JP2015018904A - Mark detection method and device, and exposure method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively detect marks when marks are provided on a rear surface of a substrate, and to detect a location information of the substrate even when the detection of marks becomes difficult.SOLUTION: A mark detection device 8 for detecting a mark formed on a wafer W, comprises: a wafer transfer device 66 for temporarily holding the wafer W where the mark 46 is formed on its rear surface; a mark detection part 52 for detecting location information of the mark 46 in a state that the wafer W is held on the wafer transfer device 66; a mark formation part for forming an alternative mark on a surface of the wafer W on the basis of the location information of the detected mark 46; a storage part for storing a positional relationship between the mark 46 and the alternative mark; a mark detection part 52 for detecting location information of the alternative mark in a state that the wafer W is held on the wafer transfer device 66; and edge detection parts 53A, 53B.

Description

  The present invention relates to a mark detection technique for detecting a mark provided on a substrate, an exposure technique using the mark detection technique, and a device manufacturing technique using the exposure technique.

  As a substrate to be exposed by an exposure apparatus such as a so-called stepper or scanning stepper used in a photolithography process for producing an electronic device (microdevice) such as a semiconductor element, a disk-shaped semiconductor wafer (hereinafter simply referred to as a wafer) There is.) In order to increase the throughput (productivity) when manufacturing electronic devices, the SEMI (Semiconductor Equipment and Materials International) standard (SEMI standards) of the diameter of the wafer is almost 125 mm, 150 mm, 200 mm, and 300 mm every few years. It is increasing at a rate of 1.25 to 1.5 times.

  Further, a notch or an orientation flat as a notch for detecting the rotation angle on the basis of the outer shape is formed at the edge portion of the conventional wafer. When the wafer is loaded into the exposure apparatus, the position of the notch portion of the wafer is detected in advance by a pre-alignment system, and rough adjustment of the rotation angle of the wafer is performed based on this result ( For example, see Patent Document 1).

U.S. Patent No. 6225012

  Recently, in order to further increase the throughput when manufacturing electronic devices, the SEMI standard has standardized a wafer having a diameter of 450 mm. In such a large wafer, if a notch for detecting the rotation angle is provided at the edge, the wafer may be distorted. In view of this, in order to detect the rotation angle of a large-sized wafer, it has been studied to provide a small mark made of, for example, a recess on the back surface.

  In this regard, the wafer is conventionally transported to the exposure apparatus with the back surface supported, and the pre-alignment system detects the notch of the wafer from the front surface (surface on which the device pattern is formed) side of the wafer. For this reason, it is difficult to detect the mark provided on the back surface of the wafer with the conventional technique. Further, since the wafer goes through many processes, the mark on the back surface of the wafer disappears due to wear during conveyance and / or processing, or the mark on the back surface of the wafer is covered with a photosensitive material or thin film during processing. May be difficult to detect. Therefore, it is preferable to consider measures when it becomes difficult to detect the mark on the back surface of the wafer.

  In view of such circumstances, the aspect of the present invention enables efficient detection of a mark when the mark is provided on the back surface of the substrate, and makes it difficult to detect the mark. Another object of the present invention is to make it possible to detect positional information of the substrate.

  According to the first aspect, there is provided a mark detection device for detecting a mark formed on a substrate, the substrate holding unit temporarily holding the substrate having the first mark formed on the back surface, and the substrate holding unit. In a state where the substrate is held, a first detection unit that detects position information of the first mark on the back surface, and a second surface on the surface of the substrate based on the detected position information of the first mark. A mark forming portion for forming a mark, a storage portion for storing a positional relationship between the first mark and the second mark, and the substrate holding portion holding the substrate, And a second detector that detects position information of the second mark.

  According to the second aspect, there is provided a mark detection device for detecting a mark formed on a substrate, the substrate holding unit temporarily holding the substrate having the first mark formed on the back surface, and the substrate holding unit. A first detector for detecting position information of the first mark on the back surface of the substrate while the substrate is held; and a pattern or reflectance distribution on the surface of the substrate in another region of the surface A mark detection device is provided that includes a second detection unit that detects position information of an identifiable feature, and a storage unit that stores a positional relationship between the first mark and the feature.

  According to the third aspect, in the exposure apparatus that illuminates the pattern with the exposure light and exposes the substrate with the exposure light through the pattern and the projection optical system, the mark detection apparatus according to the first aspect and the substrate The pattern of the substrate based on the stage that is held and moved, and the position information of the first mark formed on the back surface of the substrate detected by the mark detection device or the second mark on the surface of the substrate An exposure apparatus is provided that includes a control unit that corrects at least one of a position and a rotation angle with respect to.

  According to the fourth aspect, in the exposure apparatus that illuminates the pattern with the exposure light and exposes the substrate with the exposure light through the pattern and the projection optical system, the mark detection apparatus according to the second aspect and the substrate Based on the positional information of the stage that is held and moved, and the first mark formed on the back surface of the substrate detected by the mark detection device or the characteristic portion of the surface of the substrate, the pattern of the substrate An exposure apparatus is provided that includes a control unit that corrects at least one of a position and a rotation angle.

  According to the fifth aspect, there is provided a mark detection method for detecting a mark formed on a substrate, wherein the substrate on which the first mark is formed on the back surface is temporarily held by the substrate holding unit, and the substrate is held. The position information of the first mark on the back surface is detected in a state where the substrate is held by the portion, and the second mark is formed on the surface of the substrate based on the detected position information of the first mark. , Storing the positional relationship between the first mark and the second mark, and the position information of the second mark on the surface in a state where the substrate is held by the substrate holding portion And a mark detection method including:

  According to the sixth aspect, there is provided a mark detection method for detecting a mark formed on a substrate, wherein the substrate on which the first mark is formed on the back surface is temporarily held by the substrate holding unit, and the substrate is held. Detecting the position information of the first mark on the back surface of the substrate while the substrate is held on the surface, and distinguishing it from the pattern or reflectance distribution on the surface of the substrate in other regions of the surface A mark detection method is provided that includes detecting position information of a possible feature and storing a positional relationship between the first mark and the feature.

  According to the seventh aspect, in the exposure method of illuminating a pattern with exposure light and exposing the substrate through the pattern with the exposure light, the pattern is formed on the back surface of the substrate using the mark detection method of the fifth aspect. Detecting the position information of the first mark or the second mark formed on the surface of the substrate, placing the substrate on the stage, and the position information detected by the mark detection method. Based on this, there is provided an exposure method including correcting at least one of a position and a rotation angle of the substrate with respect to the pattern.

  According to an eighth aspect, in the exposure method of illuminating a pattern with exposure light and exposing the substrate through the pattern with the exposure light, the pattern is formed on the back surface of the substrate using the mark detection method of the sixth aspect. Detecting the position information of the first mark or the feature of the surface of the substrate, placing the substrate on the stage, and based on the position information detected by the mark detection method, And correcting at least one of a position and a rotation angle of the substrate with respect to the pattern.

  According to a ninth aspect, the method includes forming a pattern of a photosensitive layer on a substrate using the exposure apparatus or the exposure method according to the aspect of the present invention, and processing the substrate on which the pattern is formed. A device manufacturing method is provided.

  According to the aspect of the present invention, since the position information of the first mark on the back surface of the substrate is detected while the substrate is held by the substrate holding portion, the first mark can be detected efficiently. Further, since the positional relationship between the second mark or feature on the surface of the substrate and the first mark is stored, even if it becomes difficult to detect the first mark, the second mark or feature is not displayed. By detecting, the position information of the substrate can be detected.

It is the figure which represented a part showing schematic structure of the exposure apparatus which concerns on 1st Embodiment in the cross section. It is a top view which shows the wafer stage in FIG. 2 is a block diagram showing a control system and the like of the exposure apparatus of FIG. (A) is a plan view showing the surface of the wafer, (B) is an enlarged view showing a mark on the back surface of the wafer, (C) is a cross-sectional view of FIG. 4 (B), and (D) is an enlarged view showing a mark of a modification. (E) is an enlarged view showing a mark of another modified example, (F) is a plan view showing a notch of the wafer of the first conventional example, and (G) is a notch of the wafer of the second conventional example. It is a top view which shows a part. (A) is a top sectional view showing a mechanism part of the mark detection device in FIG. 1, and (B) is a sectional view taken along line BB in FIG. 5 (A). 5A is a diagram showing a mark detection unit in FIG. 5B, FIG. 6B is a partially enlarged view showing the vicinity of the edge portion of the wafer in FIG. 6A, and FIG. It is a top view which shows the surface of the inside prism. It is a flowchart which shows an example of the exposure method containing the mark detection method. (A) is a top view which shows the state which transferred the wafer from the transfer arm to the wafer delivery apparatus, (B) is sectional drawing which follows the BB line of FIG. 8 (A). FIG. 9A is a plan view showing a wafer on which an image of a substitute mark is exposed, FIG. 9B is an enlarged view showing a test region FVB in FIG. 9A and its vicinity, and FIG. (D) is an enlarged view showing an alternative mark of a modified example, (E) is an enlarged view showing an alternative mark of another modified example, and (F) is further separated. It is an enlarged view which shows the alternative mark of this modification. It is the figure which represented in part the section which shows the mechanism part of the mark detection apparatus which concerns on 2nd Embodiment. It is a flowchart which shows an example of the manufacturing method of an electronic device.

[First Embodiment]
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of an exposure apparatus EX provided with a mark detection apparatus according to the present embodiment. The exposure apparatus EX is a scanning exposure type projection exposure apparatus composed of a scanning stepper (scanner). The exposure apparatus EX includes a projection optical system PL (projection unit PU). Hereinafter, the Z axis is taken in parallel to the optical axis AX of the projection optical system PL, the Y axis is set in the direction in which the reticle R and the wafer (semiconductor wafer) W are relatively scanned in a plane orthogonal to the Z axis, the Z axis and the Y axis. The description will be made by taking the X axis in a direction perpendicular to the axis. In addition, the rotation directions around the axes parallel to the X axis, the Y axis, and the Z axis are also referred to as θx, θy, and θz directions. In the present embodiment, the plane orthogonal to the Z axis (XY plane) is substantially parallel to the horizontal plane.

  The exposure apparatus EX includes, for example, an illumination system ILS disclosed in, for example, US Patent Application Publication No. 2003/0025890, and illumination light (exposure light) IL (for example, an ArF excimer laser having a wavelength of 193 nm) from the illumination system ILS. A reticle stage RST that holds and moves a reticle R (mask) illuminated by light or a harmonic of a solid-state laser (such as a semiconductor laser). Further, the exposure apparatus EX includes a projection unit PU including a projection optical system PL that exposes the wafer W (substrate) with the illumination light IL emitted from the reticle R, a wafer stage WST that holds and moves the wafer W, and a wafer. A main control device 20 comprising a mark detection device 8 as a pre-alignment system for detecting the position information of the wafer W including the position information of the W mark (including angle information, the same applies hereinafter), and a computer for controlling the operation of the entire device. (See FIG. 3). Further, since the positions of reticle stage RST and wafer stage WST are defined by the coordinate system (X, Y, Z) composed of the X axis, Y axis, and Z axis, this coordinate system (X, Y, Z). ) Is also referred to as a stage coordinate system.

  The reticle R is held on the upper surface of the reticle stage RST by vacuum suction or the like, and a circuit pattern or the like is formed on the pattern surface (lower surface) of the reticle R. In the present embodiment, the auxiliary reticle RA (auxiliary mask) is fixed at a position shifted in the Y direction (scanning direction) with respect to the reticle R of the reticle stage RST, and is located at, for example, the center of the pattern surface (lower surface) of the auxiliary reticle RA. A substitute mark pattern 21 for forming a mark that can be used as a substitute mark for a mark on the back surface of the wafer W, which will be described later, is formed. As an example, the substitute mark pattern 21 is a combination of a plurality of opening patterns elongated in the Y direction arranged at predetermined intervals in the X direction and a plurality of opening patterns elongated in the X direction arranged at predetermined intervals in the Y direction. It is a pattern that can define a two-dimensional position. The reticle stage RST can be finely driven in an XY plane on a reticle base (not shown) by a reticle stage drive system 25 shown in FIG. 3 including, for example, a linear motor and the like, and scanning designated in the scanning direction (Y direction). It can be driven at speed.

  Position information within the moving surface of the reticle stage RST (including the position in the X direction, the Y direction, and the rotation angle in the θz direction) is transferred to the moving mirror 22 (or mirror-finished) by the reticle interferometer 24 including a laser interferometer. For example, it is always detected with a resolution of about 0.5 to 0.1 nm via the stage end face. The measurement value of reticle interferometer 24 is sent to main controller 20 in FIG. Main controller 20 controls reticle stage drive system 25 based on the measurement value, thereby controlling the position and speed of reticle stage RST.

  In FIG. 1, the projection unit PU disposed below the reticle stage RST includes a lens barrel 40 and a projection optical system PL having a plurality of optical elements held in a predetermined positional relationship within the lens barrel 40. A flat frame (hereinafter referred to as a measurement frame) 16 is supported by a frame mechanism (not shown) via a plurality of vibration isolation devices (not shown), and the projection unit PU is formed on the measurement frame 16. It is installed in the opening via a flange portion FL. The projection optical system PL is, for example, telecentric on both sides (or one side on the wafer side) and has a predetermined projection magnification β (for example, a reduction magnification such as 1/4 or 1/5).

  When the illumination area IAR of the reticle R is illuminated by the illumination light IL from the illumination system ILS, the image of the circuit pattern in the illumination area IAR is projected via the projection optical system PL by the illumination light IL that has passed through the reticle R. It is formed in an exposure area IA (an area optically conjugate with the illumination area IAR) of one shot area of W. For example, the wafer W is obtained by applying a photoresist PR (photosensitive material) with a thickness of about several tens to 200 nm to a large disk-shaped substrate SU made of a semiconductor such as silicon and having a diameter of 450 mm (FIG. 10). 4 (C)). That is, as an example, the wafer W is a 450 mm wafer. The thickness of a substrate having a diameter of 450 mm is currently assumed to be, for example, about 900 to 1100 μm (for example, about 925 μm).

  When the wafer W is a 450 mm wafer, as shown in FIG. 4A, a form in which a notch portion is not provided in the circular edge portion of the wafer W has been studied. That is, in the wafer W shown in FIG. 4A, notches such as notches and orientation flats are not provided in the edge portions described above. In this case, the surface Wa of the wafer W (the surface on which the photoresist PR of the substrate SU is applied) is regularly divided into a large number of shot areas SA vertically and horizontally, and a device pattern DP is formed in each shot area SA. The If the shot area SA is about 26 mm wide and about 33 mm long, for example, about 180 shot areas SA are formed on the surface Wa of the wafer W, for example. In the first exposure of the wafer W, the surface Wa of the wafer W is not partitioned into the shot area SA.

  Further, a surface facing the front surface Wa of the wafer W or a surface of the base material SU of the wafer W on which the photoresist PR is not applied is referred to as a back surface Wb of the wafer W. 4B shows a part of the back surface Wb of the wafer W, and FIG. 4C is a cross-sectional view of FIG. As shown in FIGS. 4B and 4C, when the wafer W is a 450 mm wafer, the wafer W is located within the peripheral region 47 from the edge Wf of the back surface Wb of the wafer W to, for example, about 1 mm to several mm. A mark 46 composed of a plurality of small recesses 46a in a row is formed along the radial direction of W. As an example, the recess 46a has a circular shape with a diameter of about 100 μm and a depth of about 20 to 70 μm. In FIG. 4C, the recess 46a is cylindrical, but the recess 46a may be hemispherical. As an example, the direction of the mark 46 (the direction along a straight line passing through the centers of the plurality of recesses 46a) is set to a predetermined angle, for example, parallel to the direction of one crystal axis of the substrate SU of the wafer W. May be. Further, the shot area SA may be formed so that the direction of the mark 46 and the longitudinal direction (or short direction) of the shot area SA on the surface of the wafer W are parallel to each other.

  As an example, the mark 46 can be formed by cutting with a fine drill or irradiation with a processing laser beam. Further, the mark 46 can be formed by a lithography process including partial photoresist coating on the back surface Wb of the wafer W, exposure of the mark pattern, development, etching, and resist stripping. In the mark 46, a plurality of concave portions 46a may be formed in a plurality of rows in the radial direction. Further, the mark 46 may be formed by forming a plurality of recesses 46 a in a single row or in a plurality of rows in a circumferential direction parallel to the edge portion of the wafer W. Also, instead of the mark 46, as shown in FIG. 4D, a plurality of rows (or even one row) of partial marks 46A1 and 46A2 in which a plurality of recesses are arranged in the radial direction of the wafer W, and a plurality of recesses are formed on the wafer. A mark 46A including one row (or a plurality of rows) of mark portions 46A3 arranged in the circumferential direction of W may be used. Further, instead of the mark 46, as shown in FIG. 4E, a mark 46B made up of one or a plurality of elongated concave portions arranged along the radial direction (or circumferential direction) of the wafer W is used. Also good.

  In this embodiment, the mark 46 is formed at one place on the back surface Wb of the wafer W, but the number of the mark 46 is not particularly limited, and a plurality of marks 46 such as three may be formed. In addition, when a plurality of marks 46 are formed on the back surface Wb, it is preferable that the shapes are different in order to distinguish each mark. For example, in the case where a plurality of marks 46 shown in FIG. 4D are provided on the back surface Wb, the height of the mark portion 46A3 (the distance from the edge of the wafer W) among the marks 46 may be varied. As a result, the marks 46 formed on the back surface Wb of the wafer W can be individually identified. For example, in the case where a plurality of marks having a shape in which the mark portion 46A3 shown in FIG. 4D is added to the mark 46 in FIG. It is desirable to vary the height of the mark portion 46A3 (distance from the edge of the wafer W).

  In the exposure apparatus EX of FIG. 1, in order to perform exposure using the liquid immersion method, the lens barrel 40 that holds the tip lens 91 that is the optical element on the most image plane side (wafer W side) constituting the projection optical system PL is used. A nozzle unit 32 that constitutes a part of the local liquid immersion device 38 is provided so as to surround the lower end portion. The nozzle unit 32 is connected to a liquid supply device 34 and a liquid recovery device 36 (see FIG. 3) via a supply tube 31A and a recovery tube 31B for supplying an exposure liquid Lq (for example, pure water). . If the immersion type exposure apparatus is not used, the local immersion apparatus 38 may not be provided.

  The exposure apparatus EX also aligns the wafer W with an aerial image measurement system (not shown) that measures the position of the image of the alignment mark (reticle mark) of the reticle R by the projection optical system PL in order to align the reticle R. For example, an image processing system (FIA system) alignment system AL, an irradiation system 90a and a light receiving system 90b, and a multi-point oblique incidence system that measures Z positions at a plurality of locations on the surface of the wafer W. An autofocus sensor (hereinafter referred to as a multi-point AF system) 90 (see FIG. 3) and an encoder 6 (see FIG. 3) for measuring position information of wafer stage WST are provided. The aerial image measurement system is provided in, for example, wafer stage WST. The alignment system AL is a predetermined wafer mark selected from the alignment marks (wafer marks) attached to each shot area SA on the surface Wa of the wafer W when the second and subsequent layers of the wafer W are exposed. Used to detect the position of

  As shown in FIG. 2, the alignment system AL is, for example, in the X direction (non-scanning direction) in a region about the diameter of the wafer W arranged away from the projection optical system PL in the −Y direction. Consists of five-lens alignment systems ALc, ALb, ALa, ALd, and ALe arranged at approximately equal intervals, and is configured so that wafer marks at different positions on the wafer W can be detected simultaneously by the five-lens alignment systems ALa to ALe. ing. In addition, the loading that is the center position of wafer stage WST when loading wafer W at a position away from −Y direction with respect to alignment systems ALa to ALe and shifted to −X direction and + X direction to some extent. The position LP and the unloading position UP, which is the center position of the wafer stage WST when the wafer W is unloaded, are set. As shown in FIG. 1, a wafer transfer device 66 is arranged above the loading position LP (+ Z direction).

  In FIG. 1, a main body 67 of a wafer transfer device 66 is supported by a frame member FR1 supported independently of the measurement frame 16, for example, so as to be movable in the Z direction. Further, near the loading position LP, a wafer transfer robot WLD for loading the wafer W into the exposure apparatus EX from the coater / developer (not shown) side is installed. As an example, the wafer transfer robot WLD includes a main body portion 64 installed on a floor surface, first and second intermediate arms 63 and 62 provided so as to be sequentially rotatable with respect to the main body portion 64, and a second intermediate portion. A fork-shaped transfer arm 61 (see FIG. 8A) is provided rotatably at the tip of the arm 62 and holds and transfers the wafer W by vacuum suction. The transfer arm 61 of the wafer transfer robot WLD transfers the wafer W placed on a rotary table (not shown) installed on the −Y direction side to below the wafer transfer device 66. The operations of the wafer transfer device 66 and the wafer transfer robot WLD are controlled by the transfer control system 50 (see FIG. 3).

  Further, the mark 46 (see FIG. 4B) formed on the back surface of the wafer W around the main body 67 of the wafer transfer device 66 and the position information of the edge portion in the vicinity thereof (including angle information, the same applies hereinafter). A mark detection unit 52 that detects the position of the wafer W and two edge detection units 53A and 53B that detect position information of two different edge portions of the wafer W are disposed. As an example, the mark detection unit 52 captures an image of the mark 46 in the test region on the back surface of the wafer W shown in FIGS. 4A and 4B, and at the same time, an image of the edge portion of the wafer W near the mark 46. Image. The test area FVB by the mark detection unit 52 in FIG. 4A is substantially the first test area (first field of view) including the mark 46 on the back surface of the wafer W, and the edge near the mark 46. This is a region combining the second region to be examined (second visual field) including the portion. The edge detection units 53A and 53B capture the image of the edge portion of the wafer W with the two test regions (fields of view) FVA2 and FVA1 at positions obtained by dividing the edge portion of the wafer W together with the test region FVB at substantially equal angular intervals. To do.

  In the present embodiment, the mark detection unit 52 and the edge detection units 53A and 53B can also detect a pattern on the surface of the wafer W near the edge portion of the wafer W and a reflectance distribution in a certain region. Detection signals from the mark detection unit 52 and the edge detection units 53A and 53B are supplied to the calculation unit 55 (see FIG. 3). The computing unit 55 processes these detection signals to position the center of the wafer W in the X and Y directions, and the rotation angle of the wafer W (for example, the direction parallel to the mark 46 on the wafer W and the stage coordinate system (X , Y, Z) is calculated and an angle formed by an axis parallel to the Y axis is supplied to the main controller 20. A storage unit 56 such as a magnetic storage device is connected to the calculation unit 55.

  In order to form a substitute mark for the mark 46 on the back surface of the wafer W on the surface of the wafer W in the vicinity of the edge portion of the wafer W, including the illumination system ILS, the reticle stage RST including the auxiliary reticle RA, and the projection optical system PL. A mark forming portion is formed that includes an exposure portion that exposes an image of the pattern 21. The mark detection device 8 includes the exposure unit, the wafer transfer device 66, the transfer control system 50, the mark detection unit 52, the edge detection units 53A and 53B, the calculation unit 55, and the storage unit 56. The main controller 20 can perform pre-alignment, for example, correction of the rough position and rotation angle of the wafer W, using the center position and rotation angle of the wafer W supplied from the calculation unit 55. The detailed configuration and operation of the mark detection device 8 will be described later. The transport control system 50 and the calculation unit 55 may have different functions on the software of the computer that constitutes the main control device 20.

  Further, another wafer delivery device (not shown) used when unloading the wafer W is disposed above the unloading position UP in FIG. 2, and unloaded near the unloading position UP. Another wafer transfer robot (not shown) for unloading the wafer W to the coater / developer side is arranged. The wafer transfer device 66 can also be used as the wafer transfer device for unloading.

  In FIG. 2, the irradiation system 90 a and the light receiving system 90 b of the multipoint AF system 90 are arranged along a region between the alignment systems ALa to ALe and the projection optical system PL as an example. With this configuration, after loading the wafer W onto the wafer stage WST at the loading position LP, the wafer stage WST is driven to move the wafer W from the exposure start position below the projection optical system PL substantially in the Y direction. In addition, the measurement of the Z position distribution on the wafer surface by the multi-point AF system 90 and the position measurement of a plurality of wafer marks on the wafer surface by the alignment systems ALa to ALe can be efficiently performed. The measurement results of the multipoint AF system 90 and the alignment system AL are supplied to the main controller 20.

  In FIG. 1, wafer stage WST is supported in a non-contact manner on an upper surface WBa parallel to the XY plane of base board WB via a plurality of unillustrated vacuum preload type static air bearings (air pads), for example. Wafer stage WST can be driven in the X and Y directions by a stage drive system 18 (see FIG. 3) including, for example, a planar motor or two sets of orthogonal linear motors. Wafer stage WST is provided in stage main body 30 driven in X and Y directions, wafer table WTB as a Z stage portion mounted on stage main body 30, and in stage main body 30. A Z stage drive unit that relatively finely drives the Z position of wafer table WTB and the tilt angles in the θx direction and θy direction is provided. A wafer holder 44 for holding the wafer W on a mounting surface substantially parallel to the XY plane by vacuum suction or the like is provided inside the central opening of the wafer table WTB.

  In the present embodiment, a portion (Z stage portion) including wafer table WTB and wafer holder 44 of wafer stage WST is configured to be rotatable with respect to stage main body 30 by an angle designated in the θz direction. The main controller 20 controls the rotation angle in the θz direction of the Z stage portion via the stage drive system 18. Instead of rotating only the Z stage part, the stage body 30 and the Z stage part as a whole may be rotated in the θz direction.

Further, the upper surface of wafer table WTB has a surface that is substantially flush with the surface of wafer W and has been subjected to a liquid repellency treatment with respect to liquid Lq, and has a rectangular outer shape (contour) and a central portion of wafer W. A flat plate member 28 having a high flatness in which a circular opening that is slightly larger than the mounting region is formed may be provided.
In the configuration of the so-called immersion type exposure apparatus provided with the above-mentioned local immersion apparatus 38, the plate body 28 further has an outer shape (see FIG. 2) surrounding the circular opening 28a. It has a rectangular (contour) and a plate portion (liquid repellent plate) 28b whose surface has been subjected to a liquid repellent treatment, and a peripheral portion 28e surrounding the plate portion 28b. A pair of two-dimensional diffraction gratings 12A and 12B elongated in the X direction so as to sandwich the plate portion 28b in the Y direction are fixed on the upper surface of the peripheral portion 28e, and elongated in the Y direction so as to sandwich the plate portion 28b in the X direction. A pair of two-dimensional diffraction gratings 12C and 12D is fixed. The diffraction gratings 12 </ b> A to 12 </ b> D are reflection type diffraction gratings on which a two-dimensional grating pattern having a period of about 1 μm with the X direction and the Y direction as periodic directions is formed.

  In FIG. 1, the measurement grating 16 is irradiated with measurement laser light (measurement light) on the diffraction gratings 12 </ b> C and 12 </ b> D so that the projection optical system PL is sandwiched in the X direction on the bottom surface of the measurement frame 16. A plurality of triaxial detection heads 14 for measuring a three-dimensional relative position in the direction and the Z direction are fixed. Further, the measurement laser beam is irradiated to the diffraction gratings 12A and 12B so that the projection optical system PL is sandwiched in the Y direction on the bottom surface of the measurement frame 16, and the three-dimensional relative position with respect to the diffraction grating is measured. A plurality of triaxial detection heads 14 are fixed (see FIG. 2). Furthermore, one or a plurality of laser light sources (not shown) for supplying laser light (measurement light and reference light) to the plurality of detection heads 14 are also provided.

  In FIG. 2, during the period in which the wafer W is exposed through the projection optical system PL, any two detection heads 14 in the line A1 in the Y direction irradiate the diffraction grating 12A or 12B with measurement light, and perform diffraction. A detection signal of interference light between the diffracted light generated from the gratings 12A and 12B and the reference light is supplied to the corresponding measurement calculation unit 42 (see FIG. 3). In parallel with this, any two detection heads 14 in one row A2 in the X direction irradiate measurement light to the diffraction grating 12C or 12D, and interference light between the diffraction light generated from the diffraction gratings 12C and 12D and the reference light. Is supplied to the corresponding measurement calculation unit 42 (see FIG. 3). In the measurement calculation unit 42 for the detection heads 14 in one column A1 and one row A2, the relative positions of the wafer stage WST (wafer W) and the measurement frame 16 (projection optical system PL) in the X, Y, and Z directions ( Relative movement amount) is obtained with a resolution of 0.5 to 0.1 nm, for example, and the obtained measurement values are supplied to the switching units 92A and 92B. In the measurement value switching units 92 </ b> A and 92 </ b> B, information on the relative position supplied from the measurement calculation unit 42 corresponding to the detection head 14 facing the diffraction gratings 12 </ b> A to 12 </ b> D is supplied to the main controller 20.

  A plurality of detection heads 14 in one column A1 and one row A2, a laser light source (not shown), a plurality of measurement calculation units 42, switching units 92A and 92B, and diffraction gratings 12A to 12D constitute a three-axis encoder 6. . The detailed configuration of such an encoder and the above-described five-eye alignment system is disclosed in, for example, US Patent Application Publication No. 2008/094593. Based on the relative position information supplied from encoder 6, main controller 20 determines the position of wafer stage WST (wafer W) in the X, Y, and Z directions with respect to measurement frame 16 (projection optical system PL), and Information such as the rotation angle in the θz direction is obtained, and wafer stage WST is driven via stage drive system 18 based on this information.

A laser interferometer that measures the three-dimensional position of wafer stage WST is provided in parallel with encoder 6 or instead of encoder 6, and wafer stage WST is driven using the measured value of this laser interferometer. May be.
Then, at the time of exposure of the exposure apparatus EX, the reticle R and the wafer W are first aligned as a basic operation. Thereafter, irradiation of the reticle R with the illumination light IL is started, and an image of a part of the pattern of the reticle R is projected onto one shot area on the surface of the wafer W via the projection optical system PL, while the reticle stage RST. The pattern image of the reticle R is transferred to the shot area by a scanning exposure operation that moves the wafer stage WST in synchronization with the Y direction using the projection magnification β of the projection optical system PL as a speed ratio (synchronous scanning). Thereafter, by repeating the operation (step movement) of moving the wafer W in the X and Y directions via the wafer stage WST and the above scanning exposure operation, for example, by the immersion method and the step-and-scan method. The pattern image of the reticle R is transferred to the entire shot area of the wafer W.

  At this time, in the detection head 14 of the encoder 6, since the optical path lengths of the measurement light and the diffracted light are shorter than those of the laser interferometer, the influence of the air fluctuation on the measurement value is very small as compared with the laser interferometer. Therefore, the pattern image of the reticle R can be transferred to the wafer W with high accuracy. In the present embodiment, the detection head 14 is disposed on the measurement frame 16 side, and the diffraction gratings 12A to 12D are disposed on the wafer stage WST side. As another configuration, the diffraction gratings 12A to 12D may be disposed on the measurement frame 16 side, and the detection head 14 may be disposed on the wafer stage WST side.

Next, the configuration and operation of the mark detection apparatus 8 of this embodiment for detecting the position information of the wafer W including the position information of the mark 46 on the back surface of the wafer W will be described in detail.
5A is a plan view showing a mechanism part of the mark detection device 8 in FIG. 1, and FIG. 5B is a cross-sectional view taken along line BB in FIG. 5A. Note that FIG. 5A is also a cross-sectional view taken along the line AA in FIG. The mechanism unit of the mark detection device 8 includes a wafer transfer device 66, a mark detection unit 52, and edge detection units 53A and 53B in addition to the above-described exposure unit. In FIG. 5B, the wafer transfer device 66 is fixed to the disc-shaped main body 67 and the upper surface of the main body 67, and is disposed so as to be movable in the Z direction within the opening formed in the frame member FR1. The columnar slide member 69, a flange portion 69F fixed to the upper end of the slide member 69, and a plurality of actuators 70 for controlling the position of the flange portion 69F in the Z direction with respect to the frame member FR1. As the actuator 70, for example, a direct-acting screw mechanism or an air cylinder can be used, and a sensor (not shown) for measuring the Z position of the flange portion 69F is also mounted. The conveyance control system 50 in FIG. 3 drives the actuator 70 based on the measurement value of the sensor, so that the Z position of the main body 67 connected to the flange 69F via the slide member 69 can be controlled. An arbitrary mechanism other than the mechanism using the actuator 70 can be used as a mechanism for controlling the Z position of the main body 67.

  The main body 67 has a circular shape slightly larger than the wafer W. The wafer transfer device 66 includes a plurality of short columnar non-contact suction devices (hereinafter referred to as suction cups) 68 fixed to the bottom surface of the main body 67 and a side surface of the main body 67 at substantially equal angular intervals ( Here, the connecting members 71A, 71B, 71C (see FIG. 5A) fixed at intervals of 120 degrees (see FIG. 5A) and the rotating members 71Am, 71Bm, etc. are attached to the connecting members 71A, 71B, 71C so as to be rotatable. L-shaped suction portions 72A, 72B, 72C. The suction cup 68 can also be called a Bernoulli cup or a Bernoulli chuck. The tip portions of the suction portions 72A to 72C can be retracted in the side surface direction of the main body portion 67 by the corresponding motors 71Am and the like, as typically indicated by the dotted line position B5. Furthermore, the tip portions of the suction portions 72A to 72C can be rotated by the corresponding motors 71Am and the like until they are parallel to the bottom surface of the main body portion 67, and the wafer W is supported on the tip portions of the suction portions 72A to 72C in this state. Is possible. A vacuum suction hole (not shown) is provided at the tip of the suction parts 72A to 72C, and a gas is sucked from the hole by a vacuum pump (not shown) through a flexible pipe (not shown). Thus, the wafer W can be sucked and held.

  FIG. 5B shows a state in which the wafer W is held by the tip portions of the suction portions 72A to 72C so as to face the plurality of suction cups 68 on the bottom surface of the main body portion 67 with a predetermined interval. As shown in FIG. 5A, as an example, the plurality of suction cups 68 are arranged so as to face the center of the surface of the wafer W and a plurality of concentrically arranged positions. In FIG. 5A, the main body 67 is represented by a two-dot chain line.

  As indicated by an arrow B1, the suction cup 68 ejects clean gas at a variable flow rate substantially radially along the surface facing the wafer W. When the distance between the surface and the wafer W increases, Bernoulli increases. When the negative pressure due to the effect is generated and the wafer W is sucked to the suction cup 68 side and the distance between the surface and the wafer W is reduced, a force that separates the wafer W from the suction cup 68 is exerted by the pressure air cushion effect. As a result, the distance between the suction cup 68 and the wafer W can be maintained at a value corresponding to the flow rate of the gas without contact. Then, the transfer control system 50 controls the distance between the plurality of suction cups 68 and the wafer W independently of each other, so that the shape of the wafer W held in a substantially non-contact manner protrudes toward the wafer stage WST, for example. Can be set to any shape including a shape (hereinafter referred to as a downward convex shape). For example, the plurality of suction cups 68 hold the wafer W in a downward convex shape and hold it in a non-contact manner, move the wafer holder 44 of the wafer stage WST to the lower side of the wafer W, and move the tips of the suction portions 72A to 72C to the side surfaces of the main body 67 By retracting in the direction and driving the actuator 70 to lower the main body 67 to the wafer holder 44 side, the large wafer W can be placed on the upper surface of the wafer holder 44 without being deformed. Generation of distortion can be prevented.

  Further, the mark detection unit 52 includes a first optical system 54A fixed to the main body 67 in the vicinity of the connecting member 71A (adsorption unit 72A), and a second optical system 54B attached to the adsorption unit 72A. Moreover, the edge detection parts 53A and 53B are being fixed to the main-body part 67 in the vicinity of the connection members 71B and 71C, respectively. Note that the first optical system 54A and the edge detection units 53A and 53B of the mark detection unit 52 may be fixed to the frame member FR1.

  FIG. 6A shows the mark detection unit 52 in FIG. In FIG. 6A, the wafer W is held at the front end portion of a suction portion 72A (not shown) of the wafer transfer device 66, and a mark 46 is formed on the back surface of the wafer W. Further, the first optical system 54A of the mark detection unit 52 emits, for example, light for detection in the visible region (hereinafter referred to as detection light), which is a wavelength region having low photosensitivity to the photoresist on the wafer W, in the approximately -Z direction. A light source 73 is provided. As an example, the light source 73 is a light emitting diode (LED), but a combination of a lamp and a light guide can be used as the light source 73. Of the detection light emitted from the light source 73, the first detection light DL1 used for detecting the edge portion of the wafer W is indicated by a dotted line, and the second detection light DL2 used for detecting the mark 46 on the back surface of the wafer W. Is represented by a solid line. In consideration of the possibility of contamination of the mark 46 caused by the wraparound of a film material or the like formed on the upper surface of the wafer W, which will be described later, at least the second detection light DL2 is light having a wide wavelength band (broadband detection light). It is preferable to use it.

  The first optical system 54A includes a first lens system 74A and a second lens system 74B for illuminating and collimating the detection lights DL1 and DL2 emitted from the light source 73, and the collimated detection lights DL1 and DL2 , And a half prism 76 that branches a part of the detection lights DL1 and DL2 reflected by the mirror M1 as detection lights DL1 and DL2 toward the wafer W in the -Z direction, And a first objective lens system 77A that condenses the branched detection lights DL1 and DL2. Further, the first optical system 54A includes a second objective lens 77B that forms an imaging optical system together with the first objective lens system 77A, a two-dimensional imaging element 79 such as a CCD type or a CMOS type, and light reception by the imaging element 79. An aperture stop for illumination disposed between the mirror M1 and the half prism 76, and an optical path length correction glass plate 80 that is disposed in front of a partial area of the surface and corrects the optical path length of the second detection light DL2. 75A (hereinafter referred to as illumination σ stop) and an imaging aperture stop 75B disposed between the half prism 76 and the second objective lens system 77B. The first optical system 54A is supported by a lens barrel member (not shown).

  As an example, since the edge portion of the wafer W is at the center of the test region (field of view) and the mark 46 on the back surface of the wafer W is at the periphery of the test region, the first detection light DL1 is within the illumination σ stop 75A. Is substantially parallel to the optical axis, and the second detection light DL2 is relatively inclined with respect to the optical axis. Further, a right-angle prism type as the second optical system 54B of the mark detection unit 52 so as to face the mark 46 on the back surface of the wafer W in the suction unit 72A (not shown in FIG. 6A) of the wafer transfer device 66. The optical member 82 is provided. As an example, the optical member 82 has an incident surface parallel to the back surface of the wafer W and two reflecting surfaces that intersect the incident surface at 45 degrees and are orthogonal to each other.

  As shown in the partial enlarged view of FIG. 6B, on the incident surface of the optical member 82, a portion facing the edge portion of the wafer W and a region in the vicinity thereof becomes a reflection surface 82b, and is in contact with the reflection surface 82b in the Y direction. Portions (including a portion facing the mark 46) are transmission surfaces 82a and 82c (see FIG. 6C). FIG. 6C is a plan view of the optical member 82 in FIG. As shown in FIG. 6C, the portions adjacent to the transmission surface 82c of the incident surface of the optical member 82 in the X direction become the reflection surfaces 82d and 82e, and the line-shaped index elongated in the Y direction in the reflection surfaces 82d and 82e. Marks 83A and 83B are formed. As an example, the index marks 83A and 83B are regions (black portions) having a lower reflectance than the other regions of the reflecting surfaces 82d and 82e, but the index marks 83A and 83B are regions having a higher reflectance than the other regions. Also good.

  In the mark detection unit 52, the first detection light DL1 emitted from the first objective lens system 77A is incident on the reflection surface 82b (see FIG. 6B) of the optical member 82. The first detection light DL1 reflected by the reflecting surface 82b passes outside the edge portion of the wafer W, and passes through the first objective lens system 77A, the half prism 76A, and the second objective lens system 77B. An image of the edge portion of the wafer W is formed at the center of the light receiving surface 79.

  On the other hand, the second detection light DL2 emitted from the first objective lens system 77A includes a transmission surface 82a of the optical member 82, two orthogonal reflection surfaces of the optical member 82, and a transmission surface 82c of the optical member 82 (FIG. 6 ( C), and enters the test region including the mark 46 on the back surface of the wafer W. Further, a part of the second detection light DL2 reflected by the two orthogonal reflecting surfaces of the optical member 82 has two index marks 83A and 83B provided so as to sandwich the transmitting surface 82c of FIG. 6C. Illuminate. The second detection light DL2 including the light beam reflected by the test region including the mark 46 and passing through the transmission surface 82c of the optical member 82 and the light beam reflected by the region including the index marks 83A and 83B is transmitted from the optical member 82. The light is returned to the first objective lens system 77A via two orthogonal reflecting surfaces and the transmitting surface 82a of the optical member 82. The second detection light DL2 returned to the first objective lens system 77A passes through the half prism 76A, the second objective lens system 77B, and the optical path length correction glass plate 80 to the periphery of the light receiving surface of the image sensor 79. Then, an image of the mark 46 on the wafer W and an image of the index marks 83A and 83B are formed.

  In the present embodiment, the imaging optical system including the objective lens systems 77A and 77B is used in the mark detection unit 52 in FIG. 6A in a state where the wafer W is held by the suction units 72A to 72C in FIG. The surface of the wafer W and the light receiving surface of the image sensor 79 are optically conjugate. Further, with respect to the imaging optical system, the optical member 82, and the optical path length correcting glass plate 80, the back surface of the wafer W (the surface on which the mark 46 is formed) and the light receiving surface of the image sensor 79 are optically conjugate. is there. Therefore, the image of the edge portion of the wafer W and the image of the mark 46 on the back surface are formed on the light receiving surface of the image sensor 79 with high contrast. Detection signals (here, imaging signals) obtained by the imaging element 79 capturing those images are supplied to the calculation unit 55 of FIG. By processing the detection signal by the calculation unit 55, the position information of the mark 46 and the edge portion of the wafer W in the vicinity of the mark 46 is obtained.

  Also, the edge detection units 53A and 53B in FIG. 5A have the same configuration as the first optical system 54A of the mark detection unit 52 in FIG. 6A. The edge detection units 53A and 53B capture images of the edge portions of the wafer W in the corresponding test areas FVA2 and FVA1, and supply the obtained detection signals (imaging signals) to the calculation unit 55. By processing the detection signal in the calculation unit 55, the position information of the corresponding edge portion can be obtained.

  Next, in the exposure apparatus EX of the present embodiment, a detection method for detecting position information and the like of the mark 46 on the back surface of the wafer W using the mark detection apparatus 8 and an example of an exposure method using this detection method are shown in FIG. This will be described with reference to a flowchart. The operation of this method is controlled by the main controller 20 and the conveyance control system 50. First, in step 102 in FIG. 7, the reticle R is loaded onto the reticle stage RST in FIG. 1, and the alignment of the reticle R is performed. At this time, the alignment of the auxiliary reticle RA is performed in advance. Thereafter, the wafer W coated with the photoresist is transferred from the coater / developer (not shown) to the transfer arm 61 of the wafer transfer robot WLD, and the tip of the transfer arm 61 holding the wafer W is shown in FIG. As shown in FIG. 4, the wafer transfer device 66 moves below the plurality of suction cups 68 (step 104). 8B is a cross-sectional view taken along line BB in FIG. 8A, and FIG. 8A corresponds to a cross-sectional view taken along line AA in FIG.

  At this time, the three suction portions 72A to 72C attached to the main body portion 67 do not collide with the wafer W moving in the Y direction, as typically shown by dotted line positions B4 and B5 in FIG. Evacuated to position. A gap is secured between the two arm portions 61a and 61b of the transfer arm 61 so that the suction portion 72A can pass therethrough. Thereafter, as shown by a solid line in FIG. 8B, the suction portions 72A to 72C are rotated to hold the wafer W at the tip portions of the suction portions 72A to 72C, and the main body portion 67 of the wafer transfer device 66 is slightly moved. By raising in the + Z direction, the wafer W is transferred from the transfer arm 61 to the wafer transfer device 66 (step 106). Substantially in parallel with this operation, wafer stage WST moves to wafer loading position LP below wafer transfer device 66. Then, the transfer arm 61 moves in the −Y direction as indicated by an arrow B8.

  Thereafter, as shown in FIGS. 5A and 5B, the detection regions DL1 and DL2 are irradiated from the first optical system 54A of the mark detection unit 52 to the test region including the edge portion of the wafer W, so that the suction unit 72A. The light receiving surface of the image sensor 79 (see FIG. 6A) in the first optical system 54A by the first detection light DL1 reflected by the second optical system 54B (the optical member 82 in FIG. 6B). Then, an image of the edge portion is formed. At the same time, the second detection light DL2 reflected by the back surface of the wafer W and the second detection light DL2 reflected by the region including the index marks 83A and 83B of FIG. 6C are transmitted via the second optical system 54B. Light is received, and an image of the mark 46 on the back surface of the wafer W and the index marks 83A and 83B is formed on the light receiving surface of the image sensor 79. The detection signal of the image sensor 79 is supplied to the calculation unit 55.

  The calculation unit 55 processes the detection signal, and as an example, with reference to the index marks 83A and 83B, the first position information including the positions in the X and Y directions of the edge portion of the wafer W, and the center of the mark 46 The second position information including the X-direction and Y-direction positions and the rotation angle of the mark 46 is obtained (step 108). As an example, the angle (tilt angle) with respect to the Y axis of the stage coordinate system (X, Y, Z) in the direction parallel to the index marks 83A, 83B is known. Therefore, as the rotation angle of the mark 46 on the back surface of the wafer, for example, an inclination angle with respect to the Y axis of the stage coordinate system (X, Y, Z) is obtained. It should be noted that without using the index marks 83A and 83B, for example, the first and second pixels are based on one or a plurality of pixels (for example, four pixels at the center and the periphery) at a predetermined position in the image sensor 79, for example. The position information may be obtained.

  Further, in parallel with step 108, detection light is irradiated from the edge detection units 53A and 53B into the test areas FVA2 and FVA1 including the edge part of the wafer W, and images of two edge parts are taken. The obtained detection signal is supplied to the calculation unit 55. The computing unit 55 obtains third position information including the positions in the X and Y directions of the corresponding two edge portions from the detection signal (step 110). Further, the computing unit 55 determines the position in the X and Y directions in the stage coordinate system at the center of the wafer W and the mark 46 from the position of the image of the three edge portions of the wafer W and the rotation angle of the image of the mark 46. A rotation angle of the stage coordinate system (and wafer W itself) with respect to the Y axis is calculated, and the calculation result is stored in the storage unit 56 and supplied to the main controller 20 (step 112).

  Then, in the state where the wafer W is held in a non-contact manner by the plurality of suction cups 68 of the wafer transfer device 66 in a non-contact manner from the state of FIG. 5B, the main body 67 of the wafer transfer device 66 is −Z. While lowering in the direction, the suction portions 72A to 72C are retracted to the outside. Further, the wafer W is lowered together with the main body 67, and when the central portion of the wafer W comes into contact with the surface of the wafer holder 44 of the wafer stage WST, vacuum suction on the wafer holder 44 side is started and the plurality of suction cups 68 are held. Is released, the entire back surface of the wafer W is placed on the wafer holder 44 and sucked (step 114). At this time, the positions of the wafer stage WST in the X direction and the Y direction may be corrected so that the center position of the wafer W obtained in step 112 comes to the center of the wafer holder 44. In this case, this correction can be regarded as a correction of the position of the wafer W. Thereafter, the main body 67 of the wafer transfer device 66 is raised.

  Then, as an example, main controller 20 uses stage drive system 18 to set wafer stage WST (or wafer holder 44) so that the rotation angle of mark 46 (wafer W) obtained in step 112 becomes a known target value. ) Is corrected, and wafer stage WST is moved in the X and Y directions so that the center position of wafer W obtained in step 112 is at the target position (step 116). As a result, the pre-alignment of the wafer W is performed. When the first layer of the wafer W is exposed by performing pre-alignment, the arrangement direction of the many shot areas SA of the wafer W is set in accordance with the direction defined by the mark 46 of the wafer W, for example. Is done. Further, when the second and subsequent layers of the wafer W are exposed, since pre-alignment has been performed, the wafer mark attached to the shot area SA to be detected on the surface of the wafer W is quickly moved to the alignment system AL. Thus, the final alignment (fine alignment) of the wafer W can be efficiently performed.

  Thereafter, in the process of driving wafer stage WST to move wafer W below projection optical system PL (exposure position), alignment of wafer W is performed using alignment system AL (step 118). Then, the reticle stage RST of FIG. 1 is driven, the substitute mark pattern 21 of the auxiliary reticle RA is moved to the center in the illumination area IAR of the illumination system ILS, and the substitute mark is used using the reticle blind in the illumination system ILS. The illumination area is limited so that the illumination light IL is irradiated only to a narrow area including the pattern 21 for use. Further, by driving wafer stage WST, as shown in FIG. 9A, for example, in region 26A close to edge portion Wf on the surface of wafer W in the region to be detected FVB of mark detection unit 52, A part is moved into the exposure area IA of the projection optical system PL of FIG. The region 26A is a region where a complete shot region SA is not formed (a region that becomes a so-called chipped shot), and is a peripheral region of the wafer W where the pattern image of the reticle R for devices is not exposed.

  Then, as shown in FIG. 9B, an image (substitute mark image) 21AP of the substitute mark pattern 21 of the auxiliary reticle RA in the area 26A of the front surface Wa of the wafer W opposed to the mark 46 on the back surface of the wafer W. Is exposed (step 120). The substitute mark pattern 21 is exposed in consideration of the positional relationship with the mark 46 on the back surface of the wafer W as described later. At this time, the main controller 20 may store the positional relationship between the mark 46 and the substitute mark pattern 21 or may be stored in an external database accessible by the main controller 20 of the exposure apparatus EX. Good.

  As an example, when the photoresist of the wafer W is a positive type, the image 21AP includes a plurality (three in this case) of line patterns having a large amount of light arranged in the Y direction and a plurality of (here here) arranged in the X direction. 3 lines) having a large amount of light. It should be noted that the images 21AP and 21CP of the substitute mark pattern 21 in FIGS. 9B and 9C are shown relatively large relative to the shot area SA. Further, since the substitute mark pattern 21 has a wider line width than the finest pattern among the device patterns, the image of the substitute mark pattern 21 is exposed by the dry method without using the liquid immersion method. May be.

  Further, wafer stage WST is driven, and as shown in FIG. 9A, the edge detection portions 53A and 53B are close to the edge portion Wf on the surface of the wafer W in the regions to be detected FVA2 and FVA1. Part of the areas 26C and 26B is sequentially moved into the exposure area IA of the projection optical system PL, and the images 21CP and 21BP of the substitute mark pattern 21 are exposed, respectively. The regions 26C and 26B are also in the peripheral region of the wafer W where the pattern image of the reticle R is not exposed as shown in FIG. 9C.

  Position information in the stage coordinate system of wafer stage WST at the time of exposure of these images 21AP to 21CP is supplied to calculation unit 55. In the calculation unit 55, the center position and rotation of the wafer W calculated based on the position in the X direction and the Y direction of each center of the images 21AP to 21CP from the position information of the wafer stage WST when the images 21AP to 21CP are exposed. An angle (for example, an angle with respect to the Y axis of the stage coordinate system in a direction orthogonal to a straight line connecting the centers of the images 21BP and 21CP) is calculated. Then, offsets (δx, δy) and δθ with respect to the center position and rotation angle (here, 0 degrees) of the wafer W after the calculation result is calculated in step 112 and corrected in step 116 are obtained. The offset (δx, δy) and δθ are stored in the storage unit 56 (step 122). The offset δθ of the tilt angle is the offset angle (relative angle) of the rotation angle of the wafer W obtained from the center of each of the images 21AP to 21CP (and later substitute marks 21AM to 21CM) with respect to the direction of the mark 46 on the back surface of the wafer W. ) Can be said.

  Thereafter, for example, by driving the wafer W using the alignment result in step 118, an image of the pattern of the reticle R is scanned and exposed on each shot area of the wafer W (step 124). Thereafter, wafer stage WST is moved to unloading position UP, for example, another wafer transfer device is lowered, and wafer W is transferred from wafer holder 44 to the wafer transfer device, thereby unloading wafer W (step 126). ). The unloaded wafer W is transferred to a coater / developer (not shown) and developed (step 130), and then proceeds to the pattern formation process (step 134) of the next layer through, for example, an etching process (step 132). . In the exposure apparatus EX, when the next wafer is exposed (step 128), the operations of steps 104 to 126 are repeated for the next wafer.

  As shown in FIG. 9A, on the surface of the wafer W that has undergone step 132, the areas to be the test areas FVAB of the mark detection unit 52 and the test areas FVA2 and FVA1 of the edge detection units 53A and 53B are formed. , Two-dimensional substitution marks 21AM, 21CM, and 21BM are formed. The substitution mark 21AM or the like is a concave / convex mark in which a portion with a large amount of light such as an image 21AP of the substitution mark pattern 21 is a recess. Thereafter, when exposure is performed on the next layer of the wafer W on which the substitute marks 21AM, 21CM, and 21BM are formed, mark detection using the substitute marks 21AM, 21CM, and 21BM is appropriately performed. For example, when the exposure operation on the surface of the wafer W is repeated, a film material (foreign matter) such as a resist material may wrap around the back surface of the wafer W. When the encircling film material adheres to the mark 46 on the back surface of the wafer W as a foreign substance, it may be difficult to detect the mark 46 by the mark detection unit 52. Further, in the exposure process of the wafer W, it may be difficult to detect the mark 46 by the mark detection unit 52 due to some cause (such as wear).

In the above case, the operation of step 108A is executed instead of steps 108 and 110 of FIG.
In this step 108A, as shown in FIG. 5B, the first optical system 54A from the first optical system 54A of the mark detection unit 52 in a state where the wafer W is held by the suction units 72A to 72C of the wafer transfer device 66. The edge of the wafer W is irradiated with the detection light DL1. Then, the first detection light DL1 reflected by the optical member 82 in FIG. 6A and the first detection light DL1 reflected by the portion including the substitute mark 21AM on the surface of the wafer W in FIG. The image is returned to the first optical system 54A in FIG. 5B, and an image of the edge portion of the wafer W and the substitute mark 21AM is picked up by the image pickup element 79 (see FIG. 6A) in the first optical system 54A. The detection signal is supplied to the calculation unit 55. In step 108A, an image of the edge portion of the wafer W is not necessarily required. In addition, an unclear image of the mark 46 on the back surface of the wafer W may be formed in the periphery of the light receiving surface of the image sensor 79, but the unclear image is not used.

  In parallel with the image pickup of the substitute mark 21AM, the edge detectors 53A and 53B in FIG. 5A pick up images of the substitute marks 21CM and 21BM on the surface of the wafer W in FIG. The signal is supplied to the calculation unit 55. The calculation unit 55 processes these detection signals in a process corresponding to step 112 in FIG. 7, and based on the center positions of the substitution marks 21AM, 21BM, and 21CM, the wafer W center position and the wafer W rotation angle ( For example, the angle with respect to the Y axis of the stage coordinate system in the direction orthogonal to the straight line connecting the centers of the substitution marks 21BM and 21CM is calculated. Further, for example, the calculation unit 55 subtracts the position and rotation angle offset (δx, δy) and δθ stored in step 122 from these calculation results to obtain the center position and rotation angle of the wafer W, and stores the obtained results. Store in the unit 56.

  Thereafter, the center position and rotation angle of the wafer W are corrected in step 116, so that the center position and rotation angle of the wafer W are detected by the mark 46 on the back surface of the wafer W detected by the mark detection unit 52 and the edge portion of the wafer W. It is set to the same position and rotation angle as those set based on the result obtained from the position and the positions of the two edge portions of the wafer W detected by the edge detectors 53A and 53B.

  According to this exposure method, when there is no notch on the outer shape of the wafer W and the mark 46 is formed on the back surface of the wafer W, the mark detection device 8 causes the mark 46 and the three edge portions of the wafer W to be formed. By detecting the position information and obtaining the center position of the wafer W and the rotation angle of the mark 46 (wafer W) from the detection result, the wafer W can be pre-aligned. Therefore, when the second and subsequent layers of the wafer W are exposed, the final alignment of the wafer W can be performed efficiently, and each shot area of the wafer W can be formed with high overlay accuracy with the pattern image of the reticle R. Can be exposed. Further, when the second and subsequent layers of the wafer W are exposed, even if it is difficult to detect the mark 46 on the back surface of the wafer W, the wafer W is formed on the basis of the substitute marks 21AM to 21CM formed on the front surface of the wafer W. The center and the rotation angle can be accurately detected, and the pre-alignment of the wafer W can be accurately performed based on the detection result.

  As shown in FIG. 4F, when a conventional wafer W1 having a diameter of 300 mm or the like and provided with a notch portion NT as a notch portion is used, for example, two test regions (fields of view) are used. The position of the edge portion of the wafer W1 is detected by the FVA1 and FVA2, the position and direction of the notch portion NT is detected in the test region FVA3, and the center and rotation angle of the wafer W1 are obtained from these detection results. On the other hand, as shown in FIG. 4G, when using a wafer W2 having a diameter of 300 mm or the like and provided with an orientation flat portion OF as a notch, for example, in two test regions FVA2 and FVA3 The position and angle of the orientation flat portion OF are detected, the position of the edge portion of the wafer W2 is detected in the test area FVA1, and the center and rotation angle of the wafer W2 are obtained from these detection results. Based on the centers and rotation angles of the wafers W1 and W2 thus obtained, the wafers W1 and W2 are pre-aligned.

On the other hand, when using a wafer W having no cutout in the outer shape and having the mark 46 formed on the back surface as in the present embodiment, the mark 46 on the back surface of the wafer is used by using the mark detection device 8. The wafer W can be pre-aligned by detecting the position information.
Further, according to the exposure apparatus of the present embodiment, the wafer W is placed in the downward convex shape in a substantially non-contact state using the wafer delivery device 66, and the wafer W is placed on the wafer holder 44 of the wafer stage WST. . For this reason, even if the wafer W is as large as a 450 mm wafer, the wafer W can be held on the wafer holder 44 in a state in which the flatness of the wafer W is maintained high without any residual distortion of the wafer W. Accordingly, high throughput can be obtained using the large wafer W, and the exposure accuracy (resolution, etc.) can be kept high on the entire surface of the wafer W, and the pattern image of the reticle R can be exposed with high accuracy.

  As described above, the exposure apparatus EX of the present embodiment includes the mark detection apparatus 8 that detects position information (including angle information) of marks formed on the wafer W (substrate). The mark detection device 8 holds the wafer W on the wafer transfer device 66 (substrate holding unit) that temporarily holds the wafer W on which the mark 46 (first mark) is formed on the back surface, and the wafer transfer device 66. The mark detection unit 52 (first detection unit) that detects the position information of the mark 46 and the replacement marks 21AM to 21CM (second display) on the surface of the wafer W based on the detected position information of the mark 46. A mark forming unit including an exposure unit (illumination system ILS, reticle stage RST including auxiliary reticle RA, and projection optical system PL) that exposes images 21AP to 21CM for forming (mark). Further, the mark detection device 8 stores the positional relationship between the mark 46 and the substitute marks 21AM to 21CM (for example, the offset of the rotation angle of the wafer W obtained from each center of the substitute marks 21AM to 21CM with respect to the direction of the mark 46). A mark detection unit 52 and edge detection units 53A and 53B (second detection units) that detect the position information of the substitute marks 21AM to 21CM in a state where the wafer W is held by the storage unit 56 and the wafer transfer device 66; It has.

  The mark detection method for detecting the position information of the mark on the wafer W according to the present embodiment includes a step 106 in which the wafer W having the mark 46 formed on the back surface is temporarily held by the wafer transfer device 66, and the wafer transfer device 66. And step 108 for detecting the position information of the mark 46 in a state where the wafer W is held. Further, the mark detection method includes steps 120, 130, and 132 for forming replacement marks 21AM to 21CM on the surface of the wafer W based on the detected position information of the mark 46, the mark 46, and the replacement marks 21AM to 21CM. The step 122 for storing the positional relationship of the above and the step 108A for detecting the position information of the substitute marks 21AM to 21CM in a state where the wafer W is held by the wafer transfer device 66.

  According to the present embodiment, the position information of the mark 46 on the back surface of the wafer W is detected while the wafer W is held by the wafer delivery device 66. That is, since the mark 46 is detected during the transfer until the wafer W is placed on the wafer stage WST, the wafer W is large like a 450 mm wafer and the mark 46 is formed on the back surface. However, the position information of the mark 46 can be detected efficiently. Furthermore, since the positional relationship between the substitute marks 21AM to 21CM formed on the front surface of the wafer W and the mark 46 on the back surface of the wafer W is stored, the substitute mark 21AM can be detected even when the mark 46 is difficult to detect. By detecting the position information of ˜21 CM, the position information including the rotation angle of the wafer W can be detected based on the detection result as in the case of detecting the position information of the mark 46 on the back surface of the wafer W.

  The exposure apparatus EX of the present embodiment is an exposure apparatus that illuminates the pattern of the reticle R with the illumination light IL for exposure and exposes the wafer W through the pattern with the illumination light IL. And the main controller for correcting the position and rotation angle of the center of the wafer W based on the position information of the mark 46 on the back surface of the wafer W or the substitute marks 21AM to 21CM on the front surface of the wafer W detected by the mark detection device 8. 20 (control unit). The exposure method using the exposure apparatus EX includes steps 108 and 108A for detecting the position information of the mark 46 on the wafer W or the substitute marks 21AM to 21CM using the mark detection method of the present embodiment, and the wafer W as the wafer stage WST. And a step of correcting the center position and rotation angle of the wafer W based on the position information detected by the mark detection method.

  According to the exposure apparatus or the exposure method of this embodiment, high throughput can be obtained by using a large wafer W. Further, even if the mark 46 is formed on the back surface of the wafer W, or even if it is difficult to detect the mark 46, the position information of the mark 46 or the alternative marks 21AM to 21CM can be detected efficiently. The pre-alignment is performed by correcting the position and the rotation angle of the wafer W using. For this reason, the final alignment of the subsequent wafer W can be efficiently performed, and higher throughput can be obtained.

In the above embodiment, the following modifications are possible.
First, in the above-described embodiment, the position and rotation angle of the center of the wafer W are corrected in step 116. However, at least one of the position and rotation angle may be corrected.
In the above embodiment, the wafer W is a 450 mm wafer as an example. However, for example, even in a 300 mm wafer or other arbitrary size wafer, a mark is provided on the back surface instead of providing a notch. First, a mark on the back surface of the wafer is detected using a detection device or detection method similar to the mark detection device 8 of the above embodiment, and a substitute mark is formed on the surface of the wafer W based on the detection result. May be.

  In the above embodiment, a two-dimensional substitute mark 21AM as shown in FIG. 9B is used as a substitute mark for the mark 46 on the back surface of the wafer W, but the shape of the substitute mark is arbitrary. is there. For example, as an alternative mark, as shown in FIG. 9D, a central portion 27Aa composed of a frame-shaped concave portion (or a convex portion, the same applies hereinafter) and the central portion 27Aa are sandwiched in the X direction and the Y direction. A two-dimensional mark 27 </ b> A including a line pattern made up of a plurality of recesses arranged respectively can be used. Further, as an alternative mark, as shown in FIG. 9 (E), a plurality of line patterns 27BY composed of recesses elongated in the X direction and a plurality of line patterns 27BY elongated so as to sandwich the line pattern 27BY in the X direction. A two-dimensional mark 27 </ b> B including a line pattern 27 </ b> BX formed of a recess can be used.

  Further, as a substitute mark for the mark 46 on the back surface of the wafer W, as shown in FIG. 9F, in the Y direction (radial direction with respect to the center of the wafer W) as in the mark 46 in FIG. 4B. An alternative mark 27C in which a plurality of small concave portions 27Ca is formed can also be used. As with the mark 46 in FIG. 4B, the direction of the straight line passing through the centers of the plurality of recesses 27Ca can be regarded as the direction of the replacement mark 27C. When the substitute mark 27C is used, an angle (relative angle) between the direction of the mark 46 and the direction of the substitute mark 27C may be stored as the positional relationship between the mark 46 and the substitute mark 27C.

  In the above embodiment, the substitute marks 21AP and the like are formed in a peripheral region near the edge portion Wf on the surface of the wafer W. However, as shown in FIG. An alternative mark 21AP or the like may be formed in the scribe line area SL between a plurality of adjacent shot areas SA. Note that the substitute marks 21AP and the like are actually large enough to fit within the scribe line area SL.

  Further, in the above embodiment, as the substitute marks for the mark 46 on the back surface of the wafer W, three substitute marks 21AM to 21CM are formed on the front surface of the wafer W as shown in FIG. However, only one substitute mark may be formed on the front surface of the wafer W so as to correspond to the mark 46 on the back surface of the wafer W, for example. For this purpose, as an example, one substitute mark 27C shown in FIG. 9F is formed in the region to be detected by the mark detection unit 52 on the front surface of the wafer W in correspondence with the mark 46 on the back surface of the wafer W. May be. In this case, after the rotation angle of the wafer W is corrected in step 116 of FIG. 7 so that the direction of the mark 46 on the back surface of the wafer W is parallel to the Y axis of the stage coordinate system, an alternative mark 27C is formed in step 120. The pattern image (a plurality of dot pattern images) of the auxiliary reticle (not shown) may be exposed in parallel with the Y axis. At this time, since the direction of the substitution mark 27C is parallel to the direction of the mark 46, it is stored as a positional relationship between the substitution mark 27C and the mark 46 that the relative angle between these marks is 0 degree. . Therefore, after that, when the mark 46 on the back surface of the wafer W cannot be detected, the mark detection unit 52 detects the substitute mark 27C on the front surface of the wafer W, and sets the direction of the substitute mark 27C as the direction of the wafer W. Thus, the rotation angle of the wafer W can be accurately corrected as in the case where the mark 46 is detected.

  Further, in the above embodiment, the substitute mark is formed on the front surface of the wafer W based on the detection result of the mark 46 on the back surface of the wafer W. However, instead of forming a substitute mark on the surface of the wafer W, as shown in FIG. 9B, a certain area on the surface Wa of the wafer W and a pattern in the surface (for example, a circuit pattern DP1 for a device). ) Or the reflectance distribution (for example, the reflectance distribution of the surface of the substrate SU or a certain layer) is detected from the position information of the pattern of another region or the region CP (hereinafter referred to as a feature) that can be distinguished from the reflectance distribution. Also good.

  When the feature CP is detected by the mark detection unit 52, as an example, a partial region centered on a certain pixel is selected from the image of the surface of the wafer W picked up by the image sensor 79 of the mark detection unit 52, and this portion A plurality of shift partial regions obtained by shifting the region by one pixel, for example, several pixels in the X direction and the Y direction are selected. Furthermore, as an example, an integrated value of absolute values of differences between detection signals of a plurality of pixels between the partial region and a plurality of shift partial regions is set as an identification value. When the identification value between the partial area and the plurality of shift partial areas is larger than a predetermined threshold value, the partial area is regarded as an image of the feature portion CP that can be distinguished from other areas. Can do.

  In this case, the calculation unit 55 processes the detection signal from the mark detection unit 52 to obtain the distribution of the detection signal for each pixel of the image of the feature CP, and stores the distribution of the detection signal in the storage unit 56. Let Further, in the calculation unit 55, the direction of the image of the mark 46 on the back surface of the wafer W and the direction of the image of the feature portion CP (for example, the direction of a straight line passing through two positions (pixels) in the image of the feature portion CP). And the amount of positional deviation between the center of the image of the mark 46 and the center of the image of the feature portion CP are obtained as information on the relative position between the mark 46 and the feature portion CP, and the information on the relative position is corrected. Is stored in the storage unit 56. Thereafter, when exposure is performed on the next layer of the wafer W and detection of the mark 46 on the back surface of the wafer W is difficult, the object including the edge portion of the wafer W detected by the mark detection unit 52 is detected. A region having a detection signal distribution closest to the distribution of the detection signal of the image of the feature portion CP is obtained as an image of the feature portion CP from the image of the detection region. Then, the position and direction of the image of the feature portion CP are obtained, and the position and direction are corrected by the stored correction information, thereby accurately determining the position and direction of the mark 46 on the back surface of the wafer W. Can be estimated. Therefore, the center and rotation angle of the wafer W can be accurately calculated in step 112 using the estimated position and direction of the mark 46.

  The mark detection device 8 in the case of detecting the feature portion CP includes a wafer transfer device 66 that temporarily holds the wafer W having the mark 46 formed on the back surface, and a state in which the wafer W is held by the wafer transfer device 66. Thus, the mark detection unit 52 (first detection unit) that detects the position information of the mark 46 on the back surface of the wafer W can be distinguished from the pattern or reflectance distribution on the surface of the wafer W in other regions of the surface. A mark detection unit 52 (second detection unit) that detects position information of the characteristic part CP, and a storage unit 56 that stores a positional relationship (such as a relative angle) between the mark 46 and the characteristic part CP.

In this embodiment, the mark detection unit 52 that detects the mark 46 and the mark detection unit 52 that detects the feature CP are the same, but the detection unit that detects the feature CP is different from the mark detection unit 52. It may be.
The mark detection method for detecting the feature portion CP includes a step 106 in which the wafer W having the mark 46 formed on the back surface is temporarily held by the wafer transfer device 66, and the wafer W is held by the wafer transfer device 66. And 108, detecting the position information of the mark 46. Further, the mark detection method detects the positional information of the feature portion CP on the surface of the wafer W (step corresponding to step 108), and stores the positional relationship between the mark 46 and the feature portion CP (corresponding to step 112). Process).

  As described above, even when the feature portion CP is used, even if the wafer W is large like a 450 mm wafer and the mark 46 is formed on the back surface, the position information of the mark 46 can be detected efficiently. Further, since the positional relationship between the feature portion CP on the front surface of the wafer W and the mark 46 on the back surface of the wafer W is stored, the position information of the feature portion CP is detected even when the detection of the mark 46 becomes difficult. Thus, based on the detection result, the position information including the rotation angle of the wafer W can be detected in the same manner as the position information of the mark 46 on the back surface of the wafer W is detected. Based on the detection result, the pre-alignment of the wafer W can be accurately performed.

  The substitute mark 27 can be provided on any layer formed on the surface of the wafer W. For example, the tendency of the degree of contamination of the mark 46 may be grasped by an experiment or simulation, and the substitute mark 27 may be formed on a specific layer based on the knowledge based on the experiment or simulation result. Furthermore, the result of the above-described experiment and the result of the simulation may be stored in a database accessible by the main controller 20 so that the main controller 20 can appropriately access the database. Further, the substitute mark 27 may be formed on only one specific layer on the surface of the wafer W, or the substitute mark 27 may be formed on a plurality of layers.

[Second Embodiment]
A second embodiment will be described with reference to FIG. The basic configuration of the exposure apparatus of the present embodiment is substantially the same as that of the exposure apparatus EX of FIG. 1, but the configuration of the mark detection apparatus and the configuration of a part of the position measurement mechanism of wafer stage WST are different. 10, parts corresponding to those in FIG. 1 and FIGS. 5A and 5B are denoted by the same or similar reference numerals, and detailed description thereof is omitted.

  FIG. 10 shows a mechanism part of the mark detection apparatus 8A according to this embodiment. In the mark detection device 8A, a wafer transfer robot WLD is used as a substrate holding unit for temporarily holding the wafer W instead of the wafer transfer device 66 of the first embodiment. In addition, a plurality of rod-like members (center pins) (not shown) that can be vacuum-sucked so as to be movable in the Z direction are arranged in wafer holder 44 of wafer stage WST, and the wafer conveyance robot WLD carries them through these rod-like members. The wafer W can be delivered from the arm 61 to the wafer holder 44. Therefore, in the present embodiment, the wafer transfer device 66 in FIG. 5A is not necessarily required.

  FIG. 10 shows a state where wafer stage WST on base board WB is moving in the −Y direction toward loading position LP below transfer arm 61 holding wafer W of wafer transfer robot WLD. Yes. An opening 30a is formed in the bottom surface of the stage main body 30 of the wafer stage WST of the exposure apparatus of the present embodiment so as to penetrate in the Y direction, and the diffraction gratings 12A to 12D in FIG. A similar two-dimensional diffraction grating 12E is fixed.

  Further, the frame member FR2 is stably supported on the floor surface via a vibration isolator (not shown). An L-shaped branch frame FR3 is fixed to the bottom surface of the frame member FR2. The transfer arm 61 and the like of the wafer transfer robot WLD can move in the notch FR3b provided in the branch frame FR3. Similar to the detection head 14 in FIG. 2, the measurement beam is irradiated to the diffraction grating 12E on the end of the elongated flat plate rod portion FR3a parallel to the Y direction of the branch frame FR3 on the + Y direction side, and the diffraction grating 12E (and thus A detection head 14A for measuring relative displacement in the X and Y directions with respect to wafer stage WST) is fixed. That is, when wafer stage WST is moved in the −Y direction, rod portion FR3a of branch frame FR3 is inserted into opening portion 30a of stage body 30, and is provided on stage body 30 by detection head 14A provided on rod portion FR3a. The diffraction grating 12E can be detected. As described above, the exposure apparatus of this embodiment includes an additional encoder including the diffraction grating 12E and the detection head 14A in addition to the encoder 6 of FIG. With this additional encoder, the position of wafer stage WST in the X and Y directions can be measured in the vicinity of loading position LP.

  The mark detection unit 52A of the present embodiment includes a first optical system 54C provided on the frame member FR2 and a second optical system 54D provided on the rod portion FR3a of the branch frame FR3. The first optical system 54C irradiates the region including the edge portion of the wafer W with the detection light DL1, receives the reflected light from the wafer W, and takes an image of the edge portion with the internal first imaging element 79A. To do.

  In the second optical system 54D, the detection light DL2 having the same wavelength region as the detection light DL1 emitted from the light source 73A is incident on the half prism 76A through the illumination lens system 74A, and is + Z direction by the half prism 76A. The detection light DL2 branched to 1 illuminates the test region including the mark 46 on the back surface of the wafer W. The detection light DL2 reflected by the test region passes through the half prism 76A, passes through an opening (not shown) provided in the rod portion FR3a, and is reflected by the mirror M2 on the bottom surface side of the rod portion FR3a. The reflected detection light DL2 forms an image of the mark 46 on the back surface of the wafer W on the light receiving surface of the second image sensor 79B via the objective lens systems 77C and 77D (imaging optical system). The imaging elements 79A and 79B respectively capture the edge portion of the wafer W and the image of the mark 46, and supply a detection signal to the calculation unit 55 in FIG.

  The frame FR2 is provided with edge detection units 53A1 and 53B1 having the same configuration as the edge detection units 53A and 53B at substantially equal angular intervals along the edge portion of the wafer W together with the first optical system 54C. The edge detection units 53A1 and 53B1 capture images of two edge portions of the wafer W, and supply detection signals to the calculation unit 55. The calculation unit 55 processes these detection signals to determine the center position and rotation angle of the wafer W. Thereafter, wafer stage WST is moved below transfer arm 61 (loading position LP), wafer W is transferred from transfer arm 61 to wafer holder 44 of wafer stage WST, and then the position and rotation angle of wafer W are corrected. Thus, pre-alignment of the wafer W is performed.

  Similarly to the first embodiment, the image 21AP, 21BP, 21CP of the pattern for the substitute mark shown in FIG. 9A is exposed on the surface of the wafer W, and the substitute marks 21AM, 21BM, 21CM are developed and etched. Is formed. Position information of these substitute marks 21AM, 21BM, and 21CM can be detected by the first optical system 54C of the mark detection unit 52A and the edge detection units 53B1 and 53A1 in FIG. Therefore, as in the first embodiment, even if it is difficult to detect the mark 46 on the back surface of the wafer W, the wafer is based on the detection result by detecting the position information of the substitute marks 21AM, 21BM, and 21CM. W pre-alignment can be performed.

In each of the above embodiments, the first optical system 54 </ b> C of the imaging method, the edge detectors 53 </ b> A and 53 </ b> B, and the like are used to detect the edge portion of the wafer W. As another configuration, for example, a parallel light beam is irradiated so as to pass through the edge portion of the wafer W, and the light passing through the edge portion is detected by a photoelectric detector such as a photomultiplier or a photodiode via a condensing optical system. The position of the edge portion may be detected from the received light amount (detection signal).
In the above embodiment, an exposure unit that exposes the pattern of the auxiliary reticle is used as the mark forming unit. As the mark forming unit, for example, an apparatus that forms a mark on the surface of the wafer by irradiating a laser pulse. Any other device can be used.

Further, in each of the above embodiments, in order to detect the position of the mark 46 on the back surface of the wafer W, the imaging type mark detection unit 52 and the second optical system 54D are used. As another configuration, for example, a detection unit that detects position information of the mark 46 by irradiating the mark 46 with a coherent light beam and detecting diffracted light generated from the mark 46 may be used.
In the first embodiment, the wafer transfer robot WLD shown in the second embodiment may be used instead of the wafer transfer device 66.
Further, as a countermeasure against contamination of the mark 46, for example, the back surface of the wafer W may be cleaned. Various methods can be used as the cleaning method. For example, the back surface may be optically cleaned before the wafer W is placed on the wafer holder 44. Alternatively, before the wafer W is placed on the wafer holder 44, a predetermined chemical solution may be applied to the back surface of the wafer W and cleaned, or the back surface of the wafer W may be polished with a grindstone or the like.

  When an electronic device (or microdevice) such as a semiconductor device is manufactured using the exposure apparatus EX or the exposure method of each of the above embodiments, the electronic device has functions and performances of the electronic device as shown in FIG. Step 221 for performing design, Step 222 for manufacturing a reticle (mask) based on this design step, Step 223 for manufacturing a substrate (wafer) as a base material of the device and applying a resist, and the exposure apparatus of the above-described embodiment Substrate processing step 224 including a step of exposing a reticle pattern to the substrate (photosensitive substrate) by (exposure method), a step of developing the exposed substrate, a heating (curing) and etching step of the developed substrate, and a device assembly step ( (Including processing processes such as dicing, bonding, and packaging) 5, and an inspection step 226, and the like.

  In other words, in this device manufacturing method, the pattern of the photosensitive layer is formed on the substrate using the exposure apparatus EX or the exposure method of the above embodiment, and the substrate on which the pattern is formed is processed (development, etc.). And doing. At this time, according to the exposure apparatus EX or the exposure method of the above embodiment, even if the substrate is large and a mark is formed on the back surface, the mark on the substrate is efficiently detected, and the alignment of the substrate is efficiently performed. Therefore, an electronic device can be manufactured with high accuracy with extremely high throughput (productivity).

The present invention can be applied to a step-and-repeat type projection exposure apparatus (stepper or the like) in addition to the above-described scanning exposure type projection exposure apparatus (scanner). Furthermore, the present invention can be similarly applied to a dry exposure type exposure apparatus other than an immersion type exposure apparatus.
In addition, the present invention is not limited to application to an exposure apparatus for manufacturing a semiconductor device, for example, an exposure apparatus for a display device such as a liquid crystal display element formed on a square glass plate or a plasma display, It can also be widely applied to an exposure apparatus for manufacturing various devices such as an image sensor (CCD or the like), a micromachine, a thin film magnetic head, and a DNA chip. Furthermore, the present invention can also be applied to an exposure apparatus when manufacturing a mask (photomask, reticle, etc.) on which a mask pattern of various devices is formed using a photolithography process.

  In addition, this invention is not limited to the above-mentioned embodiment, Of course, a various structure can be taken in the range which does not deviate from the summary of this invention.

  EX ... exposure apparatus, R ... reticle, W ... wafer, WST ... wafer stage, WLD ... wafer transfer robot, 8, 8A ... mark detection device, 21 AM-21CM ... substitution mark, 44 ... wafer holder, 46 ... mark on the back of the wafer, 52 ... Mark detection unit, 53A, 53B ... Edge detection unit, 55 ... Calculation unit, 66 ... Wafer transfer device, 67 ... Main body unit, 68 ... Suction cup, 72A to 72C ... Adsorption unit

Claims (20)

A mark detection device for detecting a mark formed on a substrate,
A substrate holding part for temporarily holding the substrate on which the first mark is formed on the back surface;
A first detection unit that detects position information of the first mark on the back surface in a state where the substrate is held by the substrate holding unit;
A mark forming unit for forming a second mark on the surface of the substrate based on the detected position information of the first mark;
A storage unit for storing a positional relationship between the first mark and the second mark;
A second detection unit for detecting position information of the second mark on the surface in a state where the substrate is held by the substrate holding unit;
A mark detection apparatus comprising: The mark forming portion is
The mark detection apparatus according to claim 1, further comprising an exposure unit that exposes the substrate through a pattern corresponding to the second mark.   3. The second mark according to claim 1, wherein the second mark is formed in a region near an edge portion of the surface of the substrate or a scribe line region between a plurality of exposed regions arranged on the surface of the substrate. Mark detection device.   The mark detection apparatus according to claim 1, wherein the second mark is a mark that defines a position in two orthogonal directions. A mark detection device for detecting a mark formed on a substrate,
A substrate holding part for temporarily holding the substrate on which the first mark is formed on the back surface;
A first detection unit that detects position information of the first mark on the back surface in a state where the substrate is held by the substrate holding unit;
A second detector for detecting position information of a feature that is distinguishable from a pattern or reflectance distribution in the surface of the substrate and in other regions of the surface;
A storage unit that stores a positional relationship between the first mark and the feature unit;
A mark detection apparatus comprising:   The mark detection device according to claim 1, wherein the first mark formed on the back surface of the substrate has a plurality of concave portions arranged along a straight line on the back surface.   The mark detection apparatus according to claim 1, wherein the substrate has a disk shape with a diameter of 300 to 450 mm. In an exposure apparatus that illuminates a pattern with exposure light and exposes the substrate through the pattern and the projection optical system with the exposure light,
The mark detection device according to any one of claims 1 to 4,
A stage for holding and moving the substrate;
Based on positional information of the first mark formed on the back surface of the substrate detected by the mark detection device or the second mark on the surface of the substrate, at least one of a position and a rotation angle of the substrate with respect to the pattern A control unit for correcting
An exposure apparatus comprising: In an exposure apparatus that illuminates a pattern with exposure light and exposes the substrate through the pattern and the projection optical system with the exposure light,
A mark detection device according to claim 5;
A stage for holding and moving the substrate;
Based on positional information of the first mark formed on the back surface of the substrate detected by the mark detection device or the characteristic portion of the surface of the substrate, at least one of a position and a rotation angle of the substrate with respect to the pattern is determined. A control unit to correct,
An exposure apparatus comprising: A mark detection method for detecting a mark formed on a substrate,
Temporarily holding the substrate on which the first mark is formed on the back surface by the substrate holding unit;
Detecting the position information of the first mark on the back surface in a state where the substrate is held by the substrate holding unit;
Forming a second mark on the surface of the substrate based on the detected position information of the first mark;
Storing a positional relationship between the first mark and the second mark;
Detecting the position information of the second mark on the surface in a state where the substrate is held by the substrate holding unit;
Mark detection method including Forming the second mark comprises:
Exposing the substrate through a pattern corresponding to the second mark;
The mark detection method according to claim 10, comprising developing the substrate.   The mark according to claim 10 or 11, wherein the second mark is formed in a region in the vicinity of an edge portion on the surface of the substrate or a scribe line region between a plurality of exposed regions arranged on the surface of the substrate. Detection method.   The mark detection method according to claim 10, wherein the second mark is a mark that defines a position in two orthogonal directions. A mark detection method for detecting a mark formed on a substrate,
Temporarily holding the substrate on which the first mark is formed on the back surface by the substrate holding unit;
Detecting the position information of the first mark on the back surface in a state where the substrate is held by the substrate holding unit;
Detecting positional information of features on the surface of the substrate that can be distinguished from patterns or reflectance distributions in other regions of the surface;
Storing a positional relationship between the first mark and the feature;
Mark detection method including   The said 1st mark formed in the back surface of the said board | substrate is a mark detection method as described in any one of Claims 10-14 which has several recessed part arrange | positioned along the straight line in the said back surface.   The mark detection method according to claim 10, wherein the substrate has a disk shape with a diameter of 300 to 450 mm. In an exposure method of illuminating a pattern with exposure light and exposing the substrate through the pattern with the exposure light,
The position information of the said 1st mark formed in the back surface of the said board | substrate using the mark detection method as described in any one of Claims 10-13, or the said 2nd mark formed in the surface of the said board | substrate is detected. And
Placing the substrate on a stage;
Correcting at least one of a position and a rotation angle of the substrate with respect to the pattern based on position information detected by the mark detection method;
An exposure method comprising: In an exposure method of illuminating a pattern with exposure light and exposing the substrate through the pattern with the exposure light,
Using the mark detection method according to claim 14 to detect position information of the first mark formed on the back surface of the substrate or the characteristic portion of the surface of the substrate;
Placing the substrate on a stage;
Correcting at least one of a position and a rotation angle of the substrate with respect to the pattern based on position information detected by the mark detection method;
An exposure method comprising: Forming a pattern of a photosensitive layer on a substrate using the exposure apparatus according to claim 8 or 9,
Processing the substrate on which the pattern is formed;
A device manufacturing method including: Forming a pattern of a photosensitive layer on a substrate using the exposure method according to claim 17 or 18,
Processing the substrate on which the pattern is formed;
A device manufacturing method including:

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