JP7804440B2 - Substrate holding device, lithography apparatus, substrate holding method, and article manufacturing method - Google Patents

Description

The present invention relates to a substrate holding device, a lithography apparatus, a substrate holding method, and a method for manufacturing an article.

In recent manufacturing processes for semiconductor devices and liquid crystal display devices, multiple layers are deposited on substrates such as semiconductor wafers and glass plates, and films that place a high amount of stress on the substrate or are relatively thick are sometimes formed. In such cases, warping of the substrate can occur, making it difficult to properly hold the substrate on a substrate holding device (substrate stage) during processes such as forming a pattern on the substrate using an exposure device. For this reason, technologies for correcting substrate warpage have been proposed. For example, Patent Document 1 discloses a transfer device with a peripheral pressing member that corrects substrate warpage. Furthermore, Patent Document 2 discloses a chuck device equipped with a sealing structure that seals the gap that forms between the back surface of a warped substrate and the top surface of the chuck.

Japanese Patent Application Laid-Open No. 2001-284434 Japanese Utility Model Application Publication No. 54-164982

In the devices described in Patent Documents 1 and 2, a member for correcting substrate warpage contacts the surface of the substrate (the surface on which the pattern is formed) or the outer periphery of the substrate, which can increase the risk of foreign matter adhering to the substrate or the substrate becoming contaminated. Therefore, there is a need for a configuration or method that can hold a substrate on a substrate stage in a way that reduces substrate warpage, without using a member that contacts the surface or outer periphery of the substrate.

The present invention therefore aims to provide an advantageous technology for holding warped substrates.

In order to achieve the above-mentioned object, one aspect of the present invention provides a substrate holding device for holding a warped substrate, comprising: a stage having a holding surface for holding the substrate; an excitation unit for applying vibrations to the substrate; and a control unit for controlling a process for causing the stage to hold the substrate, wherein the holding surface includes a first holding area for holding a first portion of the substrate and a second holding area for holding a second portion of the substrate that is different from the first portion, and wherein the control unit, during the process, causes the excitation unit to apply vibrations to the second portion of the substrate that is separated from the second holding area while the first portion of the substrate is held in the first holding area, at a resonant frequency of the second portion , thereby bringing the second holding area into contact with the second portion and causing the second portion to be held in the second holding area.

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

The present invention can provide, for example, an advantageous technique for holding a warped substrate.

Schematic diagram showing an example of the configuration of an exposure apparatus Schematic diagram showing an example of the configuration of a substrate transport system in an exposure apparatus. FIG. 1 is a diagram for explaining a process of supplying a substrate onto a substrate stage. Schematic diagram showing an example of the configuration of the substrate stage (holding surface) 10 is a flowchart showing a holding process in a substrate holding device. A schematic diagram showing the state of the holding process when the substrate driving mechanism is used as a vibration unit in time series. FIG. 10 is a diagram for explaining the time during which vibration is applied to the outer periphery of the substrate by the vibration unit. FIG. 1 is a diagram for explaining a resonance mode at the outer periphery of a substrate. FIG. 10 is a diagram showing an example in which the frequency of the vibration applied to the outer periphery of the substrate by the vibration unit is changed. A schematic diagram showing the state of the holding process in time series when the actuator that drives the lift pin is used as the vibration unit. Schematic diagram showing a modified example of the substrate stage (holding surface) A schematic diagram showing the holding process in chronological order when the substrate feeding hand is used as the vibration unit. A schematic diagram showing the holding process in chronological order when the substrate feeding hand is used as the vibration unit. FIG. 13 is a schematic diagram showing an example of the configuration of a holding surface of a substrate stage according to a fifth embodiment; A diagram showing the timing of gas injection from the injection unit. A schematic diagram showing the state of the holding process in time series when the sound wave output unit is used as the vibration unit.

The following describes the embodiments in detail with reference to the attached drawings. Note that the following embodiments do not limit the scope of the claimed invention. While the embodiments describe multiple features, not all of these features are necessarily essential to the invention, and multiple features may be combined in any desired manner. Furthermore, in the attached drawings, the same reference numbers are used to designate identical or similar components, and redundant explanations will be omitted.

In the following embodiments, an exposure apparatus that exposes a substrate to light and transfers a pattern from an original onto the substrate is used as an example of a lithography apparatus that forms a pattern on a substrate, and an example of applying a substrate holding device according to the present invention to an exposure apparatus is described, but the present invention is not limited to this. For example, the substrate holding device according to the present invention can also be applied to other lithography apparatuses, such as a molding apparatus (imprint apparatus, planarization apparatus) that uses a mold to form a composition on a substrate, or a drawing apparatus that uses a charged particle beam to form a pattern on a substrate. Furthermore, the substrate holding device according to the present invention is not limited to lithography apparatuses, and can be applied to other processing apparatuses that perform well-known processes, such as a measurement apparatus that measures substrates and a processing apparatus that processes substrates.

In this specification and the accompanying drawings, directions are indicated in an XYZ coordinate system, with the direction along the optical axis of the projection optical system 5 (described below) being the Z-axis direction and the plane perpendicular to the Z-axis direction being the XY plane. In the XYZ coordinate system, the directions parallel to the X, Y, and Z axes are the X-axis, Y-axis, and Z-axis, respectively, and rotation around the X, Y, and Z axes are the θX, θY, and θZ directions, respectively. Control or drive along the X, Y, and Z axes refers to control or drive along the X, Y, and Z axes, respectively. Control or drive along the θX, θY, and θZ axes refers to control or drive along the rotation direction around the X, Y, and Z axes, respectively. Position refers to information that can be determined based on the coordinates of the X, Y, and Z axes, and tilt (orientation) refers to information that can be determined by values of the θX, θY, and θZ axes. Positioning refers to controlling the position and/or tilt (orientation). In the following description, when the term "X-axis direction" is used, it can be defined to include the +X-axis direction and the -X-axis direction. The same applies to the "Y-axis direction" and "Z-axis direction."

First Embodiment
A first embodiment of the present invention will be described. Fig. 1 is a schematic diagram showing an example of the configuration of an exposure apparatus 100 of this embodiment. The exposure apparatus 100 of this embodiment is an apparatus that performs exposure processing to expose a substrate 9 and transfer a pattern of an original 2 onto the substrate. The exposure processing can be performed for each shot area on the substrate 9.

The exposure apparatus 100 may include, for example, an illumination system 1, an original stage 3, a projection optical system 5 (projection exposure lens), a substrate stage 8 (substrate chuck), and a substrate drive mechanism 6. The illumination system 1 illuminates the original 2. The original 2 is a mask or reticle and has a circuit pattern to be transferred onto a substrate. The original stage 3 generates an attractive force such as vacuum or electrostatic force to hold the original 2 and may be configured to be movable in each of multiple axial directions (e.g., six axial directions: X-axis, Y-axis, Z-axis, θX-axis, θY-axis, and θZ-axis) by a drive mechanism (not shown). The projection optical system 5 projects the pattern of the original 2 illuminated by the illumination system 1 onto the substrate. The substrate stage 8 has a holding surface that generates an attractive force such as vacuum or electrostatic force to hold (suction hold) the substrate 9 and may be configured to be movable in each of multiple axial directions (e.g., six axial directions: X-axis, Y-axis, Z-axis, θX-axis, θY-axis, and θZ-axis) by the substrate drive mechanism 6. The substrate 9 may be, for example, a semiconductor wafer or a glass plate. The substrate driving mechanism 6 drives the substrate stage 8 in each of a plurality of axial directions, thereby driving the substrate 9 held by the substrate stage 8 in each of a plurality of axial directions.

Here, the substrate stage 8 and substrate driving mechanism 6 may be understood as constituting part of a substrate holding device that holds the substrate 9. The specific configuration of the substrate holding device will be described later. Furthermore, the illumination system 1, original stage 3, and projection optical system 5 may be understood as constituting a formation unit that forms a pattern on a substrate held by the substrate holding device (substrate stage 8).

The exposure apparatus 100 may also include an original position measurement unit 4, a substrate position measurement unit 7, and an autofocus unit 10. The original position measurement unit 4 includes, for example, a laser interferometer and measures the XY-direction position (direction along the XY plane) of the original 2 held by the original stage 3. The substrate position measurement unit 7 includes, for example, a laser interferometer and measures the XY-direction position of the substrate 9 held by the substrate stage 8. The autofocus unit 10 measures the surface position (focus position) of the substrate 9 by irradiating light obliquely onto the surface (exposed surface) of the substrate 9 and detecting the light reflected from the surface. In this embodiment, the substrate drive mechanism 6 is configured to support the substrate stage 8 and move it in the XY directions, thereby driving the substrate stage 8 and the substrate 9 in the XY directions. Therefore, the substrate position measurement unit 7 measures the XY-direction position of the substrate drive mechanism 6 and can determine the XY-direction position of the substrate 9 based on the measurement results.

Next, the transportation of the substrate 9 in the exposure apparatus 100 will be described with reference to Figure 2. Figure 2 is a schematic diagram of the exposure apparatus 100 viewed from above (in the +Z-axis direction), and shows an example configuration of a substrate transport system for transporting (loading and unloading) the substrate 9 onto the substrate stage 8. The example in Figure 2 shows the chamber 30, substrate stage 8, substrate drive mechanism 6, pre-alignment unit 13, substrate transport hand 14, substrate feed hand 12, control unit 15, substrate load station 16, and substrate unload station 17.

The chamber 30 maintains the exposure environment at a constant temperature and humidity. The substrate stage 8 holds the substrate 9 and is positioned below the projection optical system 5 when performing exposure processing on the substrate 9. The substrate stage 8 can also be moved by the substrate drive mechanism 6 to a substrate recovery position 18 and a substrate supply position 19, indicated by triangles in Figure 2. The substrate recovery position 18 is the position to which the substrate stage 8 moves (is positioned) when recovering the substrate 9 from the substrate stage 8 after exposure processing. The substrate supply position 19 is the position to which the substrate stage 8 moves (is positioned) when transporting (supplying) the pre-aligned substrate 9 onto the substrate stage 8.

The control unit 15 is configured by a computer having a processor such as a CPU and memory, and controls each part of the exposure apparatus 100 to control each process performed by the exposure apparatus 100 (for example, the process of holding the substrate 9 by the substrate stage 8, and the process of exposing the substrate 9). In the example of Figure 2, the control unit 15 is electrically connected to the user interface 31. Note that the control unit 15 may be configured by a single computer or multiple computers.

The substrate loading station 16 is where substrates 9 loaded from outside the chamber 30 (i.e., substrates 9 that have not yet been subjected to exposure processing in the exposure apparatus 100) are placed. The substrate unloading station 17 is where substrates 9 that have already been subjected to exposure processing in the exposure apparatus 100 (i.e., substrates 9 that are being unloaded from the chamber 30) are placed. The pre-alignment unit 13 performs pre-alignment (pre-processing) on the substrate 9 prior to exposure processing. Pre-alignment can be, for example, a process of detecting the center position, orientation, and amount of warpage of the substrate 9 while rotating the substrate 9.

The substrate transport hand 14 is a substrate transport mechanism that transports a substrate 9 from the substrate loading station 16 to the pre-alignment unit 13, and retrieves the substrate 9 from the substrate stage 8 located at the substrate recovery position 18 and transports it to the substrate unloading station 17. The substrate feed hand 12 is a substrate transport mechanism (transport unit) that transports a substrate that has been pre-aligned in the pre-alignment unit 13 onto the substrate stage 8 located at the substrate supply position 19.

The substrate stage 8 is provided with a plurality of lift pins 11 (three in FIG. 2 ) that can protrude from the holding surface of the substrate stage 8 to raise and lower the substrate 9 relative to the holding surface. The lift pins 11 protrude from the holding surface of the substrate stage 8 to separate the substrate 9 from the holding surface when the substrate feed hand 12 supplies the substrate 9 onto the substrate stage 8, and when the substrate transport hand 14 retrieves the substrate 9 from the substrate stage 8. By having the lift pins 11 protrude from the holding surface of the substrate stage 8 in this manner, the substrate feed hand 12 and/or the substrate transport hand 14 can be inserted between the substrate 9 and the holding surface of the substrate stage 8. The lift pins 11 protrude from the holding surface of the substrate stage 8 either by moving the substrate stage 8 up and down while the lift pins 11 are stationary, or by moving the lift pins 11 up and down while the substrate stage 8 is stationary. The lift pins 11 can be configured to move in the X and Y directions integrally with the substrate stage 8.

Next, the process of supplying (transferring) the substrate 9 onto the substrate stage 8 by the substrate feed hand 12 will be described with reference to Figure 3. Figure 3 is a diagram for explaining the process of the substrate feed hand 12 supplying the substrate 9 onto the substrate stage 8, and Figures 3(a) to 3(e) show the operation of the substrate feed hand 12 and the lift pins 11 of the substrate stage 8 in chronological order.

First, the substrate 9 that has been pre-aligned in the pre-alignment unit 13 is retrieved by the substrate feed hand 12. The substrate feed hand 12 is then driven in the +Y-axis direction (FIG. 3(a)) to place the substrate 9 above the holding surface 8a of the substrate stage 8, which is positioned at the substrate supply position 19 (FIG. 3(b)). At this time, the lift pins 11 protrude from the holding surface 8a of the substrate stage 8, so the substrate feed hand 12 moves the substrate 9 above the holding surface of the substrate stage 8 so that the substrate 9 does not come into contact with the lift pins 11. Next, the substrate feed hand 12 is driven in the -Z-axis direction to lower the substrate 9 and place it on the lift pins 11 (FIG. 3(c)). The substrate feed hand 12 is then driven in the -Y-axis direction to retract (FIG. 3(d)). This completes the process of supplying the substrate 9 onto the lift pins 11 by the substrate feed hand 12, and the substrate 9 is placed on the lift pins 11. Then, by reducing the amount by which the lift pins 11 protrude from the holding surface 8a of the substrate stage 8, the substrate 9 can be placed (mounted) on the holding surface 8a of the substrate stage 8 (Figure 3(e)).

[Substrate holding device]
The substrate 9 that is subjected to exposure processing by the exposure apparatus 100 may be warped due to the deposition of multiple layers or the formation of a film that is highly stressful or relatively thick on the substrate 9. If the substrate 9 is warped in this way, it becomes difficult to accurately form a pattern on the substrate 9 by the exposure processing. Therefore, it is desirable to have the substrate stage 8 hold the substrate 9 so that the warpage of the substrate 9 is reduced (corrected). Therefore, the exposure apparatus 100 of this embodiment is provided with a substrate holding device that can hold the warped substrate 9. The substrate holding device includes a substrate stage 8 having a holding surface 8a that holds the substrate 9, a vibration unit that applies vibration to the substrate 9, and a control unit 15 that controls the process of holding the substrate 9 on the substrate stage 8 (holding process).

First, the configuration of the substrate stage 8 of this embodiment will be described. FIG. 4 is a schematic diagram of the holding surface 8a of the substrate stage 8 of this embodiment, viewed from above (in the +Z-axis direction), illustrating an example of the configuration of the substrate stage 8 (holding surface 8a). The holding surface 8a of the substrate stage 8 has a first holding area 81 that holds (holds by suction) a first portion of the substrate 9, and a second holding area 82 that holds (holds by suction) a second portion of the substrate 9 that is different from the first portion. The first holding area 81 and the second holding area 82 can be configured to individually control the suction forces used to attract the substrate 9. Here, the first portion of the substrate 9 is the portion that contacts the holding surface 8a when the substrate 9 is placed on it, and is described as the central portion of the substrate 9 in this embodiment. The second portion of the substrate 9 is the portion that separates from the holding surface 8a due to warping of the substrate 9 when the substrate 9 is placed on it, and is described as the outer periphery of the substrate 9 in this embodiment.

The first holding area 81 is an area surrounded by a first partition member 83a that protrudes in the +Z-axis direction from the main body of the substrate stage 8, and becomes an airtight space when the center of the substrate 9 is properly held. The first holding area 81 has a hole 84a connected to a vacuum source 88a via piping, and the vacuum pressure (suction force) of the first holding area 81 is detected by a pressure gauge 89a. The first partition member 83a may have a diameter of less than half the diameter of the substrate 9, for example, so that when the substrate 9 is placed on the holding surface 8a, the center of the substrate 9 that comes into contact with the holding surface 8a is securely held by the first holding area 81.

The second holding area 82 is surrounded by a second partition member 83b that protrudes from the main body of the substrate stage 8 in the +Z-axis direction and is separated from the first holding area 81 by a first partition member 83a. This creates an airtight space when the outer periphery of the substrate 9 is properly held. The second holding area 82 has a hole 84b connected to a vacuum source 88b via piping, and a pressure gauge 89b detects the vacuum pressure (suction force) in the second holding area 82. The second partition member 83b preferably has a diameter slightly smaller than the outer diameter of the substrate 9 so that it contacts the outer edge of the substrate 9 when the outer periphery of the substrate 9 is properly held by the second holding area 82. The second holding area 82 also has multiple through-holes 85 (three in FIG. 4 ) through which the lift pins 11 pass, allowing them to protrude from the holding surface 8a. Each of the multiple through-holes 85 is surrounded by a partition member 86.

Each of the first holding area 81 and the second holding area 82 has a plurality of protrusions 87 formed in the shape of pins or ribs. While only some of the protrusions 87 formed in each of the holding areas 81-82 are shown in Figure 4, these protrusions 87 can be provided on the entire holding surface 8 (each of the holding areas 81-82).

By configuring the holding surface 8a of the substrate stage 8 in this manner, the suction force (vacuum force, holding force) generated in each of the first holding area 81 and the second holding area 82 can be controlled individually. While Figure 4 shows an example in which the holding surface 8a is configured with two holding areas 81-82, it may also be configured with three or more holding areas. Also, while Figure 4 shows the holding areas 81-82 as concentric regions, they may also be polygonal rather than concentric or circular. Furthermore, while the example in Figure 4 uses separate vacuum sources 88a and 88b for the first holding area 81 and the second holding area 82, a common vacuum source may also be used.

Next, the holding process for holding a warped substrate 9 on the substrate stage 8 in the substrate holding device of this embodiment will be described with reference to Figures 5 and 6. Figure 5 is a flowchart showing the holding process in the substrate holding device of this embodiment. Each step in the flowchart of Figure 5 can be executed by the control unit 15. Figure 6 is a schematic diagram showing the holding process in the substrate holding device of this embodiment in chronological order. Figure 6 illustrates the substrate 9, substrate stage 8, and substrate driving mechanism 6. In this embodiment, an example will be described in which the substrate 9 has a downwardly convex warp and the substrate driving mechanism 6 is used as a vibration unit that applies vibration to the substrate 9.

In step S11, as described above with reference to FIG. 3, the control unit 15 places (arranges) the substrate 9 on the holding surface 8a of the substrate stage 8 using the substrate feed hand 12. Next, in step S12, the control unit 15 controls the vacuum sources 88a-88b to generate suction forces in the first holding area 81 and the second holding area 82 on the holding surface 8a of the substrate stage 8. At this time, as shown in FIG. 6(a), the central portion (first portion) of the substrate 9 comes into contact with the first partition member 83a when the substrate 9 is placed on the holding surface 8a in step S11, and is therefore held by the first holding area 81. On the other hand, the outer peripheral portion (second portion) of the substrate 9 is spaced from the holding surface 8a (second holding area 82) due to warping of the substrate 9, and therefore the outer peripheral edge of the substrate 9 does not come into contact with the second partition member 83b and is not held by the second holding area 82.

In step S13, as shown in FIG. 6(b), the control unit 15 generates suction forces in each of the first holding area 81 and the second holding area 82, while causing the vibration unit to vibrate the outer periphery (second portion) of the substrate 9, causing the outer periphery to resonate. In other words, with the first holding area 81 holding the center of the substrate 9 and fixing the positional relationship between the substrate stage 8 and the substrate 9, the control unit generates suction forces in the second holding area 82, while causing the vibration unit to vibrate the outer periphery of the substrate 9, causing the outer periphery to resonate.

In this embodiment, the substrate driving mechanism 6 is used as the vibration unit, and the substrate driving mechanism 6 vibrates the substrate stage 8 to impart vibration to the outer periphery of the substrate 9. At this time, the control unit 15 acquires information on the resonant frequency at which the outer periphery of the substrate 9 resonates while the center of the substrate 9 is held in the first holding region 81, and can cause the vibration unit (substrate driving mechanism 6) to vibrate the outer periphery of the substrate 9 at that resonant frequency. As shown in FIG. 7 , the control unit 15 can vibrate the outer periphery of the substrate 9 using the vibration unit (substrate driving mechanism 6) for a time period equal to or greater than half the resonance period obtained by the reciprocal of the resonance frequency. Furthermore, the control unit 15 acquires information indicating the amount of warping of the substrate 9, and can cause the vibration unit (substrate driving mechanism 6) to vibrate the outer periphery of the substrate 9 so that the outer periphery of the substrate 9 resonates with an amplitude equal to or greater than the amount of warping. This causes the outer periphery of the substrate 9 to oscillate in the Z-axis direction, so that the outer periphery of the substrate 9 comes into contact with the second holding region 82 (i.e., the outer edge of the substrate 9 comes into contact with the second partition member 83b of the substrate stage 8), allowing the outer periphery of the substrate 9 to be held by the second holding region 82. Note that the resonant frequency may also be understood as the natural frequency of the substrate 9.

In step S14, the control unit 15 determines whether the vacuum pressure (suction force) in the second holding area 82 detected by the pressure gauge 89b is within an allowable range. The allowable range can be set to the vacuum pressure (suction force) when the outer periphery of the substrate 9 is properly held by the second holding area 82. If the vacuum pressure detected by the pressure gauge 89b is within the allowable range, it is determined that the outer periphery of the substrate 9 is properly held by the second holding area 82, and the process ends. On the other hand, if the vacuum pressure detected by the pressure gauge 89b is not within the allowable range, step S13 is repeated. Note that the control unit 15 may change the frequency and amplitude of the vibration applied to the outer periphery of the substrate 9 by the vibration unit each time it returns to step S13.

Next, the frequency and amplitude of the vibration applied to the substrate 9 in step S13 described above so that the outer periphery of the substrate 9 resonates will be described. The control unit 15 stores a resonant frequency list, a resonant amplitude list, and a substrate warpage list. The resonant frequency list is a list showing the resonant frequencies of the substrate 9 for various combinations of the thickness, dimensions (size), material, etc. of the substrate 9, and is obtained in advance through experiments, simulations, etc. The resonant amplitude list is a list showing the resonant amplitude for the input amplitude at each frequency of the vibration applied to the substrate 9, and is obtained in advance through experiments, simulations, etc. The substrate warpage list is a list of the warpage amounts assumed (estimated) to occur in the substrate 9 for various combinations of the thickness, dimensions, material, etc. of the substrate 9, and is obtained in advance through experiments, simulations, etc.

The control unit 15 acquires information such as the thickness, dimensions, and material of the substrate 9 (hereinafter sometimes referred to as substrate information). The substrate information may be information input by the user via the user interface 31, or information obtained by measurement using an external measuring device. The control unit 15 then acquires information on the amount of warpage of the substrate 9 corresponding to the substrate information by referencing the substrate warpage amount list. Note that in this embodiment, information on the amount of warpage of the substrate 9 is acquired from the substrate warpage amount list based on the substrate information, but information on the amount of warpage of the substrate 9 measured by the pre-alignment unit 13 or an external measuring device may also be acquired from the pre-alignment unit 13 or the external measuring device.

The control unit 15 also references the resonance frequency list to acquire information on the resonance frequency corresponding to the substrate information. Furthermore, the control unit 15 references the resonance amplitude list for the resonance frequency corresponding to the substrate information to acquire information on the input amplitude that will produce an amplitude equal to or greater than the acquired amount of warpage of the substrate 9. Based on the thus acquired resonance frequency information and input amplitude information, the control unit 15 applies vibration to the substrate 9 using the vibration unit (substrate driving mechanism 6). This allows the outer periphery of the substrate 9 to resonate so as to come into contact with the second holding region 82.

Depending on the state (shape) of the warpage of the substrate, it may be difficult to efficiently resonate (oscillate) the outer periphery of the substrate 9 simply by vibrating the outer periphery at the primary resonant frequency. Therefore, the outer periphery of the substrate 9 may be vibrated using not only the primary resonant frequency but also secondary or higher resonant frequencies. This allows the outer periphery of the substrate 9 to resonate in various resonant modes, as shown in FIG. 8, thereby more efficiently holding the outer periphery of the substrate 9 in the second holding region 82. Figure 8(a) shows the vibration of the substrate 9 in the primary resonant mode (primary resonant frequency), Figure 8(b) shows the vibration of the substrate 9 in the secondary resonant mode (secondary resonant frequency), and Figure 8(c) shows the vibration of the substrate 9 in the tertiary resonant mode (tertiary resonant frequency).

For example, the control unit 15 may acquire in advance a resonant frequency list including a list indicating primary resonant frequencies, a list indicating secondary resonant frequencies, and a list indicating tertiary resonant frequencies, and acquire information on the primary to tertiary resonant frequencies corresponding to the substrate information. The control unit 15 may then vibrate the substrate 9 using the vibration unit at the primary to tertiary resonant frequencies in order from lowest to highest. Note that the frequencies of vibration applied to the substrate 9 are not limited to the primary to tertiary resonant frequencies; they may be only the primary and secondary resonant frequencies, or fourth or higher resonant frequencies may be added. The direction of vibration applied to the substrate 9 may be any direction, such as horizontal (X-axis direction, Y-axis direction) or vertical (Z-axis direction). However, by setting the direction perpendicular to the holding surface 8a of the substrate stage 8 (Z-axis direction), the outer periphery of the substrate 9 can be resonated efficiently.

As described above, in the substrate holding device of this embodiment, while the center of the substrate 9 is held in the first holding area 81, the vibration unit (substrate driving mechanism 6) applies vibration to the outer periphery of the substrate 9 that moves away from the second holding area 82, causing it to resonate. This allows the second holding area 82 to come into contact with the outer periphery of the substrate 9, allowing the second holding area 82 to hold the outer periphery. In other words, the substrate 9 can be held on the substrate stage 8 in a manner that reduces warping of the substrate 9, without using a member that comes into contact with the surface and outer periphery of the substrate 9.

Second Embodiment
A second embodiment of the present invention will be described. In the first embodiment, an example in which vibration is applied to the outer periphery of the substrate 9 at a predetermined resonant frequency is described. In this embodiment, an example in which the frequency of the vibration applied to the outer periphery of the substrate 9 is changed is described. Note that this embodiment basically follows on from the first embodiment, and is the same as described in the first embodiment except for the matters described below.

In this embodiment, in step S13 of the flowchart in FIG. 5 described above, the control unit 15 generates suction forces in each of the first holding area 81 and the second holding area 82 while varying the frequency of the vibrations applied to the outer periphery (second portion) of the substrate 9 by the vibration unit. For example, the control unit 15 varies (sweeps) the frequency of the vibrations applied to the outer periphery of the substrate 9 by the vibration unit over time within a frequency range that includes the resonant frequency at which the outer periphery of the substrate 9 resonates. The frequency range is preferably set to include the first to third resonant frequencies, but may also be set to include only the first resonant frequency, only the first to second resonant frequencies, or fourth or higher resonant frequencies. The frequency range varies depending on the thickness, dimensions, material, etc. of the substrate 9, but is preferably 10 to 300 Hz, for example.

Figure 9 shows an example of changing the frequency of vibration applied to the outer periphery of substrate 9 by the vibration unit. Figure 9(a) shows the time change in the frequency of vibration (input vibration) applied to the outer periphery of substrate 9 by the vibration unit, and Figure 9(b) shows the waveform of the vibration (input vibration) applied to the outer periphery of substrate 9 by the vibration unit. In Figure 9(b), the maximum value of the excitation force (amplitude) is defined as 1, the start frequency of the change is 10 Hz, and the end frequency is 300 Hz. Figure 9(c) shows the waveform of the vibration (response vibration, output vibration) generated at the outer periphery of substrate 9 when vibration is applied to the outer periphery of substrate 9 with the input waveform shown in Figure 9(b). In the example of Figure 9(a), the frequency increases over time, but the frequency may also decrease over time. In the example of Figure 9(a), the frequency changes at a constant slope over time, but the frequency may also change while changing the slope over time. Additionally, in the example of Figure 9(a), the frequency is changed continuously over time, but it may also be changed in steps over time.

As shown in Figure 9(c), for a while after vibration begins, the outer periphery of the substrate 9 vibrates at the same amplitude as the amplitude of the input vibration waveform, but as it approaches the primary resonance frequency (around 0.24 sec), the outer periphery of the substrate 9 resonates, increasing the amplitude of the outer periphery of the substrate 9. Furthermore, after the primary resonance frequency is passed, the outer periphery of the substrate 9 vibrates at the same amplitude as the amplitude of the input amplitude waveform, but as it approaches the secondary resonance frequency (around 0.32 sec), the outer periphery of the substrate 9 resonates again, increasing the amplitude of the outer periphery of the substrate 9. Furthermore, after the secondary resonance frequency is passed, the outer periphery of the substrate 9 vibrates at the same amplitude as the amplitude of the input amplitude waveform, but as it approaches the tertiary resonance frequency (around 0.6 sec), the outer periphery of the substrate 9 resonates again, increasing the amplitude of the outer periphery of the substrate 9. By changing the frequency of the vibrations applied to the outer periphery of the substrate 9 using the vibration unit in this way, it is possible to make the outer periphery of the substrate 9 resonate at the primary to tertiary resonance frequencies without having to obtain (calculate) the primary to tertiary resonance frequencies as in the first embodiment. Furthermore, by changing the frequency of the vibrations applied to the outer periphery of the substrate 9, the resonance frequency of the substrate 9 can be determined. Therefore, for a next substrate that has similar thickness, dimensions, material, etc. to the substrate 9, vibrations can be applied to the outer periphery of the substrate 9 at the determined resonance frequency without changing the frequency.

Here, the warpage shape of the substrate 9 is not limited to a shape in which the warpage angle increases concentrically from the center of the substrate 9 toward the periphery, as shown in FIG. 8(a). For example, the warpage shape of the substrate 9 may also include a shape (sometimes called a twisted shape) in which the upward and downward warpage components differ in two mutually perpendicular axial directions, as shown in FIG. 8(b). Furthermore, as shown in FIG. 8(c), the warpage shape may also include a shape (sometimes called a wavy shape) that includes higher-order components. For substrates 9 having such warpage shapes that include multiple components, it is effective to change the frequency of the vibrations applied to the periphery of the substrate 9, as in this embodiment.

The control unit 15 may also set the amplitude of the vibration applied to the outer periphery of the substrate 9 so that the outer periphery of the substrate 9 resonates at an amplitude equal to or greater than the amount of warping obtained from the substrate information (information on the thickness, dimensions, and material of the substrate 9). However, there are cases where an appropriate amplitude cannot be uniquely determined due to variations in the thickness, dimensions, and amount of warping of the substrate 9. In such cases, in addition to changing the frequency of the vibration applied to the outer periphery of the substrate 9, it is also preferable to change the amplitude of the vibration so that the amplitude gradually increases.

As described above, in this embodiment, during the holding process, the frequency of the vibration applied to the outer periphery of the substrate 9 by the vibration applying unit is changed within a frequency range that includes the resonant frequency at which the outer periphery of the substrate 9 resonates. This makes it possible to resonate the outer periphery of the substrate 9 efficiently without having to calculate the resonant frequency of the outer periphery of the substrate 9.

Third Embodiment
A third embodiment of the present invention will now be described. In the first and second embodiments, an example was described in which a substrate driving mechanism 6 was used as a vibration unit that applied vibration to a substrate 9. In this embodiment, an example will be described in which an actuator 20 (drive unit) that drives lift pins 11 is used as a vibration unit, and the actuator 20 vibrates the lift pins 11, thereby vibrating the outer periphery of a substrate 9. Note that this embodiment basically inherits the first embodiment, and is the same as described in the first embodiment except for the matters described below. Furthermore, the second embodiment may also be applied to this embodiment.

10 is a schematic diagram showing, in time sequence, the holding process when the actuator 20 that drives the lift pins 11 is used as the vibration unit. As shown in FIG. 10(a), when the substrate 9 is supplied onto the lift pins 11 from the substrate feed hand 12, the control unit 15 generates suction forces in each of the first holding area 81 and the second holding area 82. Then, as shown in FIG. 10(b), the control unit 15 lowers the lift pins 11 using the actuator 20, thereby reducing the amount of protrusion of the lift pins 11 from the holding surface 8a. As a result, the substrate 9 is placed on the holding surface 8a of the substrate stage 8, and the center of the substrate 9 is held by the first holding area 81. Next, as shown in FIG. 10(c), the control unit 15 causes the actuator 20 to abut the lift pins 11 against the outer periphery of the substrate 9, and vibrates the lift pins 11 using the actuator 20, thereby vibrating the outer periphery of the substrate 9 so that the outer periphery resonates. The method for resonating the outer periphery of the substrate 9 can be the same as that described in the first or second embodiment. This causes the outer periphery of the substrate 9 to oscillate, so that, as shown in FIG. 10(d), the outer periphery of the substrate 9 can be brought into contact with the second holding region 82, and the second holding region 82 can hold the outer periphery of the substrate 9.

Here, the lift pins 11 may be provided inside the second partition member 83b (i.e., the second holding area 82) as shown in FIG. 4, or they may be provided outside the second partition member 83b as shown in FIGS. 11(a) and 11(b). FIG. 11 is a schematic diagram of the holding surface 8a of the substrate stage 8 viewed from above (the +Z axis direction), showing an example configuration of the substrate stage 8 (holding surface 8a) of this embodiment. FIG. 11(a) shows an example configuration in which the lift pins 11 are arranged outside the circular second partition member 83b. FIG. 11(b) also shows an example configuration in which a portion of the second partition member 83b is recessed inward (toward the first holding area 81), and the lift pins 11 are arranged in this recess D.

As described above, in this embodiment, the actuator 20 (drive unit) that drives the lift pins 11 is used as the vibration unit, and the actuator 20 vibrates the lift pins 11, thereby vibrating the outer periphery of the substrate 9. As with the first and second embodiments, this embodiment also makes it possible to hold the substrate 9 on the substrate stage 8 so that warping of the substrate 9 is reduced.

Fourth Embodiment
A fourth embodiment of the present invention will be described. In this embodiment, an example will be described in which the substrate feed hand 12 is used as a vibration unit and the outer periphery of the substrate 9 is vibrated by the substrate feed hand 12. Note that this embodiment basically inherits the first embodiment, and is the same as that described in the first embodiment except for the matters described below. Furthermore, the second and third embodiments may also be applied to this embodiment.

Figures 12 and 13 are schematic diagrams showing, in time sequence, the holding process when the substrate feed hand 12 is used as the vibration unit. Figure 12 shows a side view, and Figure 13 shows a top view. The substrate stage 8 of this embodiment is configured so that when the substrate 9 is transported onto the substrate stage 8 by the substrate feed hand 12, the substrate feed hand 12 and the substrate stage 8 do not interfere (contact each other). For example, as shown in Figure 13, the substrate stage 8 of this embodiment has a structure that is smaller than the outer diameter of the substrate 9, or a structure in which a portion is cut out to prevent interference with the substrate feed hand 12. In other words, even when the substrate feed hand 12 and the substrate stage 8 are positioned so that they overlap in the Z-axis direction when viewed from above (+Z-axis direction), the dimensions are such that they do not interfere (contact) with each other.

As shown in Figures 12(a) and 13(a), the control unit 15 drives the substrate feed hand 12 in the +Y-axis direction to place the substrate 9 above the holding surface 8a of the substrate stage 8 located at the substrate supply position 19. The control unit 15 then generates suction forces in each of the first holding area 81 and the second holding area 82, and then drives the substrate feed hand 12 in the -Z-axis direction as shown in Figures 12(b) and 13(b). As a result, the substrate 9 is placed on the holding surface 8a of the substrate stage 8, and the center of the substrate 9 is held by the first holding area 81. Next, as shown in Figure 12(c), the control unit 15 abuts the substrate feed hand 12 against the outer periphery of the substrate 9 and vibrates the substrate feed hand 12, thereby vibrating the outer periphery of the substrate 9 so that it resonates. The methods described in the first or second embodiment can be applied to resonate the outer periphery of the substrate 9. This causes the outer periphery of the substrate 9 to swing, so that, as shown in Figures 12(d) and 13(c), the outer periphery of the substrate 9 comes into contact with the second holding area 82, allowing the second holding area 82 to hold the outer periphery of the substrate 9. Furthermore, once the outer periphery of the substrate 9 is held by the second holding area 82, the control unit 15 drives the substrate feed hand 12 in the -Y axis direction to retract it.

As described above, in this embodiment, the substrate feed hand 12 is used as the vibration unit, and the outer periphery of the substrate 9 is vibrated by vibrating the substrate feed hand 12. As with the first to third embodiments, this embodiment also allows the substrate 9 to be held on the substrate stage 8 so that warping of the substrate 9 is reduced.

Fifth Embodiment
A fifth embodiment of the present invention will be described. In this embodiment, an example will be described in which an ejection unit 21 that ejects gas toward the outer periphery of the substrate 9 while the central portion of the substrate 9 is held by a first holding region 81 is used as a vibration unit, and the outer periphery of the substrate 9 is vibrated by periodically ejecting gas from the ejection unit 21. Note that this embodiment basically inherits the first embodiment, and is the same as described in the first embodiment except for the matters described below. Furthermore, the second to fourth embodiments may also be applied to this embodiment.

Figure 14 is a schematic diagram of the holding surface 8a of the substrate stage 8 as viewed from above (in the +Z-axis direction), showing an example of the configuration of the substrate stage 8 (holding surface 8a) of this embodiment. As shown in Figure 14, the substrate stage 8 (holding surface 8a) of this embodiment is provided with an injection unit 21 (injection hole) that injects gas (e.g., air) toward the outer periphery of the substrate 9 while the central portion of the substrate 9 is held by the first holding region 81. The injection unit 21 is connected via a pipe to a gas supply source 22 that supplies compressed gas, and the pipe is provided with a solenoid valve 23.

When the center of the substrate 9 is held by the first holding area 81, the control unit 15 controls the solenoid valve 23 to periodically spray gas from the spray unit 21 toward the outer periphery of the substrate 9, causing the outer periphery of the substrate 9 to vibrate (resonate). The spray unit 21 is preferably positioned so that the gas hits the portion of the substrate 9 where vibration is greatest (e.g., the outer periphery). This allows the outer periphery of the substrate 9 to oscillate efficiently, bringing the outer periphery of the substrate 9 into contact with the second holding area 82 and allowing the second holding area 82 to hold the outer periphery of the substrate 9.

Figure 15 shows the timing of gas injection from the injection unit 21. Figure 15(a) shows an example in which a single solenoid valve 23 is provided for multiple injection units 21, and gas is injected from the multiple injection units 21 at the same timing by opening and closing the solenoid valve 23. In this case, it is possible to vibrate the outer periphery of the substrate 9, but considering the response time of the solenoid valve 23 and the response of the compressed gas, it is difficult to increase the frequency of the vibration applied to the outer periphery of the substrate 9. Therefore, as shown in Figures 15(b) and 15(c), it is advisable to provide a solenoid valve 23 for each of the multiple injection units 21 (injection holes), shift the phase of the timing at which gas is injected from each injection unit 21, and sequentially change the injection unit 21 that injects gas. This makes it possible to increase the frequency of the vibration applied to the outer periphery of the substrate 9.

The maximum frequency [Hz] that can be supported can be expressed as "1000 [msec] / (solenoid valve response time [msec] x 2) x number of solenoid valves 23 (injection units 21)." For example, if the solenoid valve's opening/closing response time is 10 msec, the maximum expected frequency, excluding the response of the compressed gas traveling through the piping, is 50 Hz, since it takes 10 msec to turn on and 10 msec to turn off, for a total cycle of 20 msec. Therefore, to vibrate the outer periphery of the substrate 9 at a cycle of 200 Hz, if controlled by a single solenoid valve 23, the response time would need to be 2.5 msec or less, which is difficult to achieve. On the other hand, by providing a solenoid valve 23 for each of the four injection units 21 and shifting the phase of the gas injection timing of the four injection units 21 by 5 msec, it is possible to vibrate the outer periphery of the substrate 9 at 200 Hz.

As described above, in this embodiment, the ejection unit 21 that ejects gas toward the outer periphery of the substrate 9 is used as the vibration unit, and the outer periphery of the substrate 9 is vibrated by periodically ejecting gas from the ejection unit 21. As with the first to fourth embodiments, this embodiment also makes it possible to hold the substrate 9 on the substrate stage 8 so as to reduce warping of the substrate 9.

Sixth Embodiment
A sixth embodiment of the present invention will be described. In this embodiment, an example will be described in which a sound wave output unit 25 that outputs sound waves toward the outer periphery of the substrate 9 while the central portion of the substrate 9 is held by the first holding region 81 is used as a vibration unit, and the outer periphery of the substrate 9 is vibrated by outputting sound waves from the sound wave output unit 25. Note that this embodiment basically inherits the first embodiment, and is the same as described in the first embodiment except for the matters described below. Furthermore, the second to fifth embodiments may also be applied to this embodiment.

16 is a schematic diagram showing, in time sequence, the holding process when the sonic wave output unit 25 is used as a vibration unit. In the example of FIG. 16, the sonic wave output unit 25 is provided above the substrate stage 8, but it may also be provided on the holding surface 8a of the substrate stage 8 (e.g., the second holding area 82). In FIG. 16(a), a substrate 9 is placed on the holding surface 8a of the substrate stage 8, and the center of the substrate 9 is held by the first holding area 81. While generating a suction force in the second holding area 82, the control unit 15 outputs sonic waves from the sonic wave output unit 25 toward the outer periphery of the substrate 9, as shown in FIG. 16(b). At this time, the sonic waves output from the sonic wave output unit 25 are sonic waves having a resonant frequency at which the outer periphery of the substrate 9 resonates. The method for resonating the outer periphery of the substrate 9 can be the same as that described in the first or second embodiment. This causes the outer periphery of the substrate 9 to swing, so that, as shown in FIG. 16(c), the outer periphery of the substrate 9 comes into contact with the second holding area 82, allowing the second holding area 82 to hold the outer periphery of the substrate 9.

As described above, in this embodiment, the sound wave output unit 25, which outputs sound waves toward the outer periphery of the substrate 9, is used as a vibration unit, and the outer periphery of the substrate 9 is vibrated by outputting sound waves from the sound wave output unit 25. In this embodiment, as in the first to fifth embodiments, the substrate 9 can be held on the substrate stage 8 so as to reduce warping of the substrate 9.

<Embodiment of manufacturing method of article>
The method for manufacturing an article according to an embodiment of the present invention is suitable for manufacturing articles such as microdevices, such as semiconductor devices, and elements having a microstructure. The method for manufacturing an article according to this embodiment includes a formation step of forming a pattern on a substrate using the above-described lithography apparatus (exposure apparatus), and a processing step of processing the substrate on which the pattern has been formed in the formation step. Furthermore, this manufacturing method includes other well-known processes (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The method for manufacturing an article according to this embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article compared to conventional methods.

The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Therefore, the following claims are appended to clarify the scope of the invention.

6: Substrate driving mechanism, 8: Substrate stage, 8a: Holding surface, 81: First holding area, 82: Second holding area, 9: Substrate, 11: Lift pin, 12: Substrate feed hand, 15: Control unit, 20: Actuator (driving unit), 21: Injection unit, 25: Sound wave output unit, 100: Exposure device

Claims (14)

A substrate holding device for holding a warped substrate,
a stage having a holding surface for holding the substrate;
a vibration unit that applies vibration to the substrate;
a control unit that controls a process of holding the substrate on the stage;
Equipped with
the holding surface includes a first holding area that holds a first portion of the substrate and a second holding area that holds a second portion of the substrate that is different from the first portion,
The control unit of the substrate holding device is characterized in that, during the processing, while the first portion of the substrate is held in the first holding area, the vibration unit applies vibration to the second portion of the substrate separated from the second holding area at the resonant frequency of the second portion, thereby bringing the second holding area into contact with the second portion and holding the second portion in the second holding area. The substrate holding device of claim 1, characterized in that the control unit acquires information indicating the amount of warping of the substrate, and in the processing, applies vibrations to the second portion of the substrate using the vibration unit so that the second portion resonates with an amplitude equal to or greater than the amount of warping. 3. The substrate holding device according to claim 1 , wherein the control unit applies vibration to the substrate by the vibration unit for a time period equal to or greater than half of a resonance period obtained by the reciprocal of the resonance frequency. 4. The substrate holding device according to claim 1 , wherein the resonant frequencies include a primary resonant frequency and a secondary resonant frequency at which the second portion of the substrate resonates. 5. The substrate support device according to claim 4 , wherein the resonant frequencies further include a third-order resonant frequency at which the second portion of the substrate resonates. 6. The substrate holding device according to claim 1, wherein the first portion is a central portion of the substrate, and the second portion is an outer periphery of the substrate. 7. The substrate holding device according to claim 1, wherein the vibration unit vibrates the second portion of the substrate by vibrating the stage while the first portion of the substrate is held by the first holding area. the stage has lift pins provided in the second holding area for raising and lowering the substrate relative to the holding surface;
8. The substrate holding device according to claim 1, wherein the vibration unit abuts the lift pins on the second portion of the substrate while the first portion of the substrate is held by the first holding region, and vibrates the lift pins to vibrate the second portion. the substrate holding device further includes a transport unit that transports the substrate onto the holding surface,
A substrate holding device as described in any one of claims 1 to 8, characterized in that the vibration unit abuts the transport unit against the second portion of the substrate while the first portion of the substrate is held by the first holding area, and vibrates the second portion by driving the transport unit. 10. The substrate holding device according to claim 1, wherein the vibration unit includes an ejection unit that ejects gas toward the second portion of the substrate while the first portion of the substrate is held by the first holding area, and vibrates the second portion by periodically ejecting gas from the ejection unit. The substrate holding device according to any one of claims 1 to 10, characterized in that the vibration unit includes an acoustic wave output unit that outputs acoustic waves toward the second portion of the substrate while the first portion of the substrate is held by the first holding area, and vibrates the second portion by outputting acoustic waves from the acoustic wave output unit. 1. A lithographic apparatus for forming a pattern on a substrate, comprising:
A substrate holding device according to any one of claims 1 to 11 ;
a forming unit that forms a pattern on the substrate held by the substrate holding device;
1. A lithographic apparatus comprising: A substrate holding method for holding a warped substrate on a stage, comprising:
the stage has a holding surface including a first holding area that holds a first portion of the substrate and a second holding area that holds a second portion of the substrate that is different from the first portion;
The substrate holding method includes:
a first step of holding the first portion of the substrate placed on the holding surface in the first holding area;
a second step of applying vibrations to the second portion of the substrate separated from the second holding area at a resonance frequency of the second portion while the first portion is held by the first holding area in the first step, thereby bringing the second holding area into contact with the second portion and holding the second portion in the second holding area;
A substrate holding method comprising: a holding step of holding a substrate on a stage using the substrate holding method according to claim 13 ;
a forming step of forming a pattern on the substrate held by the stage after the holding step;
a processing step of processing the substrate on which the pattern has been formed in the forming step;
a manufacturing process for manufacturing an article from the substrate processed in the processing process;
A method for manufacturing an article, comprising: