JP5146183B2 - Exposure method, device manufacturing method, and exposure apparatus - Google Patents

Description

  The present invention relates to an exposure method, a device manufacturing method, and an exposure apparatus.

  An exposure apparatus used in a photolithography process illuminates a central portion of a mask with exposure light, and exposes the substrate with exposure light through the mask. A mask used for exposure is held on a mask stage of an exposure apparatus. When holding a mask on a mask stage, for example, a technique of adsorbing a mask onto a holding member on the mask stage is known.

As the number of exposure light irradiations is increased, the temperature of the mask that receives the exposure light rises, and the mask is deformed and distorted by thermal expansion. When the mask shape is distorted, the pattern projected onto the substrate through the mask is distorted. When the mask is deformed due to thermal expansion, the deformation component includes many linear components.For example, by performing linear correction such as changing the magnification of the projection optical system with respect to the pattern projected through the mask, Pattern distortion can be easily reduced.
US Patent Application Publication No. 2005/0248744

  However, when the mask is adsorbed by the holding member, the deformation of the mask is partially suppressed at the adsorbed portion, and the mask deformation component includes a large amount of nonlinear components. Even if linear correction is performed, for example, by changing the magnification of the projection optical system, on a pattern projected through a deformed mask containing a large amount of nonlinear components, it is difficult to reduce the distortion of the pattern. . If the pattern is projected on the substrate in a distorted state, an exposure failure may occur.

  In view of the circumstances as described above, an object of the present invention is to provide an exposure method, a device manufacturing method, and an exposure apparatus that can suppress exposure defects.

  In order to achieve the above object, an exposure method according to the present invention is an exposure method in which an exposure process is performed using a substrate (M) held by a holding member (28), and a predetermined holding force is applied to the substrate. A holding step of holding the substrate by the holding member, and a releasing step of releasing the holding force acting on the substrate according to information on deformation of the held substrate.

  According to the present invention, since the holding force acting on the substrate is released according to the information on the deformation of the substrate held by the holding member, the nonlinear deformation component of the substrate caused by the holding force is eliminated. be able to. Since the pattern projected through the substrate can be in a linearly correctable state, distortion of the pattern can be reduced.

  A device manufacturing method according to the present invention is a device manufacturing method including a lithography process, and the lithography process includes the exposure method described above.

  According to the present invention, the pattern projected through the substrate can be linearly corrected, and the distortion of the pattern can be reduced, so that a high-performance device can be obtained.

  An exposure apparatus (EX) according to the present invention is an exposure apparatus that performs an exposure process using a substrate (M) held by a holding member (28), and applies a predetermined holding force to the substrate. And a control device (3) for releasing the holding force acting on the substrate in accordance with information on deformation of the held substrate.

  According to the present invention, since the control device releases the holding force acting on the substrate in accordance with the information on the deformation of the substrate held by the holding member, the nonlinear deformation of the substrate caused by the holding force. Ingredients can be eliminated. Since the pattern projected through the substrate can be in a linearly correctable state, distortion of the pattern can be reduced.

  According to the present invention, exposure failure can be suppressed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. In the following description, an XYZ orthogonal coordinate system is set, and the positional relationship of each member will be described with reference to this XYZ orthogonal coordinate system. A predetermined direction in the horizontal plane is defined as an X-axis direction, a direction orthogonal to the X-axis direction in the horizontal plane is defined as a Y-axis direction, and a direction orthogonal to each of the X-axis direction and the Y-axis direction (that is, a vertical direction) is defined as a Z-axis direction. Further, the rotation (inclination) directions around the X axis, Y axis, and Z axis are the θX, θY, and θZ directions, respectively.

  FIG. 1 is a schematic block diagram that shows an example of an exposure apparatus EX according to the first embodiment. In FIG. 1, an exposure apparatus EX exposes a mask stage 1 that can move while holding a mask M, a substrate stage 2 that can move while holding a substrate P, and a mask M held by the mask stage 1 as exposure light. Controls the illumination system IL that illuminates with EL, the projection optical system PL that projects the pattern image of the mask M illuminated with the exposure light EL onto the substrate P held by the substrate stage 2, and the overall operation of the exposure apparatus EX. And a measurement stage 4 that performs measurement and the like. The control device 3 includes a computer system, for example. Further, the exposure apparatus EX includes a chamber apparatus 5 that forms an internal space L in which the substrate P is processed. The chamber device 5 can adjust the environment (including temperature, humidity, and cleanliness) of the internal space L.

  The substrate P is a substrate for manufacturing a device, and includes a substrate on which a photosensitive film is formed, for example, a semiconductor wafer such as a silicon wafer. The photosensitive film is a film of a photosensitive material (photoresist). In the substrate P, various films such as a protective film (top coat film) may be formed on the photosensitive film.

  The mask M includes a reticle on which a device pattern projected onto the substrate P is formed. In the present embodiment, the mask M is a transmissive mask in which a predetermined pattern is formed on a transparent plate such as a glass plate using a light shielding film such as chrome. This transmission type mask is not limited to a binary mask in which a pattern is formed by a light shielding film, and also includes a phase shift mask such as a halftone type or a spatial frequency modulation type. In this embodiment, a transmissive mask is used as the mask M, but a reflective mask may be used.

  The exposure apparatus EX of the present embodiment is a scanning exposure apparatus (so-called scanning stepper) that exposes the substrate P with the exposure light EL through the mask M while moving the mask M and the substrate P synchronously in a predetermined scanning direction. is there. In the present embodiment, the scanning direction (synchronous movement direction) of the substrate P is the Y-axis direction, and the scanning direction (synchronous movement direction) of the mask M is also the Y-axis direction. The exposure apparatus EX moves the substrate P in the Y axis direction with respect to the projection area PR of the projection optical system PL, and in the illumination area IR of the illumination system IL in synchronization with the movement of the substrate P in the Y axis direction. On the other hand, the mask M is illuminated with the exposure light EL while moving the mask M in the Y-axis direction, and the substrate P is irradiated with the exposure light EL from the mask M through the projection optical system PL. The illumination area IR of the illumination system IL includes the irradiation position of the exposure light EL emitted from the illumination system IL, and the projection area PR of the projection optical system PL indicates the irradiation position of the exposure light EL emitted from the projection optical system PL. Including.

  The exposure apparatus EX includes, for example, a body 8 including a first column 6 provided on a floor surface FL in a clean room and a second column 7 provided on the first column 6. The first column 6 includes a plurality of first support columns 9 and a first plate 11 supported by the first support columns 9 via a vibration isolator 10. The second column 7 includes a plurality of second support columns 12 provided on the first plate 11 and a second plate 13 supported by the second support columns 12. The second plate 13 has a second opening 17 through which the exposure light EL passes.

  The illumination system IL illuminates a predetermined illumination region IR with exposure light EL having a uniform illuminance distribution. The mask M is movable to the illumination area IR (the irradiation position of the exposure light EL) of the illumination system IL. The illumination system IL illuminates at least a part of the mask M arranged in the illumination region IR with the exposure light EL having a uniform illuminance distribution. As the exposure light EL emitted from the illumination system IL, for example, far ultraviolet light (DUV light) such as bright lines (g-line, h-line, i-line) and KrF excimer laser light (wavelength 248 nm) emitted from a mercury lamp, Vacuum ultraviolet light (VUV light) such as ArF excimer laser light (wavelength 193 nm) and F2 laser light (wavelength 157 nm) is used. In the present embodiment, ArF excimer laser light that is ultraviolet light (vacuum ultraviolet light) is used as the exposure light EL.

  The mask stage 1 is supported by a gas bearing in a non-contact manner on the upper surface (guide surface) 13G of the second plate 13. The mask stage 1 includes a second plate 13 including an irradiation position of the exposure light EL emitted from the illumination system IL (an illumination area IR of the illumination system IL) by the operation of the mask stage driving device 15 including an actuator such as a linear motor. Along the upper surface 13G, it is movable in three directions, the X axis, the Y axis, and the θZ direction. The mask stage 1 has a first opening 16 through which the exposure light EL passes, for example, during exposure of the substrate P or measurement using the exposure light EL.

  The mask stage 1 has a mask holder 14 that holds a mask M irradiated with the exposure light EL. The mask holding unit 14 can attach and detach the mask M. In the present embodiment, the mask holding unit 14 holds the mask M so that the lower surface (pattern forming surface) Mb of the mask M and the XY plane are substantially parallel.

  On the second plate 13, a counter mass that moves in a direction (for example, −Y direction) opposite to the mask stage 1 in accordance with movement of the mask stage 1 in one direction (for example, + Y direction) in the Y axis direction. 18 is provided. The counter mass 18 is supported in a non-contact manner on the upper surface 13G of the second plate 13 by a self-weight canceling mechanism including an air pad. In the present embodiment, the counter mass 18 is provided around the mask stage 1.

  Position information of the mask stage 1 (mask M) is measured by the laser interferometer 19A of the interferometer system 19. The laser interferometer 19A irradiates the measuring surface LB to the reflecting surface 1R of the mask stage 1. The laser interferometer 19A measures the position information of the mask stage 1 with respect to the X-axis, Y-axis, and θZ directions, using the measurement light LB irradiated to the reflecting surface 1R of the mask stage 1. The control device 3 operates the mask stage driving device 15 based on the measurement result of the interferometer system 19 (laser interferometer 19A), and controls the position of the mask M held on the mask stage 1.

  The projection optical system PL irradiates the predetermined projection region PR with the exposure light EL. The substrate P is movable to the projection region PR (exposure position of the exposure light EL) of the projection optical system PL. The projection optical system PL projects an image of the pattern of the mask M at a predetermined projection magnification onto at least a part of the substrate P arranged in the projection region PR. A plurality of optical elements of the projection optical system PL are held by the lens barrel 20. The lens barrel 20 has a flange 21. The flange 21 is supported by the first plate 11. The projection optical system PL of the present embodiment is a reduction system whose projection magnification is, for example, 1/4, 1/5, or 1/8. Note that the projection optical system PL may be either an equal magnification system or an enlargement system. In the present embodiment, the optical axis AX of the projection optical system PL is parallel to the Z axis. The projection optical system PL may be any of a refractive system that does not include a reflective optical element, a reflective system that does not include a refractive optical element, and a catadioptric system that includes a reflective optical element and a refractive optical element. Further, the projection optical system PL may form either an inverted image or an erect image.

  The substrate stage 2 has a substrate holder 22 that holds the substrate P irradiated with the exposure light EL. The board | substrate holding part 22 can attach or detach the board | substrate P. As shown in FIG. In the present embodiment, the substrate holding unit 22 holds the substrate P so that the exposure surface (upper surface) Pa of the substrate P and the XY plane are substantially parallel. The substrate stage 2 is supported by a gas bearing in a non-contact manner on the upper surface (guide surface) 23G of the third plate 23. In the present embodiment, the upper surface 23G of the third plate 23 and the XY plane are substantially parallel. The third plate 23 is supported on the floor surface FL via a vibration isolator 24. The substrate stage 2 includes a third plate including an irradiation position of the exposure light EL (projection region PR of the projection optical system PL) emitted from the projection optical system PL by the operation of the substrate stage driving device 25 including an actuator such as a linear motor. The substrate P can be held and moved along the upper surface 23G of the substrate 23. In the present embodiment, the substrate stage 2 holds the substrate P on the substrate holding part 22 and has six directions on the third plate 23 including the X axis, Y axis, Z axis, θX, θY, and θZ directions. Can be moved to.

  The position information of the substrate stage 2 (substrate P) is measured by the laser interferometer 19B of the interferometer system 19. The laser interferometer 19B irradiates the measuring surface LB to the reflecting surface 2R of the substrate stage 2. The laser interferometer 19B measures the position information of the substrate stage 2 with respect to the X-axis, Y-axis, and θZ directions using the measurement light LB irradiated on the reflecting surface 2R of the substrate stage 2. Further, surface position information (position information regarding the Z axis, θX and θY directions) of the exposure surface Pa of the substrate P held on the substrate stage 2 is detected by a focus / leveling detection system (not shown). The control device 3 operates the substrate stage driving device 25 based on the measurement result of the interferometer system 19 (laser interferometer 19B) and the detection result of the focus / leveling detection system, and the substrate P held by the substrate stage 2 is controlled. Perform position control.

  The measurement stage 4 is arranged at a position overlapping with the substrate stage 2 in the X direction in FIG. 1 and moves in the six directions of the X axis, Y axis, Z axis, θX, θY and θZ directions as with the substrate stage 2. It is provided as possible. The measurement stage 4 is equipped with a measurement device (not shown) that performs various measurements such as alignment of the mask M and adjustment of the projection optical system PL.

  FIG. 2 is a perspective view of the vicinity of the mask stage 1, the counter mass 18 and the second plate 13 according to the present embodiment. FIG. 3 is a perspective view illustrating a partial configuration of the mask stage 1. 2 and 3, the mask stage 1 includes a mask stage main body 27 provided with a mask holding unit 14.

  As shown in FIG. 2, the mask stage main body 27 includes a first member 28 that is substantially rectangular in the XY plane, and a second member 29 that is connected to the + X side end of the first member 28 and that is long in the Y-axis direction. Have. The first member 28 has a reflective surface 1R on the side surface on the + Y side that is irradiated with the measurement light LB of the laser interferometer 19A. The reflecting surface 1R of the first member 28 is substantially perpendicular to the Y axis. A transmission region 18Y through which the measurement light LB of the laser interferometer 19A can pass is disposed on the side surface of the counter mass 18 on the + Y side. The laser interferometer 19A can irradiate the measurement light LB to the reflecting surface 1R of the first member 28 via the transmission region 18Y.

  A convex portion 13 </ b> A is provided substantially at the center of the second plate 13. The guide surface 13G of the second plate 13 includes the upper surface of the convex portion 13A. A vacuum preload type air pad 57 is provided on the surface of the first member 28 facing the guide surface 13G. The air pad 57 blows air (air) toward the guide surface 13G, and thereby supports the first member 28 to float (non-contact) with respect to the guide surface 13G via a clearance of, for example, several microns. The air pad 57 can also maintain the clearance by sucking air between the first member 28 and the guide surface 13G. The mask stage main body 27 is supported by the air pad 57 in a non-contact manner on the upper surface 13G of the convex portion 13A. A second opening 17 is provided substantially at the center of the convex portion 13A of the second plate 13.

  The mask holding unit 14 includes a pedestal 43 disposed around the first opening 16 in the first member 28, and a suction pad 44 provided on the pedestal 43. The suction pad 44 is provided on the upper surface 43 </ b> T of the pedestal 43. The pedestal 43 and the suction pad 44 are disposed along two opposing sides of the four sides of the first opening 16 and have a longitudinal direction in the Y-axis direction. The suction pad 44 has a holding surface 45 that holds at least a part of the lower surface Mb of the mask M.

  The holding surface 45 includes at least a part of the upper surface 43 </ b> T of the pedestal 43. In the present embodiment, the holding surface 45 is substantially parallel to the XY plane. In the present embodiment, the surface in the recess 40 including the holding surface 45 is a mounting surface 45 a on which the mask M is mounted. The suction pad 44 has a groove 46 formed in a part of the upper surface 43 </ b> T of the base 43 and a suction port 47 formed inside the groove 46. The holding surface 45 includes a portion of the upper surface 43T of the pedestal 43 where the groove 46 is not formed. The suction port 47 is connected to the pressure adjusting device 48 through a flow path 48a. By controlling the pressure adjusting device 48 with the control device 3, the gas at the suction port 47 can be sucked and the gas can be injected to the mask M side.

  The suction pad 44 holds at least part of the lower surface Mb of the mask M so as to suck. When the holding surface 45 of the suction pad 44 and a part of the lower surface Mb of the mask M are in contact with each other, the pressure adjusting device 48 connected to the suction port 47 is operated, whereby the lower surface Mb of the mask M and the groove The gas in the space surrounded by the inner surface of 46 is sucked by the suction port 47, and the space becomes negative pressure. Thereby, the lower surface Mb of the mask M is sucked and held on the holding surface 45. The mask stage 1 is movable while holding the mask M with the holding surface 45. Further, when the suction operation using the suction port 47 is stopped, the mask M can be removed from the mask holding unit 14.

  The mask M has a pattern formation region in which a pattern is formed on a part of its lower surface Mb, and the suction pad 44 including the holding surface 45 has a region other than the pattern formation region on the lower surface Mb of the mask M. Hold. The mask holding unit 14 holds the mask M so that the pattern formation region of the mask M is disposed in the first opening 16.

  The second member 29 has, on the + X side surface, a reflecting surface 1R that is irradiated with the measurement light LB of the laser interferometer 19A. The reflecting surface 1R of the second member 29 is substantially perpendicular to the X axis. On the side surface of the counter mass 18 on the + X side, a transmission region 18X that can transmit the measurement light LB of the laser interferometer 19A is disposed. The laser interferometer 19A can irradiate the measurement light LB to the reflecting surface 1R of the second member 29 via the transmission region 18X.

  The mask stage driving device 15 can move the mask stage 1. The mask stage driving device 15 includes a first driving device 30 that can move the mask stage 1 in the Y-axis and θZ directions, and a second driving device 31 that can move the mask stage 1 in the X-axis direction. In the present embodiment, the first drive device 30 includes a pair of linear motors 32 and 33. The second drive device 31 includes a voice coil motor 36.

  The first drive device 30 includes a pair of guide members 34 and 35 that are long along the Y-axis direction (movement direction). The guide members 34 and 35 are disposed inside the counter mass 18. The guide member 34 is disposed on the + X side of the first member 28, and the guide member 35 is disposed on the −X side of the first member 28. Therefore, these guide members 34 and 35 are provided at positions separated with respect to the X-axis direction. The + Y side end and the −Y side end of the guide members 34 and 35 are fixed to the inner surface of the counter mass 18 via a predetermined fixing member. The guide members 34 and 35 support the mask stage main body 27 so as to be movable in the Y-axis direction.

  The guide members 34 and 35 have coil units 51 that function as stators of the linear motors 32 and 33, respectively. The first member 28 of the mask stage 1 has a magnet unit 55 that functions as a mover for the linear motors 32 and 33. The magnet unit 55 is disposed on the end surface on the + X side and the end surface on the −X side of the first member 28, and on each of the + X side and the −X side so as to correspond to the coil unit 51 of the guide members 34 and 35. Has been placed.

  In the present embodiment, a moving magnet type that can move the mask stage body 27 in the Y-axis direction by a mover provided at the + X side end of the first member 28 and a stator provided at the guide member 34. A linear motor 32 is formed. Similarly, a moving magnet type linear motor capable of moving the mask stage body 27 in the Y-axis direction by a mover provided at the end of the first member 28 on the −X side and a stator provided on the guide member 35. 33 is formed.

  The second drive device 31 includes a guide member 37 that is long in the Y-axis direction. The guide member 37 has a coil unit that functions as a stator of the voice coil motor 36. The guide member 37 is disposed inside the counter mass 18. The guide member 37 is disposed on the −X side of the guide member 35. The + Y side end and the −Y side end of the guide member 37 are fixed to the inner surface of the counter mass 18 via a predetermined fixing member.

  A magnet unit that functions as a mover of the voice coil motor 36 is disposed at the −X side end of the mask stage main body 27. A moving magnet type voice coil motor 36 capable of moving the mask stage main body 27 in the X-axis direction by a mover provided at the −X side end of the mask stage main body 27 and a stator provided in the guide member 37 is provided. It is formed.

  The mask stage 1 can be moved in three directions of the X axis, the Y axis, and the θZ direction by the mask stage driving device 15 including the first and second driving devices 30 and 31. The mask stage main body 27 is movable while holding the mask M on the mask holding unit 14 along the XY plane including the irradiation position of the exposure light EL (illumination area of the illumination system IL).

  The counter mass 18 is a rectangular frame-like member having an opening in which the mask stage 1 can be disposed, and is movable on the upper surface of the second plate 13 in order to cancel the reaction force accompanying the movement of the mask stage 1. . The counter mass 18 cancels the reaction force accompanying the movement of the mask stage 1 by moving in a direction opposite to the movement direction of the mask stage 1.

  Further, as shown in FIG. 1, in the present embodiment, a focus / leveling detection system 70 is provided. Surface position information (position information regarding the Z-axis, θX, and θY directions) of the surface of the mask M is detected by the focus / leveling detection system 70. The focus / leveling detection system 70 can receive the detection light Lb through the mask M and the projection system 70 a that projects the detection light Lb onto the illumination area IR of the exposure light EL among the mask M held by the mask holding unit 14. And a light receiving system 70b. The projection system 70a projects the detection light Lb on the surface of the mask M from an oblique direction. The light receiving system 70b receives the detection light Lb projected onto the surface of the mask M by the projection system 70a and reflected from the surface. The light receiving system 70 b is connected to the control device 3, and a signal based on the received light is supplied from the light receiving system 70 b to the control device 3 as information relating to the change in the shape of the placement surface.

  Next, an example of the operation of the exposure apparatus EX according to the present embodiment will be described. The control device 3 causes the chamber device 5 to adjust the environment (including temperature, humidity, and cleanliness) of the internal space L. When the mask M is conveyed to the mask holding unit 14 in this state, the control device 3 sucks the lower surface Mb of the mask M to the holding surface 45 and holds the mask M on the placement surface 45a (holding process).

  After the mask M is held, the control device 3 performs preparatory work such as mask alignment and baseline measurement using a reticle microscope or the like mounted on the measurement stage 4. Thereafter, the substrate P transported to the substrate holding unit 22 is held, and fine alignment (EGA; enhanced global alignment, etc.) of the substrate P using the alignment sensor is performed, and an arrangement of a plurality of shot regions on the substrate P is performed. Find the coordinates. Then, while monitoring the measurement value of the laser interferometer based on the alignment result, the linear motor is controlled to move the substrate stage 2 to the scanning start position for the exposure of the first shot of the substrate P. The control device 3 starts scanning of the mask stage 1 and the substrate stage 2 in the Y direction. When both stages reach their respective target scanning speeds, the pattern area of the mask M is illuminated with exposure illumination light, and scanning exposure is performed. To start.

  During this scanning exposure, the control device 3 maintains the moving speed of the mask stage 1 in the Y direction and the moving speed of the substrate stage 2 in the Y direction at a speed ratio corresponding to the projection magnification of the projection optical system PL. The mask stage 1 and the substrate stage 2 are controlled synchronously. Different areas of the pattern area of the mask M are sequentially illuminated with illumination light, and the illumination of the entire pattern area is completed, whereby the scanning exposure of the first shot on the substrate P is completed. Thereby, the pattern of the mask M is reduced and transferred to the first shot area on the substrate P through the projection optical system PL.

  Thus, when the scanning exposure of the first shot is completed, the control device 3 moves the substrate stage 2 stepwise in the X and Y directions and moves it to the scanning start position for the exposure of the second shot. During this step movement, based on the measurement value of the laser interferometer 19 that detects the position of the substrate stage 2 (the position of the substrate P), the position of the substrate stage 2 in the X, Y, and θZ directions is measured in real time. . Based on the measurement result, the position of the substrate stage 2 is controlled. Thereafter, the control device 3 causes the second shot area to be scanned and exposed in the same manner as the first shot area. By this control, scanning exposure of the shot area on the substrate P and step movement for the next shot exposure are repeatedly performed, and the pattern of the mask M is sequentially transferred to all of the exposure target shot areas on the substrate P.

  As the number of exposure light irradiations is increased, as shown in FIG. 4A, the temperature of the illumination region IR of the mask M that receives the exposure light increases. As shown in FIG. 4B, the temperature distribution at this time becomes the highest in the illumination region IR of the mask M, and becomes lower as it reaches the outer periphery of the mask M. When the temperature of the mask M rises, the mask M is deformed due to thermal expansion, and distortion occurs. When distortion occurs in the shape of the mask M, the pattern projected onto the substrate P through the mask M is distorted.

  When the mask M is deformed by thermal expansion, the mask M is deformed from a rectangular shape M0 to a shape M1 in which the central portion of each side is curved outward of the mask M, as shown in FIG. The deformation component at this time is in a state in which a lot of linear components are included, although some nonlinear components are included. In this case, distortion of the pattern can be easily reduced by performing linear correction such as changing the magnification of the projection optical system PL on the pattern projected through the mask M, for example.

  On the other hand, in the present embodiment, the mask M is sucked and held by the mask holding unit 14, and as shown in FIG. 5, the deformation of the mask M is partially suppressed in the sucking portion 14M. For this reason, the mask M has a shape M2 in which the center of each side is curved inward of the mask M. The deformation component at this time includes a large amount of nonlinear components. Even if linear correction such as changing the magnification of the projection optical system PL is performed on a pattern projected through the mask M deformed with a large amount of nonlinear components, it is difficult to reduce the distortion of the pattern. It is. If the pattern is projected on the substrate P in a distorted state, an exposure failure may occur.

  Therefore, in the present embodiment, the controller 3 causes the controller 3 to perform a releasing process for releasing the holding force acting on the mask M. Specifically, the control device 3 stops the suction operation by the pressure adjusting device 48 and releases the suction force from the mask M. By this control, the suction force applied to the suction portion 14M of the mask M is released and the non-linear component included in the deformation component is removed, so that the shape of the mask M includes a large amount of linear components as shown in FIG. It becomes said shape M1. In this case, the distortion of the pattern projected through the mask M is corrected by causing the control device 3 to perform correction such as changing the magnification of the projection optical system PL.

  In this releasing step, the control device 3 not only stops the suction operation but also applies pressure in a direction different from the direction in which the holding force acts, that is, the space in contact with the lower surface Mb of the mask M is normal. It is preferable to operate the pressure adjusting device 48 so as to be a pressure. As such an operation, for example, as shown in FIG. 7, an operation of injecting gas into the suction port 47 can be cited. In this case, the mask M is separated from the mask holding portion 14 in the + Z-axis direction by the gas injection. For example, when the environment of the internal space L is adjusted by the chamber apparatus 5, the mask M is separated from the mask holding unit 14 by adjusting the + Z side of the mask stage 1 to be a low temperature. Will be cooled. By cooling the mask M, the deformation amount of the mask M can be reduced.

  Next, the timing of the release process will be described. In the present embodiment, the deformation amount of the mask M is obtained based on the exposure light amount irradiated to the mask M, and the releasing step is performed when the obtained deformation amount exceeds a preset threshold S. To. The timing of performing the releasing step is performed in an interval period immediately after the shot in which the deformation amount exceeds the threshold value S.

  Note that the threshold value S can be a deformation amount of the mask M such that a distorted pattern remains on the substrate P without correcting the distortion of the pattern projected through the mask M, for example. The threshold value S can be obtained in advance by experiments or simulations. The threshold S is preferably set so as to have a certain margin.

  FIG. 8 is a graph showing the relationship between exposure light dose and time in the exposure process. The vertical axis of the graph is the irradiation amount, and the horizontal axis of the graph is the time. As shown in FIG. 8, in the exposure process, for example, the first shot exposure is performed from time t0 to time t1, and the second shot exposure is performed from time t2 to time t3. Between time t1 and time t2 is a shot exposure interval period. Similarly, an interval period for shot exposure is from time t3 to time t4, which is the start time of the next shot exposure. Here, the exposure light irradiation amount in each shot exposure is constant.

  FIG. 9 is a graph showing the amount of deformation of the mask M when the mask M is irradiated with the exposure light shown in FIG. 8 and exposure light at the time. The vertical axis of the graph is the deformation amount of the mask M, and the horizontal axis of the graph is the time. The time shown on the horizontal axis of the graph of FIG. 9 is the same as the time shown on the horizontal axis of the graph of FIG. As the deformation amount of the mask M, for example, the deformation amount at any one of the sides of the mask M can be employed. The deformation amount of the mask M shown in FIG. 9 is a deformation amount in a state where the mask M is not held, and the deformation amount can be obtained in advance through experiments, simulations, or the like.

  As shown in FIG. 9, the deformation amount of the mask M gradually increases between time t0 and time t1 when the first shot exposure is performed. During time interval t1 to time t2, which is an interval period during which exposure light is not irradiated, the amount of deformation gradually decreases. The decrease amount of the deformation amount is smaller than the increase amount of the deformation amount from time t0 to time t1, and the deformation of the mask M remains even after the interval period.

  After the interval period, the second shot exposure is performed with the mask M remaining deformed. From time t2 to time t3 when the second shot exposure is performed, the amount of deformation of the mask M gradually increases, similar to the time between time t0 and time t1 when the first shot exposure is performed. The deformation amount of the mask M exceeds the threshold value S during the period in which the second shot exposure is performed.

  The relationship between the exposure light irradiation amount on the mask M and the deformation amount of the mask M is stored in the control device 3 in advance as data. The control device 3 can obtain the deformation amount of the mask M based on the number of shot exposures by using the data. In the present embodiment, when the deformation amount of the mask M exceeds the threshold value S during the exposure light shot, the release step is performed in the interval period after the shot exposure.

  Therefore, based on the above data that the deformation amount of the mask M exceeds the threshold value S during the second shot exposure, the control device 3 performs the above operation between time S3 and time S4, which is an interval period immediately after the second shot exposure. The release process is performed. As described above, the control device 3 obtains the deformation amount of the mask M based on the exposure light irradiation amount, and causes the release process to be performed based on the obtained deformation amount.

  Here, in the graph of FIG. 9, the deformation amount decreases between time t3 and time t4, and the deformation amount exceeds the threshold value S at time t4. However, depending on the setting of threshold value S, time t3 It is also conceivable that the deformation amount is assumed to fall below the threshold value S due to a decrease in the deformation amount between time t4 and time t4. Even in such a case, if the amount of deformation once exceeds the threshold value S during shot exposure, it is preferable to perform the release step in the immediately following interval period.

  In the above exposure process, after the exposure of one substrate P is completed, the control device 3 moves the substrate stage 2 to the delivery position of the substrate P, and places the measurement stage in the projection region PR of the projection optical system PL. 4 is moved. During the delivery of the substrate P, the control device 3 causes the mask M to be aligned again using the measurement stage 4. Considering the possibility that the position of the mask M in the X-axis direction and the Y-axis direction will be shifted when releasing the holding force of the mask M, the misalignment can be prevented by performing the alignment again. Note that the control device 3 may be configured to perform the above-described releasing step together when performing the alignment.

  As described above, according to the present embodiment, the holding force acting on the mask M is released in accordance with the information related to the deformation of the mask M held by the mask holding unit 14. The non-linear deformation component of the mask M to be eliminated can be eliminated. Since the pattern projected through the mask M can be in a linearly correctable state, pattern distortion can be reduced. Thereby, exposure failure can be suppressed.

The technical scope of the present invention is not limited to the above-described embodiment, and appropriate modifications can be made without departing from the spirit of the present invention.
In the above embodiment, the example in which the mask M is separated from the mask holding unit 14 by using the pressure adjusting device 48 when performing the releasing step has been described. However, the present invention is not limited to this, and for example, as shown in FIG. Alternatively, a moving device 60 that holds the mask M on the + Z side of the mask stage 1 and moves it in the X-axis direction, the Y-axis direction, and the Z-axis direction may be separately provided. The moving device 60 includes a holding unit 61 that holds the mask M and a moving unit 62 that moves the mask M. The control device 3 can release the holding force of the mask M using, for example, the pressure adjusting device 48 and then hold the mask M by the moving device 60 and move it in the + Z direction. Of course, the mask M may be lifted and moved by the moving device 60 without using the pressure adjusting device 48.

  Further, in the above embodiment, when the exposure on one substrate P is completed and the substrate P is transferred, the control device 3 may cause the measurement stage 4 to measure, for example, the projection optical system PL. In the measurement, the measurement stage 4 is arranged on the projection region PR and the exposure light EL is projected onto the measurement stage 4. When performing this measurement, the exposure light is irradiated on the mask M, and it can be assumed that the mask M is deformed by the exposure light irradiation. Therefore, during the measurement, the control device 3 separates the mask M in the + Z direction from the mask holding unit 14 using the moving device 60 as shown in FIG. 11, for example, and on the optical path AX of the exposure light. It is also possible to move the mask M to the position retracted in the X-axis direction or the Y-axis direction and cool the mask M at that position. Although FIG. 11 shows an example in which the mask M is retracted in the X-axis direction, it may be retracted in the Y-axis direction.

  Further, for example, the moving device 60 may be provided with a shaping device capable of shaping the mask M by applying force. In this configuration, when the mask M is held and moved, the mask M can be shaped. When the mask M is again adsorbed on the mask holding part 14, the shaped shape of the mask M can be maintained by adsorbing the mask M while it is shaped by the shaping mechanism.

  Moreover, as shown in FIG. 12, the structure which arrange | positions the temperature control apparatus 71 inside the 1st member 28 of the mask stage 1 may be sufficient. In this configuration, the temperature adjustment device 71 is provided at a position where the temperature of the mask M other than the illumination area IR of the exposure light can be adjusted. Specifically, the mask holding unit 14 is provided at a position including the position on the −Z side. The temperature adjusting device 71 can increase the temperature of the region other than the illumination region IR in the mask M. It is known that the amount of deformation of the mask M due to thermal expansion saturates when it exceeds a certain amount of deformation. Therefore, by raising the temperature of the region, the mask M can be deformed to the saturation deformation amount before the exposure light EL is irradiated. When deformed to the saturation deformation amount, the mask M is not deformed even when exposed to the exposure light EL, so that the shape of the mask M can be stabilized. It is also possible to design the mask M in advance so that the shape of the mask M that has been deformed to the saturation deformation amount does not cause pattern distortion.

  In the above embodiment, the relationship between the deformation amount of the mask M and the exposure light irradiation amount on the mask M is stored in the control device 3 in advance, and the control device 3 uses the relationship to deform the deformation amount of the mask M. However, the present invention is not limited to this. For example, a measurement device that measures the deformation amount of the mask M is separately provided, and the release process is performed when the measurement result exceeds the threshold value S. It doesn't matter. It is preferable that the measuring apparatus measures the deformation amount in the Y-axis direction on the + Y side or the −Y side where deformation due to thermal expansion is not suppressed in the mask M.

  Moreover, although the control apparatus 3 demonstrated the example which calculates | requires the deformation amount of the mask M based on the irradiation amount of exposure light as a condition of exposure processing in the said embodiment, it is not restricted to this, Exposure light conditions The deformation amount may be obtained based on conditions other than the irradiation amount.

  Moreover, although the said embodiment demonstrated the case where the illumination area | region IR of the exposure light on the mask M became long in the Y-axis direction, for example, as shown to Fig.13 (a), the exposure light on the mask M is shown. A case where the illumination region IR is shortened in the Y-axis direction is also conceivable. In this case, as shown in FIG. 13B, in the state where the mask M is held in the suction portion 14M, thermal expansion is performed so that the entire sides of the mask M on the + Y side and the −Y side are curved outward. Wake up. On the other hand, with respect to the + X side and −X side of the mask M, thermal expansion is performed so that only the central portion in the Y-axis direction protrudes outward. In this state, the mask M is deformed including nonlinear components on all four sides. When the holding force of the mask M is released in this state, as shown in FIG. 13C, the outward protrusion is reduced on the + Y side and −Y side sides of the mask M, and it can be approximated to linear deformation. . On the other hand, in the + X side and −X side sides of the mask M, the central protrusion in the Y-axis direction remains, and the nonlinear components on the + X side and −X side sides are not removed. Therefore, as shown in FIG. 13D, the holding force of the other portion is released while the holding force of the central portion 14Ma in the Y-axis direction remains in the suction portion 14M. Thus, by changing the shape of the entire mask M without changing the shape of the central portion in the Y-axis direction among the + X side and −X side sides of the mask M, the + X side and −X side sides are changed. Can be made closer to a linear deformation.

  In the above embodiment, as the exposure apparatus EX, in addition to the step-and-scan type scanning exposure apparatus (scanning stepper) that scans and exposes the pattern of the mask M by synchronously moving the mask M and the substrate P. The present invention can also be applied to a step-and-repeat projection exposure apparatus (stepper) that collectively exposes the pattern of the mask M while the mask M and the substrate P are stationary, and sequentially moves the substrate P stepwise.

  Furthermore, in the step-and-repeat exposure, after the reduced image of the first pattern is transferred onto the substrate P using the projection optical system while the first pattern and the substrate P are substantially stationary, the second pattern With the projection optical system, the reduced image of the second pattern may be partially overlapped with the first pattern and collectively exposed on the substrate P (stitch type batch exposure apparatus). ). Further, the stitch type exposure apparatus can be applied to a step-and-stitch type exposure apparatus in which at least two patterns are partially transferred on the substrate P, and the substrate P is sequentially moved.

  Further, as disclosed in, for example, US Pat. No. 6,611,316, two mask patterns are synthesized on a substrate via a projection optical system, and one shot on the substrate is obtained by one scanning exposure. The present invention can also be applied to an exposure apparatus that performs double exposure of a region almost simultaneously. The present invention can also be applied to proximity type exposure apparatuses, mirror projection aligners, and the like.

  As the exposure apparatus EX, US Pat. No. 6,341,007, US Pat. No. 6,400,441, US Pat. No. 6,549,269, US Pat. No. 6,590,634, US Pat. No. 6,208,407, and US Pat. The present invention can also be applied to a twin stage type exposure apparatus having a plurality of substrate stages as disclosed in the specification of Japanese Patent No. 6262796.

  Further, the present invention can also be applied to an immersion exposure apparatus that exposes a substrate with exposure light via a liquid as disclosed in, for example, International Publication No. 99/49504 pamphlet. The present invention can also be applied to an EUV light source exposure apparatus that exposes the substrate P with extreme ultraviolet light.

  The type of the exposure apparatus EX is not limited to an exposure apparatus for manufacturing a semiconductor element that exposes a semiconductor element pattern on the substrate P, but an exposure apparatus for manufacturing a liquid crystal display element or a display, a thin film magnetic head, an image sensor (CCD). ), An exposure apparatus for manufacturing a micromachine, a MEMS, a DNA chip, a reticle, a mask, or the like.

  In each of the above-described embodiments, an ArF excimer laser may be used as a light source device that generates ArF excimer laser light as exposure light EL. For example, as disclosed in US Pat. No. 7,023,610. A harmonic generator that outputs pulsed light with a wavelength of 193 nm may be used, including a solid-state laser light source such as a DFB semiconductor laser or a fiber laser, an optical amplification unit having a fiber amplifier, a wavelength conversion unit, and the like.

  In each of the above embodiments, the exposure apparatus provided with the projection optical system PL has been described as an example. However, the present invention can be applied to an exposure apparatus and an exposure method that do not use the projection optical system PL. Even when the projection optical system PL is not used in this way, the exposure light is irradiated onto the substrate via an optical member such as a lens.

  As described above, the exposure apparatus according to the present embodiment assembles various subsystems including the constituent elements recited in the claims of the present application so as to maintain predetermined mechanical accuracy, electrical accuracy, and optical accuracy. It is manufactured by. In order to ensure these various accuracies, before and after assembly, various optical systems are adjusted to achieve optical accuracy, various mechanical systems are adjusted to achieve mechanical accuracy, and various electrical systems are Adjustments are made to achieve electrical accuracy. The assembly process from the various subsystems to the exposure apparatus includes mechanical connection, electrical circuit wiring connection, pneumatic circuit piping connection and the like between the various subsystems. Needless to say, there is an assembly process for each subsystem before the assembly process from the various subsystems to the exposure apparatus. When the assembly process of the various subsystems to the exposure apparatus is completed, comprehensive adjustment is performed to ensure various accuracies as the entire exposure apparatus. The exposure apparatus is preferably manufactured in a clean room where the temperature, cleanliness, etc. are controlled.

  As shown in FIG. 14, a microdevice such as a semiconductor device includes a step 201 for designing a function / performance of the microdevice, a step 202 for producing a mask (reticle) based on the design step, and a substrate as a base material of the device. A substrate processing step 204 including a substrate processing (exposure processing) including exposing the substrate with exposure light through a mask and developing the exposed substrate according to the above-described embodiment; It is manufactured through an assembly step (including processing processes such as a dicing process, a bonding process, and a packaging process) 205, an inspection step 206, and the like.

  Note that the requirements of the above-described embodiments can be combined as appropriate. In addition, the disclosures of all published publications and US patents related to the exposure apparatus and the like cited in the above-described embodiments and modifications are incorporated herein by reference.

It is a schematic block diagram which shows an example of the exposure apparatus which concerns on embodiment of this invention. It is a perspective view which shows the vicinity of the mask stage which concerns on this embodiment. It is the perspective view which expanded a part of mask stage concerning this embodiment. The figure which shows the mode of the thermal expansion of a mask. The figure which shows the shape of a mask. The figure which shows the shape of a mask. FIG. 5 is a view showing one operation of the exposure apparatus according to the present embodiment. The figure which shows the relationship between the irradiation amount of exposure light with respect to a mask, and irradiation time. The figure which shows the relationship between the deformation amount of a mask, and time. The figure which shows the other form of the exposure apparatus which concerns on this invention. The figure which shows the other form of the exposure apparatus which concerns on this invention. The figure which shows the other form of the exposure apparatus which concerns on this invention. The figure which shows the other form of the exposure apparatus which concerns on this invention. The flowchart which shows an example of the manufacturing process of a microdevice.

Explanation of symbols

  EX ... Exposure device M ... Mask 1 ... Mask stage 3 ... Control device 14 ... Mask holding portion 14M ... Suction portion 48 ... Pressure adjusting device 60 ... Moving device 61 ... Holding portion 62 ... Moving portion 70 ... Temperature adjusting device

Claims (13)

An exposure method for performing an exposure process using a substrate held by a holding member,
A holding step in which a predetermined holding force is applied to the substrate to hold the substrate with the holding member;
A releasing step of releasing the holding force acting on the substrate in accordance with the information on the deformation of the held substrate ;
Equipped with a,
The release step includes
Obtaining information on deformation of the substrate based on an exposure light dose included in the exposure processing conditions;
Separating the substrate from the holding member . The exposure method according to claim 1 , wherein the releasing step further includes a cooling step of cooling the substrate in a state where the substrate is separated. The exposure method according to claim 1 , wherein the releasing step further includes a shaping step of shaping the substrate in a state where the substrate is separated. The exposure method according to any one of claims 1 to 3 , wherein in the holding step, the temperature of the substrate is adjusted in a state where the holding member holds the substrate. The substrate is a mask on which a predetermined pattern is formed,
The releasing step is performed after the exposure process for any one of the plurality of partition areas set on the wafer exposed through the pattern is completed until the exposure process for the next partition area is started. The exposure method according to any one of claims 1 to 4 , wherein: The exposure method according to claim 5 , wherein the releasing step includes a mask cooling step in which the mask is cooled at a position separated from the holding member and retracted from the optical path of the exposure light. A method of manufacturing a device with a lithographic process, said lithographic process device manufacturing method including an exposure method as claimed in any one of claims 1 to 6. An exposure apparatus that performs an exposure process using a substrate held by a holding member,
A control device for causing a predetermined holding force to act on the substrate to hold the substrate by the holding member and releasing the holding force acting on the substrate according to information on deformation of the held substrate; ,
The control device obtains information related to deformation of the substrate based on an exposure light irradiation amount included in the conditions of the exposure processing, and releases the holding force by separating the substrate from the holding member. . The exposure apparatus according to claim 8 , wherein the control device cools the substrate in a state where the substrate is separated. The exposure apparatus according to claim 8 , wherein the control device shapes the substrate in a state where the substrate is separated. The exposure apparatus according to any one of claims 8 to 10 , wherein the control device adjusts the temperature of the substrate in a state where the holding member holds the substrate. The substrate is a mask on which a predetermined pattern is formed,
The control device performs the process from the end of the exposure process for any one of a plurality of partition areas set on the wafer exposed through the pattern until the start of the exposure process for the next partition area. The exposure apparatus according to any one of claims 8 to 11 , wherein: 13. The exposure apparatus according to claim 12 , wherein the control device cools the mask at a position separated from the holding member and retracted from the optical path of exposure light.

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