Exposure apparatus, control method, and article manufacturing method

Abstract

The invention provides an exposure apparatus, a control method, and an article manufacturing method. An exposure apparatus for exposing a substrate includes: a stage configured to move while holding the substrate; a measuring device configured to measure a position of the stage; and a controller configured to control alignment of the substrate based on the position of the mark and the interval information, in which the controller causes the measuring device to measure a position of the stage in a predetermined state as a first position at a first timing; and causing the measurement device to measure the position of the stage in the predetermined state as a second position at a second timing after the first timing, and correct the interval information based on a difference between the first position and the second position.

Description

Technical Field

[0001] The present invention relates to an exposure device, a control method and an article manufacturing method. Background Art

[0002] Exposure devices are widely used in the manufacturing process of semiconductor elements and the like formed with micro patterns, and the exposure devices reduce and project the pattern formed on the original plate (e.g., mask plate) and transfer it to a substrate (e.g., wafer) coated with photoresist. The pattern resolution of the exposure device needs to be improved, and at the same time, the demand for improving the matching degree between the original plate pattern and the substrate pattern (called overlay accuracy) is becoming increasingly high. It is crucial to improve the productivity of the device (hereinafter referred to as throughput) while meeting these requirements for the attractiveness of the exposure device.

[0003] The exposure device may be provided with an off-axis detection system that detects the positions of a plurality of alignment marks provided on the substrate without passing through the projection optical system, thereby accurately and quickly performing alignment between the original and the substrate. In the case of performing alignment between the original and the substrate by using the off-axis detection system, it is necessary to obtain in advance interval information indicating the interval (so-called baseline) between the optical axis of the off-axis detection system and the optical axis of the projection optical system. Acquiring such interval information in advance makes it possible to perform alignment between the original and the substrate based on the positions of the alignment marks and the baseline obtained by using the off-axis detection system.

[0004] However, due to the influence of deformation of components caused by heat generated during operation of the exposure device, the baseline sometimes changes over time. The change in the baseline can lead to a decrease in the overlay accuracy, so it is necessary to periodically re-measure or correct the baseline (for example, see Japanese Patent Publication No. 63-224326).

[0005] Recently, exposure apparatuses have been configured to improve throughput in addition to improving overlay accuracy, and there is a need to shorten the time required to correct the baseline. Summary of the invention

[0006] The present invention provides a technique that facilitates effective correction of interval information indicating the interval (baseline) between the optical axis of an off-axis detection system and the optical axis of a projection optical system.

[0007] According to one aspect of the present invention, there is provided an exposure device for exposing a substrate through a projection optical system, the exposure device comprising: a stage configured to move while holding the substrate; an imaging device configured to capture an image of a mark on the substrate without passing through the projection optical system; a measuring device configured to measure the position of the stage; and a controller configured to control the alignment of the substrate based on the position and spacing information of the mark, the position of the mark being obtained by using the imaging device and the measuring device, and the spacing information indicating the spacing between the optical axis of the imaging device and the optical axis of the projection optical system, wherein the controller causes the measuring device to measure the position of the stage in a predetermined state as a first position at a first timing for generating the spacing information, in which a reference mark on the stage is arranged within a field of view of the imaging device; and causes the measuring device to measure the position of the stage in the predetermined state as a second position at a second timing after the first timing, and corrects the spacing information based on the difference between the first position and the second position.

[0008] According to another aspect of the present invention, there is provided a control method for an exposure device, the exposure device comprising: a projection optical system; a stage configured to move while holding a substrate; an imaging device configured to capture an image of a mark on the substrate without passing through the projection optical system; and a measuring device configured to measure the position of the stage, and the exposure device aligns the substrate based on the position and spacing information of the mark, wherein the position of the mark is obtained by using the imaging device and the measuring device, and the spacing information indicates the spacing between the optical axis of the imaging device and the optical axis of the projection optical system, the control method comprising: at a first timing for generating the spacing information, causing the measuring device to measure the position of the stage in a predetermined state as a first position, in which a reference mark on the stage is arranged within a field of view of the imaging device; and at a second timing after the first timing, causing the measuring device to measure the position of the stage in the predetermined state as a second position, and correcting the spacing information based on the difference between the first position and the second position.

[0009] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a schematic diagram showing an arrangement example of an exposure apparatus according to an embodiment of the present invention;

[0011] Figure 2 is a schematic diagram of the substrate stage viewed from above (+Z direction);

[0012] Figure 3is a schematic diagram of the substrate stage, projection optical system, and off-axis detection system viewed from above (+Z direction); and

[0013] Figure 4 is a flowchart showing the operation of the exposure apparatus according to the embodiment of the present invention. DETAILED DESCRIPTION

[0014] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Please note that the following embodiments are not intended to limit the scope of the claimed invention. A plurality of features are described in the embodiments, but the invention is not limited to all of these features, and a plurality of such features may be appropriately combined. In addition, in the accompanying drawings, the same reference numerals are given to the same or similar configurations, and their repeated descriptions are omitted.

[0015] <First Embodiment>

[0016] An exposure apparatus EXP according to a first embodiment of the present invention will be described. Figure 1 is a schematic diagram showing an example of the arrangement of the exposure device EXP according to the first embodiment. The exposure device EXP may include a master stage 2 holding a master 1 (e.g., a mask), a substrate stage 4 holding a substrate 3 (e.g., a wafer), and an illumination optical system 5 irradiating the master 1 held by the master stage 2 with exposure light. The exposure device EXP may include: a projection optical system 6 that projects a pattern of the master 1 irradiated with exposure light onto the substrate and forms an image of the pattern on the substrate; and a controller 17 that controls the overall operation of the exposure device EXP. In addition, the exposure device EXP may include: a substrate driving mechanism 18 that drives the substrate 3 by driving the substrate stage 4, and a master driving mechanism (not shown) that drives the master 1 by driving the master stage 2.

[0017] The exposure device EXP may be configured as a scanning exposure device (scanning stepper) that transfers the pattern of the original plate 1 to the substrate 3 by synchronously driving the original plate 1 and the substrate 3 in the scanning direction. Alternatively, the exposure device EXP may be configured as an exposure device (stepper) that transfers the pattern of the original plate 1 to the substrate 3 while stopping the original plate 1 and the substrate 3. In this case, in the present embodiment, the direction is defined using the XYZ coordinate system, wherein the direction coinciding with the optical axis of the projection optical system 6 is the Z-axis direction, and the directions orthogonal to the Z-axis direction in the vertical plane are the X-axis direction and the Y-axis direction. In the following description, all directions parallel to the X-axis of the XYZ coordinate system are defined as the X-axis direction, all directions parallel to the Y-axis of the XYZ coordinate system are defined as the Y-axis direction, and all directions parallel to the Z-axis of the XYZ coordinate system are defined as the Z-axis direction. The rotation directions around the X-axis, around the Y-axis, and around the Z-axis are the θX direction, the θY direction, and the θZ direction, respectively. If the exposure device EXP is configured as a scanning exposure device, the scanning direction of the original plate 1 and the substrate 3 is the Y-axis direction.

[0018] The illumination optical system 5 irradiates a predetermined illumination area of ​​the original plate 1 with exposure light having a uniform illumination distribution. The illumination optical system 5 can irradiate the original plate 1 with exposure light emitted from a light source such as a mercury lamp, a KrF excimer laser, or an ArF excimer laser. If i-rays are used as the exposure light, a mercury lamp can be used as the light source. In addition, if short-wavelength ultraviolet light is used as the exposure light, a KrF excimer laser or an ArF excimer laser can be used as the light source. Alternatively, recently, in order to manufacture semiconductor elements having micro patterns, etc., extreme ultraviolet light (EUV light) with a wavelength of several nanometers to several hundred nanometers is sometimes used as exposure light.

[0019] The original stage 2 can be constructed to move two-dimensionally along a plane perpendicular to the optical axis of the projection optical system 6 (i.e., the XY plane) and to rotate slightly along the Z direction while holding the original 1. The original drive mechanism that drives the original stage 2 includes an actuator such as a linear motor, and is controlled by the controller 17. A reflector 7 is provided on the original stage 2. A laser interferometer 9 for measuring the position of the original stage 2 is provided at a position facing the reflector 7. The laser interferometer 9 measures the X-axis direction position, the Y-axis direction position, and the θZ direction rotation angle of the original stage 2 in real time, and provides the measurement results to the controller 17. The controller 17 can position the original 1 held by the original stage 2 by controlling the original drive mechanism based on the measurement results obtained by the laser interferometer 9.

[0020] The projection optical system 6 is composed of a plurality of optical elements, and projects the pattern of the original plate 1 onto the substrate 3 at a predetermined projection magnification β. In this embodiment, the projection optical system 6 can be configured as a reduced projection system with a projection magnification β less than 1. The projection magnification β can be, for example, 1 / 4 or 1 / 5.

[0021] The substrate stage 4 is configured to be able to move while holding the substrate 3. More specifically, the substrate stage 4 may include a Z stage on which a substrate chuck holding the substrate 3 is mounted and an XY stage holding the Z stage. A substrate driving mechanism 18 that drives the substrate stage 4 includes an actuator such as a linear motor and is controlled by a controller 17. A reflection mirror 8 is provided on the substrate stage 4. Laser interferometers 10 and 12 that measure the position and posture of the substrate stage 4 are provided at a position facing the reflection mirror 8. The laser interferometer 10 measures the X-axis direction position, Y-axis direction position, and θZ direction rotation angle of the substrate stage 4 in real time, and provides the measurement results to the controller 17. The laser interferometer 12 measures the Z-axis direction position, θX direction rotation angle, and θY direction rotation angle of the substrate stage 4 in real time, and provides the measurement results to the controller 17. The controller 17 can position the substrate 3 held by the substrate stage 4 by controlling the substrate driving mechanism 18 based on the measurement results obtained by the laser interferometers 10 and 12.

[0022] In this case, the laser interferometer 10 is configured as a measuring device for measuring the position of the reference portion of the substrate stage 4. More specifically, the laser interferometer 10 irradiates the reflective surface of the reflector 8 of the substrate stage 4 with light, and detects the distance of the reflective surface of the reflector 8 of the substrate stage 4 based on the reflected light from the reflective surface, thereby measuring the position of the reflective surface as the position of the reference portion of the substrate stage 4. That is, in the present embodiment, the reference portion whose position is measured by the laser interferometer 10 is a portion of the substrate stage 4 provided with a reflective surface that reflects the light from the laser interferometer 10. In addition, the present embodiment has exemplified the laser interferometers 10 and 12 as measuring devices for measuring the position of the substrate stage 4 (the position of the reference portion). However, this is not exhaustive, and an encoder may be used. In this case, an encoder scale (grating) may be provided on the substrate stage 4 instead of the reflector 8. The reference portion whose position is measured by the encoder is a portion of the substrate stage 4 provided with an encoder scale.

[0023] The reference plates 11 are mounted on at least two corners of the substrate stage 4 and are substantially at the same level as the surface of the substrate 3 . Figure 2 FIG. 4 is a schematic diagram showing the substrate stage 4 when viewed from above (in the +Z direction). Figure 2In the case shown, a plurality (three) of reference plates 11a to 11c are provided on the substrate stage 4. Each of the reference plates 11a to 11c may include: a reference mark 111 detected by the original position detection systems 13 and 14 and a reference mark 112 detected by the position detection system 16. The relative position between the reference mark 111 and the reference mark 112 is known. In addition, the reference mark 111 and the reference mark 112 may have the same shape and may be configured as a reference mark (i.e., one reference mark) commonly used by the original position detection systems 13 and 14 and the position detection system 16. In addition, one reference plate 11 may be configured to include a plurality of reference marks 111 and a plurality of reference marks 112.

[0024] The original plate position detection system 13 is arranged near the original plate stage 2, and detects the reference mark 111 on the substrate stage through the projection optical system 6. In the present embodiment, the original plate position detection system 13 is configured as, for example, an imaging device (second imaging device) including an imaging optical system and a photoelectric conversion element such as a CCD or CMOS sensor, and captures an image of the reference mark 111 on the substrate stage through the projection optical system 6. More specifically, the original plate position detection system 13 detects (captures images of) the reference mark (not shown) on the original plate stage 2 and the reference mark 111 on the substrate stage 4 by irradiation using, for example, a light source for exposure, using the photoelectric conversion element, and supplies the obtained image to the controller 17. The controller 17 detects the relative position between the reference mark on the original plate stage 2 and the reference mark 111 on the substrate stage 4 based on the image obtained by the original plate position detection system 13. At this time, the controller 17 adjusts the relative positional relationship (in the X, Y, and Z axis directions) between the original stage 2 (original 1) and the substrate stage 4 (substrate 3) by adjusting the position / focus of the reference mark on the original stage 2 and the position / focus of the reference mark 111 on the substrate stage 4. Note that the original position detection system 13 is sometimes referred to as a through-the-lens (TTL) detection system, and is sometimes written as "TTL detection system 13" hereinafter.

[0025] In the present embodiment, the reference mark on the original plate carrier 2 and the reference mark 111 on the substrate carrier 4 detected by the TTL detection system 13 are constructed as reflective marks, but can also be constructed as transmissive marks. In this case, the original plate position detection system 14 can be used instead of the TTL detection system 13. The original plate position detection system 14 is arranged below the reference mark 111 in the substrate carrier 4, and can be constructed as a camera device (second camera device) for detecting the transmissive reference mark 111 (taking its image). While the substrate carrier 4 is driven in the X-axis direction, the Y-axis direction, and the Z-axis direction, the image (transmitted light) of the reference mark on the original plate carrier 2 and the reference mark 111 on the substrate carrier 4 can be detected by using the original plate position detection system 14. This enables the controller 17 to detect the relative position between the reference mark on the original plate carrier 2 and the reference mark 111 on the substrate carrier 4 based on the detection result obtained by the original plate position detection system 14. At this time, the controller 17 can also adjust the relative position relationship (in the X, Y and Z axis directions) between the original stage 2 (original 1) and the substrate stage 4 (substrate 3) by adjusting the position / focus of the reference mark on the original stage 2 and the position / focus of the reference mark 111 on the substrate stage 4.

[0026] The position detection system 16 is arranged on one side of the projection optical system 6, and detects a mark on the substrate stage (for example, the alignment mark 19 on the substrate 3 or the reference mark 112 on the reference plate 11) without passing through the projection optical system 6. In the present embodiment, the position detection system 16 is configured as an imaging device (first imaging device) including an imaging optical system and a photoelectric conversion element such as a CCD or CMOS sensor, and captures an image of the reference mark 112 on the substrate stage without passing through the projection optical system 6. More specifically, the position detection system 16 may include: a projection system that projects detection light onto the mark on the substrate stage 4, and a light receiving system that receives reflected light from the mark. The position detection system 16 is connected to the controller 17, and provides the controller 17 with the detection result obtained by the position detection system 16. The controller 17 can position the substrate 3 held by the substrate stage 4 in the X-axis direction, the Y-axis direction, and the θZ-axis direction by driving the substrate stage 4 in the X-axis direction, the Y-axis direction, and the θZ-axis direction based on the detection result obtained by the position detection system 16. Note that position detection system 16 is sometimes referred to as an off-axis detection system, and is sometimes written as "off-axis detection system 16".

[0027] The focus detection system 15 may include a light emitting system that emits detection light to the surface of the substrate 3 by oblique incidence, and a light receiving system that receives reflected light from the substrate 3. The detection result obtained by the focus detection system 15 may be provided to the controller 17. The controller 17 adjusts the position (focus position) and the tilt angle of the substrate 3 held by the substrate stage 4 in the Z-axis direction by causing the substrate driving mechanism 18 to drive the substrate stage 4 (Z stage) based on the detection result obtained by the focus detection system 15.

[0028] The controller 17 is composed of a processor such as a central processing unit (CPU) and a computer (information processing device) having a storage device such as a memory, and controls the exposure process on the substrate 3 by controlling each device of the exposure device EXP. The exposure process can be understood as a process of transferring the pattern of the original plate 1 to the substrate, and can also be understood as including the alignment between the original plate 1 and the substrate 3. Figure 2 As shown, the exposure process can be sequentially performed on each of the plurality of projection areas 3a arranged (set) on the substrate 3. In addition, the controller 17 is realized by, for example, a programmable logic device (PLD) such as a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), a general or dedicated computer incorporating a program, or a combination of all or part of these components.

[0029] In this case, the position information of the substrate 3 (projection area 3a) obtained by detecting the alignment mark 19 on the substrate 3 using the position detection system 16 is information based on the optical axis of the position detection system 16. Therefore, it is necessary to convert this position information into information based on the optical axis of the projection optical system 6. This conversion uses interval information indicating the interval (so-called baseline) between the optical axis of the position detection system 16 and the optical axis of the projection optical system 6. In the following description, this interval is sometimes written as "baseline", and the interval information is sometimes written as "baseline information".

[0030] Based on the difference between the position of the reference mark on the substrate stage 4 measured by the position detection system 16 (first imaging device) and the position of the reference mark on the substrate stage 4 measured by the TTL detection system 13 (second imaging device), the baseline information can be generated. More specifically, the controller 17 causes the laser interferometer 10 (measuring device) to measure the position of the substrate stage 4 while arranging the reference mark 112 on the substrate stage 4 at a predetermined position (e.g., the center of the field of view) in the field of view (field of view) of the position detection system 16. The controller 17 can also cause the laser interferometer 10 (measuring device) to measure the position of the substrate stage 4 while arranging the reference mark 111 on the substrate stage 4 at a predetermined position (e.g., the center of the field of view) in the field of view of the TTL detection system 13. This enables the controller 17 to generate the baseline information by setting the difference between the measurement result obtained using the position detection system 16 and the measurement result obtained using the TTL detection system 13 as the baseline.

[0031] When the laser interferometer 10 measures the position of the substrate stage 4, shortening the optical path between the laser interferometer 10 and the reflector 8 as much as possible can reduce the influence of the fluctuation of the refractive index of the air in the optical path. That is, the position of the substrate stage 4 can be accurately measured. Therefore, when generating baseline information, it is preferred to use the reference plate 11c that is farthest from the reflecting surface of the reflector 8 (as the reference part whose position is measured by the laser interferometer 10) among the multiple reference plates 11a to 11c (reference marks) on the substrate stage 4. Compared with the use of other reference plates 11a and 11b, the use of the reference plate 11c can shorten the optical path of the laser interferometer 10 while arranging the reference marks in the field of view of the position detection system 16 and the TTL detection system 13. In the present embodiment, although the off-axis detection system 16 and the TTL detection system 13 detect different reference marks 111 and 112, respectively, this is not exhaustive. These systems can detect the same reference mark.

[0032] The exposure apparatus EXP according to the present embodiment is provided with a temperature detector 113 that detects the temperature of the substrate stage 4. The temperature detector 113 may be arranged near the reference plate 11a closest to the reflection surface of the reflection mirror 8 among the plurality of reference plates 11a to 11c.

[0033] The operation of the above-mentioned exposure device EXP will be described below. In general, a predetermined number of substrates 3 loaded into the exposure device EXP constitutes one processing unit in consideration of portability and ensuring traceability within a semiconductor factory. Such a processing unit is composed of a plurality of substrates 3 to be subjected to similar exposure processing, and can be referred to as a "batch". Typically, due to the limitation of the maximum number of substrates 3 in a substrate transport container, 25 substrates 3 generally constitute one batch. All substrates 3 belonging to the batch are subjected to exposure processing using the same original plate 1.

[0034] When a batch is loaded into the exposure device EXP, it is assumed that there are two cases including replacement of the original plate 1 and non-replacement of the original plate 1. In either case, before starting the exposure process of the first substrate 3, it is necessary to complete the alignment between the original plate 1 and the substrate 3. That is, before the alignment, the following processing is performed: the focus position of the substrate 3 is measured using the focus detection system 15, and the position of the alignment mark 19 on the substrate 3 is measured using the off-axis detection system 16. In the first alignment, first, the reference mark 111 on the substrate stage 4 is set in the field of view of the TTL detection system 13 (for example, photographed at the center of the field of view). At this time, the laser interferometer 10 measures the X-axis direction position and the Y-axis direction position of the substrate stage 4 in real time, and provides (sends) the measurement results to the controller 17. The reference mark 112 on the substrate stage 4 is set in the field of view of the off-axis detection system 16 (for example, photographed at the center of the field of view). At this time, the laser interferometer 10 measures the X-axis direction position and the Y-axis direction position of the substrate stage 4 in real time, and provides (sends) the measurement results to the controller 17. The controller 17 calculates the difference between the two measurement results (i.e., positions (coordinates)) of the substrate stage 4 and uses the difference as a baseline to generate baseline information. In the following description, generating baseline information using both the off-axis detection system 16 and the TTL detection system 13 is sometimes abbreviated as "generating baseline information."

[0035] Once the first alignment including the baseline information generated for the head substrate 3 of the batch is completed, the head substrate 3 of the batch is subjected to exposure processing, and at the same time, the remaining substrates 3 of the batch are subjected to exposure processing in sequence. During this process, the exposure light and the energy for driving the stage are partially converted into heat, resulting in changes in the temperature of the internal space and component parts of the exposure device EXP. The interior of the exposure device EXP is composed of components with minimal dimensional changes due to heat, and is designed with consideration given to temperature regulation using an air cooling mechanism or the like. However, in practice, slight temperature changes may cause baseline changes. After the baseline changes, continuing to use the baseline information generated in the first alignment will result in a decrease in overlay accuracy.

[0036] It takes a long time for the TTL detection system 13 to detect the reference mark on the substrate stage 4 through the projection optical system 6, compared to detecting the reference mark on the substrate stage 4 through the off-axis detection system 16. Therefore, regenerating or correcting the baseline information using the TTL detection system 13 will reduce the throughput (i.e., the productivity of the device). For this reason, it is preferable to avoid using the TTL detection system 13 outside the head substrate 3 of the batch.

[0037] Therefore, in the present embodiment, only the off-axis detection system 16 is used to correct the baseline information. More specifically, the controller 17 causes the laser interferometer 10 to measure the position of the substrate carrier 4 as the first position at the first timing of generating the baseline information in a predetermined state in which the reference mark 112 is arranged within the field of view of the off-axis detection system 16. The first timing may be, for example, the timing of performing the first alignment for generating the baseline information for the head substrate 3 of the batch. The predetermined state may be a state in which the reference mark 112 is arranged at a predetermined position (for example, the center of the field of view) within the field of view of the off-axis detection system 16. Then, the controller 17 causes the laser interferometer 10 to measure the position of the substrate carrier 4 as the second position in a predetermined state at a second timing after the first timing. Then, the controller 17 corrects the baseline information based on the difference between the first position and the second position. Please note that in the following description, correcting the baseline information only using the position detection system 16 is sometimes abbreviated as "correcting the baseline information".

[0038] The correction of the baseline information uses a reference mark 112 (second reference mark) that is closer to the reference portion of the substrate carrier 4 (the reflecting surface of the reflector 8) than the reference mark 112 (second reference mark) on the reference plate 11c used to generate the baseline information. In the present embodiment, the reference mark 112 on the reference plate 11a closest to the reflector 8 among the multiple reference plates 11a to 11c on the substrate carrier 4 is used for the correction of the baseline information. The reference plate 11a among the reference plates 11a to 11c can be understood as the reference plate that is closest to the off-axis detection system 16 when the substrate carrier 4 is arranged in the substrate loading place. The substrate loading place can be defined as the place where the substrate carrier 4 is arranged when the substrate 3 is loaded (supplied) onto the substrate carrier 4 by a substrate conveying mechanism (not shown). As Figure 3 As shown, selecting the reference plate 11a in this manner allows the reference plate 11a to be arranged below the off-axis detection system 16 during the process of moving the substrate stage 4 from the substrate loading site to below the projection optical system 6. That is, the reference mark on the reference plate 11a can be arranged within the field of view of the off-axis detection system 16 without significantly changing the route of the substrate stage 4 from the substrate loading site to below the projection optical system 6. This is advantageous in terms of production volume. Figure 3 This is a schematic diagram when the substrate stage 4, the projection optical system 6, and the off-axis detection system 16 are viewed from above (in the +Z direction).

[0039] Figure 4 : is a flowchart showing the operation of the exposure apparatus EXP according to the present embodiment. Figure 4 The flowchart in FIG. 1 illustrates the operation of the exposure apparatus EXP for one batch having a plurality of (e.g., 25) substrates 3. If there are a plurality of batches, the operation may be repeated. Figure 4 Flowchart in . Figure 4 The flowchart in can be executed by the controller 17. Figure 4 The flowchart in can be understood as a flowchart showing the control method of the exposure device EXP.

[0040] Steps S101 to S104 are steps of performing exposure processing on the first (head) substrate 3 of the batch.

[0041] In step S101, the controller 17 loads the first (head) substrate 3 of the batch onto the substrate stage 4 using a substrate conveying mechanism (not shown). When the substrate stage 4 is arranged at the substrate loading place, the substrate 3 can be loaded onto the substrate stage 4. In step S102, the controller 17 generates baseline information. The baseline information is generated by detecting the reference mark 111 on the reference plate 11c using both the off-axis detection system 16 and the TTL detection system 13. As described above, the reference plate 11c can be the reference plate farthest from the reflection surface of the reflection mirror 8 (as the reference portion whose position is measured by the laser interferometer 10) among the multiple reference plates 11a to 11c on the substrate stage 4. The details of the generation of the baseline information are the same as those described above, so their description will be omitted here.

[0042] This embodiment illustrates the case where baseline information is generated for each batch. However, this is not exhaustive, and baseline information can also be generated for batches that meet predetermined conditions. The predetermined conditions include: the condition that the target batch is the first batch after the original plate 1 is replaced, and the condition that the target batch is the first batch after the exposure device EXP is repaired.

[0043] In step S103, the controller 17 causes the laser interferometer 10 to measure the position of the substrate stage 4 in a predetermined state in which the reference mark 112 on the reference plate 11a is arranged in the field of view of the off-axis detection system 16 as the first position. As described above, the reference plate 11a may be the reference plate closest to the reflection surface of the reflection mirror 8 (as the reference portion whose position is measured by the laser interferometer 10) among the plurality of reference plates 11a to 11c on the substrate stage 4. Step S103 may be understood as a step performed at the first timing of generating the baseline information. The storage device stores the position (first position) of the substrate stage 4 measured in step S103.

[0044] In step S104, the controller 17 performs an exposure process on each of the plurality of projection areas 3a on the first substrate 3. As described above, the exposure process is a process of transferring the pattern of the original plate 1 to the substrate. The exposure process may include the following processes: obtaining position information of the substrate 3 (projection area 3a) by detecting the alignment mark 19 on the substrate 3 using the off-axis detection system 16, and performing alignment between the original plate 1 and the substrate 3 based on the position information and the baseline information of the substrate 3.

[0045] Steps S105 to S110 are steps of performing exposure processing on the second substrate and subsequent substrates 3 of the batch.

[0046] In step S105, the controller 17 causes the substrate conveying mechanism (not shown) to unload (recover) the substrate 3 that has undergone the exposure process from the substrate stage 4, and simultaneously load the nth substrate 3 that is to undergo the next exposure process onto the substrate stage 4. In this case, "n" represents the ordinal number of the second or subsequent substrate 3 of the batch, and an integer greater than 2 is input. The substrate 3 can be unloaded from and loaded onto the substrate stage 4 while the substrate stage 4 is arranged at the substrate loading ground.

[0047] In step S106, the controller 17 determines whether to correct the baseline information. If the controller 17 determines to correct the baseline information, the process proceeds to step S107. If the controller 17 determines not to correct the baseline information, the process proceeds to step S109.

[0048] For example, a determination criterion for determining whether to correct the baseline information is given by checking against the operating state of the exposure device EXP and the feedback from the overlap checker and estimating the timing at which the amount of change in the baseline exceeds the allowable range. It may be configured to input a specific substrate 3 of a batch for which the baseline information is corrected during the exposure process, that is, the serial number of the substrate 3 for which the baseline information is corrected during the exposure process, into the exposure device EXP in advance. Alternatively, the controller 17 may make such a determination using an algorithm or a learning mechanism incorporated in the controller 17 based on feedback from the overlap checker or information from various sensors of the exposure device (e.g., the temperature detector 113) so as to meet the requirements of both production volume and overlap accuracy. For example, based on the overlap accuracy check result of a plurality of substrates 3 of the previous batch, the serial number of the substrate 3 for which the overlap accuracy exceeds the allowable range may be determined as the serial number of the substrate 3 to be subjected to the baseline information correction during the exposure process. The serial number of the substrate to be subjected to the baseline information correction during the exposure process may be updated sequentially. Alternatively, if the temperature of the substrate stage 4 measured by the temperature detector 113 exceeds a threshold value, it may be determined that the correction of the baseline information may be performed.

[0049] In step S107, the controller 17 causes the laser interferometer 10 to measure the position of the substrate stage 4 in a predetermined state in which the reference mark 112 on the reference plate 11a is arranged in the field of view of the off-axis detection system 16 as a second position. The reference plate 11a is the reference plate used in the above-mentioned step S103. Step S107 can be understood as a step performed at a second timing after the first timing of generating the baseline information. The storage device stores the position (second position) of the substrate stage 4 measured in step S107.

[0050] In step S107, the position of the reference mark 112 on the reference plate 11a is quickly measured by using only the off-axis detection system 16 without using the projection optical system 6 and the TTL detection system 13. In addition, the measurement in step S107 uses the reference plate 11a. Figure 3 As described above, this makes it possible to arrange the reference plate 11a below the off-axis detection system 16 without significantly changing the route of the substrate stage 4 from the substrate loading site to below the projection optical system 6, thereby providing an advantage in terms of throughput.

[0051] In step S108, the controller 17 calculates the difference between the first position obtained in step S103 and the second position obtained in step S107, and corrects the baseline information based on the difference. Let the first position be "OAS(0)" and the second position be "OAS(t)", then the correction value ΔBL for correcting the baseline information is represented by "ΔBL=OAS(0)-OAS(t)". ​​Considering the X-axis direction component and the Y-axis direction component, the correction values ​​ΔBLx and ΔBLy for correcting the baseline information can be represented by the following formula (1):

[0052] ΔBLx=OASx(0)-OASx(t)

[0053] ΔBLy=OASy(0)-OASy(t)...(1)

[0054] When the position of the reference mark 112 is measured at the first timing (step S103) for generating the baseline information and at the second timing (step S107) after the first timing, different measurement results can be obtained. The reason why the measurement results of the position of the reference mark 112 at the first timing and the second timing are different from each other may be that, for example, the baseline has changed due to the influence of the heat generated during the operation of the exposure device EXP. That is, the difference between the measurement results of the position of the reference mark 112 at the first timing and the second timing can be understood as the amount of change in the baseline. Therefore, correcting the baseline information based on the difference makes it possible to accurately align the original plate 1 with the substrate 3 that is subsequently subjected to the exposure process, and to set the overlap accuracy within the allowable range. In addition, by correcting the baseline information in a similar manner for other batches, the overlap accuracy can be improved while minimizing the degradation of the production volume by avoiding the use of the projection optical system 6 and the TTL detection system 13 to generate the baseline information.

[0055] In step S109, the controller 17 performs exposure processing on each of the plurality of shot areas 3a on the nth substrate 3. In step S110, the controller 17 determines whether the batch includes a substrate 3 to be subjected to the exposure processing next (hereinafter sometimes referred to as the next substrate 3), that is, whether the batch includes any substrate 3 that has not been subjected to the exposure processing. If there is a next substrate 3, the process returns to step S105, and steps S105 to S109 are performed on the next substrate 3. If there is no next substrate 3, the substrate conveying mechanism (not shown) unloads the substrate 3 that has been subjected to the exposure processing from the substrate stage 4, thereby terminating the process. Figure 4 Flowchart in .

[0056] As described above, the exposure apparatus EXP according to the present embodiment corrects the baseline information using only the off-axis detection system 16. This can improve the overlay accuracy and provide advantages in throughput compared to the case where the TTL detection system 13 is used to regenerate or correct the baseline information.

[0057] <Second Embodiment>

[0058] A second embodiment according to the present invention will be described. The first embodiment has illustrated a case where baseline information is corrected based on the difference between the first position obtained at the first timing (step S103) and the second position obtained at the second timing (step S107). The second embodiment will illustrate a case where baseline information is further corrected based on the difference between the first timing and the second timing regarding the distance between the reference portion of the substrate stage 4 (the reflection surface of the reflection mirror 8) and the reference mark 112 on the reference plate 11a. Note that this embodiment basically inherits the first embodiment, and can follow the first embodiment except for the matters described below.

[0059] When only the off-axis detection system 16 is used to correct the baseline information, another advantage of using the reference plate 11a that is closest to the reflector 8 among the multiple reference plates 11a to 11c on the substrate stage 4 can be seen. In order to identify the difference between the first position obtained at the first timing (step S103) and the second position obtained at the second timing (step S107) as the baseline change amount between the first timing and the second timing as described above, the following premise is required. That is, the thermal deformation (thermal expansion / contraction) of the substrate stage 4 itself caused by the change in the temperature of the substrate stage 4 itself and the change in the ambient atmospheric temperature can be ignored. When verifying the validity of this premise, it is important to consider the reference Figure 2 The placement of the reflecting mirror 8 is described. There are laser interferometers 10 and 12 for measuring the position of the substrate stage 4 at a position facing the reflecting mirror 8. The reference plate 11a for correcting the baseline information is arranged so that the distance extending from the reflecting mirror 8 in the X-axis direction and the Y-axis direction is shorter than the distance between the reflecting mirror 8 and the remaining reference plates 11b and 11c.

[0060] Typically, the coefficient of thermal expansion that describes the amount of thermal deformation per unit temperature change of a given substance is a ratio expressed as a dimensionless quantity ppm. The actual amount of thermal deformation increases with the distance from the reference point. The point serving as the reference for the amount of thermal deformation corresponds to the reflective surface (surface) of the reflector 8 on the substrate stage 4. Therefore, the amount of position change of the reference mark 112 on the reference plate 11a arranged near the reflective surface of the reflector 8 due to the thermal deformation of the substrate stage 4 is relatively small.

[0061] However, in reality, since the distance between the reflecting surface of the reflecting mirror 8 and the reference mark 112 on the reference plate 11a is not zero, the distance change amount due to the temperature (thermal deformation) of the substrate stage 4 is not zero. Therefore, even if the baseline information is corrected as in the first embodiment, a correction residual will be generated according to the distance change amount due to the temperature of the substrate stage 4. Therefore, in this embodiment, the controller 17 obtains the difference (distance difference) between the first timing and the second timing of the distance between the reflecting surface of the reflecting mirror 8 and the reference mark 112 on the reference plate 11a based on the difference between the temperature of the substrate stage 4 at the first timing and the second timing. The baseline information is further corrected based on the difference. By using the temperature detector 113 provided on the substrate stage 4, the difference between the temperature of the substrate stage 4 at the first timing and the second timing can be obtained. Please note that the distance between the reflecting surface of the reflecting mirror 8 and the reference mark 112 is sometimes written as "mark distance".

[0062] More specifically, in step S108, the controller 17 can obtain the correction value ΔBL for correcting the baseline information by "ΔBL = OAS(0) - {OAS(t) - ΔWS]". In this formula, "OAS(0)" represents the first position, "OAS(t)" represents the second position, and "ΔWS" represents the amount of change in the mark distance between the first timing and the second timing with respect to the reference mark 112 on the reference plate 11a. In addition, considering the X-axis direction component and the Y-axis direction component, the correction values ​​ΔBLx and ΔBLy for correcting the baseline information can be expressed by formula (2):

[0063] ΔBLx=OASx(0)-{OASx(t)-ΔWSx}

[0064] ΔBLy=OASy(0)-{OASy(t)-ΔWSy}...(2)

[0065] Here, a method for obtaining the changes ΔWSx and ΔWSy of the mark distance will be described. The changes ΔWSx and ΔWSy of the mark distance can be calculated based on the thermal expansion coefficient (αx, αy) of the substrate carrier 4. The thermal expansion coefficient (αx, αy) can be understood as a coefficient that converts the change in the temperature of the substrate carrier 4 into the changes ΔWSx and ΔWSy of the mark distance. In addition, the thermal expansion coefficient (αx, αy) can be obtained in advance by using reference plates 11a to 11c (reference marks 112) respectively arranged at multiple corners of the substrate carrier 4 and a temperature detector 113 that detects the temperature of the substrate carrier 4. For example, the thermal expansion coefficient (αx, αy) can be obtained by a simulation operation in an adjustment step performed in advance for the production of the exposure device EXP.

[0066] More specifically, if Figure 2 As shown, by using the reference plate 11a ( Figure 2 The upper right reference plate in ) and 11c ( Figure 2 Assume that the reference plate 11a and the reference plate 11c differ in design coordinates by (ΔX, ΔY).

[0067] First, in the initial state, the reference plate 11c ( Figure 2 The position of the reference mark 112 on the lower left reference plate in the figure is measured, and the obtained measurement value is represented by (x1, y1). The position of the reference mark 112 is measured by the off-axis detection system 16 by measuring the position of the substrate stage 4 with the laser interferometer 10 in a predetermined state where the reference mark is arranged within the field of view of the off-axis detection system 16. Similarly, the position of the reference plate 11a ( Figure 2 The position of the reference mark 112 on the upper right reference plate in the exposure apparatus EXP is determined, and the obtained measurement values ​​are represented by (x2, y2). These measurement values ​​may vary with the temperature change of the substrate stage 4 reflecting the operating state of the exposure apparatus EXP.

[0068] In a state where the read value of the temperature detector 113 (i.e., the temperature of the substrate stage 4) changes due to the operation of the exposure device EXP, a measurement similar to that in the initial state is performed. That is, by measuring the reference plate 11c ( Figure 2 The position of the reference mark 112 on the lower left reference plate in the figure is represented by (x1', y1'). Similarly, the reference plate 11a ( Figure 2The position of the reference mark 112 on the upper right reference plate in the figure is determined, and the obtained measurement value is represented by (x2', y2'). When the amount of change in the temperature of the substrate stage 4 relative to the temperature in the initial state is represented by ΔTa, the thermal expansion coefficient (αx, αy) of the substrate stage 4 can be obtained by the formula (3) given below. The thermal expansion coefficient (αx, αy) obtained in advance in this way can be stored in a storage device.

[0069] αx={(x1'-x1)-(x2'-x2)} / (ΔX·ΔTa)

[0070] αy={(y1'-y1)-(y2'-y2)} / (ΔY·ΔTa)...(3)

[0071] For the purpose of explanation, (Lx2, Ly2) represents the area with respect to the reference plate 11a ( Figure 2 The design mark distance of the reference mark 112 on the upper right reference plate in the figure, and ΔTb represents the temperature difference of the substrate carrier 4 between the first timing and the second timing. In this case, the controller 17 can calculate the change amounts ΔWSx and ΔWSy of the mark distance by the equation (4) given below. Note that the temperature difference ΔTb of the substrate carrier 4 can be obtained by using the temperature detector 113. That is, the difference between the temperature of the substrate carrier 4 detected by the temperature detector 113 at the first timing and the temperature of the substrate carrier 4 detected by the temperature detector 113 at the second timing can be obtained as the temperature difference ΔTb. ΔWSx=αx·ΔTb·Lx2

[0072] ΔWSy=αy·ΔTb·Ly2...(4)

[0073] In this way, by multiplying the thermal expansion coefficient (αx, αy) of the substrate stage 4 by the designed mark distance (Lx2, Ly2), the change amounts ΔWSx and ΔWSy of the mark distance due to the temperature (thermal deformation) of the substrate stage 4 can be obtained. As shown in the above formula (2), by further correcting the baseline information using the change amounts ΔWSx and ΔWSy of the mark distance, the overlay accuracy can be further improved.

[0074] <Example of the method for manufacturing an article>

[0075] The article manufacturing method according to an embodiment of the present invention is suitable for manufacturing articles, such as micro devices such as semiconductor devices or elements with microstructures. The article manufacturing method according to this embodiment includes: an exposure step of exposing a substrate by controlling an exposure device using the above-mentioned control method; a processing step of processing the substrate that has undergone the exposure step; and a manufacturing step of manufacturing an article from the substrate that has undergone the processing step. The exposure step can be understood as a step of forming a latent image pattern on a photoresist coated on a substrate. The processing step can be understood as a step of developing a substrate (photoresist) formed with a latent image pattern. The manufacturing method also includes other known steps (oxidation, deposition, vapor deposition, doping, flattening, etching, removal of photoresist, cutting, bonding, packaging, etc.). Compared with conventional methods, the article manufacturing method according to this embodiment is advantageous in at least one of the performance, quality, productivity and production cost of the article.

[0076] <Other embodiments>

[0077] The embodiments of the present invention may also be implemented by reading and executing computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be more completely referred to as a "non-transitory computer-readable storage medium") to perform one or more functions in the above-mentioned embodiments, and / or a computer of a system or device including one or more circuits (e.g., an application-specific integrated circuit (ASIC)) for performing one or more functions in the above-mentioned embodiments, and the embodiments of the present invention may be implemented by, for example, reading and executing the computer executable instructions from the storage medium by the computer of the system or device to perform one or more functions in the above-mentioned embodiments, and / or controlling the one or more circuits to perform one or more functions in the above-mentioned embodiments. The computer may include one or more processors (e.g., a central processing unit (CPU), a microprocessing unit (MPU)), and may include a network of separate computers or separate processors to read and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, a hard disk, a random access memory (RAM), a read-only memory (ROM), a memory of a distributed computing system, an optical disk (such as a compact disc (CD), a digital versatile disc (DVD), or a Blu-ray disc (BD) TM ), flash memory devices, memory cards, etc.

[0078] The embodiments of the present invention may also be implemented by providing software (program) for performing the functions of the above-described embodiments to a system or device via a network or various storage media, and a computer or a central processing unit (CPU) or a microprocessing unit (MPU) of the system or device reads and executes the program.

[0079] While the present invention has been described with respect to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. An exposure device for exposing a substrate through a projection optical system, the exposure device comprising: a stage configured to move while holding the substrate; an imaging device configured to capture an image of a mark on a substrate without passing through a projection optical system; a measuring device configured to measure the position of the stage; as well as a controller configured to control alignment of the substrate based on a position and interval information of the mark, the position of the mark being obtained by using an imaging device and a measuring device, and the interval information indicating an interval between an optical axis of the imaging device and an optical axis of the projection optical system, Among them, the controller causing the measuring device to measure, at a first timing when the interval information is generated, a position of the stage in a predetermined state in which the reference mark on the stage is arranged within a field of view of the imaging device as a first position; and At a second timing after the first timing, the measuring device is caused to measure the position of the stage in the predetermined state as a second position, and the interval information is corrected based on a difference between the first position and the second position.

2. The exposure device according to claim 1, wherein: The measuring device measures the position of the reference part of the stage, The distance between the reference portion on the stage and the reference mark changes due to the temperature of the stage, and The controller obtains a distance difference, which is a difference between a temperature of the stage at a first timing and a temperature of the stage at a second timing, based on a temperature difference, and further corrects the interval information by the obtained distance difference, the distance difference being a distance difference between the first timing and the second timing.

3. The exposure device according to claim 2, wherein: If "OAS(0)" represents the first position, "OAS(t)" represents the second position, and "ΔWS" represents the distance difference, the controller calculates a correction value ΔBL for correcting the interval information by the following equation: ΔBL=OAS(0)-{OAS(t)-ΔWS}.

4. The exposure device according to claim 2 or 3, further comprising: a temperature detector configured to detect a temperature of the stage, The controller obtains the temperature difference based on detection results obtained by the temperature detector at the first timing and the second timing.

5. The exposure device according to claim 2 or 3, wherein: The controller obtains in advance a coefficient for converting the amount of change in the temperature of the stage into the amount of change in the distance, and obtains the distance difference based on the temperature difference and the coefficient.

6. The exposure device according to claim 2 or 3, further comprising: a second imaging device configured to capture an image of a mark on the substrate through a projection optical system, wherein the controller generates the interval information at a first timing based on a difference between a measurement result obtained by the measuring device in a state where the second reference mark on the stage is arranged within the field of view of the imaging device and a measurement result obtained by the measuring device in a state where the second reference mark is arranged within the field of view of the second imaging device, and On the stage, the reference mark is closer to the reference portion than the second reference mark.

7. The exposure device according to claim 6, wherein: In a state where the stage is arranged at the substrate loading place, the reference mark is closer to the imaging device than the second reference mark, and The substrate loading place is a place where the stage is arranged when a substrate is loaded on the stage.

8. The exposure device according to claim 2 or 3, wherein: The measuring equipment includes an interferometer, and The reference portion is a portion of the stage provided with a reflective surface that reflects the light of the interferometer.

9. The exposure device according to claim 2 or 3, wherein: The measuring device includes an encoder, and The reference portion is a portion of the stage where the scale of the encoder is disposed.

10. The exposure apparatus according to any one of claims 1 to 3, wherein: The predetermined state is a state in which the reference mark is arranged at a predetermined position within the field of view of the imaging apparatus.

11. The exposure apparatus according to claim 10, wherein: The predetermined position is the center of the field of view of the camera device.

12. A method for controlling an exposure device, the exposure device comprising: Projection optical system; a stage configured to move while holding the substrate; an imaging device configured to capture an image of a mark on a substrate without passing through a projection optical system; and a measuring device configured to measure the position of the stage, and the exposure device performs alignment of the substrate based on the position and interval information of the mark, wherein the position of the mark is obtained by using an imaging device and a measuring device, and the interval information indicates the interval between the optical axis of the imaging device and the optical axis of the projection optical system, the control method comprising: causing the measuring device to measure, at a first timing when the interval information is generated, a position of the stage in a predetermined state in which the reference mark on the stage is arranged within the field of view of the imaging device as a first position; and At a second timing after the first timing, the measuring device is caused to measure the position of the stage in the predetermined state as a second position, and the interval information is corrected based on a difference between the first position and the second position.

13. A method for manufacturing an article, the method comprising: exposing the substrate by controlling the exposure device using the control method defined in claim 12; processing the substrate that has undergone exposure; as well as An article is manufactured from a substrate that has undergone processing.

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