JP2006041012A - Stage apparatus, exposure system, and exposing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate flexure of a mask generated by irradiation of the lighting beam while a standard position and attitude are maintained. <P>SOLUTION: On a reticle stage RST for holding a reticle R, setting portions 10a to 10d for supporting four corners of the reticle R is formed. Moreover, attracting ports 27a to 27d for attracting the reticle R through evacuation are respectively formed to the placing portions 10a to 10d. At the time of exposure process, the reticle R is attracted and held with entire portion of the attracting ports 27a to 27d. When the exposing process is interrupted, flexure in the Y direction of the reticle is eliminated by attracting and holding the reticle R only with the attracting ports 27c, 27d, and moreover flexure in the X direction of the reticle is eliminated by attracting and holding the reticle R only with the attracting ports 27b, 27c. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exposure apparatus and an exposure method used when manufacturing a semiconductor element, a liquid crystal display element, a thin film magnetic head, and other devices by using a lithography technique, and a stage apparatus used in the exposure apparatus and the like.

  When manufacturing semiconductor elements, liquid crystal display elements, thin film magnetic heads, and other devices, illumination light is irradiated to a reticle or mask (hereinafter referred to as a mask when these are generically referred to), and light passing through the mask is irradiated. An exposure apparatus is used that irradiates a substrate such as a wafer or glass plate coated with a photoresist as exposure light and transfers the mask pattern onto the substrate via a projection optical system. When a device is manufactured using this exposure apparatus, the same pattern is often transferred to each of a plurality of partitioned areas (shot areas) set on the substrate.

When the same mask is irradiated repeatedly with illumination light, part of the illumination light irradiation energy is absorbed by the mask and the mask expands. As a result, the pattern image projected on the substrate also deforms as the mask expands. As a result, the magnification or scaling (linear expansion / contraction) of the pattern transferred to the substrate changes. In order to correct the magnification or scaling due to the expansion of the mask, for example, in the following Patent Document 1, the expansion and contraction of the mask is predicted from the exposure time, the transmittance and the reflectance of the mask, and the magnification of the projection optical system is positively determined. A method of changing is disclosed.
JP-A-8-288206

  Incidentally, the mask used in the exposure apparatus is held in a state of being fixed on the mask stage by vacuum suction or the like. For example, a rectangular mask is held on the mask stage with its four corners adsorbed under reduced pressure. For this reason, even if illumination light is irradiated to the mask, the mask cannot be freely expanded without any limitation. For example, the mask is distorted in the vertical direction and bent into a bowed state, and the flatness is lowered.

  In order to faithfully transfer the mask pattern onto the substrate, the mask pattern formation surface is made to coincide with the object surface of the projection optical system and the surface of the substrate is made to coincide with the image surface of the projection optical system. It is necessary to have an optical conjugate relationship between the surface and the surface of the substrate. However, if the mask is bent into a bow, the pattern image of the mask is transferred onto the substrate with the focus shifted, and the line width and resolution differ within the shot area even when the same width pattern is transferred. There was a problem that.

  In addition, if the expansion of the mask increases to some extent, the stress generated in the mask may overcome the adsorption force and cause the mask to elongate. Cannot be predicted. For this reason, even if the magnification of the projection optical system is changed by predicting the expansion and contraction of the mask from the illuminance, the irradiation time, the transmittance and the reflectance of the mask using the technique disclosed in Patent Document 1, the magnification or There was a problem that the correction of scaling could not be performed sufficiently.

  The exposure apparatus may be provided with an off-axis type alignment sensor that measures position information of a mark (alignment mark) formed on the substrate. In this type of exposure apparatus, the baseline amount indicating the distance between the reference position of the pattern image projected on the substrate (for example, the center position of the pattern image) and the center of the measurement field of view of the alignment sensor is managed with extremely high accuracy. There is a need. However, when the mask stretches, the baseline amount also fluctuates, and as a result, there is a problem that the measurement result of the alignment mark using the alignment sensor includes an error.

  The present invention has been made in view of such problems of the prior art, and the bending caused by thermal deformation of a plate-like object such as a mask or a substrate held by suction at a plurality of locations is used as a reference for the plate-like object. The purpose is to be able to solve the problem while maintaining the position and posture. It is another object of the present invention to make it possible to transfer a mask pattern onto a substrate with high accuracy even when the thermal deformation occurs. Furthermore, it aims at enabling it to manufacture a high performance, high quality microdevice etc.

  Hereinafter, in the description shown in this section, the present invention will be described in association with the member codes shown in the drawings representing the embodiments. However, each constituent element of the present invention is limited to the members shown in the drawings attached with these member codes. Is not to be done.

  According to a first aspect of the present invention, there is provided a stage device having a stage (RST) for holding a plate-like object (R), the stage device being provided on the stage, contacting the plate-like object and its periphery, The placement unit (10a to 10d) having a plurality of suction ports (27a to 27d) for sucking the plate-like object, and the suction of the plate-like object by the plurality of suction ports are controlled. There is provided a stage apparatus including a suction control unit (34) capable of controlling at least one of the suction ports independently of other suction ports.

  In the invention according to the first aspect of the present invention, the reduced-pressure suction of the plate-like object by the suction port formed in the mounting portion on the stage is controlled independently for each suction port. The place and number to be adsorbed and fixed can be arbitrarily selected or changed. Therefore, when stress is generated in the plate-like object with the temperature change, the adsorption by at least one of the other adsorption ports is canceled while the adsorption by at least one of the adsorption ports is continued. The position of the suction port (hereinafter, sometimes referred to as “continuous suction port”) that has continued to be fixed is fixed, and the stress is released in the direction of the suction port (hereinafter, referred to as “release suction port”) where the suction has been released. By selecting or changing the continuous suction port and the release suction port as appropriate, the stress of the plate-like object can be eliminated while maintaining the reference position and posture of the plate-like object.

  According to a second aspect of the present invention, there is provided an exposure apparatus that exposes a substrate (W) through a mask (R) pattern, an illumination optical system (IL) that illuminates the mask, and a pattern of the mask. A projection optical system (PL) for projecting an image onto the substrate; a mask stage device having a mask stage (RST) for holding the mask; and a substrate stage device having a substrate stage (WST) for holding the substrate. An exposure apparatus in which at least one of the mask stage apparatus and the substrate stage apparatus includes the stage apparatus according to claim 1 is provided.

  In the invention according to the second aspect of the present invention, since the stage apparatus according to the first aspect of the present invention is adopted as a stage apparatus for holding the mask or the substrate, the reference position or posture of the mask or the substrate is maintained. Since the deformation of the mask or the substrate can be eliminated and the shape (expansion / contraction amount) of the mask or the substrate after the elimination of the deflection can be calculated, the magnification or scaling change due to the thermal deformation (expansion or contraction) of the mask or the substrate can be calculated. It can be corrected accurately. In addition, since the direction of stress relief of the mask or substrate is known and the amount of expansion / contraction of the mask or substrate can be calculated, when the baseline amount is managed, it accompanies thermal deformation of the mask or substrate. The fluctuation of the baseline amount can be accurately corrected. As a result, a fine pattern can be faithfully transferred onto a substrate with a uniform line width, and high-quality, high-performance microdevices can be manufactured with high yield and high efficiency. It becomes like this.

  According to a third aspect of the present invention, there is provided an exposure method for exposing a substrate (W) through a mask (R) pattern held on a mask stage (RST), wherein the substrate (W) is exposed at a plurality of locations around the mask. A holding step for holding the mask on the mask stage in a state where the mask is sucked, and at least one of a plurality of places where the mask is sucked according to the amount of expansion / contraction of the mask caused by the illumination light irradiation. An exposure method is provided that includes a release step for releasing suction at one location.

  In the invention according to the third aspect of the present invention, the reduced-pressure suction of at least one of the reduced-pressure suction portions of the mask is released according to the amount of expansion and contraction of the mask caused by illumination light irradiation. The stress can be released in the direction of the release suction port, and the deflection of the mask can be eliminated while maintaining the reference position and posture of the mask.

  There is an effect that bending caused by thermal deformation of a plate-like object such as a mask or a substrate attracted and held at a plurality of places can be eliminated while maintaining the reference position and posture of the plate-like object. In addition, the fine pattern can be faithfully transferred onto the substrate with a uniform line width, and high-performance, high-quality microdevices can be manufactured with high yield and high efficiency. is there.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a front view schematically showing the overall configuration of an exposure apparatus according to an embodiment of the present invention. The exposure apparatus shown in FIG. 1 sequentially transfers a pattern formed on a reticle R as a mask onto a wafer W as a substrate while synchronously moving the reticle stage RST and the wafer stage WST with respect to the projection optical system PL. • An AND-scan type exposure apparatus. In the following description, if necessary, an XYZ orthogonal coordinate system is set in the drawing, and the positional relationship of each member will be described with reference to this XYZ orthogonal coordinate system. In the XYZ orthogonal coordinate system shown in FIG. 1, the XY plane is set to a plane parallel to the horizontal plane, and the Z axis is set to the vertically upward direction. The direction along the Y axis is the scan direction (scan direction).

In FIG. 1, the illumination optical system IL shapes the cross-sectional shape of laser light emitted from a light source such as an ArF excimer laser light source (wavelength 193 nm) into a slit shape extending in the X direction, and makes the illuminance distribution uniform to perform illumination. Ejected as light. In this embodiment, a case where an ArF excimer laser light source is provided as a light source will be described as an example. In addition, an ultrahigh pressure mercury lamp that emits g-line (wavelength 436 nm) and i-line (wavelength 365 nm), or A KrF excimer laser (wavelength 248 nm), an F ₂ laser (wavelength 157 nm), a Kr ₂ laser (wavelength 146 nm), a YAG laser high-frequency generator, or a semiconductor laser high-frequency generator can be used. The illumination optical system IL is provided with an integrator sensor 33 (see FIG. 6) that measures the illuminance of illumination light (exposure light) emitted from the illumination optical system IL.

  Reticle R is mounted on mounting portion 10 (10a to 10d) provided in a state of protruding at four positions on reticle stage RST. Although details will be described later, each of the placement units 10 (10a to 10d) is formed with a suction port for suctioning the reticle R under reduced pressure. 10a-10d).

  Above the reticle stage RST, alignment systems 14a and 14b for photoelectrically detecting reticle alignment marks formed at two positions around the reticle R are provided. The detection results of the alignment systems 14a and 14b are obtained by positioning the reticle R with a predetermined accuracy with respect to the optical axis AX of the illumination optical system IL or the projection optical system PL, or moving the reticle R and the wafer W synchronously during scanning exposure. Used for. Positioning of the reticle R is performed by a drive system 12 that translates the reticle stage RST in the XY plane perpendicular to the optical axis AX and rotates it slightly in the XY plane. The drive system 12 scans the reticle stage RST in the Y direction at a constant speed when the pattern of the reticle R is transferred onto the wafer W.

  Reticle stage RST is movably held on reticle stage base structure CL1 constituting a part of the column structure of the apparatus main body, and a motor and the like of drive system 12 are also mounted on base structure CL1. Further, a beam interference portion (such as a beam splitter) of the reticle interferometer system IFR that measures a change in the position of the reticle R is also attached to the base structure CL1. The interferometer system IFR projects a length measuring beam BMr vertically onto a mirror surface portion formed on a part of the end surface of the reticle R, receives the reflected beam, and measures the position change of the reticle R. Instead of using a part of the end surface of the reticle R as a mirror surface, a reflecting member such as a retro reflector or a plane mirror may be provided on the reticle stage RST.

  The image of the pattern formed on the reticle R is imaged and projected at a projection magnification of 1/4 or 1/5 onto a wafer W as a substrate via a projection optical system PL disposed immediately below the reticle stage RST. . The lens barrel of the projection optical system PL is fixed to a lens base structure CL3 that constitutes a part of the column structure, and the lens base structure CL3 supports the reticle base structure CL1 via a plurality of column structures CL2. is doing. The reticle interferometer system IFR shown in FIG. 1 is configured such that the reflected beam of the length measuring beam BMr interferes with the reference beam reflected by the reference mirror FRr fixed on the projection optical system PL. However, an interferometer system having a configuration in which the reference mirror is fixed to the reticle base structure CL1 side or an interferometer system incorporating the reference mirror itself may be used.

  The projection optical system PL has a plurality of optical elements such as lenses, and the glass material of the optical elements is selected from optical materials such as quartz and fluorite according to the wavelength of illumination light emitted from the illumination optical system IL. . Some of the optical elements provided in the projection optical system PL are configured to be movable in the direction of the optical axis AX and the direction intersecting the optical axis AX, and the posture (angle with respect to the optical axis AX) can be adjusted. The optical characteristics such as the magnification of the projection optical system PL can be adjusted by adjusting the position or posture of these optical elements. Adjustment of the optical characteristics of the projection optical system PL is performed by the lens controller 16.

  The lens base structure CL3 is mounted on the wafer base structure CL4 on which the wafer stage WST on which the wafer W is mounted and which moves two-dimensionally along the XY plane is mounted. In this wafer stage WST, a wafer holder (not shown) that vacuum-sucks wafer W is placed in the Z direction (optical axis AX direction) so that the surface of wafer W coincides with the imaging surface of projection optical system PL. And a leveling table ZLT that is slightly moved and inclined slightly.

  The movement coordinate position of wafer stage WST in the XY plane and the minute rotation amount by yawing are measured by wafer interferometer system IFW. The interferometer system IFW projects the laser beam from the laser light source LS onto the movable mirror MRw fixed to the leveling table ZLT of the wafer stage WST and the fixed mirror FRw fixed to the lowermost part of the projection optical system PL. The reflected beam from each mirror MRw, FRw is caused to interfere, and the coordinate position of wafer stage WST and the minute rotation amount (for example, yawing amount, pitching amount, rolling amount) are measured. Instead of providing the movable mirror MRw on the leveling table ZLT, for example, the end surface of the leveling table LZT may be mirror-finished to be a reflecting surface.

  On the leveling table ZLT of wafer stage WST, a reference plate FM used for calibration of various alignment systems and focus sensors and measurement of the baseline amount is also attached. On the surface of the reference plate FM, a reference mark that can be detected by the alignment systems 14a and 14b is formed together with the mark of the reticle R under illumination light having an exposure wavelength. The baseline measurement method using the reference plate FM is disclosed in, for example, Japanese Patent Application Laid-Open No. 7-176468, and the focus calibration method using the reference plate FM is disclosed in, for example, Since it is disclosed in Japanese Patent No. 16483 and Japanese Patent Laid-Open No. 2000-21711, detailed description thereof is omitted here. Further, on the leveling table ZLT of the wafer stage WST, an illuminance sensor 18 for measuring the illuminance of exposure light irradiated onto the wafer W (wafer stage WST) is provided.

  Examples of the various alignment systems include an off-axis type alignment sensor that detects position information of alignment marks formed on the wafer W. The focus sensor described above is a sensor that measures a deviation amount and a posture (tilt) of the surface of the wafer W with respect to the image plane of the projection optical system PL in the Z-axis direction parallel to the optical axis AX of the projection optical system PL. The leveling sensor is a sensor that measures the posture (tilt) of the surface of the wafer W. Here, the above-mentioned baseline amount is an amount indicating the distance between the reference position of the reticle pattern image projected onto the wafer W (for example, the center position of the pattern image) and the center of the measurement field of view of the alignment sensor.

  Next, reticle stage RST will be described in detail. FIG. 2 is a perspective view showing a state near the reticle stage RST in FIG. FIG. 2 shows a state in which the reticle R is arranged at a position where the optical axis AX of the projection optical system PL passes through the center of the reticle R. The reticle stage RST is configured to move one-dimensionally in the Y direction on the reticle base structure CL1 with a stroke corresponding to the dimension of the reticle R. The movement of the reticle stage RST is performed by linear motor units 20a and 20b arranged extending in the Y direction on both sides of the reticle stage RST. In FIG. 1, the linear motor units 20 a and 20 b that drive the reticle stage RST are represented as a drive system 12. Each of the linear motor units 20a and 20b is entirely covered with a cover, and is forced by the exhaust ducts 21a and 21b so that the air in the motor units 20a and 20b heated by the heat generated by the motor coils does not flow outside as much as possible. Exhausted.

  Further, a movable mirror 22 extending in the Y direction is fixed to one end of the reticle stage RST in the X direction. The movable mirror 22 has an X direction measurement reticle interferometer IFRX fixed to the reticle base structure CL1. Three measurement beams BMrx are projected vertically. The reticle interferometer IFRX measures a minute position change and a minute rotation error of the reticle stage RST in the X direction (non-scanning direction). Note that a plurality of mesh openings 23a and 23b are provided immediately below the length measuring beam BMrx of the cover of the linear motor unit 20b, and the air around the length measuring beam BMrx is caused to flow into each opening by the exhaust duct 21b. A flow is drawn so as to be sucked into 23a and 23b. As a result, the optical path fluctuation of the measuring beam BMrx caused by the cover of the motor unit 20b warming is prevented.

  Reticle R is mounted on mounting portions 10a to 10d provided at four locations on stage RST. Each of the placement portions 10a to 10d is formed with a suction port for suctioning the reticle R under reduced pressure. The suction port is suctioned under reduced pressure and the reticle R is held on the placement portions 10a to 10d. In this way, the rectangular reticle R is held on the reticle stage RST in a state where the four corners are suctioned by the mounting portions 10a to 10d. The reduced-pressure suction of the reticle R by the suction port is controlled independently for each suction port. Therefore, the suction location of the reticle R by the suction port can be varied between 1 and 4 locations. Of course, it is possible not to perform the vacuum suction of the reticle R by the suction port at all.

  Further, notch corner portions CM1 and CM2 are formed at two positions on one side extending in the X direction of the reticle R, and are precisely processed at 90 ° within the main surface of the reticle R. The slopes of the notch corner portions CM1 and CM2 are optically polished, and a reflective layer is deposited on the surface thereof. Therefore, the notch corner portions CM1 and CM2 act as a kind of corner mirror, and reflect the length measuring beams BMry and BMrθ from the Y-direction measuring reticle interferometers IFRY and IFRθ fixed to the reticle base structure CL1. . These measurement beams BMry and BMrθ are incident on one of the slopes of the notch corner portions CM1 and CM2, respectively, and return to the reticle interferometers IFRY and IFRθ in parallel with the incident optical path from the other slope. Thereby, each reticle interferometer IFRY, IFRθ measures the position in the Y direction of each vertex of the two notch corner portions CM1, CM2.

  Meanwhile, reticle stage RST shown in FIG. 2 is supported on reticle base structure CL1 via an air bearing, and is moved in a non-contact manner by linear motor units 20a and 20b. Further, assuming that the Y-direction position coordinates of the notch corner portions CM1 and CM2 measured by the two interferometers IFRY and IFRθ are Yc1 and Yc2, the rotational change amount Δθc of the reticle R from the initial state is (Yc1). -Yc2) / Lk is calculated, and the coordinate position Yr in the Y direction of the reticle R at the time of scanning exposure is determined by calculation of (Yc1 + Yc2) / 2.

  Based on the coordinate position Yr, the linear motor units 20a and 20b are controlled with the same thrust to move the reticle stage RST in the Y direction at a predetermined speed, and the measured rotation change amount Δθc is always a constant value (for example, Zero), or a value that varies with an inherent tendency, and the reticle stage RST may be rotated slightly by giving a difference to the thrust of the linear motor units 20a and 20b. In FIG. 2, a region denoted by reference numeral PA is a pattern formation region of the reticle R, and a rectangular region LE extending in the X direction around the optical axis AX is an illumination light irradiation region at the time of scanning exposure. is there.

  FIG. 3 is a plan view of reticle stage RST shown in FIG. As shown in FIG. 3, the mounting portions 10 a to 10 d that support the reticle R at four locations have openings 26 so as not to block the pattern formation area PA of the reticle R and the projection optical paths of the position measurement marks M <b> 1 and M <b> 2. It is provided at the four corners. The mounting portions 10a to 10d are respectively formed with suction ports 27a to 27d for suctioning the reticle R under reduced pressure, and the suction ports 27a to 27d are connected to a suction pump (decompression source) around the reticle stage RST. Connection portions 28a to 28d are provided.

  The magnitude of the reduced pressure supplied to each of the connecting portions 28a to 28d can be individually controlled. This control is performed, for example, by providing a connection pipe that connects the connection portions 28a to 28d and the suction pump with a valve that blocks or opens the pipe line of the connection pipe, and controls the open / close state of the valve. Note that a suction pump may be provided in each of the connecting portions 28a to 28d so that drive control of each suction pump is individually controlled.

  If a predetermined reduced pressure is supplied to all of the connecting portions 28a to 28d, the four corners of the reticle R can be firmly adsorbed and held on the reticle stage RST. On the other hand, when there is a connection part 28a to 28d that does not supply a reduced pressure, the reticle R is adsorbed under reduced pressure only by the suction port connected to the connection part to which the reduced pressure is supplied, and the connection part to which no reduced pressure is supplied. At the connected suction port, the reticle R is not sucked under reduced pressure, and the reticle is placed on the placement portion having the suction port without being fixed.

  In a state where the decompression is supplied to all the connection portions 28a to 28d and the reticle R is sucked and held by all the suction ports 27a to 27d, when the reticle R is irradiated with the illumination light, the irradiation energy of the illumination light is irradiated to the reticle R. As a result, the reticle R bends greatly as shown in FIG. FIG. 4 is a diagram illustrating an example of bending caused by the expansion of the reticle R. Here, the X-direction bending that occurs in the reticle R will be described, but the same bending also occurs in the Y-direction. Moreover, in FIG. 4, the bending is exaggerated. The deflection of the reticle R caused by the expansion of the reticle R is, for example, an upward convex shape (see FIG. 4A), a downward convex shape (see FIG. 4B), or an S-shape (see FIG. 4C). Then, the stress is stored in the reticle R. When the stress stored in the reticle R becomes larger than the smallest suction force among the suction ports 27a to 27d, the reticle R is displaced at the position of the suction port having the suction force.

  On the other hand, if there are an adsorption port that adsorbs the reticle R under reduced pressure and an adsorption port that does not adsorb the reticle R under reduced pressure, the expansion of the reticle R caused by irradiation of illumination light occurs from the adsorption port adsorbed under reduced pressure. FIG. 5 is a diagram illustrating an example of adsorption of the reticle R by the adsorption ports 27a to 27d. In FIG. 5, for example, when the reticle R is sucked under reduced pressure only by the suction ports 27c and 27d, the reticle R expands in the −Y direction with the suction ports 27c and 27d as base points. Further, when the reticle R is sucked under reduced pressure only by the suction ports 27b and 27c, the reticle R expands in the + X direction with the suction ports 27b and 27c as base points. By controlling the reduced pressure suction portion of the reticle R by the suction ports 27a to 27d, the reticle R expands in the XY plane, the stress is released, and the bending is eliminated.

  By the way, when the reticle R expands in the XY plane due to illumination light irradiation, the reticle interferometers IFRX, IFRY, and IFRθ erroneously measure that the reticle R has moved by the amount that the reticle R has expanded. Further, the pattern image formed on the reticle R is enlarged and projected onto the wafer W by the amount of expansion of the reticle R. Furthermore, the baseline amount also fluctuates. Therefore, in the present embodiment, the irradiation energy accumulated in the reticle R is calculated from the illuminance of the illumination light irradiated onto the reticle R, the irradiation time of the illumination light with respect to the reticle R, and the transmittance and reflectance of the reticle R. The amount of expansion / contraction of the reticle R is calculated based on the irradiated energy, and the measurement results of the reticle interferometers IFRX, IFRY, IFRθ, the magnification of the projection optical system PL, and the amount of baseline are corrected based on the calculated amount of expansion / contraction. . Note that the linear expansion coefficient of the reticle R used when calculating the expansion / contraction amount of the reticle R is obtained in advance.

  FIG. 6 is a block diagram showing a schematic configuration of a control system for controlling the operation of the exposure apparatus according to the present embodiment. In FIG. 6, only the configuration related to the present invention of the control system provided in the exposure apparatus is shown, and the same components as those shown in FIGS. 1 to 5 are denoted by the same reference numerals. is there. The reticle interferometer system IFR shown in FIG. 6 includes the reticle interferometers IFRX, IFRY, and IFRθ shown in FIG. 2, measures the position and amount of rotation of the reticle R in the XY plane, and mainly uses the measurement results. Output to the control system 30. The reticle stage control system 31 performs drive control of the linear motor units 20a and 20b that drive the reticle stage RST based on a control signal output from the main control system 30.

  Based on the control signal output from the main control system 30, the lens controller 16 determines the position of the optical element provided in the projection optical system PL in the optical axis AX direction, the position in the direction intersecting the optical axis AX, and the posture. By controlling, the optical characteristics such as the magnification of the projection optical system PL are adjusted. Note that the lens controller 16 not only changes the environment (atmospheric pressure, etc.) and changes in optical properties caused by the incidence of illumination light, but also changes in optical properties caused by the expansion and contraction of the reticle R. It is corrected. In the present embodiment, the change in the magnification of the pattern image due to the expansion and contraction of the reticle R is corrected by adjusting the magnification of the projection optical system PL by the lens controller 16. The wafer interferometer system IFW measures the position and rotation amount of the wafer W in the XY and outputs the measurement result to the main control system 30. Wafer stage control system 32 controls the position and rotation amount of wafer stage WST in the XY plane by driving a linear motor unit provided in wafer stage WST based on a control signal output from main control system 30. The actuator (not shown) is driven to control the posture (tilt) of the leveling table ZLT.

  The integrator sensor 33 is provided in the illumination optical system IL shown in FIG. 1, measures the illuminance of the illumination light emitted from the illumination optical system IL (illumination light irradiated on the reticle R), and the measurement result is mainly used. Output to the controller 30. The decompression control unit (adsorption control unit) 34 is a valve provided in each of the connection pipes connecting the connection units 28a to 28d and the suction pump shown in FIG. 3 based on a control signal output from the main control system 30. Open / closed state, or driving of a suction pump provided for each of the connection portions 28a to 28d, and which of the suction ports 27a to 27d controls the suction of the reticle R is controlled. The illuminance sensor 18 measures the illuminance of illumination light irradiated on the wafer W (wafer stage WST).

  The main control system 30 controls the exposure apparatus as a whole. Specifically, a control signal is output to reticle stage control system 31 based on the measurement result of reticle interferometer system IFR, and a control signal is output to wafer stage control system 32 based on the measurement result of wafer interferometer system IFW. Output. In addition, when the pattern formed on the reticle R is transferred onto the wafer W, each of the reticle stage control system 31 and the wafer stage control system 32 so that the reticle stage RST and the wafer stage WST move synchronously. A control signal is output. Note that a synchronization error between the reticle R and the wafer W (including a position error in the X and Y directions and a rotation error about the Z axis) generated during the synchronous movement is caused by fine movement of at least one of the reticle stage RST and the wafer stage WST. It is corrected.

  Further, the main control system 30 calculates the irradiation energy accumulated in the reticle R from the measurement results of the integrator sensor 33 and the illuminance sensor 18, the irradiation time of the illumination light on the reticle R, and the transmittance and reflectance of the reticle R, A calculation unit that calculates the expansion / contraction amount of the reticle R based on the calculated irradiation energy is provided. When the calculation result by the calculation unit exceeds a predetermined threshold value set in advance, a control signal is output to the depressurization control unit 34 to control the depressurization suction portion of the reticle R by the suction ports 27a to 27d. That is, in the state where the four corners of the reticle R are attracted to the suction ports 27a to 27d, if the calculated value of the expansion / contraction amount of the reticle R is increased to some extent, the reticle R will be bent as shown in FIG. As a result, the reticle R is expanded in the XY plane as shown in FIG. 5 to release the stress accumulated in the reticle R.

  Further, the main control system 30 outputs a control signal for controlling the size of the projection image projected on the wafer W by the expansion / contraction of the reticle R to the lens controller 16 based on the calculated expansion / contraction amount of the reticle R. Further, the main control system 30 is a distance between the measurement visual field center of the off-axis type alignment sensor that acquires the position information of the alignment mark formed on the wafer W and the reference position of the pattern image of the reticle projected on the wafer W. Is used to control wafer stage WST. Since the baseline amount changes when the reticle R expands or contracts, the main control system 30 corrects the baseline amount using the calculated reticle expansion / contraction amount. That is, in this embodiment, as described above, by releasing the vacuum suction of at least one suction port, the reticle R expands in the XY plane with the remaining suction port that has not been released as a base point, and the stress is released. However, since the stress release criterion does not necessarily coincide with the center CC of the reticle R, when the stress release is performed, the center CC of the reticle R and the center of the projection optical system PL (optical axis AX). Displaced. Accordingly, even if the magnification of the projection optical system PL is adjusted in this state, the baseline amount changes, so that the main control system 30 expands and contracts the reticle R after releasing the stress, that is, its center by the expansion and contraction of the reticle R. A deviation amount of CC is calculated, and the baseline amount is corrected using the calculated deviation amount as an offset. When the reticle R expands and contracts, the position of the reticle R is erroneously detected by the amount of expansion / contraction in the reticle interference system IFR. Therefore, the main control system 30 corrects the measurement result of the reticle interference system IFR with the calculated amount of expansion / contraction of the reticle R, and then outputs a control signal for controlling the reticle stage RST to the reticle stage control system 31.

  Next, a method for calculating the amount of expansion / contraction of the reticle R will be described. Expansion and contraction of the reticle R occurs when illumination light irradiated on the reticle R is absorbed by the reticle R, and irradiation energy is accumulated in the reticle R and is thermally deformed. Since the thermal deformation of the reticle R is considered to occur in proportion to the temperature distribution of the reticle R, the main control system 30 obtains the amount of expansion / contraction of the reticle R by simulating this temperature distribution. The temperature distribution of the reticle R can be obtained by decomposing the reticle R into certain finite elements and calculating the temperature change at each point using a method such as a difference method or a finite element method. In the following description, a method for calculating the temperature distribution of the reticle R using the difference method will be described as an example.

  First, a reticle on which a pattern is not formed in advance is arranged on the reticle stage RST, and the reticle R is irradiated with illumination light, and the ratio between the measured value of the integrator sensor 33 and the measured value of the illuminance sensor 18 is obtained. Since the amount of heat absorbed by the reticle R depends on the location due to the distribution of the pattern formed on the reticle R, the presence of a pattern obtained by dividing the reticle R into, for example, 16 blocks of 4 × 4. Calculate the heat absorption of each block based on the rate. Note that the reflectance and transmittance of the reticle necessary for calculating the heat absorption amount are measured in advance and stored in the main control system 30. The pattern presence rate of each block is obtained by the ratio between the measurement value of the integrator sensor 33 and the measurement value of the illuminance sensor 18. The illuminance sensor 18 measures the amount of illumination light that passes through each block and forms an image on the illuminance sensor 18 independently for each block.

  Next, the reticle R on which the pattern is formed is placed on the reticle stage RST and the same measurement is performed, and the pattern presence rate is obtained using the measurement result of the reticle on which the pattern is not formed. This measurement may be performed every time the reticle is replaced, or may be measured in advance and stored in the main control system 30. Of course, if the pattern presence rate is known from the data at the time of manufacturing the reticle, there is no need to perform measurement.

  Each block set to the reticle R absorbs an amount of heat proportional to the illuminance of the illuminating light to be irradiated, the irradiation time of the illuminating light, and the pattern presence rate, and the heat absorbed by each block is absorbed between the blocks. It is moved or released into the air or conducted to the reticle stage RST. The heat absorption amount of each block is calculated based on the pattern presence rate for each block obtained by the above method. Since this specific calculation formula is disclosed in detail in JP-A-4-192317, it is omitted here.

  When the temperature distribution of each block is obtained by the above method, the mutual distance change of the center point of each block can be obtained from the obtained temperature distribution of each block and the linear expansion coefficient of the reticle R. Thereby, the movement of each point on the reticle R can be determined, and the expansion / contraction amount of the reticle R can be obtained based on this movement. The linear expansion coefficient of the reticle R is measured in advance and stored in the main control system 30.

  Next, the operation at the time of exposure of the exposure apparatus having the above configuration will be described with reference to the flowchart shown in FIG. Note that the flowchart shown in FIG. 7 is a flowchart in the case where the exposure process is performed on one wafer W placed on wafer stage WST. When performing an exposure process, each process of the flowchart shown in FIG. 7 is repeated.

  When the exposure process is started, first, the main control system 30 reads various exposure conditions from an exposure data file stored in advance. Here, the exposure conditions read from the exposure data file include the arrangement of each shot area set on the wafer W, the illumination conditions, information indicating the type of the reticle R to be used, the reticle stage RST at the time of exposure and the wafer stage WST. Various information such as acceleration is included. When reading of the various exposure conditions is completed, the main control system 30 sets the illumination conditions and the like of the illumination optical system IL according to the read exposure conditions. Next, the main control system 30 carries in the reticle R to be used from the reticle library (not shown) based on the information indicating the type of the reticle R included in the exposure conditions, arranges it on the reticle stage RST, and sucks the suction port. The four corners of reticle R are sucked under reduced pressure using 27a to 27d, and then relative alignment between reticle R on reticle stage RST and wafer stage WST is performed. Thereafter, wafer W is placed on wafer stage WST, and position information of wafer W on wafer stage WST is measured.

  When the above processing is completed, the main control system 30 outputs a control signal to the reticle stage control system 31, places the reticle R at the movement start position, and outputs a control signal to the wafer stage control system 32. The shot area to be exposed (here, the first shot area) is moved to the exposure start position. The exposure start position is a position where the acceleration of wafer stage WST is started in order to scan and expose the shot area. When the above process ends, the main control system 30 starts an exposure process for the shot area (step S1).

  Specifically, main control system 30 outputs an exposure start command to reticle stage control system 31 and wafer stage control system 32, and starts acceleration of reticle stage RST and wafer stage WST. Each stage finishes accelerating. For example, the speed of wafer stage WST reaches maximum speed Vw, and the speed of reticle stage RST is maximum speed Vr = α · Vw (α is the projection magnification from reticle R to wafer W). , The main control system 30 commands the illumination optical system IL to irradiate illumination light, whereby illumination light having a uniform illuminance distribution is irradiated onto the reticle R, and the reticle R is irradiated onto the shot region. Pattern transfer starts.

  While the reticle stage RST and wafer stage WST are synchronously moved (scanned) at the maximum speed, the pattern of the reticle R is sequentially transferred to the shot area on the wafer W via the projection optical system PL. When the reticle stage RST and the wafer stage WST are scanned for a predetermined time and the transfer of the pattern of the reticle R to the shot area is completed, the main control system 30 stops the emission of the illumination light by the illumination optical system IL and the reticle stage control system. A control signal is output to 31 and wafer stage control system 32 to decelerate reticle stage RST and wafer stage WST. With the above processing, the exposure processing for one shot area is completed.

  When the exposure process for one shot area is completed, main control system 30 determines whether or not the exposure process has been completed for all shot areas set on wafer W on wafer stage WST (step S2). ). If there is a shot area to be exposed next, that is, if it is determined that the exposure processing for all shot areas of one wafer has not been completed (in the case of “No”), the process proceeds to step S3.

  In step S <b> 3, the main control system 30 controls the vacuum suction location using the suction ports 27 a to 27 d for eliminating the deflection of the reticle R (deflection elimination control: the exposure processing for one shot region performed in step S <b> 1. It is determined whether or not the exposure process is N (N is a positive integer) times from the previous execution of steps S5 to S10. Note that the variable N is appropriately set according to how the reticle R is bent or the amount of bending caused by the irradiation of the illumination light to the reticle R. That is, if the reticle R bends as illustrated in FIG. 4 even when the number of illumination light irradiations is small, the variable N is set to a small value. Conversely, if the reticle deflection is small enough to be ignored even if the number of illumination light irradiations is large, the variable N is set to a large value. Further, the expansion / contraction amount of the reticle R can be obtained from the heat absorption calculation of the reticle R described above, and the variable N can be determined according to the obtained expansion / contraction amount.

  If the determination result in step S 3 is “NO”, the main control system 30 outputs a control signal to the reticle stage control system 31 to reverse the direction of movement of the reticle R and to the wafer stage control system 32. In response to this, a control signal is output, wafer stage WST is moved, and the next shot area to be exposed is moved to the exposure start position (step S12). After the above processing, exposure processing for the shot area is performed (step S1). When the determination result of steps S2 and S3 is “NO”, the above processing is repeated, and the exposure processing of the shot areas set on the wafer W is sequentially performed.

  Here, if the exposure process for one shot area performed in step S1 corresponds to the Nth exposure process from the previous execution of the deflection elimination control and the determination result in step S3 is “YES”, the reticle stage RST is changed. After the end of deceleration (step S4), the deflection elimination control is started. In the deflection elimination control, first, the main control system 30 outputs a control signal to the decompression control unit 34, and among the decompression and suction at the four corners of the reticle R by the suction ports 27a to 27d, the suction and suction by the suction ports 27a and 27b. Then, the reticle R is sucked under reduced pressure only by the suction ports 27c and 27d (step S5). Note that this deflection elimination control is performed when the speed of the reticle stage RST is zero (that is, during stopping: before deceleration inversion and before starting reverse acceleration).

  Next, the reduced pressure adsorption of the reticle R using only the adsorption ports 27c and 27d is continued for a certain time (for example, 0.1 second) (step S6), and then the reduced pressure adsorption using the adsorption ports 27a and 27b is resumed. The four corners of the reticle R are sucked under reduced pressure by 27a to 27d (step S7). By the processing in steps S5 and S6, the reticle R expands in the −Y direction with the suction ports 27c and 27d as the base points, and the stress accumulated in the reticle R is released, and the reticle R is moved in the Y direction by the processing in step S7. The four corners are adsorbed under reduced pressure.

  Next, the main control system 30 outputs a control signal to the decompression control unit 34, cancels decompression adsorption by the adsorption ports 27a, 27d, and adsorbs the reticle R under reduced pressure only by the adsorption ports 27b, 27c (step S8). . In the same manner as described above, the reduced pressure adsorption of the reticle R only by the adsorption ports 27b and 27c is continued for a certain time (for example, 0.1 second) (step S9), and then the reduced pressure adsorption by the adsorption ports 27a and 27d is resumed. The four corners of the reticle R are sucked under reduced pressure by the ports 27a to 27d (step S10). By the processing in steps S8 and S9, the reticle R expands in the + X direction with the suction ports 27b and 27c as the base points, and the stress accumulated in the reticle R is released, and the reticle R is moved in the X direction by the processing in step S10. In the extended state, the four corners are adsorbed under reduced pressure.

  By performing the deflection elimination control in steps S5 to S10 described above, the reticle R is attracted and held on the reticle stage RST in a state where the reticle R is stretched in the X direction and the Y direction (a state where the stress is released and the deflection is eliminated). It will be.

  When the execution of the deflection elimination control (steps S5 to S10) is completed, the main control system 30 accumulates in the reticle R between the time when the previous deflection elimination control is executed and the time when the current deflection elimination control is executed. Irradiation energy (measured values of the integrator sensor 33 and the illuminance sensor 18 when the exposure process of step S1 is performed, irradiation time of irradiation light, and accumulated heat amount absorbed by the reticle R from the transmittance and reflectance of the reticle R) And the expansion / contraction amount of the reticle R is calculated from the calculated irradiation energy and the linear expansion coefficient of the reticle R. When the expansion / contraction amount of the reticle R is obtained, the main control system 30 outputs a control signal to the lens controller 16 to correct the magnification of the projection optical system PL in accordance with the expansion / contraction amount of the reticle R (step S11). .

  Further, the main control system 30 corrects the baseline amount using the calculated amount of expansion / contraction of the reticle R, and controls the reticle stage RST after correcting the measurement result of the reticle interference system IFR with the amount of expansion / contraction of the reticle R. The control signal to be corrected is corrected. Thereafter, the control signal output from the main control system 30 to the reticle stage RST is obtained by correcting the expansion / contraction amount of the reticle R. When the above processing is completed, the main control system 30 outputs a control signal to the reticle stage control system 31, inverts the moving direction of the reticle R, and outputs a control signal to the wafer stage control system 32. Then, wafer stage WST is moved, and the shot area to be exposed next is moved to the exposure start position (step S12). Next, the process returns to step S1, and the exposure process for the shot area is performed.

  As described above, in the present embodiment, the reduced pressure suction of the reticle R by the suction ports 27a to 27d can be performed independently for each of the suction ports 27a to 27d. For this reason, even if the reticle R is irradiated with illumination light with the four corners of the reticle R being fixed and the reticle R is bent, the reticle R is stretched to release the stress and the bending of the reticle R can be eliminated. .

  Further, the suction ports 27a and 27b are opened and the reticle R is sucked under reduced pressure only by the suction ports 27c and 27d, thereby extending the reticle R in the -Y direction with reference to the suction ports 27c and 27d, and the suction ports 27a and 27d. And the reticle R is decompressed and sucked only by the suction ports 27b and 27c to extend the reticle R in the + X direction with the suction ports 27b and 27c as a reference, thereby making the extension direction of the reticle R constant. As a result, the position of the center CC of the reticle R changes before and after the deflection elimination control, but after the deflection elimination, the reticle R only extends in the XY plane with the suction port 27c as a base point. Therefore, by calculating the amount of expansion / contraction due to the irradiation energy accumulated in the reticle R subjected to the deflection elimination control, it is possible to accurately correct the change in magnification or scaling and the change in the baseline amount due to the expansion of the reticle R. it can. That is, based on the calculated expansion / contraction amount of the reticle R, the magnification change of the pattern image of the reticle R is corrected by adjusting the magnification of the projection optical system PL by the lens controller 16, and the deviation amount of the center CC of the reticle R described above is corrected. Based on this, the baseline amount is corrected.

  Further, during the exposure process, the four corners of the reticle R are suctioned at a reduced pressure, and the bend elimination control is performed after the speed of the reticle stage RST becomes zero. There is no displacement of the reticle R due to. In addition, since the bend elimination control is performed after the exposure process for one shot area is completed until the exposure process for the next shot area is started, it is possible to minimize a decrease in throughput due to the bend elimination. it can. Even if the speed of reticle stage RST is not necessarily zero, when the acceleration is zero, bend elimination control may be performed.

  As a result, a fine pattern can be faithfully transferred onto a substrate with a uniform line width, and a high-performance and high-quality microdevice can be manufactured with a high yield. If the reticle R is greatly bent by illumination light irradiation, it is desirable to set the value of the variable N to “1” and to perform the bend elimination control every time the exposure processing of each shot area is completed.

  A semiconductor element as a device includes a step of designing a function and performance of the device, a step of manufacturing a reticle based on the design step, a step of manufacturing a wafer from a silicon material, and the exposure apparatus of the above-described embodiment. It is manufactured through a step of exposing and transferring a pattern to a wafer, a device assembly step (including a dicing process, a bonding process, and a package process), an inspection step, and the like.

  In the above embodiment, the case where the change in the magnification of the pattern image due to the expansion of the reticle R (the magnification of the projection optical system PL) is corrected has been described. However, the optical characteristics to be corrected are not limited to the magnification. At least one of the optical characteristics of the projection optical system PL, for example, distortion, curvature of field, and the like is calculated by calculating the change due to the influence of the reticle R, and the optical characteristics of the projection optical system PL are adjusted by using the lens controller 16 so as to correct them. You may control. In the above-described embodiment, the suction port that sucks the reticle R under reduced pressure is used. However, for example, electrostatic suction or a suction port that uses vacuum suction and electrostatic suction together may be used. Furthermore, in the above-described embodiment, the suction ports are provided in each of the plurality of placement units. However, the number of placement units is not limited to four, and may be arbitrary, for example, one, and the suction port may be the same. The number is not limited to four but may be plural. In the above-described embodiment, a plurality of (four) suction ports are configured to be independently controllable. However, all the suction ports may not be independently controllable, for example, the reticle R is bent. Depending on the tendency and the like, at least one suction port may be controllable independently of the other suction ports.

  Note that the configuration of the exposure apparatus including the reticle stage RST, the reticle interferometer, and the like to which the mounting unit that performs the above-described deflection elimination control is applied is not limited to the above embodiment, and may be arbitrary. For example, a part of the drive system 12 (such as the stators of the linear motor units 20a and 20b) may be used as a counter mass to suppress vibrations.

  In the above embodiment, a transmissive reticle made of synthetic quartz, for example, is held on the reticle stage RST. However, in an exposure apparatus using a charged particle beam such as an electron beam or an ion beam, an X-ray exposure apparatus, or the like. The present invention may be applied to a stage on which a transmission type mask (stencil mask, membrane mask) used or a reflection type mask used in an EUV exposure apparatus is mounted. Furthermore, the present invention may be applied to a stage on which an object on which a mask pattern is transferred is placed.

  In the above embodiment, the step-and-scan type exposure apparatus is described as an example of the exposure apparatus. However, the step-and-repeat type or step-and-stitch type exposure apparatus, mirror projection aligner, and the like are described. For example, the present invention can be applied to an immersion type exposure apparatus disclosed in International Publication WO99 / 49504 or the like in which a liquid (for example, pure water) is filled between the projection optical system PL and the wafer. The immersion exposure apparatus may be a scanning exposure system using a catadioptric projection optical system, or a static exposure system using a projection optical system with a projection magnification of 1/8. In the latter immersion type exposure apparatus, it is preferable to adopt a step-and-stitch method in order to form a large pattern on the substrate. Also, not only exposure apparatuses used for manufacturing semiconductor elements and liquid crystal display elements, but also exposure apparatuses, reticles, and masks used for manufacturing plasma displays, thin film magnetic heads, and image sensors (CCD, etc.) are manufactured. Therefore, the present invention can also be applied to an exposure apparatus that transfers a circuit pattern to a glass substrate or a silicon wafer. In other words, the present invention can be applied regardless of the exposure method and application of the exposure apparatus.

  Furthermore, in the above-described embodiment, the description has been given by taking the mask (reticle R) as an example to eliminate bending. However, in an exposure apparatus used for manufacturing a mask, for example, blanks (mask manufacturing substrate) as a base material of the mask ) Is the substrate to be processed, but the present invention can also be applied to the elimination of the bending of the mask manufacturing substrate. In addition, the present invention can be applied not only to these exposure apparatuses but also to any apparatus provided with a stage apparatus that holds a plate-like object by suction.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

It is a front view which shows typically the whole structure of the exposure apparatus which concerns on embodiment of this invention. It is the perspective view which showed the mode of the reticle stage vicinity in FIG. FIG. 3 is a plan view of the reticle stage shown in FIG. 2. It is a figure which shows the example of the bending produced by expansion | swelling of a reticle. It is a figure which shows the example of adsorption | suction of the reticle R by an adsorption | suction port. It is a block diagram which shows the typical structure of the control system which controls operation | movement of the exposure apparatus which concerns on embodiment of this invention. It is a flowchart which shows the process of the exposure apparatus which concerns on embodiment of this invention.

Explanation of symbols

10a to 10d: placement unit 16 ... lens controller (optical characteristic control unit)
27a to 27d ... Suction port 30 ... Main control system (calculation unit)
34 ... Depressurization control unit (adsorption control unit)
IL: Illumination optical system PL ... Projection optical system R ... Reticle (mask)
RST ... Reticle stage (mask stage)
W ... Wafer (substrate)
WST ... Wafer stage (substrate stage)

Claims (10)

A stage device having a stage for holding a plate-like object,
A mounting portion provided on the stage, having a plurality of suction ports that contact the plate-like object and its periphery and suck the plate-like object;
And a suction control unit that controls suction of the plate-like object by the plurality of suction ports and that can control at least one of the plurality of suction ports independently of other suction ports. apparatus. An exposure apparatus that exposes a substrate through a mask pattern,
An illumination optical system for illuminating the mask;
A projection optical system that projects an image of the pattern of the mask onto the substrate;
A mask stage device having a mask stage for holding the mask;
A substrate stage device having a substrate stage for holding the substrate;
An exposure apparatus, wherein at least one of the mask stage apparatus and the substrate stage apparatus includes the stage apparatus according to claim 1. The amount of irradiation energy accumulated in the mask or the substrate with the illumination of the mask or the exposure of the substrate is calculated, and the amount of expansion or contraction of the mask or the substrate is calculated based on information related to the calculated amount of irradiation energy. A calculation unit for calculating,
The suction control unit controls the suction of the mask or the substrate by the suction port based on the calculation result of the calculation unit, and releases stress due to expansion and contraction of the mask or the substrate. 2. The exposure apparatus according to 2.   The exposure apparatus according to claim 3, further comprising an optical characteristic control unit that controls an optical characteristic of the projection optical system based on a calculation result of the calculation unit. An exposure method for exposing a substrate through a mask pattern held on a mask stage,
A holding step of holding the mask on the mask stage in a state in which the mask is adsorbed at a plurality of locations around the mask;
And a releasing step of releasing attraction of at least one of the plurality of locations adsorbing the mask according to the amount of expansion and contraction of the mask caused by irradiation of the illumination light.   The method further includes a calculation step of calculating an irradiation energy amount accumulated in the mask with illumination of the mask and calculating an expansion / contraction amount of the mask based on information related to the calculated irradiation energy amount. The exposure method according to claim 5.   7. The exposure according to claim 6, further comprising an optical characteristic control step of controlling an optical characteristic of a projection optical system that projects an image of the pattern of the mask onto the substrate based on a calculation result of the calculation step. Method.   In the releasing step, the speed of the mask stage is zero after the exposure process for one of the plurality of partitioned areas set on the substrate is finished and the exposure process for the next partitioned area is started. The exposure method according to claim 5, wherein the exposure method is performed.   In the releasing step, when the substrate is exposed while the mask stage and the substrate stage are moved synchronously, the stress due to the expansion / contraction of the mask in the synchronous movement direction and the expansion / contraction of the mask in a direction intersecting the synchronous movement direction The exposure method according to any one of claims 5 to 8, wherein the suction of the mask is released so as to release the stress caused by. The holding step includes a step of holding the four corners on the mask stage by vacuum-adsorbing the four corners so that the two sides of the rectangular mask are substantially parallel to the synchronous movement direction,
The release step includes
The first release that releases the stress caused by the expansion and contraction of the mask in the synchronous movement direction by releasing the adsorption of one set of the suction points of the two sets of suction points along the side parallel to the direction intersecting the synchronous movement direction. Steps,
After sucking again the suction location released in the first release step, the suction of one set of suction locations of the two sets of suction locations along the side parallel to the synchronous movement direction is released to move in the synchronous movement direction. The exposure method according to claim 9, further comprising: a second releasing step of releasing stress due to expansion and contraction of the mask in the intersecting direction.

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