JP2007115829A - Mask carrying device, mask carrying method, and exposure method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make an apparatus inexpensive and speed up processing by adjusting the position of a mask on the basis of drawing error information. <P>SOLUTION: In a sensor unit 3 of a reticle carrying device as a mask carrying device, drawing error of a pattern is estimated in advance by matching a reticle R mechanically with a predetermined reference in terms of an outer shape reference using a reference member 32, and measuring a mark RM of the reticle R. Further, also on a reticle stage RST, the reticle R is matched mechanically with a predetermined reference in terms of an outer shape reference using a reference member 82, the reticle stage RST is moved so as to cancel the estimated drawing error of the pattern, and thereafter reticle alignment is implemented. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mask carrying method and apparatus for carrying a mask, and an exposure method using them.

  In a photolithography process, which is one of the semiconductor element manufacturing processes, exposure processing, development processing, and various types of wafer processing are repeatedly performed. The above exposure process uses an exposure apparatus to transfer a pattern formed on a mask or reticle (hereinafter referred to as a mask when collectively referred to) to a wafer (substrate) coated with a photosensitive agent such as a photoresist. The development process is a process for developing a photosensitive agent on the wafer after the exposure process to form a resist pattern on the wafer. The wafer processing is, for example, processing for etching a wafer into the shape of a resist pattern, processing for doping impurities into the wafer, processing for forming wiring on the wafer, and other processing.

  A single layer is formed on the wafer by performing the above exposure processing, development processing, and various types of wafer processing. In general, a semiconductor element is manufactured by repeatedly performing the exposure process, the development process, and various wafer processes several times to several tens of times while exchanging a plurality of masks, and overlapping a plurality of layers. Therefore, an exposure apparatus used for exposure processing includes a storage apparatus that stores a plurality of masks, a mask transfer apparatus that appropriately takes out the masks stored in the storage apparatus, and automatically transfers them onto a mask stage included in the exposure apparatus. It has. For details of the conventional mask transfer apparatus, see, for example, Patent Document 1 below.

  Incidentally, the mask stage includes an alignment device for detecting and correcting (aligning) the position and posture (rotation in the mask surface) of the mask carried in by the transport device. The alignment apparatus includes a measuring device that optically detects a mark formed on the mask and measures information indicating the position and rotation of the mask on the mask stage. Based on the measurement result of the measuring device, the mask is provided. The stage is driven to correct the mask position and orientation.

  If the mark formed on the mask carried on the mask stage is in the measurement visual field of the measurement device provided in the mask stage alignment device, the position and orientation of the mask are corrected from the detection result of the mark. be able to. However, it is necessary to correct the position and orientation of the mask with high precision. Therefore, it is necessary to measure the mark using a high-magnification camera (sensor), that is, a sensor with a small measurement field of view. In some cases, the mark may not be within the measurement field of view of the measurement device. In this state, the mark cannot be detected by the measurement device. For this reason, conventionally, a mask stage having a large movable range is adopted, and two measuring apparatuses, a rough measurement camera that measures marks at a low magnification and a fine measurement camera that measures marks at a high magnification, are used. Using a camera equipped with two cameras, perform rough measurement at a low magnification, adjust the mask position and orientation so that the mark falls within the measurement field of view of the fine measurement camera, and then use the fine measurement camera. It is designed to measure a precise position and posture at high magnification. As described above, in the conventional technique, the movable range of the mask stage is large, and the alignment apparatus requires two cameras. Therefore, the configuration of the mask stage and the measurement apparatus is complicated and expensive, and the rough measurement is performed before fine measurement. Since measurement needs to be performed, there is a problem that alignment takes a long time.

The present invention has been made in view of these points, and an object thereof is to reduce the cost of the apparatus and increase the processing speed.
Japanese Patent Laid-Open No. 10-163094

  According to the present invention, there is provided a mask transport apparatus for transporting a mask stored in a mask storage section to a transport destination apparatus using the mask, wherein the mask taken out from the mask storage section is temporarily mounted. An adjusting device that abuts the mounting table, the end of the mask placed on the mounting table and a predetermined reference member, and aligns the mask on the mounting table with a reference defined by the reference member In order to obtain drawing error information of the pattern drawn on the mask, the reference mark formed on the mask is optically adjusted with the adjusting device aligned with the reference. There is provided a mask transport device having a measuring device for measuring the position of the mask and a control device for adjusting the position of the mask in the transport destination device based on the obtained drawing error information.

  In the present invention, the drawing error of the pattern formed on the mask is acquired before being transferred to the transfer destination apparatus with reference to the outer shape of the mask, and the position of the mask is adjusted based on the drawing error information in the transfer destination apparatus. As a result, the movable range of the mask can be reduced, and a measurement device with a small measurement visual field can be used without using a measurement device with a large measurement visual field. Therefore, the cost of the device can be reduced and the processing speed can be increased. Can be achieved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the overall configuration of the exposure apparatus will be outlined first, and then the reticle transfer apparatus as the mask transfer apparatus will be described in detail.

[Exposure equipment]
FIG. 1 is a front view schematically showing the overall configuration of an exposure apparatus according to an embodiment of the present invention. The exposure apparatus shown in FIG. 1 employs a step-and-scan method in which the pattern formed on the reticle R is sequentially transferred onto the wafer W while the reticle stage RST and the wafer stage WST are moved synchronously with respect to the projection optical system PL. It is an exposure apparatus. In the following description, an XYZ orthogonal coordinate system is set in the drawing, and the positional relationship of each member will be described with reference to this XYZ orthogonal coordinate system. In the XYZ orthogonal coordinate system shown in FIG. 1, the XY plane is set to a plane parallel to the horizontal plane, and the Z axis is set to the vertically upward direction. The direction along the X axis is the scan direction (scan direction).

In FIG. 1, the illumination optical system IL shapes the cross-sectional shape of laser light emitted from a light source such as an ArF excimer laser light source (wavelength 193 nm) into a slit shape extending in the Y direction, and uniformizes the illuminance distribution for illumination. Ejected as light. In this embodiment, the case where an ArF excimer laser light source is provided as a light source will be described as an example. In addition, an ultrahigh pressure mercury lamp that emits g-line (wavelength 436 nm) and i-line (wavelength 365 nm), or A KrF excimer laser (wavelength 248 nm), an F ₂ laser (wavelength 157 nm), and other light sources can be used.

  The reticle R is attracted and held on the reticle stage RST, and a movable mirror MRr to which the length measuring beam BMr from the reticle interferometer system IFR is irradiated is fixed to one end of the reticle stage RST. Positioning of the reticle R is performed by a reticle driving device DR that translates the reticle stage RST in the XY plane perpendicular to the optical axis AX and rotates it slightly in the XY plane. The reticle driving device DR scans the reticle stage RST in the X direction at a constant speed when the pattern of the reticle R is transferred onto the wafer W. Above the reticle stage RST, alignment systems OB1 and OB2 for photoelectrically detecting reticle alignment marks RM (see FIG. 4C) formed at two positions around the reticle R are provided. The detection results of the alignment systems OB1 and OB2 are used to position the reticle R with a predetermined accuracy with respect to the optical axis AX of the illumination optical system IL or the projection optical system PL.

  Reticle stage RST is movably held on reticle stage base structure CL1 that forms part of the column structure of the apparatus body, and a motor and the like of reticle drive apparatus DR are also mounted on base structure CL1. Further, a beam interference portion (such as a beam splitter) of the reticle interferometer system IFR that measures a change in the position of the reticle R is also attached to the base structure CL1. Interferometer system IFR projects length measurement beam BMr onto moving mirror MRr attached to one end of reticle stage RST, receives the reflected beam, and measures the positional change of reticle R.

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

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

  The lens base structure CL3 is mounted on the wafer base structure CL4 on which the wafer stage WST that mounts the wafer W and moves two-dimensionally along the XY plane is mounted. Although not shown, wafer stage WST is provided with a wafer holder for vacuum-sucking wafer W, and a leveling table for finely moving and tilting the wafer holder in the Z direction (optical axis AX direction). Yes.

  The movement coordinate position of wafer stage WST in the XY plane and the minute rotation amount by yawing are measured by wafer interferometer system IFW. The interferometer system IFW projects the laser beam from the laser light source LS onto the movable mirror MRw fixed to the leveling table of the wafer stage WST and the fixed mirror FRw fixed to the bottom of the projection optical system PL. The coordinate position and minute rotation amount (yawing amount) of wafer stage WST are measured by causing the reflected beams from mirrors MRw and FRw to interfere.

  On the leveling table of wafer stage WST, various alignment systems, focus sensors, and a reference plate FM used for calibration of the leveling sensor and measurement of the baseline amount are also attached. On the surface of the reference plate FM, reference marks that can be detected by the alignment systems OB1 and OB2 are formed together with the mark RM of the reticle R under illumination light having an exposure wavelength.

  Examples of the various alignment systems described above include off-axis type alignment sensors that measure position information of alignment marks formed on the wafer W. The focus sensor is a sensor that measures the amount of deviation of the surface of the wafer W relative to the image plane of the projection optical system PL, and the leveling sensor is a sensor that measures the attitude (tilt) of the surface of the wafer W. The baseline amount is an amount indicating the distance between the reference position of the reticle pattern image projected onto the wafer W (for example, the center position of the pattern image) and the center of the measurement field of the alignment sensor.

[Reticle conveyor]
FIG. 2 is a perspective view showing the configuration of the reticle conveying apparatus according to the embodiment of the present invention. The reticle transport apparatus shown in FIG. 2 takes out the reticle R from the reticle cases 1a and 1b that store a plurality of substantially square reticles R and transports the reticle R onto the reticle stage RST, and also transfers the reticle R on the reticle RST to the reticle case 1a, It is a device that conveys to 1b, and includes a reticle carrying robot 2, a sensor unit (alignment stage) 3, a buffer 4, a table 6, and a swivel arm 7.

  FIG. 3 is a front view showing the configuration of the reticle case and the storage / separation unit. Note that the reticle cases 1a and 1b and the storage / separation units 14 corresponding to the reticle cases 1a and 1b have the same configuration. Therefore, the reticle 1a and the storage / separation unit 14 corresponding thereto will be described as an example.

  The reticle case 1a is a SMOF (Standard of Mechanical Interface) type case (so-called Sumif pod), and includes a cover 11 that opens at the bottom side, a bottom plate 12 that is attached to the cover 11 so that the opening of the cover 11 can be opened and closed, and a bottom plate And a lock mechanism (not shown) for releasably fixing the cover 11 and the bottom plate 12 in a state in which the hold shelf 13 is housed inside the cover 11. 3 shows a state where the lock 11 is released and the cover 11, the bottom plate 12, and the holding shelf 13 are separated. The holding shelf 13 is provided with a plurality of (6 in the example shown in FIG. 3) shelves, and the reticle R is horizontally inserted and held in each of these shelves.

  The reticle case 1a is placed on the storage / separation unit 14 provided on the port base plate 10 disposed in the smiff port SP (see FIG. 2). A mounting portion 15 that receives and holds the reticle case 1 a is supported and fixed by a support column 17 on the upper portion of the storage / separation unit 14, so that a space 16 is defined below the mounting portion 15. The attachment portion 15 is provided with a mechanism (not shown) for releasing the lock between the cover 11 of the attached reticle case 1a and the bottom plate 12, and an opening 15a for allowing the bottom plate 12 and the holding shelf 13 to pass therethrough. Is provided. The storage / separation unit 14 includes a vertical movement mechanism having a moving plate 18 that is driven up and down by a ball screw mechanism or the like. The bottom plate 12 and the holding shelf 13 that are unlocked from the cover 11 are arranged on the moving plate 18. And is moved up and down in the space 16. At this time, the cover 11 remains attached to the attachment portion 15.

  Here, the reticle R conveyed by the reticle conveying device will be described. 4A and 4B are diagrams illustrating an example of the reticle R, in which FIG. 4A is a perspective view, FIG. 4B is a cross-sectional view taken along line AA in FIG. c) is a plan view. A pattern is formed on the reticle R using chromium or the like on one surface of a transparent glass substrate, and a transparent pellicle PR is installed on the surface on which this pattern is formed (hereinafter referred to as a reticle surface). The pellicle PR is provided in order to prevent foreign matter such as dust or dust from adhering to the reticle surface, thereby preventing an image of the foreign matter from being formed on the surface of the wafer W during exposure.

  Further, as shown in FIG. 4C, two position measurement marks RM are provided outside the pattern formation area PA where the reticle surface pattern is formed and inside the area where the pellicle PR is installed. One is formed. The mark RM shown in FIG. 4C is a combination of two square patterns and cross patterns having different sizes. These marks RM are used when the position and rotation of the reticle on the reticle stage RST are measured using the alignment systems OB1 and OB2 shown in FIG. 1, and the outer shape is used as a reference on the sensor unit 3 shown in FIG. This is used when measuring the pattern drawing error. In addition, a barcode BC in which identification information of the reticle R is set is formed or affixed outside the pattern area PA of the reticle R. As the barcode BC, a one-dimensional code, a two-dimensional code, other codes, or a combination thereof can be used. The barcode BC may be formed or attached to the side surface of the reticle R.

  Returning to FIG. 2, the reticle transfer robot 2 is an articulated robot installed on the base 20, and rotates to the vertical axis moving unit 22 that moves in the Z-axis direction along the vertical axis slider 21 and to the vertical axis moving unit 22. The rotary moving unit 23 is supported by the rotary moving unit 23, the rotary moving unit 24 is rotatably supported by the rotary moving unit 23, and the fork unit 25 is rotatably supported by the rotary moving unit 24.

  When the reticle transport robot 2 transports the reticle R of the storage / separation unit 14 to the reticle stage RST, the reticle transport robot 2 takes out the specific reticle R from the storage / separation unit 14 and transports the extracted reticle R to the sensor unit 3. Further, the reticle R is conveyed from the sensor unit 3 to the buffer 4 and from the buffer 4 to the cradle 6 in order. Further, when the reticle R is transported from the reticle stage RST to the cradle 6 by the turning arm 7, the reticle R placed on the cradle 6 is transported to the buffer 4 or the storage separation unit 14.

  The sensor unit 3 is a multi-functional unit having various functions. In this embodiment, the sensor unit 3 is formed in the reticle R, a mechanical alignment function that mechanically aligns the position and orientation of the reticle R with a predetermined reference based on the outer shape reference. By measuring the alignment mark RM, a drawing error measuring function for measuring a drawing error of a pattern formed on the reticle R, a barcode reading function for reading the barcode BC of the reticle R, and adhesion of foreign matter to the surface of the reticle R A foreign matter detection function for detecting the presence or absence of The sensor unit 3 includes a stage 3a, and four support portions 31 for supporting the reticle R from below are arranged on the stage 3a. At the upper part of these support portions 31, suction ports are provided so that the reticle R can be vacuum-sucked. The stage 3a is a stage configured to be movable in the Y direction in relation to a foreign substance detection device 33 described later. The stage 3a may be of a type that cannot move, or may be of a type that can be moved and rotated in the XY plane.

  On the stage 3a, a substantially U-shaped reference member (mechanical guide) 32 having a pressing surface orthogonal to the X direction and a pressing surface orthogonal to the Y direction is provided. The reference member 32 is configured to be slidable along a guide (not shown) at an angle of 45 degrees with respect to the X or Y direction in the XY plane, and is driven by a driving device (not shown). . The reference member 32 is positioned at a predetermined reference position in the advanced state, and is positioned at a predetermined retracted position in the retracted state. The four pressing surfaces of the reference member 32 are brought into contact with the side surface on the −X direction side and the side surface on the −Y direction side among the four side surfaces of the reticle R placed on the support portion 31 and moved to the reference position. By doing so, the position and orientation of the reticle R in the XY plane are mechanically corrected. This mechanical correction (mechanical alignment) is performed in a state where the vacuum suction of the reticle R by the support portion 31 is released. In addition, when correcting the position and orientation of the reticle R by the reference member 32, the four side surfaces of the reticle R are set so that the corresponding side surfaces of the reticle R are accurately positioned along the respective pressing surfaces of the reference member 32. Among them, a pressing pin that urges the side surface on the + X direction side and the side surface on the + Y direction side to press in the −X direction and the −Y direction, or a fixing pin may be provided so as to contact the side surface. Instead of these pressing pins or fixing pins, a pressing member or fixing member having the same shape as that of the reference member 32 may be provided at a point-symmetrical position with respect to the reference member 32 on the diagonal line of the reticle R.

  Above the stage 3a (+ Z direction), illumination devices 34a and 34b for irradiating illumination light to the mark RM of the reticle R placed on the support portion 31 are provided. Translucent holes 34c and 34d that transmit the illumination light are formed at positions on the stage 3a where the illumination light from the illumination devices 34a and 34b is irradiated, and below the translucent holes 34c and 34d (−Z direction). Is provided with a measuring device 36 for optically measuring the mark RM through the light transmitting holes 34c and 34d.

  The measuring device 36 outputs an optical system that condenses illumination light through the light transmitting holes 34c and 34d, an image sensor such as a CCD that receives illumination light collected by the optical system, and an image sensor. An image processing apparatus that performs image processing on the image signal is provided. The position of the mark RM is measured by the image processing device performing image processing on the image signal from the image sensor, and the measured position information of the mark RM is sent to a reticle conveyance control device 90 described later. The reticle conveyance control device 90 calculates a pattern drawing error based on the sent (measured) position information of the mark RM and the design value information of the mark RM. Note that, for example, in FIG. 4C, the pattern drawing error is determined by using the point where the side E1 and the side E2 of the reticle R intersect as the origin O and the side E1 as the X axis or the side E2 as the Y axis. With reference to the XY orthogonal coordinate system to be used, the amount of deviation (dx, dy) in the X and Y directions from the design value (x, y) of one mark RM and the center of one mark RM and the other mark RM are connected. It can be expressed by an angle (dθ) between the line and the X axis.

  Since the reticle R is accurately positioned at the reference position by the reference member 32 on the support portion 31 on the basis of the outer shape, the measurement of the mark RM is performed without the mark RM of the reticle R entering the measurement field of view of the measuring device 36. There is nothing that can't be done. Note that the size of the measurement field of view of the measurement device 36 (magnification of the optical system) depends on the relationship between the accuracy of mechanical alignment by the reference member 32 and the maximum allowable value of pattern drawing error based on the outer shape of the reticle R. The mark RM is set so as to be within the measurement visual field.

  In the vicinity of the stage 3a, a barcode reader 35 for reading a barcode BC formed on or attached to the reticle R is provided. A different barcode is affixed to each of the reticles R, and the reticle R can be identified by reading the barcode. Note that main control system 100 (see FIG. 5) controls information relating to each reticle R (information indicating the type of pattern formed, transmittance, flatness, etc.) and information corresponding to a barcode. ) Or a database in the host computer 103 (see FIG. 5), which is higher, can obtain information about the reticle R necessary for performing the exposure process simply by reading the barcode of the reticle R.

  A foreign object detection device 33 is provided in the vicinity of the stage 3a. The foreign matter detection device 33 detects the presence or absence of foreign matter such as dust or dust attached to the surface of the reticle R or the pellicle PR, or scratches placed on the support portion 31. The foreign object detection device 33 irradiates the surface of the reticle R or the surface of the pellicle with detection light from an oblique direction and receives the obtained scattered light to detect the presence or absence of the foreign substance, the size of the foreign substance, or the distribution thereof. In this embodiment, the foreign object detection device 33 fixes a light source that emits detection light to the surface of the reticle R and a light receiving sensor (including an optical system) that receives scattered light on the surface of the reticle R, and the stage 3a is set to Y. By moving in the direction, the entire surface of the reticle R can be detected. In this configuration, when the pellicle surface (back surface) of the reticle R is inspected, the reticle transport robot 2 can turn the reticle R on the support portion 31 upside down. In addition, in order to inspect the front surface and the back surface of the reticle R at the same time, the same light source and the light receiving sensor may be provided on the back surface side. Further, instead of moving the stage 3a, the light source, the light receiving sensor, and the like may be moved in the Y direction. Further, the reticle R to be detected by foreign matter may be held by the fork portion 25 of the reticle transfer robot 2 and moved in the Y direction by the reticle transfer robot 2 instead of being moved by the stage 3a.

  The buffer 4 is provided below the stage 3a (in the −Z direction), and doors 41 and 42 that can be opened and closed are provided on one side surface thereof, and a plurality of storage shelves (about a dozen or so) are provided therein. Is arranged. The buffer 4 is provided to temporarily store a plurality of reticles R whose positions and orientations have been corrected by the sensor unit 3 and to adjust the reticle R to the environment inside the exposure apparatus. The position of the buffer 4 is not limited to the lower side of the stage 3 and may be a side of the sensor unit 3 or other place.

  The cradle 6 completes the mechanical position correction (mechanical alignment) of the reticle R, the measurement of the mark RM, the reading of the bar code BC, and the detection of foreign matter in the sensor unit 3, and the reticle carried by the reticle carrying robot 2. R or a stage for temporarily placing the reticle R transported from the reticle stage RST by the swing arm 7 described later, that is, for transferring the reticle R between the reticle transport robot 2 and the swing arm 7. It is a stand. The cradle 6 has four support portions 61 for supporting the reticle R.

  The swivel arm 7 is generally composed of a swivel motor 71, a swivel plate 72 whose center is attached to the rotation shaft of the swivel motor 71, and two holding portions 73 a and 73 b respectively attached to both ends of the swivel plate 72. The reticle R is held by at least one of the holding portions 73a and 73b, and the reticle R is transported between the stage 6 and the reticle stage RST. The turning motor 71, the turning plate 72, and the holding portions 73a and 73b are configured to be integrally movable in the Z direction by the vertical drive mechanism UD. The rotation axis of the turning motor 71 is set in a direction parallel to the Z direction, and is set at an intermediate position between the holding portion 73a and the holding portion 73b.

  The holding part 73a includes a first arm part 74a and a second arm part 74b. The first arm portion 74 a and the second arm portion 74 b are configured to be movable in parallel along the Y direction by a slider 75 attached to one end of the rotating plate 72. The slider 75 moves the first arm portion 74a and the second arm portion 74b in the opposite directions by the same distance, thereby changing the distance between the first arm portion 74a and the second arm portion 74b to perform an opening / closing operation. Let The first arm portion 74a includes four support portions that support the reticle R to be conveyed from below (-Z direction). At the upper part of these support portions, suction ports are provided so that the reticle R can be selectively vacuum-sucked. Note that the holding unit 73b has the same configuration as the holding unit 73a, and thus description thereof is omitted.

  Although not shown, a rectangular opening that allows the exposure light transmitted through the reticle R to pass therethrough is formed substantially at the center of the reticle stage RST. Four support portions 81 that support the reticle R are disposed in the vicinity of the four corners of the opening. Each support portion 81 is formed with a suction port for vacuum-sucking the reticle R.

  On the reticle stage RST, a substantially square reference member (mechanical guide) 82 having a pressing surface orthogonal to the X direction and a pressing surface orthogonal to the Y direction is provided. The reference member 82 is configured to be slidable along a guide (not shown) at an angle of 45 degrees with respect to the X or Y direction in the XY plane, and is driven by a driving device (not shown). . The reference member 82 is positioned at a predetermined reference position in the advanced state, and is positioned at a predetermined retracted position in the retracted state. The pressing surfaces of the reference member 32 are brought into contact with the side surface on the −X direction side and the side surface on the −Y direction side among the four side surfaces of the reticle R placed on the support portion 81, and moved to the reference position. By doing so, the position and orientation of the reticle R in the XY plane are mechanically corrected. This mechanical correction (mechanical alignment) is performed in a state where the vacuum suction of the reticle R by the support portion 81 is released.

  Note that when correcting the position and orientation of the reticle R by the reference member 82, the four side surfaces of the reticle R are set so that the corresponding side surfaces of the reticle R are accurately positioned along the respective pressing surfaces of the reference member 82. Among them, a pressing pin that urges the side surface on the + X direction side and the side surface on the + Y direction side to be pressed in the −X direction and the −Y direction, or a fixing pin may be provided so as to contact the side surface. Instead of these pressing pins or fixing pins, a pressing member or fixing member having the same shape as the reference member 82 may be provided at a position point-symmetric with the reference member 82 on the diagonal line of the reticle R. As the reference member 82 (and its drive mechanism, etc.), it is desirable to use the same member as the reference member 32 (and its drive mechanism, etc.). The reference member 82 may have a configuration different from that of the reference member 32. In this case, a member that contacts the same portion as the contact portion of the reference member 32 with respect to the reticle R may be used. Is desirable.

  Above the reticle stage RST (+ Z direction), alignment sensors 84a and 84b for measuring the mark RM of the reticle R placed on the support portion 81 are arranged. These alignment sensors 84a and 84b are provided in the alignment systems OB1 and OB2.

  Next, the main part of the control system of the exposure apparatus including the reticle transport apparatus described above will be described with reference to the block diagram shown in FIG. In FIG. 5, components corresponding to the configurations shown in FIGS. 2 to 4 are denoted by the same reference numerals. A reticle transport control device 90 in FIG. 5 is a device that collectively controls the operations of the reticle transport device. The reticle transport control device 90 is positioned below the main control system 100 that controls the overall operation of the exposure apparatus, and controls the operation of the reticle transport device under the control of the main control system 100. The reticle conveyance control device 90 receives the measurement result of the measurement device 36, the detection result of the foreign object detection device 33, and the barcode information read by the barcode reader 35. The storage device 91 stores information necessary for the reticle transport control device 90 to control the reticle transport device.

  Also, the robot drive device 92 shown in FIG. 5 is a device that drives the reticle transport robot 2, the reference member drive device 93 is a device that moves (retreats) the reference member 32, and the stage drive device 94 is a sensor unit. 3 is a device for driving the third stage 3 a, and the swing arm drive device 95 is a device for driving the swing arm 7. The reticle conveyance control device 90 outputs a control signal to each of these devices to control the operation of the entire reticle conveyance device. The reference member driving device 102 is a device that moves (retreats) the reference member 82, and the stage driving device DR is a device that drives the reticle stage RST. Reticle stage control apparatus 101 outputs a control signal to each of these apparatuses to control the alignment operation of reticle R on reticle stage RST and the movement of the stage.

  Next, the reticle conveying operation will be described with reference to the flowchart shown in FIG. When a control signal is output from the reticle transport control device 90 to the robot drive device 92 in a state where at least one of the reticle cases 1a and 1b storing the reticle R is placed on the storage / separation unit 14, the reticle transport robot 2 One reticle R is taken out from the storage / separation unit 14 and conveyed onto the stage 3a of the sensor unit 3, and the reticle R is placed on the four support portions 31 of the stage 3a (S10). At this stage, the reticle R is not absorbed by the support portion 31. Next, the reference member 32 is advanced by the reference member driving device 93 and stopped at a predetermined reference position. Accordingly, the side surface of the reticle R is pushed by the pressing surface of the reference member 32, and the corresponding side surface (the side surface on the −X side and the side surface on the −Y side) of the reticle R corresponds to the reference member 32 as the reticle R moves. By accurately following the pressing surface, the position and posture of the reticle R are matched with a predetermined reference (S11).

  Next, illumination light is emitted from the illumination devices 34a and 34b and applied to the reticle R, and the illumination light transmitted through the reticle R passes through the light transmitting holes 34c and 34d and is received by the imaging device provided in the measurement device 36. The Each of the optical images of the mark RM formed on the reticle R is formed on the light receiving surface of the image sensor, and these optical images are converted into image signals and output from the image sensor. The image signal output from the image sensor is subjected to image processing by an image processing device provided in the measuring device 36, and position information of each mark RM is measured (S12). These position information measurement results are output to the reticle conveyance control device 90, and the reticle conveyance control device 90, based on each position information measurement result, draws a pattern formed on the reticle R (position displacement in the X direction with respect to the reference). Amount dx, Y-direction positional deviation amount dy, and rotation amount dθ). This drawing error is sent to the reticle stage control apparatus 101 for use in reticle alignment described later. Note that the position information of the mark RM measured by the measuring device 36 may be sent from the reticle transport control device 90 to the reticle stage control device 101, and the reticle stage control device 101 may calculate the pattern R drawing error. . Reference numeral 103 denotes a host computer that comprehensively manages the manufacturing line including the exposure apparatus or the entire manufacturing factory including the plurality of manufacturing lines. The position information of the mark RM measured by the measuring apparatus 36 is used as the host computer 103 or the main computer. The pattern drawing error may be calculated by the host computer 103 or the main control system 100 so as to be sent to the control system 100, and this calculation result may be sent to the reticle stage control apparatus 101.

  Next, the barcode BC formed on or attached to the reticle R on the stage 3a is read by the barcode reader 35, and the reading result is sent to the main control system 100 via the reticle conveyance control device 90 (S13). . Here, the barcode reader 35 has been described as reading the barcode while the reticle R is stationary on the stage 3a. However, as the barcode reader 35, for example, a line sensor whose longitudinal direction is set in the X direction is used. Alternatively, the stage 3a may be read by moving in the Y direction. In this case, the reticle R is held in a state where it is sucked and held by the support portion 31.

  Next, it is detected by the foreign material detection device 33 whether or not foreign material has adhered to the surface of the reticle R (S14). In this detection, the surface of the reticle R is irradiated from the light source in an oblique direction, and the scattered light from the surface is received by the light receiving sensor, and the stage 3a is moved in the Y direction so that the entire surface of the reticle R is exposed. This is done by collecting data across From the collected data, the presence / absence of a foreign substance is determined, and if a foreign substance exists, the size or distribution of the foreign substance is obtained. The detection result is sent to the main control system 100 via the reticle conveyance control device 90, and processing for notifying the operator when a foreign object is found is performed. The stage 3a is moved in a state where the reticle R is sucked and held by the support portion 31. When the stage 3a is moved for reading the barcode BC, the barcode BC reading operation and foreign object detection may be performed simultaneously in parallel.

  When the foreign object detection is completed, a control signal is output from the reticle transport control device 90 to the robot drive device 92, and the reticle R is unloaded from the sensor unit 3 by the reticle transport robot 2 and stored in one of the storage shelves of the buffer 4. (S15). When a plurality of reticles R are stored in the reticle cases 1a and 1b, the above operation is repeated, and after each of the reticles R is subjected to the various processes described above by the sensor unit 3, the buffer 4 It is stored in the storage shelf. Since the environment (temperature and humidity) inside the buffer 4 is adjusted, each reticle R can be adjusted to the environment inside the exposure apparatus by temporarily storing the reticle R in the buffer 4. .

  When the exposure start command is output from the main control system 100 after the storage of the reticle R in the buffer 4 is completed, the reticle transport control device 90 reads out the information stored in the storage device 91 and the main control system 100. The information indicating the storage shelf of the buffer 4 in which the reticle R to be used first for the exposure processing instructed by the storage unit 4 is obtained. The reticle transport control device 90 then outputs a control signal to the robot drive device 92, causes the reticle transport robot 2 to take out the reticle R stored in the storage shelf indicated by the read information, and mounts it on the table 6. (S16).

  Next, the reticle R placed on the placing table 6 is transported to the reticle stage RST by the turning arm 7 (S17). First, one of the holding parts 73a and 73b (here 73a) is positioned above the pedestal 6 and the first and second arm parts 74a and 74b are opened in a direction away from each other in the X direction. The turning motor 71, the turning plate 72, and the holding portions 73a and 73b are integrally moved in the −Z direction by the vertical drive mechanism UD to lower the holding portion 73a to a position where the reticle R can be held. Next, after the first and second arm portions 74a and 74b are moved in directions close to each other, the swing motor 71, the swing plate 72, and the holding portions 73a and 73b are integrally moved in the + Z direction by the vertical movement mechanism UD. Let At this time, when the reticle R is transferred from the support portion 61 of the cradle 6 to the support portion of the holding portion 73a, the reticle R is sucked by the support portion of the holding portion 73a.

  When the vertical drive mechanism UD is driven until the reticle R reaches a predetermined height position, the turning motor 71 is driven to turn the turning arm 7 and the holding portion 73a for holding the reticle R is arranged at the delivery position. Arranged above reticle stage RST (+ Z direction). Next, the swing motor 71, the swing plate 72, and the holding portions 73a and 73b are integrally moved in the −Z direction by the vertical drive mechanism UD. When the holding portion 73a comes close to the reticle stage RST by driving the vertical drive mechanism UD, the adsorption of the reticle R by the holding portion 73a is released, and the reticle R is placed on the support portion 81 of the reticle stage RST. After the first and second arm portions 74a and 74b are lowered to the extent that they do not interfere with the reticle R, the first and second arm portions 74a and 74b are moved away from each other, and the swing motor 71 is moved by the vertical drive mechanism UD. The swivel plate 72 and the holding portions 73a and 73b are integrally moved in the + Z direction and arranged at a predetermined height position. With the above operation, reticle R is transferred from holding unit 73a to reticle stage RST.

  When the delivery of the reticle R is completed, the reticle stage control device 101 instructs the reference member driving device 102 to advance the reference member 82 to the reference position. In response to this, the reference member 82 is advanced and stopped at a predetermined reference position. Accordingly, the side surface of the reticle R is pushed by the pressing surface of the reference member 82, and the corresponding side surface (the side surface on the −X direction side, the side surface on the −Y direction side) of the reticle R is moved along with the movement of the reticle R. The position and posture of the reticle R are matched with a predetermined reference on the outer shape reference (S18). Thereafter, the reference member 82 is withdrawn. Next, reticle stage control apparatus 101 instructs stage drive apparatus DR to cancel the drawing error based on the drawing error information received from reticle transfer control apparatus 90 (S19). That is, when the drawing error information is (dx, dy, dθ), the reticle stage RST is moved and rotated by (−dx, −dy, −dθ). As a result, the mark RM of the reticle R is positioned within the measurement visual field of the alignment sensors 84a and 84b.

  The processing of S18 and S19 will be described with reference to FIGS. 7 (A) to 7 (D). FIG. 7A shows a state in which the reticle R is placed on the reticle stage RST by the swing arm 7. In this state, since the reticle R is not accurately positioned, the mark RM of the reticle R is located at a position completely deviated from the measurement field MF of the alignment sensors 84a and 84b. It should be noted that adsorption to the reticle R by the support part 81 of the reticle stage RST is not performed at this time. Next, as shown in FIG. 7B, when the reference member 82 is advanced to a predetermined reference position, the position of the reticle R is mechanically corrected, and the outer shape of the reticle R matches the reference. However, if there is a pattern drawing error, the mark RM of the reticle R is also located slightly off the measurement field MF of the alignment sensors 84a and 84b. Thereafter, as shown in FIG. 7C, the reference member 82 is withdrawn, and suction to the reticle R is performed by the support portion 81 of the reticle stage RST. Next, as shown in FIG. 7D, the reticle stage RST is moved by (−dx) in the X direction so as to cancel the pattern drawing error (dx, dy, dθ), and in the Y direction. It is moved by (−dy) and further rotated by (−dθ) in the XY plane. As a result, the mark RM on the reticle R enters the measurement visual field MF of the alignment sensors 84a and 84b, and measurement by the alignment sensors 84a and 84b becomes possible.

  Next, the position and rotation of the reticle R on the reticle stage RST are accurately measured using the alignment systems OB1 and OB2 (alignment sensors 84a and 84b), and the illumination optical system IL or the projection optical system PL is measured based on the measurement result. The reticle R is positioned with a predetermined accuracy with respect to the optical axis AX, and the relative alignment between the reticle R on the reticle stage RST and the wafer stage WST is performed (S20).

  Thereafter, an exposure process is performed (S21). First, reticle stage RST is driven by stage driving device DR to place reticle R at the exposure start position, and wafer stage W is driven to expose one of the shot areas of wafer W held on wafer stage WST. Located at the start position. Then, acceleration of reticle stage RST and wafer stage WST is started, the speed of wafer stage WST reaches maximum speed Vw, and the speed of reticle stage RST increases to maximum speed Vr = Vw / α (α is from reticle R to wafer W). Illumination light is emitted from the illumination optical system IL when the projection magnification reaches (for example, α = 1/4 or 1/5), and the illumination light having a uniform illuminance distribution is irradiated onto the reticle R. Pattern transfer of the reticle R onto the wafer W is started via the projection optical system PL.

  While the reticle stage RST and wafer stage WST are synchronously moved (scanned) at the maximum speed, the pattern of the reticle R is sequentially transferred to one shot area on the wafer W via the projection optical system PL. When reticle stage RST and wafer stage WST are scanned for a predetermined time and pattern transfer of reticle R to the shot area is completed, emission of illumination light from illumination optical system IL is stopped, and reticle stage RST and wafer stage WST are Decelerated. With the above processing, the exposure processing for one shot area is completed.

  Next, the moving direction of reticle stage RST is reversed and wafer stage WST is moved to place the next shot area to be exposed at the exposure start position, and the next shot area is exposed. The above operation is repeated for all the shot areas set on the wafer W. When all the shot areas are exposed, the exposure process for wafer W on wafer stage WST ends, wafer W on wafer stage WST is unloaded from the exposure apparatus, and a new wafer W is transferred onto wafer stage WST. Then, the same exposure process is performed. By repeating the above processing, for example, one lot of wafers W is exposed.

  When the exposure process is completed, the main control system 100 outputs a control signal to the reticle driving device DR to move the reticle stage RST to a delivery position below (-Z direction) the holding portion 73a, and to the turning arm driving device 95. A control signal is output and the reticle R on the reticle stage RST is transported to the stage 6 (S22). Next, the reticle transport control device 90 outputs a control signal to the robot drive device 92, and the reticle transport robot 2 moves the reticle R on the table 6 to the storage shelf of the buffer 4 (the storage in which the reticle R is stored). To the shelf). If the reticle R is not used in the subsequent steps, the reticle R on the table 6 may be transported to the reticle cases 1a and 1b by the reticle transport robot 2.

  Next, modifications of the reference member 82 and its drive mechanism will be described with reference to FIGS. 8 (A) to 8 (D). As shown in FIGS. 8A and 8B, the reference member 32 used in the above example advances and retreats at an angle of 45 degrees with respect to the X direction and the Y direction in the XY plane. It was of construction. In the above example, there is no problem because the reference member 82 and its driving mechanism are provided on the reticle stage RST. However, from the viewpoint of high-precision exposure, the reticle stage RST that is a movable part is preferably as simple as possible. . For this reason, it is desirable to provide the reference member 82 and its drive mechanism not on the reticle stage RST but in a fixed portion such as the reticle stage base structure CL1. In this case, in the configuration shown in FIGS. 8A and 8B, the reference member 82 may become an obstacle to the operation of the reticle stage RST. Therefore, in this case, as shown in FIGS. 8C and 8D, the guide Gi is directed to the corresponding corner of the reticle R from the oblique lower side with respect to the XY plane. It is preferable that the reference member 82 is configured to advance and retreat from the diagonally downward direction along the guide Gi. When the reticle stage RST is moved, as shown in FIG. 8C, if the reference member 82 is moved away, the reference member 82 does not become an obstacle to the operation of the reticle stage RST, and the reticle stage RST is moved. In the case of performing R mechanical alignment, as shown in FIG. 8D, the function can be sufficiently exhibited by advancing. In addition, you may comprise so that the advancing / retreating direction of the reference member 82 may be performed from diagonally upward. Such a configuration may also be adopted for the reference member 32 of the sensor unit 3 and its drive mechanism.

  According to the above-described embodiment, the pattern is obtained by measuring the mark RM of the reticle R by mechanically aligning the reticle R with the reference in the outer shape reference using the reference member 32 in the sensor unit 3 of the reticle conveying apparatus. The reticle R is also moved on the reticle stage RST by using the reference member 82 to mechanically align the reticle R with a predetermined reference on the basis of the outer shape and to cancel the drawing error. Since the rotation is performed, the mark RM of the reticle R on the reticle stage RST can be reliably positioned in the measurement visual field of the alignment sensors 84a and 84b. For this reason, as the alignment sensors 84a and 84b, those with high magnification (those with a narrow measurement field of view) can be adopted, and rough alignment (mark measurement and fine adjustment of the stage) is performed with a low magnification sensor as in the past. After that, there is no need for rough alignment in advance to simplify the configuration of the alignment system in order to position the mark RM in the measurement field of the high-precision sensor, such as fine alignment with a high-magnification sensor. In addition, the time required for alignment can be shortened.

  Further, since the single sensor unit 3 performs mechanical positioning (mechanical alignment) of the reticle R, measurement of pattern drawing errors, bar code reading, and foreign object detection, these are performed in separate units. Compared to the case, the configuration can be simplified, the reticle R need not be transported between units, and the processing time can be shortened.

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

  For example, in the above embodiment, the reference members 32 and 82 are formed in a substantially square shape so as to simultaneously press the two side surfaces of the reticle R with a single drive mechanism. A reference member having a single pressing surface and its driving mechanism are provided to press one of the side surfaces, and a reference member having a single pressing surface and its driving mechanism are provided to press the other side surface. Thus, a similar function may be realized. In the above embodiment, the mechanical alignment of the reticle R is performed by moving the reference members 32 and 82 forward and backward while the stages 3a and RST are fixed (stopped). A similar mechanism may be realized by moving the stages 3a and RST while being fixed at the reference position. Further, in the above embodiment, the mechanical alignment of the reticle R by the reference members 32 and 82 is performed in a state where the suction by the support portions 31 and 81 of the stages 3a and RST is simply released, but the suction for the suction is performed. Air may be discharged from the opening or another discharge opening, and mechanical alignment may be performed in a state where the reticle R is slightly lifted from the support portions 31 and 82 by the principle of the air bearing.

  In the above-described embodiment, the step-and-scan type exposure apparatus has been described as an example of the exposure apparatus, but the present invention can also be applied to a step-and-repeat type exposure apparatus. Further, not only an exposure apparatus used for manufacturing a semiconductor element, but also an exposure apparatus used for manufacturing a liquid crystal display element, a plasma display, a thin film magnetic head, and an imaging element (CCD, etc.), and a reticle or mask. In addition, the present invention can be applied to an exposure apparatus that transfers a circuit pattern onto a glass substrate or a silicon wafer. In other words, the present invention can be applied regardless of the exposure method and application of the exposure apparatus.

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

It is a front view which shows typically the whole structure of the exposure apparatus which concerns on embodiment of this invention. It is a perspective view which shows the structure of the reticle conveying apparatus which concerns on embodiment of this invention. It is a front view which shows the structure of a reticle case. It is a figure which shows an example of a reticle. It is a block diagram which shows the structure of the control system which concerns on embodiment of this invention. It is a flowchart which shows the reticle conveyance process and exposure process of embodiment of this invention. FIG. 5 is a diagram for explaining the operation of the reference member on the reticle stage and the correction of the pattern drawing error according to the embodiment of the present invention. It is a figure which shows the reference | standard member of the embodiment of this invention, its drive mechanism, and these modifications.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1a, 1b ... Reticle case, 2 ... Reticle transfer robot, 3 ... Sensor unit, 6 ... Stand, 7 ... Turning arm, 32 ... Reference member, 33 ... Foreign object detection device, 34a, 34b ... Illumination device, 35 ... Bar code Reader, 36 ... Measuring device, 82 ... Reference member, 84a, 84b ... Alignment sensor, R ... Reticle, RM ... Mark, RST ... Reticle stage

Claims (11)

A mask transfer device for transferring a mask stored in a mask storage unit to a transfer destination device using the mask,
A mounting table for temporarily mounting the mask taken out of the mask storage unit;
An adjustment device for bringing the end of the mask placed on the mounting table into contact with a predetermined reference member and aligning the mask on the mounting table with a reference defined by the reference member;
In order to obtain drawing error information of a pattern drawn on the mask, the reference mark formed on the mask is optically measured under the condition that the mask is aligned with the reference by the adjusting device. A measuring device to
And a controller that adjusts the position of the mask in the transport destination apparatus based on the obtained drawing error information. The transport destination device is:
A stage capable of moving in a state where the mask that has been transported is placed;
A stage-side adjustment device having the same configuration as the adjustment device and having a stage reference for the stage in the same positional relationship as the reference for the mounting table,
After the mask placed on the stage is aligned with the stage reference by the stage side adjustment device, the control device adjusts the position of the mask by driving the stage based on the drawing error information. The mask transfer apparatus according to claim 1, wherein:   The mask transport apparatus according to claim 1, further comprising a foreign matter detection device that optically detects the presence or absence of foreign matter on the surface of the mask placed on the mounting table.   The mask transport device according to claim 1, further comprising an information detection device that detects a unique information mark formed on the mask placed on the mounting table.   5. The mask transfer apparatus according to claim 1, wherein the reference member is provided so as to advance and retreat in a direction oblique to a plane parallel to the pattern surface. A mask transport method for transporting a mask stored in a mask storage unit to a transport destination apparatus using the mask,
An extraction step of taking out the mask from the mask storage unit and placing it on a mounting table for temporarily mounting the mask;
An adjustment step of bringing the end of the mask placed on the mounting table and a predetermined reference member into contact with each other and aligning the mask on the mounting table with a reference defined by the reference member;
In order to obtain drawing error information of a pattern drawn on the mask, the reference mark formed on the mask is optically measured under the condition that the mask is aligned with the reference by the adjusting device. Measuring steps to
And a position adjusting step for adjusting the position of the mask in the transport destination apparatus based on the drawing error information obtained in the measuring step. The transport destination device is:
A stage capable of moving in a state where the mask that has been transported is placed;
A stage-side adjustment device having the same configuration as the adjustment device and having a stage reference for the stage in the same positional relationship as the reference for the mounting table,
In the position adjusting step, after the mask placed on the stage is aligned with the stage reference by the stage side adjusting device, the position of the mask is driven by driving the stage based on the drawing error information. The mask transfer method according to claim 6, wherein adjustment is performed.   The mask transport method according to claim 6 or 7, further comprising a foreign matter detection step for optically detecting the presence or absence of foreign matter on the surface of the mask placed on the mounting table.   The mask transport method according to claim 6, further comprising an information detection step of detecting a unique information mark formed on the mask placed on the mounting table.   10. The adjustment step according to claim 6, wherein the reference member is advanced in a direction oblique to a plane parallel to the pattern surface to align the mask with the reference. 10. The mask conveying method according to 1. An exposure method for exposing and transferring a mask pattern onto an object,
A transporting step for transporting the mask using the mask transporting method according to any one of claims 6 to 9;
An exposure method comprising: exposing the object through the mask pattern after performing the position adjusting step.

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