JP2005310832A - Stage control method, exposure method and stage apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stage control method and a stage apparatus for controlling a mask stage for holding a mask to which a pattern is formed and a substance stage for holding a substance to which the pattern is transferred, a stage apparatus, and an exposure method utilizing the stage control method with which high precision exposure can be realized within a short period of time. <P>SOLUTION: In a sub-routine 601, when a wafer stage is moving in the X-axis direction, bending in the X-axis and Z-axis directions of a moving mirror for measuring Y-position extending in the X-axis direction is detected with an interferometer for measuring amount of yawing within the XY plane of a wafer stage. In a sub-routine 603, burning of the predetermined pattern to the wafer is conducted by taking the detected bending of the moving mirror into consideration and a residual error of bending of the moving mirror is detected from the result of such burning process. In the exposure of the step 613, the residual error is defined as the correcting value of the measurement result of pitching amount of the wafer stage and relative displacement of a reticle stage RST resulting from an Abbe error is corrected. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a stage control method, an exposure method, and a stage apparatus, and more specifically, a stage that controls a mask stage that holds a mask on which a pattern is formed and an object stage that holds an object to which the pattern is transferred. The present invention relates to a control method, a stage apparatus, and an exposure method using the stage control method.

  Conventionally, in a lithography process for manufacturing an electronic device such as a semiconductor element (integrated circuit) or a liquid crystal display element, a pattern of a mask or a reticle (hereinafter referred to as “reticle”) held on a mask stage (reticle stage) is used. An image is held on a photosensitive substrate (hereinafter referred to as “substrate” or “wafer”) such as a wafer or a glass plate which is held on an object stage and coated with a resist (photosensitive agent) via a projection optical system. A projection exposure apparatus for transferring to each shot area is used. As this type of projection exposure apparatus, a step-and-repeat type reduction projection exposure apparatus (so-called stepper) has been conventionally used, but recently, a step-and-repeat that performs exposure while synchronously scanning a reticle and a wafer. A scanning projection exposure apparatus (so-called scanning stepper) is also attracting attention.

  In these exposure apparatuses, in order to improve the control accuracy of both stages holding the reticle or wafer from the viewpoint of exposure accuracy, it is extended on the stage to reflect the measurement beam of the interferometer that measures the position information of each stage. A small distortion (so-called moving mirror bending) of the moving mirror (plane mirror) is detected from the measurement results of the interferometer itself and the actual exposure result, and the stage is controlled while taking into account the detected moving mirror bending. Is going.

  For example, a predetermined pattern is sequentially transferred onto a substrate held on the stage while moving the stage along the extending direction of the movable mirror, and the movable mirror is bent from the amount of positional deviation of the predetermined pattern image formed on the substrate. Has been proposed (see, for example, Patent Document 1). In addition, while moving the stage at a predetermined interval along the extending direction of the movable mirror, the position information of the stage measured by the length measuring beams irradiated in parallel with each other at a predetermined interval along the extending direction. There has also been proposed a method in which the difference is sequentially measured as a local inclination of the moving mirror, and the bending of the moving mirror is detected based on the integrated value of the difference (see, for example, Patent Document 2).

  As described above, further improvement in stage control is required with improvement in exposure accuracy, and even moving mirror bending has become a matter of concern. However, although the method disclosed in Patent Document 1 for detecting the bending of the movable mirror from the exposure result uses the actual exposure result, the detection accuracy is very good, but the pattern is actually transferred onto the wafer. However, it is necessary to develop the wafer, which is not advantageous from a time point of view, and is not suitable for multiple measurements. Further, this method can only detect the bending of the moving mirror corresponding to the range in which the pattern can be actually transferred onto the wafer, and cannot actually measure the bending of the entire reflecting surface of the moving mirror. There was also inconvenience.

  Further, in the method of detecting the moving mirror bending from the integrated value of the difference between the measurement values of the interferometer, there is a disadvantage that the spatial frequency component of the movable mirror bending that can be detected is limited by the distance between the length measuring beams.

  More recently, not only the position of the wafer stage that holds the wafer in a plane perpendicular to the optical axis of the projection optical system but also the tilt of the wafer stage relative to the plane has been measured by an interferometer. In this case, in order to correct a so-called Abbe error caused by the tilt of the wafer stage measured by the interferometer, the position of the reticle stage holding the reticle is shifted relative to the position of the wafer stage by the Abbe error, for example. Thus, the relative position between the reticle stage and the wafer stage is controlled.

  In this method, that is, the method of measuring the tilt of the wafer stage and correcting the Abbe error based on the measurement result, the moving mirror bending in the direction orthogonal to the plane is also a concern, and the bending is corrected. A method has also been proposed (see, for example, Patent Document 3). As described above, the irradiation point of the length measuring beam to the moving mirror is steadily increasing, and it is necessary to detect the bending of the moving mirror in a multifaceted manner.

However, in the method disclosed in Patent Document 3, there is a limit to the spatial frequency component of the movable mirror bending that can be detected due to the same restrictions as the method disclosed in Patent Document 2. In addition, when the interferometer that measures the tilt of the wafer stage is a single-pass interferometer in which the length of the measuring beam is irradiated once on the movable mirror, the influence of the movable mirror tends to increase. Therefore, it is expected that the detection accuracy of the movable mirror bending that can be detected is improved. However, in the method disclosed in Patent Document 3, the measurement value of the interferometer that measures the tilt of the wafer stage is measured by the measurement of another interferometer. Since the correction is made with the amount of tilt of the movable mirror obtained from the value, there may be a case where a measurement error occurs due to a difference in measurement equipment.
JP-A-8-227839 JP-A-9-275072 International Publication WO00 / 22376 Pamphlet

  From the first aspect, the present invention made under the above circumstances holds a mask stage (RST) that holds a mask (R) on which a pattern is formed, and an object (W) to which the pattern is transferred. A stage control method for controlling an object stage (WST), wherein shape information of a reference surface used for position measurement of the stage provided on at least one of the mask stage and the object stage is detected, and the shape information A first step of generating first correction information for correcting a relative position between the mask stage and the object stage; and a relative relationship between the mask stage and the object stage based on the first correction information. A second step of transferring the pattern while correcting the position; based on the arrangement information of the pattern on the object transferred in the second step; A third step of generating second correction information for further correcting the relative position between the mask stage and the object stage; and position control between the mask stage and the object stage based on the first and second correction information. A stage control method including:

  According to this, in the first step, first correction information for correcting the relative position of both stages is generated from the shape information of the reference plane used for position measurement of one of the mask stage and the object stage. Later, in the third step, second correction information is generated based on the arrangement information of the pattern on the transferred object while controlling the relative position of both stages based on the first correction information. In the process, it is possible to realize the relative position control of both stages based on both the first and second correction information, that is, the shape information of the reference surface and the arrangement information of the pattern on the transferred object.

  From a second viewpoint, the present invention includes a mask stage (RST) that holds a mask (R) on which a pattern is formed, and an object stage (WST) that holds an object (W) to which the pattern is transferred. A stage control method for controlling, wherein the object stage is held on the object stage while being moved to a plurality of positions arranged in a matrix at predetermined intervals with respect to two axes orthogonal to each other in a two-dimensional plane. A first step of sequentially transferring and forming partitioned areas S (m, n) including a predetermined pattern on the object; and based on the positional deviation amount of the predetermined pattern with respect to the two axes in adjacent partitioned areas. A second step of detecting information on a deviation of the partition area from the arrangement reference in a plane; and the mask stage and the object stage based on the detection result It controls the position of the third step and, a stage control method including.

  According to this, in the first step, the partition area including the pattern is transferred and formed in a matrix on the object, and in the second step, two-dimensionally based on the positional deviation amount of the pattern transfer position in the adjacent partition area. Information relating to the deviation of the partition area from the arrangement reference in the plane is detected. In this way, it is possible to detect information relating to the deviation of the partition region from the arrangement reference from the actual transfer result.

  According to a third aspect of the present invention, there is provided an exposure method for transferring a pattern formed on a mask (R) onto a photosensitive object (W), and holding the photosensitive object using the stage control method of the present invention. The exposure method includes a step of transferring the pattern to the photosensitive object held on the object stage while controlling the object stage (WST) and the mask stage (RST) holding the mask. In such a case, the pattern formed on the mask can be transferred to the photosensitive object while controlling the object stage holding the photosensitive object and the mask stage holding the mask using the stage control method of the present invention. Therefore, highly accurate exposure can be realized.

  According to a fourth aspect of the present invention, there is provided a mask stage (RST) that can move while holding a mask (R) on which a pattern is formed; and a two-dimensional object that holds an object (W) onto which the pattern is transferred. An object stage (WST) movable along a first axis direction in a plane and a second axis direction orthogonal to the first axis and having a reference plane orthogonal to the second axis; and using the reference plane A measuring device (18Y) that measures position information of the object stage in the second axis direction; and the movement from the position information measured by the measuring device while moving the object stage along the first axis direction. A first generator (20) for detecting mirror shape information, and generating first correction information used for correcting a relative position between the mask stage and the object stage based on the shape information; Correction And further correcting the relative position between the mask stage and the object stage based on the arrangement information of the pattern on the object transferred while correcting the relative position between the mask stage and the object stage based on the information. A second generation device (20) that generates the second correction information; based on the first correction information generated by the first generation device and the second correction information generated by the second generation device. And a control device (19) for controlling the position of the object stage and the mask stage.

  According to this, after the 1st production | generation apparatus produces | generates the 1st correction information which correct | amends the relative position of both stages from the shape information of the reference plane used for the position measurement of a stage, the 2nd production | generation apparatus uses the Based on the arrangement information of the pattern on the transferred object while controlling the relative position of both stages based on the correction information of 1, the second correction information for further correcting the relative position of both stages is generated, and the control device Thus, the relative position control of both stages can be performed based on both the first and second correction information, that is, the position information of the reference plane and the arrangement information of the pattern on the transferred object.

  From a fifth aspect, the present invention is a stage device that can move in a two-dimensional plane while holding an object (W or the like) used for exposure, and has two axes orthogonal to each other in the two-dimensional plane. A transfer device (20) for sequentially transferring and forming partitioned regions including a predetermined pattern on an object held on the stage while moving the stage (WST) to a plurality of positions arranged in a matrix at predetermined intervals with respect to The object on the stage based on the information about the deviation of the partition area from the arrangement reference in the two-dimensional plane calculated from the positional deviation amount of the predetermined pattern with respect to the two axes between the partition areas adjacent to each other. And a control device (19) for performing alignment control between the pattern and the pattern to be transferred.

  According to this, a partition area including a predetermined pattern is transferred and formed in a matrix on the object by the transfer device, and based on the positional deviation amount of the actual transfer position of the predetermined pattern in the adjacent partition areas by the control device. Thus, it is possible to detect information on the deviation of the partition area from the arrangement reference in the two-dimensional plane, and to perform alignment control of the stage and the pattern based on the information, that is, based on the actual transfer result.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 shows a schematic configuration of an exposure apparatus 100 according to an embodiment to which the stage control method of the present invention is applied. The exposure apparatus 100 is a so-called step-and-scan scanning exposure apparatus. In this embodiment, an axis parallel to the optical axis AX of the projection optical system PL described later is taken as the Z axis. The X axis corresponds to the first axis of the present invention, the Y axis corresponds to the second axis, and the Z axis corresponds to the third axis.

  The exposure apparatus 100 includes an illumination system 10, a reticle stage RST on which a reticle R as a mask is mounted, a projection optical system PL, a wafer stage WST on which a wafer W as an object (photosensitive object) is mounted, and an alignment detection system AS. And a main control device 20 that performs overall control of the entire apparatus.

  The illumination system 10 includes, for example, a light source, an illuminance uniformizing optical system including an optical integrator, a relay lens, a variable ND filter, a variable field stop (reticle blind or masking) as disclosed in Japanese Patent Laid-Open No. 6-349701. (Also called a blade) and a dichroic mirror or the like (both not shown). As the optical integrator, a fly-eye lens, a rod integrator (an internal reflection type integrator), a diffractive optical element, or the like is used.

In this illumination system 10, on a reticle R on which a circuit pattern or the like is drawn, a slit-shaped illumination area (a rectangular illumination area elongated in the X-axis direction) defined by the reticle blind is illuminated by illumination light (exposure light) IL. Illuminate with almost uniform illumination. Here, as the illumination light IL, far ultraviolet light such as KrF excimer laser light (wavelength 248 nm), ArF excimer laser light (wavelength 193 nm), vacuum ultraviolet light such as F ₂ laser light (wavelength 157 nm), or the like is used. . As the illumination light IL, it is also possible to use an ultraviolet bright line (g-line, i-line, etc.) from an ultra-high pressure mercury lamp.

  On reticle stage RST, reticle R is fixed, for example, by vacuum suction. Reticle stage RST is XY perpendicular to the optical axis of illumination system 10 (corresponding to optical axis AX of projection optical system PL described later) by a reticle stage drive unit (not shown) using a linear motor, a voice coil motor or the like as a drive source. It can be driven minutely in a plane and can be driven at a set scanning speed in a predetermined direction (here, the Y-axis direction which is the horizontal direction in FIG. 1).

  In reticle stage RST, for example, a reflecting surface made of a moving mirror or the like is formed on the −X side surface and the + Y side surface, and the position of reticle stage RST within the stage moving surface irradiates the reflecting surface with laser light. A reticle laser interferometer (hereinafter referred to as a “reticle interferometer”) 16 constantly measures with a resolution of about 0.5 to 1 nm, for example. Here, actually, a reticle X interferometer and a reticle Y interferometer are provided, but in FIG. 1, these are typically shown as a reticle interferometer 16. At least one of the reticle Y interferometer and the reticle X interferometer, for example, the reticle Y interferometer, is a two-axis interferometer having two measurement axes, and the reticle stage RST is based on the measurement value of the reticle Y interferometer. In addition to the Y position, the rotation amount (yawing amount) in the θz direction (rotation direction around the Z axis) can also be measured. Here, the reticle Y interferometer is a two-axis interferometer. Position information (including rotation information such as yawing amount) of reticle stage RST from reticle interferometer 16 is supplied to stage controller 19 and main controller 20 via this. In response to an instruction from main controller 20, stage controller 19 controls driving of reticle stage RST via a reticle stage drive unit (not shown) based on the position information of reticle stage RST, and holds it on reticle stage RST. The position of the reticle R is controlled.

  The projection optical system PL is disposed below the reticle stage RST in FIG. 1, and the direction of the optical axis AX is the Z-axis direction. As the projection optical system PL, a birefringent optical system that is telecentric on both sides and has a predetermined reduction magnification β (for example, 1/5 or 1/4) is used. For this reason, when the illumination area of the reticle R is illuminated by the illumination light IL from the illumination system 10, a reduced image (partial inverted image) of a pattern corresponding to the illumination area in the circuit pattern on the reticle R is projected. It is projected onto a projection area (hereinafter also referred to as “exposure area”) in the field of view of the projection optical system PL conjugate to the illumination area on the wafer W via the optical system PL, and transferred to the resist layer on the surface of the wafer W. The

  The wafer stage WST is disposed on a base (not shown) below the projection optical system PL in FIG. 1, and is driven by a wafer stage drive unit 24 including an actuator and the like provided with a linear motor and an encoder. , Z, θz (rotation direction about the Z axis), θx (rotation direction about the X axis), and θy (rotation direction about the Y axis), and a single stage that can be driven in six directions of freedom. A wafer holder (not shown) is placed on wafer stage WST, and wafer W is fixed on the wafer holder by, for example, vacuum suction.

  In wafer stage WST, reflecting surfaces (reference surfaces) made of moving mirrors are formed on the −X side surface and the + Y side surface, and the position of wafer stage WST is a wafer laser interferometer that irradiates the reflecting surface with laser light. A system (hereinafter referred to as a “wafer interferometer system”) 18 constantly measures, for example, with a resolution of about 0.5 to 1 nm. Actually, as shown in FIG. 2A, in wafer stage WST, movable mirror 27Y extends in the X-axis direction along the side surface on the + Y side, and movable mirror 27X is on the -X side. It extends in the Y-axis direction along the side surface. The wafer interferometer system 18 includes a wafer Y interferometer system 18Y having a length measuring axis parallel to the Y axis and irradiating a length measuring beam to the moving mirror 27Y, and a moving mirror 27X having a length measuring axis parallel to the X axis. And a wafer X interferometer system 18X for irradiating a length measuring beam.

  The wafer Y interferometer system 18Y includes laser interferometers 18YL, 18YR, and 18YP arranged at predetermined intervals along the X-axis direction. Of these, the laser interferometers 18YL and 18YR are double-pass interferometers that irradiate the movable mirror 27Y with the measurement beam once irradiated and reflected on the movable mirror 27Y. The laser interferometer 18YP includes two measurement beams. This is a single-pass interferometer that has a long beam and irradiates each measurement beam only once to two measurement points having the same X position and different Z positions.

As shown in FIG. 2B, the irradiation position YL (hereinafter referred to as “measurement point YL”) of the laser beam interferometer 18YL on the reflecting surface of the movable mirror 27Y and the laser interferometer 18YR. The Z position of the measurement beam LYR and the irradiation position YR (hereinafter referred to as “measurement point YR”) on the reflecting surface of the movable mirror 27Y is the same at Z _A , and the distance between them is the predetermined distance LY1. It is set to be. Further, the measurement points YL and YR are arranged so as to be line symmetric with respect to the optical axis AX of the projection optical system PL. The Z position of the irradiation position YA (hereinafter referred to as measurement point YA) on the reflecting surface of the movable mirror 27Y of the + Z side (upper) length measurement beam LYA of the two length measurement beams of the laser interferometer 18YP. Z _A is the same as the Z position of the measurement points YL and YR of the laser interferometers 18YL and 18YR. Further, an interval in the Z-axis direction between the Z position Z _A and the irradiation position YB (hereinafter referred to as a measurement point YB) of the measurement beam LYB on the −Z side (lower stage) is defined by D, and the measurement point YB The Z position is Z _B. Also, let L be the difference in height between the Z position Z _A and the surface of the wafer W.

  Although not shown in FIG. 2A and the like, the laser interferometers 18YL and 18YR also measure parallel to the Y axis with respect to a reference mirror (not shown) fixed to the + Y side surface of the projection optical system PL. Each beam is irradiated with a long beam and the reflected beam is received. The laser interferometers 18YL and 18YR combine these reflected beams with the received measurement beams LYL and LYR, and detect the Y position of the reflecting surface of the movable mirror 27Y at the measurement points YL and YR from the received light of the combined light. doing. The Y position of the reflecting surface of the movable mirror 27Y at the detected measurement points YL and YR is output to the stage control device 19. The laser interferometer 18YP detects the Y position of the reflecting surface of the movable mirror 27Y at the measurement points YA and YB, and outputs the difference in the Y position between the measurement points YA and YB to the stage controller 19.

  The wafer X interferometer system 18X has the same configuration as the wafer Y interferometer system 18Y. That is, the wafer X interferometer system 18X includes double-pass laser interferometers 18XL and 18XR and a single-pass laser interferometer 18XP. The laser interferometers 18XL and 18XR have two measurement points (measurement points XL and XR) on the movable mirror 27X that have the same Z position and different Y positions by a predetermined interval (referred to as LX1) with respect to the optical axis AX. Are measured by irradiating measurement beams LXL and LXR, respectively, and measuring the X position of the reflecting surface of the movable mirror 27X at the measurement points XL and XR. In addition, the laser interferometer 18XP has a measurement beam LXA for two measurement points (measurement points XA and XB) having the same Y position and different Z positions (which may be the same as D). , LXB are irradiated, the X position of the movable mirror 27X at the measurement points XA, XB is measured, and the difference between the X positions is sent to the stage controller 19. The Z position of the measurement point XA is the same as the Z position of the measurement points XL and XR, and the interval between the measurement point XA and the measurement point XR is LX2.

Although not shown, an optical path changing plate (not shown) including a prism or the like for changing the optical path of the light beam applied to the movable mirrors 27Y and 27X of the laser interferometers 18YL, 18YR, 18XL, and 18XL is provided. Yes. This optical path changing plate is configured to be inserted / retracted on the optical path of each length measuring beam of the laser interferometers 18YL, 18YR, 18XL, and 18XR by an unillustrated driving device under the instruction of the main controller 20. . When the optical path changing plate is inserted in the optical path of these length measuring beams, each length measuring beam is bent in the −Z direction and the −Y direction (or + X direction), for example, as shown in FIG. The Z positions of the measurement points YL, YR, etc. on the reflecting surface of the movable mirror 27Y are the same Z _B as the Z position of the measurement point YB. The detailed configuration of these optical path changing plate and wafer interferometer system 18 is disclosed in, for example, International Publication WO 00/22376 pamphlet, and thus detailed description thereof is omitted.

  The stage controller 19 acquires position information of the wafer stage WST based on the detection result sent from the wafer interferometer system 18. For example, the Y position of wafer stage WST is acquired based on the measured values (for example, the average value thereof) of laser interferometers 18YL and 18YR, and the measured value of laser interferometer 18YP (the position of the reflecting surface at measurement points YA and YB). ) To obtain the pitching amount (rotation about the X axis) θx of wafer stage WST. Further, the X position (for example, average value) of wafer stage WST is calculated based on the measured values of laser interferometers 18XL and 18XR, and the rolling amount of wafer stage WST (around the Y axis) is calculated based on the measured values of laser interferometer 18XP. Rotation) θy is acquired. Further, the yawing amount (θz) is acquired based on the difference between the measurement values of the laser interferometers 18YL and 18YR and the difference between the measurement values of the laser interferometers 18XL and 18XR. That is, stage control device 19 can acquire at least position information of wafer stage WST in the direction of five degrees of freedom based on the measurement value of wafer interferometer system 18.

  FIG. 3 shows a schematic configuration of a control block of the stage control device 19. The stage controller 19 includes a synchronization control unit 80, a wafer stage controller WSC, and a reticle stage controller RSC. In FIG. 3, a wafer stage system Wp is a control block that represents the wafer stage drive unit 24, wafer stage WST, and wafer interferometer system 18 as an integrated control target model, and a reticle stage system Rp is a reticle stage (not shown). This is a control block that expresses the stage drive unit, reticle stage RST, and reticle interferometer 16 as an integrated control model.

The synchronization control unit 80, under instructions from the main controller 20, to the wafer stage controller WSC, and outputs the movement command P _w of the wafer stage WST. The measurement value sent from the wafer interferometer system 18 is input to the wafer stage controller WSC. The wafer stage controller WSC includes the movement command P _w, based on the measurement value sent from the wafer interferometer system 18, for example, performs the feedback control, the wafer stage system Wp (specifically, wafer stage drive section 24 ) Is output.

The measurement value of the wafer interferometer system 18 is also input to the synchronous control unit 80. When performing synchronous control of wafer stage WST and reticle stage RST, synchronization control unit 80 provides a movement command so that reticle stage RST operates following wafer stage WST based on the measurement value of wafer interferometer system 18. create a P _R, and outputs it to the reticle stage controller RSC. At that time, the synchronization control unit 80 corrects the position information of the five degrees of freedom of the wafer stage WST obtained from the measurement value of the wafer interferometer system 18 by a preset correction function, and corrects the corrected wafer stage WST. 5 and outputs a move command P _R with respect to the reticle stage RST based on the position information of the degrees of freedom. This correction function will be described later.

The reticle stage controller RSC includes the movement command P _R, based on the position information obtained from the reticle interferometer 16, for example, performs the feedback control, the reticle stage system Rp (specifically, a reticle stage drive (not shown) Part)).

  As described above, the stage controller 19 operates the wafer stage WST to follow the reticle stage RST when performing synchronous control of both the stages WST and RST. Of course, when there is no need to synchronize both stages WST and RST, for example, in a case other than during scanning exposure, the synchronous control unit 80 constituting the stage control device 19 performs a wafer stage controller under the instruction of the main control device 20. Independent movement commands can be output to the WSC and the reticle stage controller RSC, respectively.

  That is, the stage control device 19 can control both the stages WST and RST according to the instruction from the main control device 20. For example, it is possible to control wafer stage WST so as to be parallel to the XY plane according to an instruction from main controller 20, and measurement points YA and YB (or the reflection surface of movable mirror 27Y (or 27X)) It is also possible to control wafer stage WST so that the difference between the measured values at XA, XB) is always zero.

  Returning to FIG. 1, a reference mark plate FM is fixed in the vicinity of wafer W on wafer stage WST. The surface of the reference mark plate FM is set to substantially the same height as the surface of the wafer W, and at least a pair of reticle alignment reference marks and a reference mark for baseline measurement of the alignment detection system AS are formed on this surface. Has been.

  The alignment detection system AS is an off-axis alignment sensor disposed on the side surface of the projection optical system PL. As this alignment detection system AS, for example, a broadband detection light beam that does not sensitize a resist on a wafer is irradiated onto a target mark, and an image of the target mark formed on a light receiving surface by reflected light from the target mark is not shown. An image processing type FIA (Field Image Alignment) type sensor that captures an image of an index using an imaging device (CCD) or the like and outputs an image pickup signal thereof is used. In addition to the FIA system, a target mark is irradiated with coherent detection light, and scattered light or diffracted light generated from the target mark is detected, or two diffracted lights (for example, of the same order) generated from the target mark. Of course, it is possible to use an alignment sensor for detecting the interference by using them alone or in combination as appropriate. The imaging result of the alignment detection system AS is output to the main controller 20.

  Further, the exposure apparatus 100 of the present embodiment supplies an image forming light beam for forming a plurality of slit images toward the best image forming surface of the projection optical system PL from an oblique direction with respect to the optical axis AX direction (not shown). And an oblique incidence type multi-point focus detection system comprising a light receiving system (not shown) that receives each reflected light beam of the imaging light beam on the surface of the wafer W through a slit. As this multipoint focus detection system, for example, one having the same configuration as that disclosed in Japanese Patent Application Laid-Open No. 6-283403 (corresponding US Pat. No. 5,448,332) is used, and this multipoint focus detection system is used. Is supplied to the main controller 20. In response to an instruction from the main controller 20, the stage controller 19 performs wafer stage WST via the wafer stage drive unit 24 based on position information on the surface near the exposure area of the wafer W from the multipoint focus detection system. Are driven in the Z direction and the tilt direction. Thereby, for example, during scanning exposure, so-called autofocus / leveling control is realized in which the exposure area on the wafer W is adjusted within the depth of focus on the image plane of the projection optical system PL.

  In FIG. 1, the control system is mainly configured by a main control device 20 and a stage control device 19 subordinate thereto. The main controller 20 includes a so-called microcomputer (or workstation) comprising a CPU (central processing unit), a main memory, etc., and corresponds to a processing algorithm at the time of an exposure operation shown by a flowchart described later by this CPU. The overall device is controlled by executing a program or the like. The main controller 20 includes, for example, a storage device including a hard disk, an input device including a pointing device such as a keyboard and a mouse, and a display device such as a CRT display (or a liquid crystal display) (all not shown). Connected externally.

By the way, since the wafer interferometer system 18 performs measurement at each measurement point using the reflecting surfaces of the movable mirrors 27Y and 27X as a reference surface, the reflecting surfaces of the movable mirrors 27Y and 27X are required to have high flatness. However, the movable mirrors 27Y and 27X are required to have a certain length in a direction perpendicular to the measurement axis of the wafer interferometer system 18 according to the movement stroke of the wafer stage WST in the XY plane. As shown exaggeratedly, the reflecting surface has a certain degree of bending. Therefore, information related to the bending state of the reflecting surfaces of the movable mirrors 27Y and 27X is stored in advance, and the measurement value of the wafer interferometer system 18 is corrected so that the control of the wafer stage WST is not affected by the bending. There is a need. In the synchronous control unit 80 of the stage controller 19 shown in FIG. 3, correction information regarding the bending state of the movable mirrors 27Y and 27X is stored, and the measurement value of the wafer interferometer system 18 is corrected using the correction information. , to create a motion command P _R of the reticle stage RST based on the position information of the corrected wafer stage WST.

Further, as described above, the exposure apparatus 100 performs autofocus / leveling control by measurement of a multipoint focus detection system during scanning exposure. When this control is performed, for example, as shown in FIG. 5A, when the surface of the wafer W is inclined by an angle θ with respect to the Z-axis direction, the stage control device 19 moves the wafer stage WST to that angle. The rotation is about the X axis by θ. With this operation, the surface of the wafer W coincides with the image plane of the projection optical system PL within the depth of focus. However, the laser interferometer with the actual Y position of the wafer W and the reflection surface of the movable mirror 27Y as reference planes. A so-called Abbe error occurs at the Y position of wafer stage WST measured by 18YL and 18YR. For example, if the difference between the measured Z position Z _A and the Z position on the surface of the wafer W is L, the Abbe error magnitude ΔY _A is expressed as the following equation.
ΔY _A = L · θ (1)

Thus, when wafer stage WST is rotated about the X axis by angle θ, the output value of laser interferometer 18YP (the difference between the measured value at measurement point YA and the measured value at measurement point YB) is: If the movable mirror 27Y itself is not inclined, it should be a value corresponding to D · θ. Therefore, when the measured value and DA, the Abbe error [Delta] Y _A from the measured value DA can be calculated using the following equation.
ΔY _A = (DA / D) · L (2)

Therefore, this Abbe error ΔY _A is derived from the measured value DA of the laser interferometer 18YP, and the movement command in the Y-axis direction of the reticle stage RST calculated in the synchronization control unit 80 is corrected based on the Abbe error ΔY _A. Regardless of this Abbe error, the relative position between the irradiation region of the reticle R and the exposure region on the wafer W can be controlled with high accuracy. As a result, the pattern formed on the reticle R is accurately transferred to the wafer W without being displaced in the Y-axis direction.

Incidentally, as described above, the movable mirrors 27Y and 27X are also inclined to some extent in the Z-axis direction, and the inclination is not uniform with respect to the extending direction. FIG. 5B shows a case where the angle θ of the surface of the wafer W is 0, but the inclination angle of the movable mirror 27Y with respect to the Z axis is θ. Even in this case, the measured value DA of the laser interferometer 18YP is a value corresponding to D · θ. Therefore, the synchronous control unit 80 of the stage control device 19 calculates the above equation (2) based on this measurement value to obtain the Abbe error, and the wafer stage WST is obtained even though the tilt angle θ of the wafer W is zero. Is misrotated around the X axis by an angle θ and a movement command is generated so as to correct the Y position of the reticle stage RST by L · θ. As a result, the transfer position is ΔY _A It will only shift. Therefore, in this embodiment, in order to avoid such misidentification, the tilt angle of the movable mirror 27Y with respect to the Z axis is also measured in advance, and the relative position control of both stages WST and RST is performed in consideration of this tilt angle.

  Next, the exposure operation in the exposure apparatus 100 having the above configuration will be described with reference to the flowcharts of FIGS. 6 to 8 showing the processing algorithm of the CPU in the main controller 20. In this exposure operation, for the sake of simplicity, it is assumed that scanning and exposure are performed while measuring the bending and tilting of only the movable mirror 27Y and performing stage control in consideration of the bending and tilting. As a premise, it is assumed that correction information has not yet been set in the synchronous control unit 80 of the stage control device 19.

  As shown in FIG. 6, first, a subroutine 601 for moving mirror bending measurement using the wafer interferometer system 18 is performed. In this subroutine 601, first, as shown in FIG. 7, in step 701, the wafer is transferred to the stage controller 19 via the wafer stage driving unit 24 so that the surface of the wafer stage WST is substantially parallel to the XY plane. Instructs to control stage WST.

In the next step 703, the optical path changing plate is driven via a plate driving device (not shown), and is retracted from the optical paths of the length measuring beams LYL and LYR emitted from the laser interferometers 18YL and 18YR. As a result, the measurement beams LYL and LYR are irradiated to the Z position Z _A of the movable mirror 27Y. Subsequently, in step 705, the stage controller 19 is instructed to move the wafer stage WST to the measurement start position while the stage controller 19 controls the wafer stage WST to be parallel to the XY plane. To do. Stage controller 19 moves wafer stage WST to the measurement start position via wafer stage drive unit 24. As the measurement start position, for example, a position shown by a solid line in FIG. 9 is set. This position is the position of wafer stage WST when wafer stage WST is positioned closest to the −X side. At this position, the measurement point YL corresponding to the measurement beam LYL is located near the + X side end of the reflecting surface of the movable mirror 27Y. Hereinafter, the X position of wafer stage WST at this time is X ₀ .

In the next step 707, the measurement values of the laser interferometers 18YL, 18YR, and 18YP are reset with the wafer stage WST positioned at the measurement start position. As a result, the measured values of the laser interferometers 18YL, 18YR, and 18YP are all zero. Next, in step 709, the movable mirror bending (one-dimensional shape) of the movable mirror 27Y along the X-axis direction at the Z position Z _A is measured. Below, this moving mirror bending measuring method will be described in detail.

  First, while the wafer stage WST is moved in the + X direction, for example, at the interval LY1 between the measurement point YL and the measurement point YR via the wafer stage drive unit 24, the measurement value of the wafer interferometer system 18 at each movement destination. Are sequentially acquired via the stage control device 19. That is, every time the movement at the interval LY1 is completed, the X position of the reflecting surface of the movable mirror 27X measured at the measurement points XL and XR by the laser interferometers 18XL and 18XR, and the measurement point YL by the laser interferometers 18YL and 18YR. , YR is obtained via the stage control device 19.

  Here, since wafer stage WST moves in the + X direction, length-measuring beams LXL and LXR emitted from laser interferometers 18XL and 18XR continue to irradiate substantially at the same position on movable mirror 27X. The positions of the measurement points XL and XR on 27X do not change, and the measurement results of these laser interferometers 18XL and 18XR are not affected by the shape of the movable mirror 27X. Therefore, the rotation amount detected from the measured values of laser interferometers 18XL and 18XR can be regarded as the yawing amount of wafer stage WST itself.

On the other hand, since the measurement points YL and YR emitted from the laser interferometers 18YL and 18YR substantially move on the movable mirror 27Y, the measurement results of these interferometers are the shape of the reflecting surface of the movable mirror 27Y. To be affected. When this influence is analyzed, the difference between the measurement values at the measurement points YL and YR of the laser interferometers 18YL and 18YR is the local shape of the reflecting surface of the movable mirror 27Y at the Z position Z _A and the yaw amount θz of the wafer stage WST. It can be regarded as the sum. Therefore, a value (θy−θx) obtained by subtracting the rotation amount θx obtained by the measurement value measured by the laser interferometers 18XL and 18XR from the rotation amount θy obtained by the measurement value measured by the laser interferometers 18YL and 18YR. A value obtained by multiplying the interval LY1 between the measurement points YL and YR can be obtained as the local tilt amount dY of the movable mirror 27Y. Main controller 20 obtains a local tilt amount dY when wafer stage WST is at each X position X _i (i = 0, 1, 2, 3,...). The X position X _i of wafer stage WST when this tilt amount dY is obtained can be obtained from the average of the measured values of laser interferometers 18XL and 18XR.

That is, in this step 709, the local inclination (dY (dY ()) of each movable mirror 27Y at each X position X _n (n = 1, 2, 3,...) With respect to the X-axis direction of the movable mirror 27Y at the Z position Z _A. X _n , Z _A )) is measured and stored in a storage device (not shown).

  In the next step 711, it is determined whether or not the measurement of the bending of the upper and lower movable mirrors 27Y has been completed. If this determination is affirmed, the process proceeds to step 715, and if not, the process proceeds to step 713. Here, since the measurement of the bending of the movable mirror 27Y in the lower stage has not been completed, the determination is denied and the routine proceeds to step 713.

In the next step 713, the optical path changing plate is inserted into the optical path of the measuring beams LYL and LYR via a plate driving device (not shown), and the Z positions of the measuring points YL and YR are changed to Z _B. After step 713 is completed, the process returns to step 705.

Thereafter, step 705 (moves to the measurement start position) → step 707 (reset of the wafer interferometer system 18) → step 709 (shape measurement of the movable mirror 27Y) → step 711 (determination) is executed again, and the lower stage, that is, the Z position local slope dY (X _n, Z _B) of the moving mirror 27Y in the X-axis direction of the interferometer 27Y in the Z _B is calculated and is stored in a storage device (not shown).

If the determination in step 711 is affirmed, the process proceeds to step 715. In step 715, the one-dimensional shape data DY (X _n , Z _A ) of the movable mirror 27Y relating to the Z position Z _A is generated using the following equation.

生成されたＸ位置Ｘ_nに対応する移動鏡２７Ｙの１次元形状データＤＹ（Ｘ_n，Ｚ_A）は、不図示の記憶装置に格納される。同様に、Ｚ位置Ｚ_Bに関する移動鏡２７Ｙの１次元形状データＤＹ（Ｘ_n，Ｚ_B）を、上記式（３）と同様の演算により生成して、不図示の記憶装置に格納する。

The one-dimensional shape data DY (X _n , Z _A ) of the movable mirror 27Y corresponding to the generated X position X _n is stored in a storage device (not shown). Similarly, the one-dimensional shape data DY (X _n , Z _B ) of the movable mirror 27Y related to the Z position Z _{B is} generated by the same calculation as the above equation (3) and stored in a storage device (not shown).

In the next step 717, the one-dimensional shape data DY (X _n , Z _A ) and DY (X _n , Z _B ) stored in a storage device (not shown) are converted into XY using a curve interpolation method such as a spline curve. By smoothly interpolating in the plane, the one-dimensional shape functions DY (X, Z _A ) and DY (X, Z _B ) of the movable mirror 27Y in the X-axis direction are generated. Information about the calculated function, such as the coefficient of the function, is stored in a storage device (not shown). Here, if the obtained function DY (X, Z _A ) is as shown in the following equation, the coefficient a _j in the equation is stored.

FIG. 10 shows an example of the one-dimensional shape functions DY (X, Z _A ) and DY (X, Z _B ) thus obtained. Since the difference between the one-dimensional shape functions DY (X, Z _A ) and DY (X, Z _B ) represents a tilt component in the Z-axis direction in the movable mirror 27Y, this tilt component is used in stage control described later. Considering this, the Abbe error is corrected based on the measurement value of the laser interferometer 18YP.

By the way, both the one-dimensional shape functions DY (X, Z _A ) and DY (X, Z _B ) are measured values of the wafer interferometer 18 that are reset when the wafer stage WST is at the measurement start position in step 709. Therefore, the difference between the one-dimensional shape functions DY (X, Z _A ) and DY (X, Z _B ) at the measurement start position is related to the tilt component of the movable mirror 27Y at that position. It will be zero. Due to the deviation caused by the reset of the interferometer at the measurement start position, the difference between DY (X, Z _A ) and DY (X, Z _B ) and the actual tilt component of the movable mirror 27Y An offset occurs.

Therefore, in the next step 719, this offset component is calculated. Here, the wafer stage WST is measured in the same manner as in step 709 while controlling the wafer stage WST so that the measurement value of the laser interferometer 18YP, that is, the difference between the measurement values at the measurement points YA and YB becomes zero. The pitching amount θx of the wafer stage WST is acquired from information obtained from an encoder or the like attached to the actuator constituting the wafer stage driving unit 24 and measuring the driving amount of the actuator by moving in the + X direction from the starting position. Then, the change in the rotation amount of wafer stage WST based on the difference between DY (X, Z _A ) and DY (X, Z _B ) obtained in the moving mirror bending measurement in step 709, and the current wafer stage WST. The difference from the change in the pitching amount θx is obtained. This difference is caused by whether or not the control related to the pitching amount θx has been performed on the wafer stage WST, and can be regarded as corresponding to the tilt component of the movable mirror 27Y at the measurement start position. Accordingly, in the present embodiment, this difference is calculated as an offset component between the correction function DY (X, Z _A ) and the correction function DY (X, Z _B ), and this is calculated as the correction function DY (X, Z _B). ).

Instead of performing step 719, prior to the step 701, a plurality of reference marks relating XY2 dimensional directions on the wafer stage WST to load the tool wafer is formed, at the time of measurement at the Z position Z _A, the position of the reference mark on the tool wafer when the wafer stage WST is the measurement start position, when the measurement of the Z position Z _B, and the position of the reference mark on the tool wafer when the wafer stage WST is the measurement start position The offset component may be detected from an alignment detection system AS or the like, and the offset component may be obtained from the amount of misalignment of the reference mark when measuring the Z position Z _A and when measuring the Z position Z _B. Such an offset component measurement method is disclosed in the pamphlet of International Publication No. WO 00/22376, and thus detailed description thereof is omitted.

Returning to FIG. 7, in the next step 721, a function obtained by adding the offset component detected in step 719 to the difference between the functions DY (X, Z _A ) and DY (X, Z _B ) A function for correcting a difference between measurement values at the measurement points YA and YB, that is, a pitching correction function P (X) is created.

In the next step 723, information (for example, information on the one-dimensional shape function DY (X, Z _A ) and the pitching correction function P (X) at the Z position Z _A is given to the synchronous control unit 80 constituting the stage controller 19. The coefficients of those functions are set as device parameters. After this setting is completed, the synchronization control unit 80 corrects the difference between the measured values of the laser interferometers 18YL and 18YR with the one-dimensional shape function DY (X, Z _A ) and also measures the measured values of the laser interferometer 18YP. That is, the difference between the measured value of the position of the reflecting surface of the movable mirror 27Y at the measurement point YA and the measured value of the position of the reflecting surface of the movable mirror 27Y at the measurement point YB is used for the pitching correction function P (X). Will be corrected. Hereinafter, a correction method using this pitching function will be described.

First, let X be the average value of the measured values of the current laser interferometers 18XL and 18XR, that is, the X position of wafer stage WST. In this case, the X position X ′ of the measurement points YA and YB is obtained by the following equation.
X ′ = X−LY1 / 2−LY2 (5)
Here, in the above formula (5), the value of X ′ obtained when X ₀ is substituted for X, that is, the X position of the measurement points YA and YB when the laser interferometer 18YP is reset is X ′ ₀ .

Then, the optical path difference L ′ generated by the inclination of the movable mirror 27Y in the Z-axis direction can be obtained using the following equation.
L ′ = {DY (X ′, Z _A ) −DY (X ′, Z _B )
_{- (DY (X '0,} Z A) -DY (X' 0, Z B))} ... (6)

The optical path difference DA ′ of the measurement beam of the wafer stage WST corresponding to the pitching amount θx of the wafer stage WST can be obtained using the following equation, where DA is the actual measurement value of the laser interferometer 18YP.
DA ′ = DA−L ′ (7)

Therefore, in the synchronous control unit 80 constituting the stage controller 19, first, X ′ is calculated from the X position of the wafer stage WST using the above equation (5), and further, from this X ′, the above equation (6). L ′ is calculated using the above and DA ′ is calculated from the L ′ and the actual measurement value DA of the laser interferometer 18YP using the above equation (7). Then, the synchronization control unit 80 obtains an Abbe error [Delta] Y _A the calculated DA 'is substituted into the following equation, in order to cancel the Abbe error [Delta] Y _A, a position command regarding the Y-axis direction with respect to the reticle stage RST [Delta] Y _A Will only correct.
ΔY _A = (DA ′ / D) · L (8)

Returning to FIG. 7, after the process of step 721 is completed, the subroutine 601 is terminated, and the process proceeds to a subroutine 603 for measuring the moving mirror bending by printing in FIG. In this subroutine 603, as shown in FIG. 8, first, in step 801, a measurement reticle _RT for printing measurement is loaded onto the reticle stage RST, and in step 803, the wafer is replaced. Thereby, wafer W is loaded onto wafer stage WST. When a tool wafer is held on wafer stage WST, the tool wafer on wafer stage WST is unloaded using a wafer unloader (not shown), and wafer stage WST is used using a wafer loader (not shown). An unexposed wafer is loaded on top.

FIG. 11A shows an example of a measurement reticle _RT . FIG. 11A shows a state when the pattern area PA is viewed from the −Z side in a state where the measurement reticle _RT is held on the reticle stage RST. In FIG. 11A, the axis on the reticle passing through the center of the reticle, that is, the reticle center RC, corresponding to the X axis, is indicated as X _R, and the axis on the reticle corresponding to the Y axis is indicated as Y _R. . As shown in FIG. 11A, the same evaluation marks A ₁ , A at the same intervals in the Y _R axis direction are provided at the ends in the + X _R direction in the pattern area PA of the measurement reticle _{RT. 2} and A ₃ are formed, and the same evaluation marks B ₁ , B ₂ and B ₃ are formed at equal intervals in the X _R axis direction at the end in the + Y _R direction, and in the −X _R direction The same evaluation marks C ₁ , C ₂ , C ₃ are formed at equal intervals in the Y _R axis direction at the end portions of the Y _R axis, and at equal intervals in the X _R axis direction at the end portions in the −Y _R direction. Thus, the same evaluation marks D ₁ , D ₂ , D ₃ are formed.

The evaluation marks A ₁ , A ₂ , A ₃ and the evaluation marks C ₁ , C ₂ , C ₃ are formed at substantially line symmetrical positions with respect to the Y _R axis, and the evaluation marks B ₁ , B ₂ , the B ₃ and marks for evaluation _{D 1, D 2, D 3} , and is formed substantially line symmetrical positions with respect to X _R-axis.

The evaluation marks A _{1 to} A ₃ and C _{1 to} C ₃ are dot pattern rows arranged at a predetermined pitch, for example, in the X-axis direction, like the evaluation mark A ₁ shown as a representative in FIG. , and the evaluation mark a ₁ to 90 ° evaluation mark of the rotated form _{B 1 ~B 3, D 1 ~D} 3 is FIG. 11 (C) as evaluation mark B ₁ representatively shown in For example, it is a dot pattern array arranged at a predetermined pitch in the Y-axis direction. The evaluation mark A ₁ or the like may be formed as an opening pattern in the light shielding film or may be formed from the light shielding film in the transmission part. In any case, when the images of the evaluation marks A ₁ , B ₁ ,... Are exposed on the wafer W coated with the photoresist and developed, a resist pattern image (evaluation consisting of uneven dot pattern rows) is evaluated. Mark image). However, the present invention is not limited to this, and the evaluation marks A _{1 to} A ₃ , B _{1 to} B ₃ , C _{1 to} C ₃ , and D _{1 to} D ₃ may be configured by line patterns. Further, it is necessary to select whether the photoresist on the wafer W is a positive type or a negative type depending on whether or not each evaluation mark is a light shielding film. Further, two cross-shaped alignment marks (not shown) for reticle alignment are formed on the measurement reticle _{RT so as} to oppose each other in the vicinity of the outer periphery thereof.

Returning to FIG. 8, in the next step 805, the reticle pattern image of m rows and n columns is transferred onto the wafer W so that the ends in the X-axis direction and the Y-axis direction between adjacent transfer images overlap each other. Specifically, the wafer stage WST is moved at a predetermined pitch by stepping driving in the X-axis direction by a predetermined interval, while the end portion in the X-axis direction (this is the column direction) between adjacent images. In order to overlap each other, n reticle pattern images, which are reticle pattern images of the measurement reticle _RT , are sequentially transferred and formed by scanning exposure. Hereinafter, this reticle pattern image is referred to as a shot area, and is designated as shot areas S (1,1), S (1,2),..., S (1, n), respectively. Then, after moving wafer stage WST by a predetermined pitch in the Y-axis direction (this is the row direction), wafer stage WST is moved again by a predetermined pitch along the X-axis, and the X between adjacent images is changed. The measurement reticle _RT is arranged so that the axial ends thereof overlap each other and each image has a shot region S (1, n) corresponding to the same row and the Y axial ends overlap each other. An image is formed by sequentially transferring n shot areas in the X-axis direction (column direction) by scanning exposure. The shot areas are S (2,1), S (2,2),..., S (2, n), respectively. Similarly, n shot regions are sequentially transferred and formed along the X-axis direction (column direction) for the third row, the fourth row,. In this manner, m rows and n columns of shot regions are transferred and formed on the wafer W in a matrix.

FIG. 12 representatively shows shot regions S (1,1), S (1,2), and S (1,3) as part of the shot region of m rows and n columns. Note that the interval in the X-axis direction between the center of the shot region S (m, n) and the center of the adjacent shot region is defined to be smaller than the interval LY1 between the measurement points YL and YR. At this time, the synchronization control unit 80 of the stage controller 19 corrects the measurement values of the laser interferometers 18YL and YR based on the one-dimensional shape function DY (X, Z _A ), and the pitching correction function P ( It is assumed that the measured value of the laser interferometer 18YP is corrected by X ′).

  In the next step 807, the wafer is unloaded from wafer stage WST by a wafer unloader (not shown). The unloaded wafer is transferred to a coater / developer (not shown) and developed. When this development is completed, the process proceeds to the next step 809 where the wafer is loaded again onto wafer stage WST using a wafer loader (not shown). At this time, it is assumed that the wafer is mounted in substantially the same manner as it was previously mounted on wafer stage WST.

In the next step 811, the misalignment between the pattern images A _{1 to} A ₃ and the pattern images C _{1 to} C ₃ in the adjacent shot regions in the shot region of m rows and n columns using the alignment detection system AS. Measure the amount. For example, FIG. 12 shows the amount of positional deviation in the Y-axis direction between the pattern images C _{1 to} C _{3 in the} shot area S (1,1) and the pattern images A _{1 to} A _{3 in} the shot area S (1,2). BY _{111 to} BY ₁₁₃ , the pattern images C _{1 to} C ₃ in the shot area S (1,2), and the pattern displacement amounts A _{1 to} A _{3 in} the shot area S (1,3) in the Y-axis direction BY _{121 to} BY ₁₂₃ are shown. In this step 811, wafer stage WST is driven as necessary, and shots including positional deviation amounts BY _{111 to} BY ₁₁₃ and positional deviation amounts BY _{121 to} BY ₁₂₃ shown in FIG. 12 using alignment detection system AS. Y-axis direction displacement amounts BY _{ij1 to} BY _between the pattern images C _{1 to} C _{3 in the} region S (i, j) and the pattern images A _{1 to} A _{3 in} the adjacent shot region S (i, j + 1) _Measure all _ij3 . The measurement result is sent from the alignment detection system AS to the main controller 20. These measurement results are stored in a storage device (not shown).

In the next step 813, an average value of the positional deviation amounts BY _ijk corresponding to the shot area S (i, j) is calculated using the following equation.

ここで、ＢＹ_ijは、ショット領域（ｉ，ｊ）での位置ずれ量ＢＹ_ijkの平均値である。次のステップ８１５では、平均値ＢＹ_ijのｊ列（ｊ＝１〜ｎ−１）での平均値ＢＹ_jを次式を用いてそれぞれ算出する（ｉ＝１〜ｍ−１）。

Here, BY _ij is an average value of the positional deviation amounts BY _{ijk in} the shot area (i, j). In the next step 815, the average value BY _j of the average value BY _ij column j (j = 1~n-1) respectively calculated using the following equation (i = 1~m-1).

次のステップ８１７では、列毎（ｊ行、ｊ＝１〜ｎ−１）の平均値ＢＹ_jから、そのＢＹ_jの平均値を、次式を用いて差し引いた値ＢＹ’_jを求める。

In the next step 817, the average value BY _j for each column (j row, j = 1~n-1), the average value of the BY _j, determining the value BY _'j minus using the following equation.

次のステップ８１９では、次式を用いてＢＹ’_jを列毎に積算し、ｊ列におけるＹ軸方向の位置ずれ量ＢＹ’_jの積算値ＢＹ''_jを作成する。

In the next step 819, using the following equation 'integrates the _j for each column, Y-axis direction positional deviation amount BY in column j' BY creating a cumulative value BY '' _j of _j.

次のステップ８２１では、両端、すなわち第１列目及び最終列目でのＹ軸方向の位置ずれ量の積算値がともに０となるように、次式を用いて、積算値ＢＹ''_jから傾斜成分（一次成分）を差し引いて、最終的な位置ずれ量の積算値ＢＹ'''_jを求める。

In the next step 821, the integrated value BY ″ _j is calculated using the following equation so that the integrated value of the positional deviation amount in the Y-axis direction at both ends, that is, the first column and the last column is both 0. By subtracting the slope component (primary component), the final integrated value BY ′ ″ _j of the positional deviation amount is obtained.

ここで、この積算値ＢＹ'''_jは、ｊ列のショット領域の中心のＸ座標（これをＸ_jと置く）における位置ずれ量に対応しているので、積算値ＢＹ'''_jを、積算値ＢＹ'''（Ｘ_j）とおくことができる。この積算値ＢＹ'''（Ｘ_j）が、本発明の配列情報に対応する。

Here, since this integrated value BY ′ ″ _j corresponds to the amount of displacement in the X coordinate of the center of the j-th shot area (which is referred to as X _j ), the integrated value BY ′ ″ _j is , Integrated value BY ′ ″ (X _j ). This integrated value BY ′ ″ (X _j ) corresponds to the array information of the present invention.

In the next step 823, the center X coordinate _Xj of the shot is measured by the laser interferometer 18YP using the following equation based on the interval LY1 between the measurement points LY and LR and the interval LY2 between the measurement point YA and the measurement point LR. The position coordinates X ′ _j of the points YA and YB are converted.
X ′ _j = X _j -LY1 / 2-LY2 (14)

In the next step 825, the correction function BY (X ′) related to the X-axis direction is obtained by performing curve interpolation of BY ′ ″ (X ′ _j ) in the XY plane using, for example, a curve interpolation method such as spline interpolation. Create This correction function BY (X ′) corresponds to the second correction information of the present invention.

In the next step 827, information regarding the created correction function BY (X ′) is set in the synchronous control unit 80 of the stage control device 19. Thereafter, the synchronous control unit 80 determines the bending component L ′ of the movable mirror 27Y in the X-axis direction from the measurement value from the wafer interferometer 18YP, that is, the difference DA of the positional information of the movable mirror 27Y at the measurement points YA and YB. Then, the X position of wafer stage WST, that is, the average value of the measured values of laser interferometers 18XL and 18XR is substituted for X in the above expression (14) from the subtraction result. X ′ is obtained, further corrected with a value obtained when the X ′ is substituted into the correction function BY, and an Abbe error ΔY _A is obtained based on the corrected difference. That is, in the synchronous control unit 80 of the stage control device 19, the Abbe error ΔY _A is calculated using the following equation.
ΔY _A = ((DA−L′−BY (X ′)) / D) · L (15)
Thereafter, during the scanning exposure, the synchronization control unit 80 corrects the movement command of the reticle stage RST in the Y-axis direction by the Abbe error obtained by the above equation (15).

  After step 827 is completed, the process of subroutine 603 is terminated, and the process proceeds to step 605 in FIG.

In step 605, the reticle on reticle stage RST is exchanged. At this point, since the measurement reticle R _T on the reticle stage RST is held, a measurement reticle R _T Unload by a reticle unloader (not shown) loads the reticle R by a reticle loader (not shown) . In step 607, a preparatory work such as so-called reticle alignment and baseline measurement is performed using the reference mark plate FM or the like.

  In the next step 609, the wafer on wafer stage WST is exchanged. As a result, the measurement wafer held on wafer stage WST is unloaded by a wafer unloader (not shown), and wafer W is loaded on wafer stage WST by a wafer loader (not shown). This wafer W is assumed to be a wafer in which one or more shot areas are already formed.

  Then, in step 611, wafer alignment is performed for obtaining the arrangement coordinates of each shot area on the wafer W on the coordinate system of the wafer stage. In such wafer alignment, as disclosed in, for example, Japanese Patent Application Laid-Open No. 61-44429 and US Pat. No. 4,780,617 corresponding thereto, the wafer W is detected using the alignment detection system AS shown in FIG. The coordinate position of a wafer mark (not shown) in a predetermined number of shot areas (sample shots) selected from above is detected, and all the results on the wafer W are detected by an EGA (Enhanced Global Alignment) method that statistically processes the measurement results. The array coordinates relating to the shot area are calculated. The coordinate position of the wafer mark is detected based on the measurement values obtained by the laser interferometers 18XL, 18XR, 18YL, and 18YR, and the measurement values obtained by the laser interferometer 18YP and the laser interferometer 18XP.

In the next step 613, based on the relationship between the arrangement coordinate of each shot area on the wafer W, the base line, the coordinate system of the wafer stage WST, and the coordinate system of the reticle stage RST in consideration of the correction function, The exposure target shot area on W is positioned at the scanning start position, the reticle R is positioned at the corresponding position, and the reticle R and the wafer W are synchronously moved while irradiating the exposure light IL, thereby scanning. Perform exposure operation. That is, during scanning exposure, the synchronization control unit 80 of the stage controller 19 uses the wafer stage WST as the correction function DY (X, Z _A ) using the measurement values obtained by the laser interferometers 18XL, 18XR, 18YL, and 18YR. after having corrected based, and generates a movement command P _R with respect to the reticle stage RST.

  Further, during scanning exposure, the Z position, pitching amount and rolling amount of the exposure area on the wafer W are detected by a multi-point focus detection system (not shown), and based on the detection result, the stage controller 19 Wafer stage WST is driven via wafer stage drive unit 24 so that the exposure area on wafer W matches the image plane of projection optical system PL within the range of the depth of focus. Therefore, the synchronous control unit 80 calculates the Abbe error by calculating the above equation (14) and the like based on the measured value by the laser interferometer 18YP in order to correct the Abbe error caused by the tilt of the wafer stage WST caused by this control. Then, the movement command in the Y-axis direction is corrected by the Abbe error. In this way, the relative position of wafer stage WST and reticle stage RST can be controlled regardless of the bending and tilting of movable mirror 27Y, and the distortion of the arrangement of shot areas formed on wafer W can be controlled. Is corrected.

  In the next step 615, the wafer W is unloaded. After step 615 ends, the exposure operation ends.

In the present embodiment, the number of times of moving mirror bending measurement at each Z position (Z _A , Z _B ) using the interferometer in the subroutine 601 and the shot arrangement of the shot area S (m, n) for the wafer in the subroutine 603 are as follows. Although the number of times of formation is one each, this may be performed a plurality of times. In this way, the influence of measurement errors can be reduced. In this case, for the moving mirror bending measurement using the interferometer, since the measurement time per time is relatively short, it is easy to increase the number of times of measurement. Since the measurement time becomes longer, if the number of times of measurement is increased, the overall measurement time becomes longer accordingly.

  In addition, the arithmetic expressions in the present embodiment, that is, the above expressions (1) to (15) can be variously modified, and the replacement of the operation order is possible as long as no contradiction arises. Such an arithmetic expression can be omitted.

  6 to 8, only the process for generating the correction function for correcting the measurement value of the wafer Y interferometer system 18Y for correcting the error due to the bending and tilting of the moving mirror 27Y has been described. A correction function for correcting the measurement value of the wafer X interferometer system 18X (laser interferometers 18XL, 18XR, 18XP) due to 27X bending and tilting can also be generated by performing the same processing as in the subroutines 601 and 603. it can. If the information (coefficients, etc.) of the generated correction function is set as an apparatus parameter in the synchronous control unit 80, the X-axis direction of the wafer stage WST and the reticle stage RST, etc. regardless of the bending component and the inclination component of the movable mirror 27X. It is possible to perform scanning exposure while accurately controlling the relative position of.

  As is apparent from the above description, in exposure apparatus 100 of the present embodiment, reticle stage RST corresponds to the mask stage, and wafer stage WST corresponds to the object stage. Also, the wafer interferometer system 18 corresponds to a measuring device, of which the laser interferometers 18YL and 18YR correspond to the first measuring device (first device), and the laser interferometer 18YP corresponds to the second measuring device (second device). Device). The main control device 20 corresponds to a first generation device and a second generation device.

  That is, the function of the first generating device is realized by the processing of the subroutine 601 (FIGS. 6 and 7) performed by the CPU of the main control device 20, and the processing of the second generating device is performed by the processing of the subroutine 603 (FIGS. 6 and 8). The function is realized. Further, step 709 (FIG. 7) at the time of measuring the upper movable mirror curve corresponds to the first sub process, and step 709 (FIG. 7) at the time of measuring the lower movable mirror curve corresponds to the third sub process. Steps 715 to 721 correspond to the second sub-process. In the present embodiment, the function of the main control device 20 is realized by one CPU, but may be realized by a plurality of CPUs.

As described above in detail, according to the stage control method of the present embodiment, in subroutine 601, while moving wafer stage WST along the X-axis direction, reference plane (moving mirror 27 </ b> Y) of wafer stage WST in the Y-axis direction is moved. Position information of the reflecting surface of the wafer stage is sequentially measured using the wafer interferometer system 18, and as a result of the measurement, a correction function DY (X, Z _A ) and a correction function P (X ′) of the position information of the wafer stage WST are generated. To do. Then, in the subroutine 603, the reticle pattern of the measurement reticle _RT is transferred, and a correction function BY (as a residual of the moving mirror bending of the moving mirror 27Y based on the transfer result of the reticle pattern (shot region arrangement information) ( X ′). Further, in step 613, scanning exposure is performed while controlling wafer stage WST based on these correction functions DY (X, Z _A ), P (X ′), BY (X ′)). In this way, since the relative position control of both stages WST and RST is performed based on both the shape information of the reflecting surface of the movable mirror 27Y and the pattern arrangement information on the transferred wafer, the pattern arrangement is transferred. The measurement time can be shortened rather than performing multiple times to obtain the moving mirror bend, and it is also possible to measure the moving mirror bend that was not obtained only by measuring the moving mirror bend with an interferometer. Therefore, highly accurate stage control can be realized.

  One of the components that are difficult to measure unless the actual exposure result is the influence of tilt components such as the movable mirror 27Y that cause the Abbe error to be misidentified. This is a factor of measurement error due to the occurrence of Abbe error accompanying the autofocus / leveling control during scanning exposure. In the exposure apparatus 100 of this embodiment, the position of the reticle stage RST is adjusted. This is because Abbe error is absorbed. For example, in the interferometer measurement of the subroutine 601 (that is, the measurement of only the operation on the wafer stage side), even if the tilt component such as the movable mirror 27Y can be measured with high accuracy, it is affected by other errors. End up. Therefore, in order to accurately form the shot region array with high accuracy, it is desirable to add correction based on the actual exposure result as in this embodiment.

  Further, since the interval between the shot areas to be transferred and formed in the subroutine 603 is defined to be smaller than the interval LY1 between the measurement points YL and YR, the movable mirror that can be detected by measuring the movable mirror bending from the actual exposure result. The spatial frequency of bending can be improved.

  Moreover, in this embodiment, since the moving mirror bending is calculated | required by interferometer measurement, the bending of the reflective surface whole area | region of a moving mirror can be measured directly and accurately. That is, as in the method disclosed in JP-A-8-227839, it is possible to accurately measure the moving mirror curvature without estimating the moving mirror bending that cannot be directly measured from the exposure result.

  In the exposure apparatus 100 of the present embodiment, the position of the reflecting surface of the moving mirror 27Y in the Y-axis direction is determined by two measurement points YL and YR that are separated by a predetermined interval LY1 in the X-axis direction along the reflecting surface of the moving mirror 27Y. Laser interferometers 18YL and 18YR for measuring are provided. In the subroutine 601, in step 709, the difference in the Y-axis direction of the position of the reflecting surface of the movable mirror 27 </ b> Y between the measurement points YL and YR while moving the wafer stage WST along the X-axis direction at a predetermined interval LY <b> 1. Are sequentially measured, and in Steps 715 to 721, based on the measurement result in Step 709, the bending of the moving mirror in the X-axis direction of the reflecting surface of the moving mirror 27Y is detected. In this way, the bending of the reflecting surface of the movable mirror 27Y can be easily detected by the measurement of the wafer Y interferometer system 18Y itself that constitutes the exposure apparatus 100.

  Further, in the present embodiment, in the measurement of the bending of the movable mirror 27Y performed in the subroutine 601, the wafer stage WST is sequentially moved at the predetermined interval LY1 in the X-axis direction, and the measurement values of the laser interferometers 18YL and 18YR each time. However, the present invention is not limited to this. For example, the wafer stage WST is moved in the X-axis direction at a constant speed, and the Y position of the reflecting surface of the movable mirror 27Y is acquired by predetermined sampling using either one of the laser interferometers 18YL and 18YP. You may do it.

  Further, this measurement is not limited to that by the wafer Y interferometer system 18Y. For example, the moving mirror bending in the X-axis direction of the moving mirror 27Y may be obtained by another interferometer system different from the wafer Y interferometer system 18Y. For example, a Fizeau interferometer that can measure the bending of the movable mirror 27Y in the X-axis direction at a time may be used. In this case, it is expected that the measurement error between the wafer interferometer system 18 and the interferometer system for moving mirror bending measurement will be larger than that in the present embodiment. Therefore, a correction function is generated from actual printing. The effect of the present invention will be more exhibited.

In the present embodiment, the subroutine 601 further includes a laser interferometer 18YP that measures the Y position of the reflecting surface of the movable mirror 27Y at two measurement points YA and YB separated by a predetermined distance D along the Z axis. In step 713, the Z positions of the two measurement points YL and YR are shifted to the −Z side by a predetermined distance D using the optical path changing plate to set Z _B, and then steps 705 to 709 are performed again. Based on the measurement result in the second step 709 and the measurement result in the second step 709, a one-dimensional shape in the X-axis direction of the reflecting surface of the movable mirror 27Y is detected. In this way, the tilt component in the Z-axis direction of the reflecting surface of the moving mirror 27Y is obtained from the one-dimensional shape of the reflecting surface of the moving mirror 27Y in the upper stage and the one-dimensional shape of the reflecting surface of the moving mirror 27Y in the lower stage. Can be easily measured.

But the method of calculating | requiring the inclination component regarding the Z-axis direction of the movable mirror 27Y is not restricted to this. For example, whenever the wafer stage WST is moved by a predetermined interval LY1, the optical path changing plate is inserted / retracted, and the Z positions of the measurement points LY, LR of the laser interferometers 18YL, 18YR with respect to the same X position are Z _A And both local slopes when Z _B may be obtained together. If the Fizeau interferometer described above is used, it is possible to measure the inclination as well as the bending in the X-axis direction.

  In the present embodiment, the wafer Y interferometer system 18Y is configured from the laser interferometers 18YL, 18YR, and 18YP, but is not limited thereto. For example, the laser interferometer 18YP may not be provided. In this case, the correction information (correction function BY (X ′)) generated in the subroutine 603 may be used as a correction function for correcting the measurement values of the laser interferometers 18YL and 18YR. Further, in addition to laser interferometers 18YL and 18YR, the Y position of wafer stage WST may be detected by a new laser interferometer. In this case, the average value of the measurement values of three or more interferometers becomes the Y position of wafer stage WST, and the yawing amount of wafer stage WST is obtained, for example, by least square approximation of three or more measurement values. do it. This determination method is the same even when the laser interferometer 18YP includes three length measuring beams. The possibility of deformation of these configurations is the same for the wafer X interferometer system 18X.

  In the present embodiment, the correction function BY (X ′) as the second correction information based on the arrangement information obtained in the subroutine 603 is used for correcting the measurement value of the laser interferometer 18YP. Of course, the laser interferometers 18YL and 18YR may be used for correcting the measurement values.

In the present embodiment, the measurement reticle _RT shown in FIG. 11A is used, but the present invention is not limited to this. For example, a reticle on which only patterns A ₂ , B ₂ , C ₂ , and D ₂ are formed may be used. Each pattern may be a line and space pattern or a box mark.

  In the present embodiment, in step 717 and step 825, a continuous correction function regarding the Y-axis direction obtained by the curve interpolation method is detected as the first and second correction information. In this way, it is possible to detect the bending of the reflecting surface of the movable mirror 27Y corresponding to not only the discrete X positions but also the continuous X positions, and a continuous and smooth correction is realized using the correction function. be able to. In addition, as a curve employ | adopted at the time of curve interpolation, all curves, such as a Bezier curve other than the spline curve mentioned above, are employable.

  However, the interpolation method is not limited to curve interpolation, and may be linear interpolation. Further, a correction map generated by mapping the moving mirror bending data at the X position X obtained in the subroutine 601 and the subroutine 603 with respect to the X-axis direction without generating a correction function is stored in a storage device (not shown). In addition, the measurement value may be corrected using the correction map. Even in this case, when the X position of wafer stage WST is not the X position on the correction map, the interpolation value of the correction map value at the X position in the vicinity on the correction map may be used as the correction amount of the measurement value. it can.

In the exposure apparatus 100 of the present embodiment, the position of the reticle stage RST is adjusted when correcting the Abbe error during the scanning exposure in Step 613. This is also because the relative position between the reticle R and the wafer W can be corrected in this manner, and the positional deviation due to the Abbe error of the shot area transferred onto the wafer W can be reduced. Needless to say, the position information of the wafer stage WST may be directly corrected. Further, the correction function DY (X, Z _A ) related to the X-axis direction of the movable mirror 27Y is used to correct the positional information of the wafer stage WST, and the correction functions P (X ′) and BY (X used for correcting the Abbe error. ') May be used for correcting the movement command of the reticle stage RST.

  In the exposure operation of the present embodiment, the relative position between both stages WST and RST is controlled using the correction function created as described above, while the wafer W on the wafer stage WST is moved on the reticle stage RST. Since the pattern formed on the reticle R is transferred, highly accurate exposure can be realized.

  However, the subroutines 601 and 603 need not be performed prior to the exposure operation. When the exposure apparatus 100 is started up, the subroutines 601 and 603 may be performed when the wafer holder is replaced and when the stage is replaced.

  Further, in the exposure apparatus 100 of the present embodiment, the laser interferometers 18YL and 18YR are of a double-pass method that irradiates measurement beams LYL and LYR having a measurement axis parallel to the Y-axis direction with respect to the reflecting surface of the movable mirror 27Y. As the interferometer, the laser interferometer 18YP is a single-pass type interferometer that irradiates a measuring beam having a measuring axis parallel to the Y-axis direction with respect to the reflection surface, but the laser interferometers 18YL, 18YR, All 18YPs may be double-pass interferometers or single-pass interferometers. When the laser interferometer 18YP is a single-pass system and the laser interferometers 18YL and 18YR are a double-pass system as in the above embodiment, the measurement error of the tilt of the movable mirror tends to increase. The correction by the correction function BY (X ′) generated in the subroutine 603 exhibits a significant effect. In the exposure apparatus of the present embodiment, the laser interferometer YP is a differential interferometer that measures the difference in the Y position between the measurement points YA and YB. Instead, the reference mirror of the measurement point YA is used. Two absolute value measurement type interferometers that independently measure the Y position relative to and the Y position relative to the reference mirror of the measurement point YB may be used. In this case, the inclination component in the Z-axis direction of the movable mirror 27Y can be obtained by taking the difference between the measurement values measured independently. Further, in this case, an interferometer that measures the measurement point YA can be shared with the laser interferometer 18YR. In this way, the number of interferometer axes of wafer Y interferometer system 18Y can be reduced.

In the above embodiment, the measurement reticle _RT on which the measurement patterns (patterns A _{1 to} A ₃ , B _{1 to} B ₃ , C _{1 to} C ₃ , D _{1 to} D ₃ ) are formed is actually applied to the wafer. in transferring the measurement pattern R _T, the transfer results were obtained residual of motion curvature mirror on the wafer stage WST based on the (positional deviation amount of the pattern), the carried out using a measurement reticle R _T By performing the same processing as the subroutine 603 in the embodiment, it is possible to measure the distortion of the shot arrangement (so-called wafer grid) on the wafer W in the exposure apparatus 100. Hereinafter, a method for measuring distortion of the wafer grid will be described.

  In this measurement, first, similarly to the subroutine 603 in FIG. 8 (specifically, step 805), the shot region of m rows and n columns is set so that the end portions of adjacent images in the X axis direction and the Y axis direction are the same. As shown in FIG. 13A, a shot region S (m, n) is formed in a matrix form by transferring the wafer W over the entire area of the bare wafer W so as to overlap, and developing the wafer W. (First step). Also in this case, the X-axis direction is the column direction (column number is n), and the Y-axis direction is the row direction (row number is m).

  FIG. 13B representatively shows a shot area S (m, n), a shot area S (m, n + 1) and a shot area S (m + 1, n) adjacent to the shot area S (m, n). As shown in FIG. 13B, the shot area S (m, n + 1) has a dotted line when the shot area S (m, n) is used as a reference if the shot area array (grid) is not distorted. It should be formed at the position indicated by. However, in actuality, it is assumed that the shot area S (m, n + 1) is formed at a position indicated by a solid line. In this case, as shown in FIG. 13B, the center of the shot region S (m, n + 1) is displaced by SX (m, n) in the X-axis direction and BY (m, n) in the Y-axis direction. doing. The shot region S (m + 1, n) is also shifted from the position indicated by the dotted line when there is no grid distortion to the position indicated by the solid line. The amount of deviation is BX (m, n) in the X-axis direction and SY (m, n) in the Y-axis direction.

The positional deviation amounts SX (m, n), BY (m, n), BX (m, n), and SY (m, n) are the positional deviation amounts of the pattern formed in the portion where the adjacent shot areas overlap. Can be obtained from That is, the positional deviation in the X-axis direction and Y-axis direction between the images of the patterns C _{1 to} C _{3 in} the shot area S (m, n) and the images of the patterns A _{1 to} A _{3 in} the shot area S (m, n + 1). The average values of the quantities correspond to SX (m, n) and BY (m, n), respectively, and the images of the patterns D _{1 to} D ₃ of the shot area S (m, n) and the shot area S (m + 1, n) The average values of the positional deviation amounts in the X-axis direction and the Y-axis direction with respect to the images of the patterns B _{1 to} B ₃ of) correspond to BX (m, n) and SY (m, n), respectively. The amount of positional deviation between these pattern images can be detected using the alignment detection system AS, as in the above embodiment (step 811).

The positional shift amount obtained as described above is a relative positional shift amount with respect to the adjacent shot region. Therefore, in the present embodiment, these positional deviation amounts are integrated, and the deviation amount ΔX (X _{n + 1} , Y) of the coordinates (X _{n + 1} , Y _m ) of the shot center in each shot area S (m, n + 1). _m ) and the shift amount ΔX (X _n , Y _{m + 1} ) of the coordinates (X _n , Y _{m + 1} ) of the shot center in the shot area S (m + 1, n) are calculated using the following equations.

ここで、ｎ_minは、ｍ行において、最も−Ｘ側に存在するショット領域の列番号であり、ｍ_minは、ｎ列において、最も−Ｙ側に存在するショット領域の行番号であるものとする。すなわち、ショット領域Ｓ（ｍ，ｎ＋１）における中心座標（Ｘ_m,n+1，Ｙ_m,n+1）におけるＸ軸及びＹ軸方向に関するグリッドの歪み量は、ショット領域Ｓ（ｍ，ｎ_min）からショット領域Ｓ（ｍ，ｎ＋１）までのＳＸ（ｍ，ｊ），ＢＹ（ｍ，ｊ）の積算値となる（ｊ＝ｎ_min〜ｎ＋１）。また、ショット領域Ｓ（ｍ＋１，ｎ）における中心座標（Ｘ_m+1,n，Ｙ_m+1,n）におけるＸ軸及びＹ軸方向に関するグリッドの歪み量は、ショット領域Ｓ（ｍ_min，ｎ）からショット領域Ｓ（ｍ＋１，ｎ）までのＢＸ（ｉ，ｎ），ＳＹ（ｉ，ｎ）の積算値となる（ｉ＝ｍ_min〜ｍ＋１）。

Here, n _min is the column number of the shot region that is closest to the −X side in the m row, and m _min is the row number of the shot region that is closest to the −Y side in the n column. To do. That is, the amount of distortion of the grid in the X-axis and Y-axis directions at the center coordinates (X _{m, n + 1} , Y _{m, n + 1} ) in the shot area S (m, n + 1) is determined by the shot area S (m, n _min ) To the shot area S (m, n + 1), and the integrated value of SX (m, j) and BY (m, j) (j = n _{min to} n + 1). In addition, the amount of distortion of the grid in the X-axis and Y-axis directions at the center coordinates (X _{m + 1, n} , Y _{m + 1, n} ) in the shot area S (m + 1, n) is the shot area S (m _min , n ) To the shot area S (m + 1, n), and the integrated value of BX (i, n) and SY (i, n) (i = m _{min to} m + 1).

The boundary conditions in the above formula (16), formula (17), formula (18), and formula (19) are ΔX (X _nmin , Y _m ) = 0 and ΔY (X _nmin , Y _m ) = 0, respectively. , ΔX (X _n , Y _mmin ) = 0 and ΔY (X _n , Y _mmin ) = 0 are set, respectively, and the distortion amount of the grid at the position coordinates (X _n , Y _m ) based on the set boundary conditions ΔX (X _n , Y _m ) and ΔY (X _n , Y _m ) are calculated.

Using the above formula (16), formula (17), formula (18), and formula (19), the grid distortion amount ΔX (X _n , X in the X-axis and Y-axis directions at the position coordinates (X _n , Y _m ). After calculating Y _m ) and ΔY (X _n , Y _m ), a two-dimensional correction map is calculated based on the detection result (second step).

In this case, function fitting using a cubic function or a Fourier series polynomial is performed on the correction map of the grid distortion amount in the X-axis and Y-axis directions at the position coordinates (X _n , Y _m ). Also good. FIG. 14 shows an example of an actual shot arrangement deviation with respect to an ideal arrangement reference. In FIG. 14, the design values of the coordinates (X _n , Y _m ) of the shot center of the shot area S (m, n) are connected on the lattice by dotted lines. The vertical lines and horizontal lines indicated by the solid lines indicate correction functions F (X ₁ ), F (X ₂ ), F (X) representing the distortion amount of the grid created by the function fitting corresponding to each row and each column. ₃ ), ..., F (X ₇ ), F (Y ₁ ), F (Y ₂ ), F (Y ₃ ), ..., F (Y ₇ ), an ideal grid (arrangement standard) indicated by dotted lines It is the line typically expressed by the deviation from.

When all of the above equations (16) to (19) are calculated, two ΔX (X _n , Y _m ) and ΔY (X _n , Y _m ) are calculated with the same XY coordinates. become. In this case, the average value of the two values is calculated as the final ΔX (X _n , Y _m ), ΔY (X _n , Y _m ), and the average value is used to create a correction map or correction function. It may be used, or one of them may be selected. In calculating the grid distortion amount, the ratio between the weights of the calculation results of the equations (16) and (17) and the weights of the calculation results of the equations (18) and (19) is not 1: 1. , You may make it place specific gravity on the calculation result of either type | formula. In this case, with respect to Expressions (18) and (19), the average value for each row (i.e., the average of j columns (j = n _{min to} n _max )) regarding the amount of distortion of the grid used when obtaining these expressions. Value) and the calculation result may be used to generate a correction map or a correction function.

  The correction map or the correction function created as described above is set in the synchronous control unit 80 of the stage controller 19 as in the above embodiment. Then, based on the correction function set in the synchronous control unit 80 of the stage controller 19, relative position control between the wafer stage WST and the reticle stage RST is performed, and scanning exposure similar to step 613 is performed (third step). ). In this way, it is possible to cancel the influence due to the distortion of the arrangement of the shot areas inherent to the exposure apparatus 100, so that more accurate overlay exposure can be realized.

  As is apparent from the above description, in correcting the distortion of the wafer grid, the main controller 20 corresponds to the transfer device and a part of the controller, and the stage controller 19 is a part of the controller. Corresponding to the part.

  As described above, according to this method, the shot areas S (m, n) including the pattern image are transferred and formed in a matrix on the wafer, and the pattern is transferred to the adjacent shot areas S (m, n). Arrangement standard of shot region S (m, n) in the XY plane based on positional displacement amount SX (m, n), BY (m, n), BX (m, n), SY (m, n) Detect information about deviation from In this way, it is possible to accurately detect information relating to the deviation of the shot area from the arrangement reference based on the actual transfer result.

  In this case as well, the position of wafer stage WST may be corrected based on the amount of grid distortion, not the position of reticle stage RST.

  In the above embodiment, the correction function for correcting the bending and tilt of the movable mirror 27Y and the like provided on the wafer stage WST is generated. Similarly, the bending and tilt of the movable mirror provided on the reticle stage RST are generated. Needless to say, the present invention can also be applied to correcting the above.

  As a reticle stage or wafer stage of an exposure apparatus, a stage composed of a coarse movement stage and a fine movement stage (hereinafter referred to as “coarse / fine movement type stage”) is known. In this case, the fine movement stage is configured to hold a reticle or wafer and to position a relatively short stroke with high accuracy (high response). The coarse movement stage is configured so that the fine movement stage can be moved over a relatively long distance. The present invention can also be applied to an exposure apparatus having such a coarse / fine movement type stage. In this case, the reticle stage RST in the above embodiment is set to correspond to the reticle fine movement stage that holds the reticle, and the wafer stage WST in the above embodiment is set to correspond to the wafer fine movement stage that holds the wafer. Good.

  A projection optical system PL composed of a plurality of lenses is incorporated in the exposure apparatus main body, and thereafter optical adjustment is performed, and a reticle stage RST and wafer stage WST consisting of a large number of mechanical parts are attached to the exposure apparatus main body to perform wiring and The exposure apparatus 100 of the above-described embodiment can be manufactured by connecting piping and further performing general adjustment (electrical adjustment, operation check, etc.). The exposure apparatus is preferably manufactured in a clean room where the temperature, cleanliness, etc. are controlled.

  In the above-described embodiment, the case where the present invention is applied to a scanning exposure apparatus such as a step-and-scan method has been described, but it is needless to say that the scope of the present invention is not limited to this. That is, the present invention can be suitably applied to a step-and-repeat reduction projection exposure apparatus. The present invention can also be suitably applied to exposure in a step-and-stitch reduction projection exposure apparatus that combines a shot area and a shot area. The present invention can also be applied to a twin stage type exposure apparatus having two wafer stages. Of course, the present invention can also be applied to an exposure apparatus using a liquid immersion method.

  The use of the exposure apparatus is not limited to the exposure apparatus for semiconductor manufacturing, but for example, an exposure apparatus for liquid crystal that transfers a liquid crystal display element pattern to a square glass plate, an organic EL, a thin film magnetic head, an image sensor (CCD, etc.), micromachines, DNA chips and the like can also be widely applied to exposure apparatuses. Further, in order to manufacture reticles or masks used in not only microdevices such as semiconductor elements but also light exposure apparatuses, EUV exposure apparatuses, X-ray exposure apparatuses, electron beam exposure apparatuses, etc., glass substrates or silicon wafers, etc. The present invention can also be applied to an exposure apparatus that transfers a circuit pattern.

The light source of the exposure apparatus of the above embodiment is not limited to an ArF excimer laser light source, but a pulsed laser light source such as a KrF excimer laser light source or an F ₂ laser light source, g-line (wavelength 436 nm), i-line (wavelength 365 nm), or the like. It is also possible to use an ultra-high pressure mercury lamp that emits a bright line. In addition, a single wavelength laser beam oscillated from a DFB semiconductor laser or fiber laser is amplified by, for example, a fiber amplifier doped with erbium (or both erbium and ytterbium), and a nonlinear optical crystal is obtained. It is also possible to use harmonics that have been converted into ultraviolet light. The magnification of the projection optical system may be not only a reduction system but also an equal magnification or an enlargement system.

  In the above embodiment, it is needless to say that the illumination light IL of the exposure apparatus is not limited to light having a wavelength of 100 nm or more, and light having a wavelength of less than 100 nm may be used. For example, in recent years, in order to expose a pattern of 70 nm or less, EUV (Extreme Ultraviolet) light in a soft X-ray region (for example, a wavelength region of 5 to 15 nm) is generated using an SOR or a plasma laser as a light source, and its exposure wavelength Development of an EUV exposure apparatus using an all-reflection reduction optical system designed under (for example, 13.5 nm) and a reflective mask is underway. In this apparatus, a configuration in which scanning exposure is performed by synchronously scanning a mask and a wafer using arc illumination is conceivable.

  The present invention can also be applied to an exposure apparatus that uses a charged particle beam such as an electron beam or an ion beam. The electron beam exposure apparatus may be any of a pencil beam method, a variable shaped beam method, a cell projection method, a blanking aperture array method, and a mask projection method. For example, in an exposure apparatus that uses an electron beam, an optical system including an electromagnetic lens is used.

  For semiconductor devices, the step of designing the function and performance of the device, the step of manufacturing a reticle based on this design step, the step of manufacturing a wafer from a silicon material, and transferring the reticle pattern to the wafer by the exposure apparatus of the above-described embodiment And a device assembly step (including a dicing process, a bonding process, and a packaging process), an inspection step, and the like.

  As described above, the stage control method and the stage apparatus of the present invention are suitable for controlling a stage that holds an object used for exposure, and the exposure method of the present invention includes a semiconductor element, a liquid crystal display element, and the like. It is suitable for a lithography process for manufacturing, and the device manufacturing method of the present invention is suitable for production of a micro device.

It is a figure which shows schematically the structure of the exposure apparatus which concerns on one Embodiment of this invention. 2A is a diagram schematically showing the configuration of the wafer stage and the wafer interferometer system, and FIG. 2B is a diagram showing measurement points of the wafer interferometer system on the movable mirror. 2 (C) is a diagram when two measurement points are in the lower stage. It is a block diagram which shows the schematic structure of a stage control apparatus. It is a figure for demonstrating a movable mirror bending. FIG. 5A is a diagram showing how the position of the reticle stage is corrected by the Abbe error, and FIG. 5B is a diagram showing how the position of the reticle stage is corrected by the inclination of the movable mirror. is there. It is a flowchart which shows the exposure operation | movement with the exposure apparatus in one Embodiment of this invention. It is a flowchart which shows the subroutine of the movement mirror bending measurement by an interferometer. It is a flowchart which shows the movable mirror bending measurement subroutine by baking. It is a figure which shows the mode of the movement of the wafer stage at the time of performing the movement mirror bending measurement by an interferometer. It is a figure which shows the correction | amendment function of the movable mirror bending of an upper-lower stage. FIG. 11A is an overall view of the measurement reticle, FIG. 11B is an enlarged view of the pattern A ₁ , and FIG. 11C is an enlarged view of the pattern B ₁ . It is a figure which shows an example of the baking result of the reticle for measurement. FIG. 13A is a diagram showing a result of printing onto the wafer W when grid correction information is detected, and FIG. 13B is an enlarged view around the shot region S (n, m) in the result of printing. It is. It is a figure which shows the shift | offset | difference with an ideal grid and an actual grid.

Explanation of symbols

18 ... Wafer interferometer system (measuring device), 18YL, 18YR, 18XL, 18YR ... Laser interferometer (first measuring device, first device), 18YP, 18XP ... Laser interferometer (second measuring device, second device) , 19: Stage control device (control device), 20: Main control device (first generation device, second generation device, transfer device, part of control device), 24 ... Wafer stage drive unit, 100 ... Exposure device, PL ... projection optical system, R ... reticle (mask), R _T ... measurement reticle, RST ... reticle stage (mask stage), W ... wafer (object), WST ... wafer stage (object stage).

Claims (14)

A stage control method for controlling a mask stage for holding a mask on which a pattern is formed and an object stage for holding an object to which the pattern is transferred,
Detect shape information of a reference surface used for position measurement of the stage provided on at least one of the mask stage and the object stage, and based on the shape information, determine a relative position between the mask stage and the object stage. A first step of generating first correction information to be corrected;
A second step of transferring the pattern while correcting a relative position between the mask stage and the object stage based on the first correction information;
A third step of generating second correction information for further correcting the relative position between the mask stage and the object stage based on the arrangement information of the pattern on the object transferred in the second step;
And a fourth step of controlling the position of the mask stage and the object stage based on the first and second correction information. A first measuring device is provided that measures the position of the reference plane in a second axis direction orthogonal to the first axis by a plurality of first measurement points that are separated from each other by a predetermined interval in the first axis direction along the reference plane. ,
The first step includes
A first sub-step of sequentially measuring a difference in the second axis direction between the first measurement points while moving the stage at a predetermined interval along the first axis direction;
The stage control method according to claim 1, further comprising: a second sub-step of detecting the shape information of the reference surface based on the measurement result. A second measuring device for measuring a position of the reference plane in the second axis direction by a plurality of second measurement points spaced apart from each other by a predetermined distance along a third axis orthogonal to the first axis and the second axis; Be prepared,
The first step includes a third sub-step of further performing the first sub-step after shifting the plurality of first measurement points in the third axis direction by the predetermined interval,
The said 2nd sub process detects the said shape information of the said reference plane based on the measurement result of the said 1st sub process, and the measurement result of the said 3rd sub process. Stage control method.   The at least one of said 1st and 2nd correction information is detected as a continuous correction function regarding the said 1st axis direction using a curve interpolation method, The any one of Claims 1-3 characterized by the above-mentioned. The stage control method described in 1.   5. The stage control method according to claim 1, wherein in the fourth step, alignment is performed by correcting a position of the mask stage with respect to the object stage. A stage control method for controlling a mask stage for holding a mask on which a pattern is formed and an object stage for holding an object to which the pattern is transferred,
A partition area including a predetermined pattern on an object held on the object stage while moving the object stage to a plurality of positions arranged in a matrix at predetermined intervals with respect to two axes orthogonal to each other in a two-dimensional plane. A first step of sequential transfer formation;
A second step of detecting information on a deviation of the partition area from the arrangement reference in the two-dimensional plane based on a positional deviation amount of the predetermined pattern with respect to the two axes in the partition areas adjacent to each other;
And a third step of controlling the position of the mask stage and the object stage based on the detection result. In the second step,
Creates a continuous value function representing the amount of positional deviation in the two axial directions as information about the deviation from the arrangement reference by function fitting using the positional deviation amount of the predetermined pattern in the partitioned areas arranged in the axial direction. The stage control method according to claim 6, wherein: In the second step,
When creating the continuous value function, the weight of the positional deviation amount of the predetermined pattern between the adjacent areas in the axial direction of one of the two axes is determined between the adjacent areas in the other axial direction. The stage control method according to claim 7, wherein the stage control method is set to be larger than a weight of a positional deviation amount of the predetermined pattern. An exposure method for transferring a pattern formed on a mask onto a photosensitive object,
Using the stage control method according to any one of claims 1 to 8, an object stage that holds a photosensitive object and a mask stage that holds a mask are controlled while the photosensitive object held on the object stage is controlled. An exposure method comprising a step of transferring the pattern. A mask stage movable while holding a mask on which a pattern is formed;
The object to which the pattern is transferred is held and is movable along a first axis direction in a two-dimensional plane and a second axis direction orthogonal to the first axis, and a reference plane orthogonal to the second axis is provided. An object stage having;
A measuring device for measuring position information of the object stage in the second axis direction using the reference plane;
The shape information of the reference plane of the movable mirror is detected from the position information measured by the measurement device while moving the object stage along the first axis direction. Based on the shape information, the mask stage and the mask stage A first generation device that generates first correction information used for correcting a relative position with respect to the object stage;
Relative position between the mask stage and the object stage based on the arrangement information of the pattern on the object transferred while correcting the relative position between the mask stage and the object stage based on the first correction information A second generation device for generating second correction information for further correcting
A control device that controls the position of the object stage and the mask stage based on the first correction information generated by the first generation device and the second correction information generated by the second generation device And a stage apparatus. The measuring device is
A first device that respectively measures position information about the second axis on the reference plane at a plurality of first measurement points that are separated by a predetermined interval in the first axis direction;
A second device for measuring position information of the reference plane in the second axis direction at a plurality of second measurement points separated by a predetermined interval along a third axis orthogonal to the two-dimensional plane. The stage apparatus according to claim 10. The control device includes:
The stage apparatus according to claim 11, wherein a relative position of the mask stage with respect to the object stage is adjusted based on the first correction information and the second correction information. The first device is a double-pass interferometer that irradiates a measurement beam having a measurement axis parallel to the second axis direction with respect to the reference plane.
The said 2nd apparatus is a single path | pass type interferometer which irradiates the length measurement beam which has a length measurement axis | shaft parallel to the said 2nd axis direction with respect to the said reference plane. Stage equipment. A stage device that holds an object used for exposure and can move in a two-dimensional plane,
While the stage is moved to a plurality of positions arranged in a matrix at predetermined intervals with respect to two axes orthogonal to each other in the two-dimensional plane, the partition area including the predetermined pattern is sequentially transferred to the object held on the stage. A transfer device to form;
The object on the stage based on the information about the deviation of the partition area from the arrangement reference in the two-dimensional plane calculated from the positional deviation amount of the predetermined pattern with respect to the two axes between the adjacent partition areas. And a control device for performing alignment control between the pattern and the pattern to be transferred.

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