (gain). , a filter 127c and a limiter 127d (drive limit value) are applied. Thereby, the operation amount (target drive amount) of the substrate stage 105 for performing height control and tilt control of the substrate W can be determined.

Next, scanning exposure for a plurality of shot areas will be described with reference to FIGS. 4A to 4C. 4A to 4C show a shot area 201a for which scanning exposure has already been completed, a shot area 201b for which scanning exposure is performed next to shot area 201a, and a shot area 201c for which scanning exposure is performed next to shot area 201b. It is shown. The shot areas 201a and 201b are complete shot areas, which are arranged in the central portion of the substrate W and do not include the edge of the substrate W, and onto which the entire pattern of the mask M is transferred. On the other hand, the shot region 201c is arranged at the periphery of the substrate W and includes the edge of the substrate W, and only part of the pattern of the mask M is transferred (in other words, part of the pattern of the mask M is not transferred). This is the missing shot area.

Circle marks and cross marks in FIGS. 4A to 4C indicate measurement target locations on the shot area to be subjected to surface position measurement by the measurement unit 102 (measurement points 203 to 205). Circle marks indicate valid measurement target locations located inside the substrate W, and x marks indicate invalid measurement target locations located outside the substrate W. FIG. In the examples shown in FIGS. 4A to 4C, measurement target points 311 to 313 are set for the shot area 201b, and measurement target points 321 to 323 are set for the shot area 201c. Here, in FIGS. 4A to 4C, in order to facilitate understanding of the drawings and explanations, the points to be measured are arranged at intervals wider than the interval (distance Lp) between the measurement points in the measuring unit 102 in the scanning direction (Y direction). However, in reality, they can be arranged at intervals narrower than the interval between the measurement points. Also, the measurement target locations are set in advance based on the layout information (design information) of the shot areas on the substrate W, and the valid/invalid determination can be performed using the method described in Patent Document 1, for example. .

FIG. 4A shows the state immediately before scanning exposure of the shot area 201b is started. When the irradiation region 202 exits the shot region 201a and the scanning exposure of the shot region 201a ends, the main control unit 127 ends the driving of the substrate stage 105 in the direction R (+Y direction), and moves the substrate stage 105 by the width of the shot region 201a. − Drive the substrate stage 105 in the X direction. This results in the state shown in FIG. 4A. Then, the main control unit 127 starts driving the substrate stage 105 (scanning the substrate W) in the direction F (−Y direction) in order to scan and expose the next shot area 201b.

In the scanning exposure of the shot area 201b, during scanning of the substrate W in the direction F, as shown in FIG. A surface position measurement of the target portion 311 is performed. Based on the measurement results, the main control unit 127 controls the substrate stage 105 so that the substrate surface in the irradiation area 202 is arranged at the best focus position when the measurement target portion 311 is arranged in the irradiation area 202 . The height control and tilt control of the substrate W are performed by . Similar control is performed for other measurement target locations 312, 313, . . . in the shot region 201b. When the irradiation region 202 exits the shot region 201b and the scanning exposure of the shot region 201b ends, the main control unit 127 ends the driving of the substrate stage 105 in the direction F, and moves the substrate stage 105 in the -X direction by the width of the shot region 201b. The substrate stage 105 is driven. Then, in order to scan and expose the next shot area 201c, the substrate stage 105 starts to be driven (scanning of the substrate W) in the direction R (+Y direction).

In the scanning exposure of the shot area 201c, during scanning of the substrate W in the direction R, as shown in FIG. A surface position measurement of the target portion 321 is performed. Based on the measurement result, the main control unit 127 controls the substrate stage 105 so that the substrate surface in the irradiation area 202 is arranged at the best focus position when the measurement target portion 321 is arranged in the irradiation area 202 . The height control and tilt control of the substrate W are performed by . Similar control is performed for other measurement target locations 322, 323, . . . in the shot region 201b. When the irradiation region 202 exits the shot region 201c and the scanning exposure of the shot region 201c ends, the main controller 127 ends driving the substrate stage 105 in the F direction.

Here, the height (position in the Z direction) of the substrate W during scanning exposure can be controlled if there is one or more effective measurement target locations (circles) among the plurality of measurement target locations arranged in the X direction. be. That is, the height control of the substrate W is started when surface position measurement is performed at one of the plurality of measurement points 204a to 204c (or 205a to 205c) in the measurement unit 102. FIG. On the other hand, the tilt of the substrate W during scanning exposure (tilt around the Y-axis) is controlled when there are not two or more valid measurement target points (circles) among the plurality of measurement target points arranged in the X direction. can't That is, tilt control of the substrate W is started when surface position measurement is performed at two of the plurality of measurement points 204a to 204c (or 205a to 205c) in the measurement unit 102. FIG.

In the present embodiment, the height control of the substrate W is started when the surface position measurement is performed at one measurement point. The height control of the substrate W may be started when the position measurement is performed. Similarly, the tilt control of the substrate W is started when surface position measurement is performed at two measurement points, but the present invention is not limited to this, and a second number (predetermined number) of measurement points set in advance is used. The height control of the substrate W may be started when the surface position measurement is performed. However, the second number is greater than the first number.

For example, in the scanning exposure of the shot region 201c, which is the missing shot region, there is only one effective measurement target location (circle) in the measurement target location 321 where the surface position measurement is first performed at the measurement point 205 . On the other hand, there are two effective measurement target locations (circles) in the measurement target locations 322 where the surface position measurement at the measurement point 205 is performed next. Therefore, while the height control of the substrate W is started when the first measurement target point 321 is measured, the tilt control of the substrate W is not started when the first measurement target point 321 is measured, and the next measurement target point 321 is not started. It will be started when the point 322 is measured. That is, in the scan exposure of the imperfect shot area, the period from the start time of tilt control of the substrate W to the start time of the exposure in the irradiation area 202 is shortened compared to the scan exposure of the complete shot area.

In such scanning exposure of the imperfect shot area, if tilt control of the substrate W is performed in the same manner as scanning exposure of the complete shot area, the vibration (amplitude) of the substrate W generated by the tilt control of the substrate W will be reduced by the exposure start time. It becomes difficult to keep it within the allowable range. As a result, the transfer accuracy of the pattern of the mask M may deteriorate. In other words, the vibration of the substrate, which is generated by tilt control of the substrate and remains after the start of exposure, may affect the accuracy of pattern formation on the substrate. Here, the vibration (amplitude) of the substrate W can be defined as a control deviation with respect to the target height and target tilt of the substrate W. FIG. In addition, the substrate W is held by the substrate stage 105, and the substrate W and the substrate stage 105 can be considered as a unit. can also be captured.

The above matter will be specifically described with reference to FIG. FIG. 5 is a diagram showing a control profile of the height Z (Z-direction position) and tilt X (tilt about the Y-axis) of the substrate W, and the vibration of the substrate W at that time (control deviation Err). The horizontal axis indicates time T. FIG. FIGS. 5A and 5B show the case of scanning exposure of a complete shot area (for example, shot area 201b). FIG. FIG. 5(b) shows the vibration of the substrate W, respectively. 5(c) to (d) show the case of scanning exposure of an imperfect shot region (for example, shot region 201c). FIG. 5(d) shows the vibration of the substrate W, respectively.

5, at time t0, surface position measurement is performed at one of the plurality of measurement points 204a to 204c (or 205a to 205c) in the measurement unit 102, and height control of the substrate W is started. time. Time t1 is the time at which surface position measurement is performed at two of the plurality of measurement points 204a to 204c (or 205a to 205c) in the measurement unit 102, and tilt control of the substrate W is started. Further, time t2 is the time (exposure start time) at which the irradiation region 202 reaches the shot region and the exposure of the shot region is started.

In scanning exposure of a complete shot area (for example, shot area 201b), the initial surface position measurement is performed at two or more measurement points. slope control can be started at the same timing (ie, time t0≈time t1). In this embodiment, the height of the substrate W is controlled by using a control profile that is set so that the vibration of the substrate W (control deviation Err) is within the allowable range at the time difference between the time t0 (t1) and the exposure start time t2. control and tilt control. Thereby, as shown in FIG. 5B, the vibration of the substrate W can be kept within the allowable range by the exposure start time t2. Here, the control profile can be defined as a drive profile of the substrate stage 105, and can be determined by, for example, the target height and target tilt of the substrate W, the drive speed of the substrate stage 105, the drive limit value, the drive time, and the like. . In this embodiment, the drive speed, drive limit value, and drive time of the substrate stage 105 relate to the drive of the substrate stage 105 in the height direction and tilt direction of the substrate W, respectively.

On the other hand, in the scanning exposure of the imperfect shot area (for example, the shot area 201c), tilt control of the substrate W is not started in the first surface position measurement. The time difference between t1 and exposure start time t2 is shortened. In this case, conventionally, the tilt of the substrate W was controlled using a control profile similar to that of the complete shot area. Vibration of the substrate W may remain even after exposure is started. That is, it may be difficult to keep the vibration of the substrate W generated by tilt control of the substrate W within the allowable range by the exposure start time t2.

Therefore, the exposure apparatus 100 (main controller 127) of the present embodiment determines the time difference between the tilt control start time t1 of the substrate W and the exposure start time t2 (hereinafter sometimes simply referred to as "time difference"). , the control profile used for tilt control of the substrate W is determined (changed). For example, the main control unit 127 determines the control profile so that the vibration of the substrate W caused by tilt control of the substrate W is smaller when the time difference is smaller than the threshold than when the time difference is greater than the threshold. do it. Further, the main controller 127 may determine the control profile such that the smaller the time difference, the smaller the vibration of the substrate W caused by tilt control of the substrate W. As a result, it is possible to reduce the vibration of the substrate W that is caused by the tilt control of the substrate W and remains after the start of exposure, for example, in scanning exposure of an imperfect shot region. An example of determining the control profile according to the time difference between the tilt control start time t1 of the substrate W and the exposure start time t2 will be described below.

[Example of determination of control profile]
FIG. 6 is a diagram showing an example of determination of a control profile (tilt control profile) used for tilt control of the substrate W in this embodiment. In FIG. 6, the solid line (Z) indicates the height control profile of the substrate W, the dashed line (TiltX) indicates the conventional tilt control profile of the substrate W, and the dashed line (TiltX') indicates the present 4 shows a tilt control profile of the substrate W in the embodiment. The horizontal axis indicates time T. FIG. Here, the tilt control profile of the substrate W can be defined as the driving profile of the substrate stage 105 as described above. , driving limit value, driving time, and the like.

FIG. 6A is a diagram showing an example of determining the tilt control profile of the substrate W by changing the drive limit value of the substrate stage 105. FIG. For example, in the conventional (TiltX), even if the time difference is smaller than the threshold t _lim (insufficient shot area), the value Limit used in the scanning exposure of the complete shot area is used as the driving limit value of the substrate stage 105. In this case, the inclination of the substrate W was controlled. On the other hand, in the present embodiment (TiltX'), when the time difference is smaller than the threshold _tlim , the main controller 127 sets the driving limit value of the substrate stage 105 to be smaller than the value Limit used in the scanning exposure of the complete shot area. The tilt of the substrate W is controlled by changing the value to Limit'. As a result, since the tilt of the substrate W can be changed gently, the vibration of the substrate W caused by the tilt control of the substrate W can be reduced, and the vibration of the substrate W remaining after the start of exposure can be reduced.

Further, the main controller 127 may change the target tilt of the substrate W when the time difference is smaller than the threshold t _lim . Specifically, the target tilt of the substrate W may be changed to a value Target' smaller than the value Target used in the scanning exposure of the complete shot area. This also makes it possible to gently change the tilt of the substrate W, so that the vibration of the substrate W caused by the tilt control of the substrate W can be reduced.

FIG. 6(b) determines the tilt control profile of the substrate W by changing the driving speed of the substrate stage 105 at the start timing of the tilt control of the substrate W (hereinafter sometimes referred to as “initial driving speed”). It is a figure which shows the example which carries out. For example, in the conventional (TiltX), even if the time difference is smaller than the threshold t _lim (missing shot area), the value Vd used in the scanning exposure of the complete shot area is used as the initial driving speed of the substrate stage 105. In this case, the inclination of the substrate W was controlled. On the other hand, in the present embodiment (TiltX′), when the time difference is smaller than the threshold t _lim , the main controller 127 sets the initial driving speed of the substrate stage 105 to be smaller than the value Vd used in scanning exposure of the complete shot area. The tilt of the substrate W is controlled by changing the value to Vd'. In this case, it is preferable to control the driving speed of the substrate stage 105 until the substrate W reaches the target tilt Target so that the driving time of the substrate stage 105 becomes the same as in the conventional tilt control (example shown in FIG. 6B). , the driving speed is kept constant at the value Vd'). This also makes it possible to gently change the tilt of the substrate W, so that the vibration of the substrate W caused by the tilt control of the substrate W can be reduced.

Also, instead of the initial driving speed of the substrate stage 105, the main control unit 127 may change the average driving speed of the substrate stage 105 until the substrate W reaches the target tilt Target. Specifically, when the time difference is smaller than the threshold value t _lim , the main controller 127 changes the average driving speed of the substrate stage 105 to a value smaller than the value used in the scanning exposure of the complete shot area, and Inclination control of W may be performed.

FIG. 6C is a diagram showing an example of determining the tilt control profile of the substrate W by changing the driving time of the substrate stage 105 until the substrate W reaches the target tilt Target. For example, in the conventional (TiltX), even if the time difference is smaller than the threshold t _lim (missing shot area), the value Td used in the scanning exposure of the complete shot area is used as the driving time of the substrate stage 105. , tilt control of the substrate W was performed. On the other hand, in the present embodiment (TiltX'), when the time difference is smaller than the threshold _tlim , the main controller 127 sets the driving time of the substrate stage 105 to a value longer than the value Td used in the scanning exposure of the complete shot area. The tilt of the substrate W is controlled by changing to Td'. This also makes it possible to gently change the tilt of the substrate W, so that the vibration of the substrate W caused by the tilt control of the substrate W can be reduced.

A similar effect can be obtained by changing the filter constant (cutoff frequency) of the filter 127c. Specifically, the main control unit 127 changes the filter constant (cutoff frequency) of the filter 127c to a value smaller than the value used in the scanning exposure of the complete shot area, thereby controlling the tilt of the substrate W. Therefore, the vibration of the substrate W can be reduced.

Here, depending on the device configuration of the substrate stage 105 and the like, as shown in FIG. good. Alternatively, the drive speed (initial drive speed, average drive speed) of the substrate stage 105 may be changed to a value larger than the value used in the scanning exposure of the complete shot area. In this case, since the tilt of the substrate W can reach the target tilt in a short period of time, the period from the end time of driving the substrate stage 105 for controlling the tilt of the substrate W to the exposure start time t2 can be extended. can. That is, in this case, although the vibration of the substrate W caused by tilt control of the substrate W may increase, the period up to the exposure start time t2 is extended. can be increased, and vibration of the substrate W remaining after the start of exposure can be reduced. A similar effect can be obtained by changing the control gain of the PID compensator 127b.

As described above, the exposure apparatus 100 of the present embodiment determines (changes) the tilt control profile of the substrate W according to the time difference between the tilt control start time t1 of the substrate W and the exposure start time t2. As a result, even when the time difference is shortened, for example, in scan exposure of an imperfect shot area, the vibration of the substrate W caused by tilt control of the substrate W is reduced, and the vibration of the substrate W remaining after the start of exposure is reduced. can do.

<Second embodiment>
A second embodiment according to the present invention will be described. Here, the flow of scanning exposure processing according to the present invention will be described. FIG. 7 is a flowchart showing scanning exposure processing. Each step of the flowchart can be controlled by the main controller 127 . The present embodiment basically follows the first embodiment, and the apparatus configuration, scanning exposure, and the like are the same as those described in the first embodiment.

In S1, the main controller 127 uses a substrate transport mechanism (not shown) to load the substrate W onto the substrate stage 105 and hold it on the chuck. In S2, the main controller 127 executes pre-measurement and correction for the global alignment process in S6, which will be described later (pre-alignment process). Specifically, the main controller 127 uses a low-magnification alignment scope (not shown) to adjust the position, rotation, etc. of the substrate W so that the marks on the substrate are within the field of view of a high-magnification alignment scope (not shown) used for global alignment. Measure and correct the amount of deviation. In S3, the main controller 127 measures the surface heights of the substrate at a plurality of locations using, for example, the measurement unit 102, and calculates and corrects the overall tilt of the substrate W (global tilt step). In this step, some shot areas (sample shot areas) out of a plurality of shot areas on the substrate W can be selected as multiple locations for surface height measurement.

In S4, the main controller 127 performs determination processing for determining the height control profile and tilt control profile of the substrate W used for scanning exposure. If the height control profile is pre-determined and does not need to be changed, only the tilt control profile can be determined in this step. The determination process is performed using, for example, the leading substrate or dummy substrate of a lot including a plurality of substrates W subjected to similar preprocessing, and this step is omitted for the substrates W after determining the tilt control profile. can be Here, the inclination control profile determination process may be performed for each shot area of the substrate W (for example, the leading substrate or the dummy substrate). It may be performed only for the shot area. The details of this step will be described later.

In S5, the main control unit 127 calculates and corrects correction values for the inclination of the projection lens in the projection optical system 101 and the field curvature (projection lens correction step). A light amount sensor and a reference mark provided on the substrate stage 105 and a reference plate provided on the mask stage 103 can be used to calculate the correction value. Specifically, the main controller 127 causes the light amount sensor to measure the light amount change of the exposure light when the substrate stage 105 is scanned in the XYZ axial directions. Then, the main control unit 127 obtains the amount of deviation of the reference mark from the reference plate based on the amount of change in the amount of light output from the light amount sensor, and calculates a correction value for correcting the amount of deviation.

In S6, a high-magnification alignment scope (not shown) is used to measure the alignment marks on the substrate W, and the amount of positional deviation (including the amount of rotational deviation) of the entire substrate W and the amount of positional deviation common to each shot area are calculated. Correct (global alignment step). Here, in order to measure the alignment mark with high accuracy, the contrast of the alignment mark must be at the best contrast position (height). The measurement unit 102 and an alignment scope can be used for the measurement of this best contrast position. Specifically, the main control unit 127 moves the substrate stage 105 to a predetermined height (Z direction), causes the alignment scope to measure the contrast, and causes the measurement unit 102 to measure the surface height. Repeat several times. At this time, the main control unit 127 associates and saves the measurement result of the surface height and the measurement result of the contrast corresponding to each surface height. Then, the main control unit 127 obtains the surface height with the highest contrast based on the obtained plurality of contrast measurement results, and determines the best contrast position (height).

In S7, the main control unit 127 performs scanning exposure while causing the measurement unit 102 to measure the surface position of the shot area to be exposed (scanning exposure step). This step can be performed according to the method described in the first embodiment. Specifically, while scanning the substrate W (shot area), the main control unit 127 measures the surface position of the shot area at the measurement points (204 or 205) of the measurement unit 102 prior to exposure in the irradiation area 202. Then, height control and tilt control of the substrate W are performed based on the measurement results. In the height control and tilt control of the substrate W in this step, the height control profile and tilt control profile determined in S4 can be applied to the shot area to be exposed. In this step, all shot areas on the substrate W can be subjected to scanning exposure. Further, in S8, the main controller 127 terminates holding of the substrate W by the substrate stage 105, and unloads the substrate W from the substrate stage 105 using a substrate transport mechanism (not shown). Thus, a series of exposure steps for one substrate W is completed. If there are other substrates W, the above scanning exposure process can be repeated.

Next, the inclination control profile determination process performed in S4 of the flowchart shown in FIG. 7 will be described. FIG. 8 is a flow chart showing the inclination control profile determination process. Each step of the flowchart can be controlled by the main controller 127 . In this embodiment, the substrate stage 105 is driven under a plurality of driving conditions having different driving parameters, and the driving condition that minimizes the maximum value of the vibration (control deviation) of the substrate W among the plurality of driving conditions is applied. An example of determining a tilt control profile will now be described. As driving parameters, for example, as described in the first embodiment, the driving limit value, driving speed, driving time, etc. of the substrate stage 105 can be used. In the following description, an example will be described in which the driving time of the substrate stage 105 is used as the driving parameter, and four types of driving conditions, in which the driving time is between 8 ms and 5 ms and differ by 1 ms, are used as the plurality of driving conditions.

At S4-1, the main control unit 127 sets one driving condition out of a plurality of driving conditions. At S4-2, the main controller 127 drives the substrate stage 105 using one drive condition set at S4-1. In this step, it is preferable to drive the substrate stage 105 in the same manner as the scanning exposure in the step of S7 without irradiating the substrate W with the exposure light. Further, in this process, while the substrate stage 105 is being driven, the surface position of the substrate W can be measured by the measuring unit 102 (which may be any of the measuring points 203 to 205).

In S4-3, the main control unit 127 acquires the vibration (control deviation) of the substrate W based on the result of substrate surface measurement performed by the measurement unit 102 while the substrate stage 105 is driven in S4-2 ( calculate). In S4-4, the main controller 127 determines whether or not the vibration of the substrate W has been obtained under all of the plurality of drive conditions. In this embodiment, as described above, it is determined whether or not the vibration of the substrate W has been obtained for each of the four drive times of 8 ms, 7 ms, 6 ms, and 5 ms. If the vibration of the substrate W has not been acquired under all drive conditions, the process returns to S4-1, changes the drive conditions, and repeats S4-1 to S4-3. On the other hand, when the vibration of the substrate W is obtained under all driving conditions, the process proceeds to S4-5.

At S4-5, the main controller 127 determines the tilt control profile. For example, the main control unit 127 selects the driving condition that minimizes the maximum value of the vibration (control deviation) of the substrate W from among a plurality of driving conditions, and applies the selected driving condition to the driving profile of the substrate stage 105. A slope control profile is determined by applying. In addition, the main control unit 127 controls the inclination by applying to the drive profile of the substrate stage 105 a drive condition that minimizes the standard deviation of the vibration of the substrate W (control deviation) instead of the maximum value of the vibration of the substrate W. A profile may be determined. Such tilt control profile determination processing can be performed for each shot area (or for each representative shot area).

Here, the driving time of the substrate stage 105 is used as the driving parameter, but the driving limit value or the driving speed of the substrate stage 105 may be used as the driving parameter. For example, the driving amount of the substrate stage 105 for arranging the surface of the substrate W at the best focus position varies depending on the flatness of the substrate W. FIG. If the flatness of the substrate W is low, the driving amount of the substrate stage 105 is correspondingly increased. Therefore, when exposure processing is performed on a lot in which the flatness of the substrate W is low, it is preferable to use the drive limit value of the substrate stage 105 as a drive parameter. The flatness of the substrate W can be measured in advance by, for example, an external measuring device.

In addition, if the drive limit value of the substrate stage 105 is used as a drive parameter, the tilt of the substrate W does not reach the initial target tilt (Target) and a control residual error occurs. can be disadvantageous. Therefore, when performing scanning exposure of a substrate W (lot) that requires high pattern formation productivity, or when the depth of focus of the projection optical system 101 is small, at least one of the driving time and the driving speed of the substrate stage 105 is driven. It is good to use it as a parameter.

Also, the time interval between the start time of driving the substrate stage 105 and the start time of exposure of the shot area in the irradiation area 202 varies depending on the scanning speed of the substrate W (substrate stage 105) during scanning exposure. That is, the slower the scanning speed of the substrate W, the longer the time interval tends to be. Therefore, if the time interval is relatively long (than the predetermined interval), that is, if the scanning speed of the substrate W is relatively slow (below the predetermined speed), at least one of the driving time and the driving speed of the substrate stage 105 is driven. It is effective to use it as a parameter. For example, when exposure processing is performed on a substrate W (lot) whose scanning speed is relatively slow, at least one of the driving time and the driving speed of the substrate stage 105 may be used as a driving parameter. A similar effect can be obtained by changing the control gain of the PID compensator 127b.

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

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, the claims are appended to make public the scope of the invention.

100: exposure apparatus, 101: projection optical system, 102: measurement unit, 103: mask stage, 104: control unit, 105: substrate stage, 106: illumination optical system, 201: shot area, 202: irradiation area, 203 to 205 : Measuring point

Claims (10)

An exposure apparatus for exposing a shot area of a substrate by scanning a stage holding the substrate with respect to exposure light,
a measurement unit that measures a surface position of the shot area prior to exposure of the shot area with the exposure light during scanning of the stage ;
a control unit that controls the inclination of the substrate based on the measurement result of the measurement unit;
including
The control unit
starting tilt control of the substrate when the surface position is measured at a plurality of measurement points by the measurement unit;
At least before the exposure start time according to the time difference between the start time of tilt control of the substrate and the exposure start time, so that the vibration of the substrate at the exposure start time of the shot region by the exposure light is reduced . determining a control profile for driving the stage for tilt control of the substrate during a period of . The control unit determines the control profile such that the vibration of the substrate at the exposure start time is smaller when the time difference is smaller than the threshold than when the time difference is larger than the threshold. 2. The exposure apparatus according to claim 1, wherein: 2. The exposure apparatus according to claim 1, wherein the controller determines the control profile such that the smaller the time difference, the smaller the vibration of the substrate at the exposure start time . The control unit further controls the height of the substrate based on the measurement result of the measurement unit,
the substrate height control is initiated when the surface position is measured at a first number of measurement points;
4. The substrate tilt control according to any one of claims 1 to 3, wherein the substrate tilt control is started when the surface position is measured at the plurality of measurement points, which is a second number larger than the first number. 2. The exposure apparatus according to item 1 or 2. 5. The controller according to any one of claims 1 to 4, wherein the controller controls the inclination of the substrate by driving the stage, and determines a drive profile of the stage as the control profile according to the time difference. 2. The exposure apparatus according to item 1 or 2. The control unit determines the drive profile by changing at least one of a drive speed of the stage, a drive limit value for limiting the amount of drive of the stage, and a drive time of the stage. 6. The exposure apparatus according to claim 5, characterized by: 7. The exposure apparatus according to any one of claims 1 to 6, wherein the plurality of measurement points are arranged along a direction intersecting the scanning direction of the substrate. 8. The control section according to any one of claims 1 to 7, characterized in that, when exposing a defective shot area where only a part of the pattern of the original is transferred, the control section determines the control profile according to the time difference. 2. The exposure apparatus according to item 1 or 2. the substrate includes a plurality of shot areas,
9. The exposure apparatus according to claim 1, wherein said control section determines said control profile for each shot area. an exposure step of exposing a substrate using the exposure apparatus according to any one of claims 1 to 9;
and a processing step of processing the substrate exposed in the exposure step,
A method for manufacturing an article, comprising manufacturing an article from the substrate processed in the processing step.

Images