WO2015178109A1 - Wafer position detection apparatus, wafer position detection method, and storage medium - Google Patents

Wafer position detection apparatus, wafer position detection method, and storage medium Download PDF

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Publication number
WO2015178109A1
WO2015178109A1 PCT/JP2015/060719 JP2015060719W WO2015178109A1 WO 2015178109 A1 WO2015178109 A1 WO 2015178109A1 JP 2015060719 W JP2015060719 W JP 2015060719W WO 2015178109 A1 WO2015178109 A1 WO 2015178109A1
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Prior art keywords
wafer
light
mark
luminance
detecting
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PCT/JP2015/060719
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French (fr)
Japanese (ja)
Inventor
秀明 柏木
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東京エレクトロン株式会社
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Publication of WO2015178109A1 publication Critical patent/WO2015178109A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/68—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for positioning, orientation or alignment

Definitions

  • the present invention relates to a technique for detecting the position of a wafer.
  • a semiconductor wafer “hereinafter referred to as (wafer)” is placed on a holding table (mounting table) and rotated once, and an optical sensor is used during the rotation.
  • An alignment device that detects the orientation and center position of the wafer based on the acquired radial relationship data of the peripheral edge of the wafer is used.
  • wafer alignment is necessary is that the notch and orientation flat formed on the wafer in order to identify the crystal orientation of silicon are aligned in a predetermined direction during the process so that the reliability of process result evaluation can be improved. It is possible to increase the sex.
  • the peripheral area of the wafer must be processed, and by providing these notches, a device cannot be formed in that area. Furthermore, the characteristics of the device formed in the peripheral area of the notch may be deteriorated due to the influence of processing when the notch is formed.
  • a wafer having no notch in the peripheral region has been proposed. In such a case, the conventional method cannot detect the orientation of the wafer.
  • JP 2012-69590 A Paragraph 0002
  • the present invention has been made under such circumstances, and an object of the present invention is to provide a wafer position detecting device, a wafer position detecting method, and a method for detecting the position of a wafer in a wafer not having a notch. Is to provide a storage medium storing the.
  • the wafer position detection apparatus of the present invention has a mounting table for mounting a wafer on which a mark for alignment consisting of a plurality of dots is formed on the back surface; A rotation mechanism for rotating the mounting table; Light irradiation for forming a light irradiation region provided with a light projecting unit and irradiated with light projected from the light projecting unit in a region through which the mark of the wafer passes when the mounting table is rotated. And a mechanism for receiving the reflected light of the light irradiated to the light irradiation area by the light irradiation mechanism, and the light receiving area for the reflected light is provided to extend outward from the central portion side of the wafer.
  • Line sensor A data processing unit that detects the orientation of the wafer based on data in which the position in the rotation direction of the wafer is associated with the luminance obtained by the line sensor when the mounting table is rotated at least once. It is characterized by that.
  • the wafer position detection apparatus may have the following configuration.
  • the mark includes a plurality of dots arranged outward from the center of the wafer.
  • the length of the light receiving region of the line sensor is set so that the periphery of the wafer is positioned in the light irradiation region when the mounting table is rotated.
  • the data processing unit is configured to detect the position of the periphery of the wafer for each position in the rotation direction of the wafer based on the luminance distribution obtained by the line sensor.
  • the data processing unit executes a step of detecting the mark based on a luminance of a pixel corresponding to a position close to a central portion of the wafer by a certain position from a peripheral position of the wafer for each position in the rotation direction of the wafer. It is configured to detect the orientation of the wafer.
  • the step of detecting the mark based on the luminance of the pixel is a step of detecting the mark based on a comparison result between the luminance and a preset luminance.
  • the data processing unit is configured to detect the center position of the wafer in addition to the orientation of the wafer based on the luminance distribution.
  • the data processing unit is configured to detect the size of the wafer in addition to the orientation of the wafer based on the luminance distribution.
  • the light reflectance of the dots constituting the mark is smaller than the light reflectance of the back surface of the wafer.
  • the light irradiation areas of the line sensors are arranged along the radial direction of a circle centered on the rotation center of the mounting table.
  • a wafer on which a positioning mark composed of a plurality of dots is formed on the back surface is placed on a mounting table and rotated at least once, and the position in the rotation direction of the wafer and the light irradiated on the back surface of the wafer are Data is obtained by associating the brightness with the brightness obtained by reflection and light reception by the line sensor. Therefore, since the orientation of the wafer can be detected based on this data, the position of the wafer without a notch can be detected.
  • FIG. 1 is a perspective view showing a configuration example of a position detection apparatus 2 for a wafer W according to an embodiment of the present invention.
  • the position detection device 2 includes a wafer holder 20 that rotatably holds a wafer W on which position detection is performed, and a position detection device that irradiates the lower surface of the wafer W held by the wafer holder 20 with position detection light.
  • a light irradiation mechanism 3 and a line sensor 4 in which light receiving elements for detecting light irradiated from the light irradiation mechanism 3 and reflected by the wafer W are arranged in a line to form a light receiving region are provided.
  • the wafer holding unit 20 places a wafer W on which position detection is to be performed on the upper surface side, and supports a vacuum chuck 21 which is a mounting table for attracting and fixing the wafer W and the vacuum chuck 21 from the lower surface side.
  • the rotary shaft 22 extends in the vertical direction, and the rotary motor 23 is provided on the lower end side of the rotary shaft 22 and rotates the vacuum chuck 21 around the vertical axis.
  • An exhaust path (not shown) is formed in the vacuum chuck 21 and the rotary shaft 22, and the wafer W is sucked and held through a suction port 211 opened on the upper surface of the vacuum chuck 21.
  • the rotary motor 23 can adjust the rotation angle around the vertical axis of the rotation shaft 22 by an encoder, and specifies the rotation angle (position in the rotation direction) from the state where it is placed on the vacuum chuck 21 (home position).
  • the wafer W can be rotated while moving.
  • the rotation motor 23 is controlled by the motor control unit 201 shown in the block diagram of FIG. 4 so that the rotation angle and the rotation speed of the rotation shaft 22 are controlled. For example, the rotation angle for one rotation (360 °) is divided by 6000 to obtain 0.06. Can be grasped in ° increments.
  • the rotating shaft 22 and the rotating motor 23 constitute a rotating mechanism for rotating the vacuum chuck 21.
  • the light irradiation mechanism 3 shown in FIGS. 2 and 3 includes an LED (Light Emitting Diode) light 31 that is a light projecting unit that projects light for position detection, and an optical path of light projected from the LED light 31.
  • the lens 32,34,35 and the half mirror 33 which comprise are provided.
  • the LED light 31 emits a red LED (not shown) with electric power supplied from the power supply unit 311 and projects circular red light in the horizontal direction.
  • the power supply from the power supply unit 311 is cut off via the LED control unit 312 shown in FIG.
  • ramp which comprises a light projection part is not limited to the kind which uses LED, You may use EL (ElectroLuminescence) lamp and a discharge lamp.
  • a circular lens 32 is disposed at the light projection destination of the LED light 31, and the diffused light from the LED light 31 is converted into circular parallel light.
  • a half mirror 33 having a flat reflecting surface for converting the traveling direction upward is disposed in the traveling direction of the light passing through the circular lens 32.
  • the half mirror 33 is arranged so that parallel light that has passed through the circular lens 32 is incident at an angle of 45 ° with respect to the reflection surface, and a part of the incident light changes its traveling direction upward.
  • the half mirror 33 is disposed on the lower side of these regions so that the irradiation region of the light whose traveling direction has been changed is positioned in the peripheral region of the wafer W and the outer region thereof (FIGS. 1 and 2). 3).
  • a cylindrical plane convex lens (hereinafter referred to as a first cylindrical plane lens 34) that collects the circular parallel light reflected by the half mirror 33 toward a linear focal point is provided above the half mirror 33. Yes.
  • the first cylindrical planar lens 34 has a linear light irradiation region condensed by the first cylindrical planar lens 34 extending in the radial direction of the wafer W, and an outer region from the peripheral region of the wafer W. Are arranged so as to be irradiated over a distance (from the central portion side of the wafer W toward the outside).
  • the light irradiated to the outer region passes as it is, while the peripheral region of the wafer W is passed.
  • the light applied to the light is reflected.
  • the reflected light passes through the first cylindrical flat lens 34 and is converted into parallel light, and then enters the half mirror 33, and a part thereof is below the half mirror 33. Pass through.
  • a cylindrical planar convex lens (hereinafter referred to as a second cylindrical planar lens 35) that condenses the reflected light that has passed through the half mirror 33 toward a linear focal point is provided below the half mirror 33.
  • the line sensor 4 is disposed below the second cylindrical planar lens 35, and the second cylindrical planar lens 35 condenses the reflected light along the arrangement direction of the light receiving elements of the position detecting device 2. Has been placed.
  • the line sensor 4 includes a light receiving area 40 in which light receiving elements such as a CMOS (Complementary Metal Oxide Semiconductor) and a CCD (Charge Coupled Device) are arranged in a straight line, and the luminance of light incident on each light receiving element in the light receiving area 40. (Intensity) can be detected.
  • the line sensor 4 of this example has a configuration in which 512 CMOSs as light receiving elements are arranged in a line in a light receiving region 40 having a length of 6.4 mm.
  • the light receiving region 40 is placed on the vacuum chuck 21, is disposed above the line sensor 4, and is provided so as to extend outward from the center side of the wafer W.
  • the brightness of the light (pixel) incident on each light receiving element is converted into 256 gradation digital data (luminance data) by the line sensor control unit 401 shown in FIG. It is output toward the later-described control unit 5 side that executes W position detection. Details of the data output from the line sensor control unit 401 and the position detection operation of the wafer W performed by the control unit 5 will be described later.
  • the position detection device 2 having the configuration described above includes a control unit 5.
  • the control unit 5 includes a CPU (Central Processing Unit) 51 and a storage unit (not shown).
  • the storage unit operates the position detection device 2, that is, the wafer W held by the wafer holding unit 20 at least around the vertical axis.
  • a program in which a group of steps (commands) for the operation of irradiating the position detection light from the LED light 31 while rotating it and specifying the position of the wafer W based on the reflected light incident on the line sensor 4 is recorded.
  • This program is stored in a storage medium such as a hard disk, a compact disk, a magnetic optical disk, or a memory card, and installed in the computer therefrom.
  • FIG. 5 shows a configuration example of the wafer W on which position detection is performed using the position detection apparatus 2 of this example.
  • the conventional wafer W has a notch formed in the peripheral region.
  • a position detection method using a transmitted light method is adopted that detects the orientation and center position of the wafer W from a change in the amount of light obtained by passing light for inspection through this notch and detecting it using an optical sensor. Yes.
  • notches are not formed in the outer peripheral area of the wafer W shown in FIG. 5, and the contour shape is circular.
  • an alignment mark M is formed on the lower surface side of the wafer W. The mark M is formed in place of the above-described notch (orientation flat or notch), and is formed by, for example, shaving the lower surface of the wafer W shallowly by laser marking.
  • the mark M in this example is configured by a dot pattern in which a plurality of dots having a depth of several tens of ⁇ m and a diameter of about 100 ⁇ m are arranged at a pitch of about several hundreds of ⁇ m.
  • a dot row in which four dots are arranged radially from the center of the wafer W toward the outside is formed, and three more dot rows are formed on the wafer W.
  • a rectangular mark M having a size of 0.6 mm ⁇ 0.4 mm is formed by arranging them adjacent to each other in the circumferential direction.
  • the method of forming the mark M by shallowly cutting the back surface of the wafer W is as follows: The stress applied to the wafer W is small and no unique shape is formed. For this reason, it is possible to suppress the deterioration in characteristics that has conventionally occurred in a semiconductor device formed around the notch.
  • the mark M and the dots constituting the mark M are sufficiently small with respect to the curvature of the wafer W.
  • the dot rows of the mark M are substantially equidistant (w [mm]) from the end (periphery position) of the wafer W as shown in FIG. ) Are formed at positions that are separated from each other, and the dot rows are detected as being arranged in parallel to each other.
  • the position detection apparatus 2 of this example detects the orientation of the wafer W by detecting the above-described mark M.
  • FIG. 6A to 6E show the light receiving region 40 and the mark M of the line sensor 4 in which the light receiving elements are arranged in a line when the wafer W is rotated while irradiating the position detecting light from the light irradiation mechanism 3.
  • FIG. The positional change with respect to time is shown.
  • a radial direction of a circle centering on the rotation center of the vacuum chuck 21 from the peripheral region to the outer region of the wafer W (when the rotation center and the center of the wafer W are placed in alignment) Forming a linear light irradiation region extending in the radial direction of the wafer W and detecting the reflected light by the line sensor 4, the region where the reflected light reflected from the lower surface of the wafer W is detected, and the reflection
  • the boundary with the region where no light is detected is specified as the end of the wafer W (the position of the periphery of the wafer W). Further, when the mark M passes through the linear light irradiation region (corresponding to the light receiving region 40 shown in FIGS.
  • the brightness of reflected light decreases due to light scattering, and
  • the brightness detected by the light receiving element corresponding to the position where the mark M has passed decreases. That is, the light reflectance of the dots constituting the mark M is smaller than the light reflectance of the back surface of the wafer W.
  • FIGS. 7A to 7E schematically show the luminance distribution of light incident on the line sensor 4 at each position shown in FIGS. 6A to 6E.
  • the horizontal axis indicates the luminance of light incident on the line sensor 4
  • the vertical axis indicates the address (0 to 511) of the light receiving element provided in the line sensor 4.
  • the light incident on the line sensor 4 includes the peripheral area of the wafer W where the position detection light is reflected and the wafer W where the position detection light passes. The brightness is different from the outer area.
  • an inclined surface called a bevel is formed in the vicinity of the end portion of the wafer W, and reflected light is scattered at the bevel portion.
  • the luminance of the light incident on the line sensor 4 does not show a step-like change at the edge of the wafer W, and the boundary from the position just before the outer edge of the wafer W is the boundary. A luminance distribution in which the luminance gradually increases over the inner position of the wafer W is obtained.
  • the luminance at the edge position of the wafer W when the luminance continuously changes due to the influence of the bevel portion is previously grasped by a preliminary experiment or the like. Then, the position where the luminance of the incident light exceeds the threshold value is detected as the edge portion of the wafer W with the luminance at the edge position as a threshold value.
  • the luminance of the light incident on the line sensor 4 is lowered at the position where the dot is formed as shown in FIGS. 7B to 7D (corresponding FIG. 6). (Refer to (b) to (d)). Further, as compared with the dot passing position in the state where the dot row has entered the irradiation region (that is, the light receiving region 40) (FIGS. 6B and 6D) (FIGS. 7B and 7D). The amount of decrease in luminance is larger in the dot passing position (FIG. 7C) in the state where the two adjacently arranged dot rows enter (FIG. 6C).
  • the luminance detected by the actual line sensor 4 has the luminance change patterns shown in FIGS. 7B to 7D according to the number of light receiving elements arranged (resolution). Smoothed (refer to the luminance data at the mark detection position in FIGS. 13A to 13C described later). Therefore, in the position detection device 2 of the present example, a position where the luminance change of incident light is increased by passing the mark M through the light irradiation region (a position where the sensitivity for detecting the mark M is high) is set in advance as the mark detection position. And an area where the mark M is formed is detected based on the luminance change at the position.
  • the position detection device 2 of this example detects the position of the end portion of the wafer W and the formation position of the mark M on the back surface of the wafer W based on the luminance data detected by the line sensor 4. be able to.
  • the brightness data (gradation data) of all the pixels of 512 pixels acquired at 6000 points during one rotation of the wafer W and detected by the line sensor 4 are output as image data to the control unit 5 for image analysis.
  • the edge of the wafer W and the mark M are detected by the above-described method, it is necessary to process data as large as 3.1 MB (6000 points ⁇ 512 pixels ⁇ 8 bits (256 gradations) ⁇ 3.1 MB).
  • the system configuration becomes complicated and the apparatus cost increases.
  • the position detection apparatus 2 of the present example uses the line sensor control unit 401 to extract only information necessary for the detection of the edge and the mark M by using the feature of the arrangement position of the edge and the mark M of the wafer W. Then, a process of writing in the memory 52 provided in the control unit 5 is executed. From this viewpoint, the control unit 5 and the line sensor control unit 401 constitute a data processing unit of the position detection device 2. Details of processing executed by the line sensor control unit 401 will be described below.
  • the line sensor control unit 401 performs scanning by the line sensor 4 from the radially outer side to the inner side of the wafer W at each sampling point.
  • the acquired luminance data is compared with a preset threshold value.
  • the address data (0 to 511) of the light receiving element at the position where the magnitude of the luminance data exceeds the threshold value (becomes brighter than the threshold value) is written in the memory 52 of the control unit 5 as 9-bit end position data. .
  • the control unit 5 specifies the position of the end of the wafer W based on the address of each light receiving element and the information indicating where the light receiving element is arranged on the line sensor 4. Then, by aligning the end positions for 6000 points in association with the rotation angle of the wafer W, as shown in FIG. 8, the end of the wafer W when the wafer W held on the vacuum chuck 21 is rotated once. The displacement of the part position can be grasped. Then, the diameter of the wafer W is obtained from the median value of the displacement range of the end position, and the eccentricity between the rotation center of the vacuum chuck 21 and the center of the wafer W is obtained from the difference between the median value and the maximum displacement amount. The amount can be determined.
  • the data amount of these wafers W is 6.8 kB (6000 points ⁇ 9 bits ⁇ 6.8 kB).
  • the diameter and the amount of eccentricity can be specified.
  • the displacement direction of the wafer W held by the vacuum chuck 21 cannot be specified only by the displacement of the end position shown in FIG. Therefore, the orientation of the wafer W on the vacuum chuck 21 is detected using the detection result of the mark M.
  • the mark M is marked on the inner region from a position separated by w [mm] from the end. Has become a standard. Accordingly, the mark detection position at which the mark M is detected is also a position that is closer to the center side by a predetermined distance (w ′ [mm]) from the end of the wafer W. For this reason, as shown in FIG. 8, when the end of the wafer W moves in accordance with the rotation of the wafer W held on the vacuum chuck 21, the mark detection position described above also moves (the broken line in FIG. 8). ).
  • the line sensor control unit 401 of this example includes a preset distance (w ′ [mm]) from the edge of the wafer W specified based on the above-described threshold determination among the luminance data acquired from each light receiving element. ),
  • the luminance data (256 gradations, 8 bits) of the pixel obtained from the light receiving element on which the reflected light from the position close to the center side of the wafer W is incident on the memory 52 of the control unit 5 as the luminance data at the mark detection position.
  • the luminance data is not limited to that obtained from one light receiving element, and for example, an average value of luminance data of pixels obtained from a plurality of adjacent light receiving elements may be used.
  • the control unit 5 grasps the luminance change of the reflected light at the mark detection position as shown in FIG. 9 by arranging the luminance data for 6000 points in association with the rotation angle (position in the rotation direction) of the wafer W. Can do. Then, the position (for example, the crystal direction, the center of the wafer W, the mark, and the mark) where the mark M is formed is the position where the decrease in the brightness of the reflected light is detected (the position where the brightness is lower than the preset brightness). The angle formed by the direction connecting the M formation position can be specified. Based on the angle of the wafer W, the eccentric direction of the wafer W placed on the vacuum chuck 21 can be specified, and the x direction component and the y direction component of the eccentric amount can be specified. At this time, by using the luminance data at the mark detection position specified in advance by the line sensor control unit 401, the orientation of the wafer W can be specified with a data amount of 6 kB (6000 points ⁇ 8 bits ⁇ 6 kB).
  • the wafer W is transferred into the housing of the position detection device 2 by an external wafer transfer mechanism, and the wafer W is placed on the vacuum chuck 21 of the wafer holder 20.
  • the center of the wafer W and the center of rotation of the vacuum chuck 21 coincide with each other, and the mark M formed on the back surface of the wafer W is also in advance. It will be in the state of facing the set direction.
  • the position detection of the wafer W is started (start).
  • the LED light 31 is turned on to start light projection onto the wafer W, and the wafer W is rotated.
  • the vacuum chuck 21 changes the preset direction.
  • the detection operation is started at the facing timing (step S101).
  • the counter is reset (step S102)
  • the brightness of reflected light incident on the line sensor 4 at the detection start position is compared with a threshold value, and the position of the edge of the wafer W is specified (step S103).
  • Luminance data is acquired at a mark detection position close to the center side by a preset distance from the end position (step S104).
  • step S105 the edge position data and the luminance data acquired by these operations are stored in the memory 52 in association with the rotation angle of the wafer W.
  • step S106 the counter is incremented (step S106) and compared with the set sampling number (step S107).
  • step S107 the previous detection operation is performed.
  • step S108 the operations of steps S103 to S106 are repeated to sequentially acquire the edge position data at each sampling point and the luminance data at the mark detection position.
  • step S107 When the wafer W has made at least one rotation and data acquisition has been completed at all sampling points (step S107; YES), the LED light 31 is turned off and the rotation of the wafer W is stopped. Based on the acquired edge position data and luminance data at the mark detection position, the diameter and eccentricity of the wafer W are determined based on the displacement of the edge position shown in FIG. 8 and the luminance change at the mark detection position shown in FIG. The amount and the direction of the wafer W are specified (step S109, end).
  • the position detection device 2 has the following effects.
  • the wafer W on which the alignment mark M composed of a plurality of dots is formed on the back surface is placed on the vacuum chuck 21 and rotated at least once, and the position of the wafer W in the rotation direction and the light irradiated on the back surface of the wafer W are irradiated.
  • the brightness obtained by receiving the light with the line sensor 4 is acquired. Therefore, since the orientation of the wafer can be detected based on this data, the position of the wafer W not having a notch can be detected.
  • the position detection apparatus 2 of the present example has described a method of detecting the position of the edge of the wafer W and the mark M formed on the back surface of the wafer W using light reflected from the back surface of the wafer W.
  • the LED light 31 is arranged on one side of the upper and lower surfaces across the wafer W, and the line sensor 4 is arranged on the other side so that the light emitted from the LED light 31 is detected. May employ a transmitted light system that detects the end position based on the position blocked by the wafer W, or may not detect the end itself.
  • the mark detection position is specified by setting a position that is a predetermined distance from the position where the end portion of the wafer W after the correction of the positional deviation is positioned as a mark detection position.
  • Luminance data may be acquired by the method described above.
  • the light receiving area 40 of the line sensor 4 is set so as to cover the area where the arrangement position of the mark M is considered to change according to the change in the diameter of the wafer W.
  • the mark may be detected by obtaining all the luminance data (gradation data) in the area and analyzing the image. Since the light receiving region 40 is narrower than when detecting the edge of the wafer W, an increase in the amount of image data can be suppressed.
  • the configuration example of the light irradiation mechanism 3 is not limited to that illustrated in FIGS. 1 to 3.
  • a rod lens, a ball lens, a FAC (Fast-Axis Collimating Lens) lens, or the like may be employed instead of the cylindrical planar convex lens (the first cylindrical planar lens 34 and the second cylindrical planar lens 35).
  • the shape of the light irradiation region formed by the light irradiation mechanism 3 is not limited to the case where the light irradiation region is formed in a straight line corresponding to the light receiving region 40 of the line sensor 4.
  • the shape of the light irradiation region May be circular or rectangular.
  • the line sensor 4 is also used in the conventional detection method of the transmitted light type wafer W, it is diverted to a system that executes the detection method of the reflected light type only by changing the configuration of the light irradiation mechanism 3. You can also
  • the number of marks M provided on the back surface of the wafer W is not limited to one, and a plurality of marks M are provided at positions separated from each other in the circumferential direction of the wafer W to improve the reliability of mark M detection. May be.
  • the dot arrangement may be changed variously so that the mark M can be handled as character information.
  • the carrier 102 containing the wafer W to be processed is placed on the placing table 101 provided in the carrier block S1 of the coating and developing apparatus, the wafer W is taken out by the delivery arm C.
  • the taken wafer W is transferred to the transfer module CPL2 in the shelf unit U2 provided in the processing block S2, and transferred into the BCT layer B2 by the transfer arm A2, thereby forming an antireflection film.
  • the wafer W is transferred to the transfer module BF2 of the shelf unit U2, and transferred to the COT layer B3 via the transfer module CPL3 and the transfer arm A3, and a resist film is formed by the liquid processing module 103.
  • a peripheral exposure module 104 for exposing the resist film in advance is provided.
  • the wafer holding unit 20 shown in FIG. 1 is accommodated in a housing, and the wafer holding unit 20 has a position where the wafer W is transferred to and from the transfer arm A3 and a position where the peripheral exposure is performed. It is configured to be movable in the horizontal direction.
  • An exposure unit such as an ultraviolet lamp is provided above the peripheral part of the wafer W moved to the position where the peripheral exposure is performed, and peripheral exposure is performed by irradiating the wafer W with ultraviolet rays.
  • the edge exposure module 104 incorporates the position detection device 2 of the present invention. Using this position detection device 2, the diameter of the wafer W and the amount of eccentricity of the wafer W held on the vacuum chuck 21 are correctly detected. Then, the rotation operation of the wafer W held by the vacuum chuck 21 and the lateral movement operation of the wafer holding unit 20 are combined, and the change in the wafer W diameter according to the result detected by the position detection device 2 By moving the exposure position so that the eccentricity of the wafer W is offset, the correct area can be exposed.
  • the wafer W is transferred to the transfer module BF3 of the shelf unit U2 by the transfer arm A3, and then, for example, the transfer module BF3 ⁇ the transfer arm D1 ⁇ the transfer module CPL4 To the transfer arm A4, and an antireflection film is formed on the resist film in the TCT layer B4. Thereafter, the wafer W is transferred to the transfer module TRS4 by the transfer arm A4. In some cases, the antireflection film is not formed on the resist film, or the wafer W is subjected to a hydrophobic treatment instead of forming the antireflection film below the resist film.
  • the wafer W after the formation of the antireflection film transferred to the transfer module TRS4 is further transferred to the transfer module CPL11, and the transfer module of the shelf unit U3 is provided by the shuttle arm E dedicated for transfer provided in the upper part of the DEV layer B1. It is conveyed to CPL12.
  • the wafer W is taken into the interface block S3 and transferred to the exposure apparatus S4 by the interface arm F, where a predetermined exposure process is performed. Thereafter, the wafer W is placed on the delivery module TRS6 of the shelf unit U3 and returned to the processing block S2.
  • the wafer W returned to the processing block S2 is developed in the DEV layer B1, and then transferred to the heating module provided in the processing module group U1, where the solvent remaining in the resist pattern is removed. . Then, for example, it is transported to the cooling module provided in the processing module group U1 by the transport arm A1 and cooled.
  • the wafer W thus developed is inspected for the film thickness of the resist film, the line width (CD) of the recesses forming the resist pattern, and the width (pitch) of a pair of adjacent uneven portions.
  • Each wafer W is added with pass / fail information of these items, and is used as a judgment material for determining whether or not to execute processing in the subsequent apparatus.
  • the position detection device 2 of the present invention is also incorporated in this inspection apparatus, and the accurate inspection position grasped based on the result of detecting the diameter of the wafer W to be inspected, the eccentric amount of the mounting position, and the orientation of the wafer W. Evaluation of the inspection result associated with is performed.
  • the inspection device is disposed in the shelf unit U2, for example.
  • the wafer W that has been inspected is transferred to the transfer table in the access range of the transfer arm C in the shelf unit U2, and returned to the carrier 102 via the transfer arm C.
  • the position detection device 2 of the present invention is incorporated in the coating and developing device has been described above, but the device provided with the position detection device 2 is not limited to this example.
  • the wafer W is mounted on a single-wafer type liquid processing apparatus that supplies various processing liquids to the wafer W held on the spin chuck and performs liquid processing, or a mounting table provided in a vacuum vessel to form a film.
  • the position detection device 2 may be used for alignment of a wafer W mounted on a spin chuck or a mounting table provided in a vacuum processing apparatus that performs processing, etching processing, or ashing processing.
  • the position detection device 2 detects the position and corrects the positional deviation and the like to the wafer conveyance mechanism.
  • a method of delivering W can be considered.
  • Example 5 A detection test of the mark M formed on the wafer W shown in FIG. 5 was performed by the position detection device 2 having the same configuration as that shown in FIGS. A. Experimental conditions The mark M (0.6 mm ⁇ 0.4 mm) having the structure described with reference to FIGS. 5 and 6 is formed at a position 1.0 mm from the end of the wafer W having a diameter of 300 mm, and the length of the light receiving region is Position detection was performed using a line sensor 4 having 6.4 mm and 512 light receiving elements (CMOS) (pixel number pixel). As shown in FIGS.
  • CMOS light receiving elements
  • the line sensor 4 has a diameter of the wafer W across the peripheral area of the inner wafer W and the outer area of the end with the end of the wafer W interposed therebetween. It arrange
  • the value of the luminance data starts to rise from the position on the outer region side of the edge of the wafer W, and the wafer W side
  • the value of the luminance data increases with the same inclination in (A) to (C). Therefore, it can be understood that the position of the end portion of the wafer W can be accurately grasped by setting an appropriate threshold value.
  • the luminance data indicating the amount of reflected light incident on the line sensor 4 is obtained at the position (A) where the position deviated from the mark M is scanned. There is no decline.
  • the value of the luminance data drops at the position where the mark M is formed.
  • an area where the value of the luminance data is lower than that of the position (B) is formed at the position (C) scanned on the second dot row.
  • the reason why the value of the brightness data is lower at the position (C) than at the position (B) is that the amount of reflected light incident on the line sensor 4 is reduced due to the influence of adjacent dots. It is thought that.
  • the mark detection position is set at an appropriate position. As shown in FIG. 9, it was confirmed that the formation position of the mark M can be detected based on the change in the luminance data at the mark detection position.

Abstract

[Problem] Provided is a wafer position detection apparatus or the like for detecting the position of a wafer that is not provided with a notch. [Solution] In a position detection apparatus (2) for a wafer (W), the wafer (W) having an alignment mark (M) formed on the rear surface is placed on a placing table (21), said mark being configured from a plurality of dots, and rotating mechanisms (22, 23) rotate the placing table (21). A light irradiation mechanism (3) forms a light irradiation region in a region where the mark (M) passes when the placing table (21) is rotated, and a line sensor (4) is provided such that a light receiving region extends toward the outer side from the center section side of the wafer (W), said light receiving region receiving reflection light of light radiated to the light irradiation region. When the wafer (W) is rotated once, data processing units (5, 401) detect wafer direction on the basis of data wherein the position in the rotation direction and luminance obtained by means of the line sensor (4) are associated with each other.

Description

ウエハの位置検出装置、ウエハの位置検出方法、及び記憶媒体Wafer position detection apparatus, wafer position detection method, and storage medium
　本発明は、ウエハの位置を検出する技術に関する。 The present invention relates to a technique for detecting the position of a wafer.
　半導体装置の製造プロセスにおいては、特許文献１などに記載されているように、半導体ウエハ「以下(ウエハという)」を保持台（載置台）に載置して１回転させ、その間に光センサーにより取得したウエハの周縁の径方向の関係データに基づいて、ウエハの向き及び中心位置を検出する位置合わせ装置が用いられている。ウエハの位置合わせが必要な理由としては、シリコンの結晶方向を特定するためにウエハに形成されたノッチやオリエンテーションフラットなどを、プロセス時に所定の向きに揃えておくことにより、プロセス結果の評価の信頼性を高めることなどが挙げられる。また、搬送アームに対するウエハの位置がずれていると、搬送されているウエハが装置の構成部材に衝突したり、あるいはプロセス用の載置台からはみ出したりするなどの不具合が生じることからも、ウエハの中心位置合わせが必要である。さらにまた、ウエハに塗布されたレジスト膜の周縁部を除去するＥＢＲ（Edge Bead Remover）処理のように、ウエハの周縁を基準に処理を行う場合は、ウエハの周縁位置に関する情報が必要となる。 In the manufacturing process of a semiconductor device, as described in Patent Document 1 or the like, a semiconductor wafer “hereinafter referred to as (wafer)” is placed on a holding table (mounting table) and rotated once, and an optical sensor is used during the rotation. An alignment device that detects the orientation and center position of the wafer based on the acquired radial relationship data of the peripheral edge of the wafer is used. The reason why wafer alignment is necessary is that the notch and orientation flat formed on the wafer in order to identify the crystal orientation of silicon are aligned in a predetermined direction during the process so that the reliability of process result evaluation can be improved. It is possible to increase the sex. In addition, if the position of the wafer with respect to the transfer arm is shifted, problems such as the wafer being transferred colliding with a component of the apparatus or protruding from the mounting table for the process may occur. Center alignment is required. Furthermore, when processing is performed based on the peripheral edge of the wafer, such as EBR (Edge BeadrRemover) processing for removing the peripheral portion of the resist film applied to the wafer, information on the peripheral position of the wafer is required.
　ところでノッチやオリエンテーションフラットは、ウエハの周縁領域を加工しなければならず、またこれらの切り欠きを設けることによりその領域にデバイスを形成できなくなる。さらには切り欠きを形成する際の加工の影響などにより、切り欠きの周辺領域に形成されたデバイスの特性が悪くなってしまう場合もある。　
　これらの課題に対し、周縁領域に切り欠きを設けないウエハが提案されており、このような場合には、従来の手法では、ウエハの向きを検出することができない。 By the way, in the notch and the orientation flat, the peripheral area of the wafer must be processed, and by providing these notches, a device cannot be formed in that area. Furthermore, the characteristics of the device formed in the peripheral area of the notch may be deteriorated due to the influence of processing when the notch is formed.
To solve these problems, a wafer having no notch in the peripheral region has been proposed. In such a case, the conventional method cannot detect the orientation of the wafer.
特開２０１２－６９５９０号公報：段落０００２JP 2012-69590 A: Paragraph 0002
　本発明はこのような事情の下になされたものであり、その目的は、切り欠きを備えないウエハにおいてウエハの位置を検出するためのウエハの位置検出装置、ウエハの位置検出方法、及びこの方法を記憶した記憶媒体を提供することにある。 SUMMARY OF THE INVENTION The present invention has been made under such circumstances, and an object of the present invention is to provide a wafer position detecting device, a wafer position detecting method, and a method for detecting the position of a wafer in a wafer not having a notch. Is to provide a storage medium storing the.
　本発明のウエハの位置検出装置は、裏面に複数のドットからなる位置合わせ用のマークが形成されたウエハを載置するための載置台と、
　前記載置台を回転させるための回転機構と、
　投光部を備え、前記載置台を回転させたときに、前記ウエハのマークが通過する領域に、前記投光部から投光された光が照射される光照射領域を形成するための光照射機構と、前記光照射機構により前記光照射領域に照射された光の反射光を受光するために設けられ、前記反射光の受光領域が、ウエハの中央部側から外側に向かって伸びるように設けられたラインセンサーと、
　前記載置台を少なくとも１回転させたときに、ウエハの回転方向の位置と前記ラインセンサーにより得られた輝度とを対応付けたデータに基づいてウエハの向きを検出するデータ処理部と、を備えたことを特徴とする。 The wafer position detection apparatus of the present invention has a mounting table for mounting a wafer on which a mark for alignment consisting of a plurality of dots is formed on the back surface;
A rotation mechanism for rotating the mounting table;
Light irradiation for forming a light irradiation region provided with a light projecting unit and irradiated with light projected from the light projecting unit in a region through which the mark of the wafer passes when the mounting table is rotated. And a mechanism for receiving the reflected light of the light irradiated to the light irradiation area by the light irradiation mechanism, and the light receiving area for the reflected light is provided to extend outward from the central portion side of the wafer. Line sensor,
A data processing unit that detects the orientation of the wafer based on data in which the position in the rotation direction of the wafer is associated with the luminance obtained by the line sensor when the mounting table is rotated at least once. It is characterized by that.
　前記ウエハの位置検出装置は、以下の構成を備えていてもよい。
（ａ）前記マークは、ウエハの中央部から外側に向かって配列された複数のドットを含むこと。　
（ｂ）前記ラインセンサーの受光領域の長さは、前記載置台を回転させたときにウエハの周縁がその光照射領域に位置するように設定されていること。このとき、前記データ処理部は、ラインセンサーにより得られた輝度分布に基づいて、ウエハの回転方向の位置ごとのウエハの周縁の位置を検出するように構成されていること。前記データ処理部は、ウエハの回転方向の位置ごとにウエハの周縁の位置から一定位置だけウエハの中央部に寄った位置に対応する画素の輝度に基づいて前記マークを検出するステップを実行してウエハの向きを検出するように構成されていること。前記画素の輝度に基づいて前記マークを検出するステップは、前記輝度と予め設定された輝度との比較結果により前記マークを検出するステップであること。
（ｃ）前記データ処理部は、前記輝度分布に基づいて、ウエハの向きに加えてウエハの中心位置を検出するように構成されていること。
（ｄ）前記データ処理部は、前記輝度分布に基づいて、ウエハの向きに加えてウエハの大きさを検出するように構成されていること。
（ｅ）前記マークを構成するドットの光反射率は、ウエハの裏面の光反射率よりも小さいこと。　
（ｆ）前記ラインセンサーの光照射領域は、載置台の回転中心を中心とする円の径方向に沿って並んでいること。 The wafer position detection apparatus may have the following configuration.
(A) The mark includes a plurality of dots arranged outward from the center of the wafer.
(B) The length of the light receiving region of the line sensor is set so that the periphery of the wafer is positioned in the light irradiation region when the mounting table is rotated. At this time, the data processing unit is configured to detect the position of the periphery of the wafer for each position in the rotation direction of the wafer based on the luminance distribution obtained by the line sensor. The data processing unit executes a step of detecting the mark based on a luminance of a pixel corresponding to a position close to a central portion of the wafer by a certain position from a peripheral position of the wafer for each position in the rotation direction of the wafer. It is configured to detect the orientation of the wafer. The step of detecting the mark based on the luminance of the pixel is a step of detecting the mark based on a comparison result between the luminance and a preset luminance.
(C) The data processing unit is configured to detect the center position of the wafer in addition to the orientation of the wafer based on the luminance distribution.
(D) The data processing unit is configured to detect the size of the wafer in addition to the orientation of the wafer based on the luminance distribution.
(E) The light reflectance of the dots constituting the mark is smaller than the light reflectance of the back surface of the wafer.
(F) The light irradiation areas of the line sensors are arranged along the radial direction of a circle centered on the rotation center of the mounting table.
　本発明は、裏面に複数のドットからなる位置合わせ用のマークが形成されたウエハを載置台に載置して少なくとも１回転させ、ウエハの回転方向の位置と、ウエハの裏面に照射した光を反射させ、ラインセンサーで受光して得られた輝度とを対応付けたデータを取得している。従って、このデータに基づいてウエハの向きを検出することができるので、切り欠きを備えないウエハの位置を検出することができる。 In the present invention, a wafer on which a positioning mark composed of a plurality of dots is formed on the back surface is placed on a mounting table and rotated at least once, and the position in the rotation direction of the wafer and the light irradiated on the back surface of the wafer are Data is obtained by associating the brightness with the brightness obtained by reflection and light reception by the line sensor. Therefore, since the orientation of the wafer can be detected based on this data, the position of the wafer without a notch can be detected.
発明の実施の形態に係る位置検出装置の構成を示す斜視図である。It is a perspective view which shows the structure of the position detection apparatus which concerns on embodiment of invention. 前記位置検出装置の光照射機構の構成を示す第１の説明図である。It is a 1st explanatory view showing the composition of the light irradiation mechanism of the position detecting device. 前記光照射機構の構成を示す第２の説明図である。It is the 2nd explanatory view showing the composition of the light irradiation mechanism. 前記位置検出装置の電気的構成を示すブロック図である。It is a block diagram which shows the electric constitution of the said position detection apparatus. 前記位置検出装置にて位置検出が行われるウエハの裏面の構成例を示す平面図である。It is a top view which shows the structural example of the back surface of the wafer in which position detection is performed by the said position detection apparatus. 前記位置検出装置に設けられたラインセンサーと、ウエハに設けられた位置合わせ用のマークとの位置関係を示す説明図である。It is explanatory drawing which shows the positional relationship of the line sensor provided in the said position detection apparatus, and the mark for alignment provided in the wafer. 前記位置関係に応じた、前記ラインセンサーから出力される輝度データの分布を示す説明図である。It is explanatory drawing which shows distribution of the luminance data output from the said line sensor according to the said positional relationship. 前記ラインセンサーにて検出されたウエハの端部の変位を示す説明図である。It is explanatory drawing which shows the displacement of the edge part of the wafer detected by the said line sensor. 前記ウエハのマーク検出位置における輝度データの変化を示す説明図である。It is explanatory drawing which shows the change of the luminance data in the mark detection position of the said wafer. 前記位置検出装置によりウエハの位置を検出する動作の流れを示すフロー図である。It is a flowchart which shows the flow of the operation | movement which detects the position of a wafer with the said position detection apparatus. 前記位置検出装置を備える塗布、現像装置の一例を示す平面図である。It is a top view which shows an example of the application | coating and developing apparatus provided with the said position detection apparatus. 前記塗布、現像装置の縦断側面図である。It is a vertical side view of the coating and developing apparatus. 前記マークが設けられたウエハをラインセンサーによりスキャンしたときの輝度データの分布を示す説明図である。It is explanatory drawing which shows distribution of the brightness | luminance data when the wafer provided with the said mark was scanned with the line sensor.
　図１は、本発明の実施の形態に係るウエハＷの位置検出装置２の構成例を示す斜視図である。位置検出装置２には、位置検出が行われるウエハＷを回転自在に保持するウエハ保持部２０と、このウエハ保持部２０に保持されたウエハＷの下面に位置検出用の光を照射するための光照射機構３と、光照射機構３から照射され、ウエハＷにて反射した光を検出するための受光素子がライン状に並べられて受光領域を形成するラインセンサー４とを備えている。 FIG. 1 is a perspective view showing a configuration example of a position detection apparatus 2 for a wafer W according to an embodiment of the present invention. The position detection device 2 includes a wafer holder 20 that rotatably holds a wafer W on which position detection is performed, and a position detection device that irradiates the lower surface of the wafer W held by the wafer holder 20 with position detection light. A light irradiation mechanism 3 and a line sensor 4 in which light receiving elements for detecting light irradiated from the light irradiation mechanism 3 and reflected by the wafer W are arranged in a line to form a light receiving region are provided.
　ウエハ保持部２０は、位置検出が行われるウエハＷがその上面側に載置されると共に、当該ウエハＷを吸着固定する載置台である真空チャック２１と、この真空チャック２１を下面側から支持し、鉛直方向に伸びる回転軸２２と、この回転軸２２の下端側に設けられ、当該真空チャック２１を鉛直軸回りに回転させる回転モーター２３と、を備えている。　
　真空チャック２１及び回転軸２２内には不図示の排気路が形成され、真空チャック２１の上面に開口する吸引口２１１を介してウエハＷを吸着保持する。 The wafer holding unit 20 places a wafer W on which position detection is to be performed on the upper surface side, and supports a vacuum chuck 21 which is a mounting table for attracting and fixing the wafer W and the vacuum chuck 21 from the lower surface side. The rotary shaft 22 extends in the vertical direction, and the rotary motor 23 is provided on the lower end side of the rotary shaft 22 and rotates the vacuum chuck 21 around the vertical axis.
An exhaust path (not shown) is formed in the vacuum chuck 21 and the rotary shaft 22, and the wafer W is sucked and held through a suction port 211 opened on the upper surface of the vacuum chuck 21.
　回転モーター２３は回転軸２２の鉛直軸周りの回転角度をエンコーダーによって調節することが可能であり、真空チャック２１に載置された状態（ホームポジション）からの回転角度（回転方向の位置）を特定しながらウエハＷを回転させることができる。回転モーター２３は、図４のブロック図に示すモーター制御部２０１によって回転軸２２の回転角度や回転速度が制御され、例えば一回転（３６０°）分の回転角度を６０００分割して、０．０６°刻みで把握することができる。　
　回転軸２２や回転モーター２３は、真空チャック２１を回転させるための回転機構を構成している。 The rotary motor 23 can adjust the rotation angle around the vertical axis of the rotation shaft 22 by an encoder, and specifies the rotation angle (position in the rotation direction) from the state where it is placed on the vacuum chuck 21 (home position). The wafer W can be rotated while moving. The rotation motor 23 is controlled by the motor control unit 201 shown in the block diagram of FIG. 4 so that the rotation angle and the rotation speed of the rotation shaft 22 are controlled. For example, the rotation angle for one rotation (360 °) is divided by 6000 to obtain 0.06. Can be grasped in ° increments.
The rotating shaft 22 and the rotating motor 23 constitute a rotating mechanism for rotating the vacuum chuck 21.
　図２、図３に示した光照射機構３は、位置検出用の光を投光する投光部であるＬＥＤ（Light Emitting Diode）ライト３１と、ＬＥＤライト３１から投光された光の光路を構成するレンズ３２、３４、３５やハーフミラー３３とを備える。　
　ＬＥＤライト３１は、電源部３１１から供給された電力により不図示の赤色ＬＥＤを発光させ、円形の赤色光を横方向に投光する。電源部３１１からの電力の給断は、図４に示すＬＥＤ制御部３１２を介して実行される。なお、投光部を構成するランプはＬＥＤを用いる種類のものに限定されるものではなく、ＥＬ（ElectroLuminescence）ランプや放電ランプを用いてもよい。 The light irradiation mechanism 3 shown in FIGS. 2 and 3 includes an LED (Light Emitting Diode) light 31 that is a light projecting unit that projects light for position detection, and an optical path of light projected from the LED light 31. The lens 32,34,35 and the half mirror 33 which comprise are provided.
The LED light 31 emits a red LED (not shown) with electric power supplied from the power supply unit 311 and projects circular red light in the horizontal direction. The power supply from the power supply unit 311 is cut off via the LED control unit 312 shown in FIG. In addition, the lamp | ramp which comprises a light projection part is not limited to the kind which uses LED, You may use EL (ElectroLuminescence) lamp and a discharge lamp.
　図２、図３に示すように、ＬＥＤライト３１の投光先には円形のレンズ３２が配置され、ＬＥＤライト３１からの拡散光を円形の平行光に変換する。円形のレンズ３２を通過した光の進行方向には、その進行方向を上向きに変換するための平坦な反射面を有するハーフミラー３３が配置されている。ハーフミラー３３は、円形のレンズ３２を通過した平行光が、前記反射面に対して４５°の角度で入射するように配置され、入射した光の一部は、その進行方向を上向きに変える。ハーフミラー３３は、進行方向が変換された光の照射領域を、ウエハＷの周縁領域、及びその外方領域に位置させるように、これらの領域の下方側に配置されている（図１、図３）。 As shown in FIGS. 2 and 3, a circular lens 32 is disposed at the light projection destination of the LED light 31, and the diffused light from the LED light 31 is converted into circular parallel light. A half mirror 33 having a flat reflecting surface for converting the traveling direction upward is disposed in the traveling direction of the light passing through the circular lens 32. The half mirror 33 is arranged so that parallel light that has passed through the circular lens 32 is incident at an angle of 45 ° with respect to the reflection surface, and a part of the incident light changes its traveling direction upward. The half mirror 33 is disposed on the lower side of these regions so that the irradiation region of the light whose traveling direction has been changed is positioned in the peripheral region of the wafer W and the outer region thereof (FIGS. 1 and 2). 3).
　ハーフミラー３３の上方側には、ハーフミラー３３にて反射された円形の平行光を直線状の焦点へ向けて集光する円筒平面凸レンズ（以下、第１円筒平面レンズ３４という）が設けられている。第１円筒平面レンズ３４は、当該第１円筒平面レンズ３４にて集光された直線状の光照射領域がウエハＷの径方向に向けて伸び、且つ、ウエハＷの周縁領域からその外方領域に亘って照射されるように（ウエハＷの中央部側から外側に向かって伸びるように）配置されている。 A cylindrical plane convex lens (hereinafter referred to as a first cylindrical plane lens 34) that collects the circular parallel light reflected by the half mirror 33 toward a linear focal point is provided above the half mirror 33. Yes. The first cylindrical planar lens 34 has a linear light irradiation region condensed by the first cylindrical planar lens 34 extending in the radial direction of the wafer W, and an outer region from the peripheral region of the wafer W. Are arranged so as to be irradiated over a distance (from the central portion side of the wafer W toward the outside).
　図３に示すように、ウエハＷの周縁領域からその外方領域に亘って直線状の光が照射されると、前記外方領域に照射された光はそのまま通過する一方、ウエハＷの周縁領域に照射された光は反射する。図２、図３に示すように、この反射光は、第１円筒平面レンズ３４を通過して平行光に変換された後、ハーフミラー３３に入射してその一部はハーフミラー３３の下方側へ通過する。 As shown in FIG. 3, when linear light is irradiated from the peripheral region of the wafer W to the outer region, the light irradiated to the outer region passes as it is, while the peripheral region of the wafer W is passed. The light applied to the light is reflected. As shown in FIGS. 2 and 3, the reflected light passes through the first cylindrical flat lens 34 and is converted into parallel light, and then enters the half mirror 33, and a part thereof is below the half mirror 33. Pass through.
　ハーフミラー３３の下方側には、ハーフミラー３３を通過した反射光を直線状の焦点へ向けて集光する円筒平面凸レンズ（以下、第２円筒平面レンズ３５という）が設けられている。第２円筒平面レンズ３５の下方側にはラインセンサー４が配置されており、第２円筒平面レンズ３５は当該位置検出装置２の受光素子の配置方向に沿って前記反射光を集光するように配置されている。 A cylindrical planar convex lens (hereinafter referred to as a second cylindrical planar lens 35) that condenses the reflected light that has passed through the half mirror 33 toward a linear focal point is provided below the half mirror 33. The line sensor 4 is disposed below the second cylindrical planar lens 35, and the second cylindrical planar lens 35 condenses the reflected light along the arrangement direction of the light receiving elements of the position detecting device 2. Has been placed.
　ラインセンサー４は、ＣＭＯＳ（Complementary Metal-Oxide Semiconductor）やＣＣＤ（Charge Coupled Device）などの受光素子を直線状に並べた受光領域４０を備え、受光領域４０内の各受光素子に入射した光の輝度（強度）を検出することができる。本例のラインセンサー４は、６．４ｍｍの長さの受光領域４０に、受光素子として５１２個のＣＭＯＳを１列に並べた構成となっている。この受光領域４０は、真空チャック２１に載置され、ラインセンサー４の上方に配置されウエハＷの中央部側から外側に向かって伸びるように設けられている。 The line sensor 4 includes a light receiving area 40 in which light receiving elements such as a CMOS (Complementary Metal Oxide Semiconductor) and a CCD (Charge Coupled Device) are arranged in a straight line, and the luminance of light incident on each light receiving element in the light receiving area 40. (Intensity) can be detected. The line sensor 4 of this example has a configuration in which 512 CMOSs as light receiving elements are arranged in a line in a light receiving region 40 having a length of 6.4 mm. The light receiving region 40 is placed on the vacuum chuck 21, is disposed above the line sensor 4, and is provided so as to extend outward from the center side of the wafer W.
　各受光素子に入射した光（画素）の輝度は、図４に示すラインセンサー制御部４０１にて２５６階調のディジタルデータ（輝度データ）に変換され、所定のデータ加工が行われた後、ウエハＷの位置検出を実行する後述の制御部５側へ向けて出力される。ラインセンサー制御部４０１から出力されるデータの詳細や、制御部５にて行われるウエハＷの位置検出動作については後述する。 The brightness of the light (pixel) incident on each light receiving element is converted into 256 gradation digital data (luminance data) by the line sensor control unit 401 shown in FIG. It is output toward the later-described control unit 5 side that executes W position detection. Details of the data output from the line sensor control unit 401 and the position detection operation of the wafer W performed by the control unit 5 will be described later.
　以上に説明した構成を備えた位置検出装置２は、制御部５を備えている。制御部５はＣＰＵ（Central Processing Unit）５１と不図示の記憶部とを備え、記憶部には位置検出装置２の作用、即ち、ウエハ保持部２０に保持されたウエハＷを鉛直軸周りに少なくとも１回転させながらＬＥＤライト３１から位置検出用の光を照射し、ラインセンサー４に入射した反射光に基づいてウエハＷの位置を特定する動作についてのステップ（命令）群が組まれたプログラムが記録されている。このプログラムは、例えばハードディスク、コンパクトディスク、マグネットオプティカルディスク、メモリーカードなどの記憶媒体に格納され、そこからコンピュータにインストールされる。 The position detection device 2 having the configuration described above includes a control unit 5. The control unit 5 includes a CPU (Central Processing Unit) 51 and a storage unit (not shown). The storage unit operates the position detection device 2, that is, the wafer W held by the wafer holding unit 20 at least around the vertical axis. A program in which a group of steps (commands) for the operation of irradiating the position detection light from the LED light 31 while rotating it and specifying the position of the wafer W based on the reflected light incident on the line sensor 4 is recorded. Has been. This program is stored in a storage medium such as a hard disk, a compact disk, a magnetic optical disk, or a memory card, and installed in the computer therefrom.
　次に、上述の位置検出装置２を用いてウエハＷの位置を特定する手法について説明する。図５は本例の位置検出装置２を用いて位置検出が行われるウエハＷの構成例を示している。　
　背景技術にて説明したように、従来のウエハＷには、周縁領域に切り欠きが形成されている。そして、この切り欠きに検査用の光を通過させ、光センサーを用いて検出して得た光量変化から、ウエハＷの向きや中心位置の検出を行う透過光方式の位置検出法を採用している。 Next, a method for specifying the position of the wafer W using the above-described position detection apparatus 2 will be described. FIG. 5 shows a configuration example of the wafer W on which position detection is performed using the position detection apparatus 2 of this example.
As described in the background art, the conventional wafer W has a notch formed in the peripheral region. Then, a position detection method using a transmitted light method is adopted that detects the orientation and center position of the wafer W from a change in the amount of light obtained by passing light for inspection through this notch and detecting it using an optical sensor. Yes.
　これに対して図５に示したウエハＷの外周領域には、切り欠きが形成されておらず、その輪郭形状は円形となっている。一方でウエハＷの下面側には、位置合わせ用のマークＭが形成されている。　
　マークＭは、既述の切り欠き（オリエンテーションフラットやノッチ）に替えて形成されるものであり、例えばレーザー刻印によりウエハＷの下面を浅く削ることによって形成されている。 On the other hand, notches are not formed in the outer peripheral area of the wafer W shown in FIG. 5, and the contour shape is circular. On the other hand, an alignment mark M is formed on the lower surface side of the wafer W.
The mark M is formed in place of the above-described notch (orientation flat or notch), and is formed by, for example, shaving the lower surface of the wafer W shallowly by laser marking.
　図５、図６に示すように、本例のマークＭは、深さ数十μｍ、直径１００μｍ程度のドットを、数百μｍ程度のピッチで複数個並べて配置したドットパターンによって構成されている。ドットパターンの構成に特段の限定はないが、本例では４つのドットをウエハＷの中央部から外側に向かって径方向に配列したドット列を形成し、さらに３本のドット列をウエハＷの周方向に向けて互いに隣り合うように並べることにより例えば０．６ｍｍ×０．４ｍｍの長方形のマークＭを構成している。 As shown in FIGS. 5 and 6, the mark M in this example is configured by a dot pattern in which a plurality of dots having a depth of several tens of μm and a diameter of about 100 μm are arranged at a pitch of about several hundreds of μm. Although there is no particular limitation on the configuration of the dot pattern, in this example, a dot row in which four dots are arranged radially from the center of the wafer W toward the outside is formed, and three more dot rows are formed on the wafer W. For example, a rectangular mark M having a size of 0.6 mm × 0.4 mm is formed by arranging them adjacent to each other in the circumferential direction.
　ウエハＷのスライシングを行う前のインゴットの周縁領域を大幅に切削加工して特異な形状の切り欠きを形成する場合と比較して、ウエハＷの裏面を浅く削ってマークＭを形成する手法は、ウエハＷに加わるストレスが小さく、特異形状も形成されない。このため、従来、切り欠きの周辺に形成した半導体装置に発生していた特性の低下を抑えることができる。 Compared with the case where the peripheral region of the ingot before slicing of the wafer W is significantly cut to form a notch with a unique shape, the method of forming the mark M by shallowly cutting the back surface of the wafer W is as follows: The stress applied to the wafer W is small and no unique shape is formed. For this reason, it is possible to suppress the deterioration in characteristics that has conventionally occurred in a semiconductor device formed around the notch.
　ここで例えば直径３００ｍｍや４５０ｍｍのウエハＷの場合、マークＭや当該マークＭを構成するドットはウエハＷの曲率に対して十分に小さい。このためラインセンサー４の解像度（５１２ｐｉｘｅｌ／６．４ｍｍ）で見たとき、図６に示すようにマークＭのドット列はウエハＷの端部（周縁の位置）からほぼ等距離（ｗ［ｍｍ］）だけ離れた位置から形成が開始され、またドット列同士は互いに平行に配置されているものとして検出される。
　本例の位置検出装置２は、上述のマークＭを検出することによりウエハＷの向きを検出する。 Here, for example, in the case of a wafer W having a diameter of 300 mm or 450 mm, the mark M and the dots constituting the mark M are sufficiently small with respect to the curvature of the wafer W. For this reason, when viewed at the resolution of the line sensor 4 (512 pixels / 6.4 mm), the dot rows of the mark M are substantially equidistant (w [mm]) from the end (periphery position) of the wafer W as shown in FIG. ) Are formed at positions that are separated from each other, and the dot rows are detected as being arranged in parallel to each other.
The position detection apparatus 2 of this example detects the orientation of the wafer W by detecting the above-described mark M.
　図６（ａ）～（ｅ）は、光照射機構３から位置検出用の光を照射しながらウエハＷを回転させとき、受光素子が一列に配列されたラインセンサー４の受光領域４０とマークＭとの位置関係の時間変化を示している。ウエハＷの周縁領域からその外方領域に亘って、真空チャック２１の回転中心を中心とする円の径方向（前記回転中心とウエハＷの中心とが一致して載置されている場合には、ウエハＷの径方向）に伸びる直線状の光照射領域を形成し、その反射光をラインセンサー４にて検出すると、ウエハＷの下面にて反射した反射光が検出される領域と、当該反射光の検出が行われない領域との境がウエハＷの端部（ウエハＷの周縁の位置）として特定される。また、前記直線状の光の照射領域（図６（ａ）～（ｅ）に示す受光領域４０に対応している）をマークＭが通過すると、光の散乱により反射光の輝度が低下し、マークＭが通過した位置に対応する受光素子にて検出される輝度が低下する。即ち、マークＭを構成するドットの光反射率は、ウエハＷの裏面の光反射率よりも小さくなっている。 6A to 6E show the light receiving region 40 and the mark M of the line sensor 4 in which the light receiving elements are arranged in a line when the wafer W is rotated while irradiating the position detecting light from the light irradiation mechanism 3. FIG. The positional change with respect to time is shown. A radial direction of a circle centering on the rotation center of the vacuum chuck 21 from the peripheral region to the outer region of the wafer W (when the rotation center and the center of the wafer W are placed in alignment) Forming a linear light irradiation region extending in the radial direction of the wafer W and detecting the reflected light by the line sensor 4, the region where the reflected light reflected from the lower surface of the wafer W is detected, and the reflection The boundary with the region where no light is detected is specified as the end of the wafer W (the position of the periphery of the wafer W). Further, when the mark M passes through the linear light irradiation region (corresponding to the light receiving region 40 shown in FIGS. 6A to 6E), the brightness of reflected light decreases due to light scattering, and The brightness detected by the light receiving element corresponding to the position where the mark M has passed decreases. That is, the light reflectance of the dots constituting the mark M is smaller than the light reflectance of the back surface of the wafer W.
　図７（ａ）～（ｅ）は、図６（ａ）～（ｅ）に示した各位置において、ラインセンサー４に入射する光の輝度分布を模式的に示している。各図の横軸はラインセンサー４に入射した光の輝度を示し、縦軸はラインセンサー４に設けられている受光素子の番地（０～５１１番）を示している。　
　図７（ａ）～（ｅ）に示すように、ラインセンサー４に入射する光は、位置検出用の光が反射するウエハＷの周縁領域と、位置検出用の光が通過してしまうウエハＷの外方領域とで輝度が異なっている。一方で、ウエハＷの端部付近には、ベベルと呼ばれる傾斜面が形成されており、ベベル部では反射光が散乱してしまう。このため、ラインセンサー４に入射する光の輝度は、ウエハＷの端部を境としたステップ状の変化を見せず、ウエハＷの外方の端部手前の位置から、当該端部を境としたウエハＷの内側の位置に亘って、徐々に輝度が高くなる輝度分布を呈する。 FIGS. 7A to 7E schematically show the luminance distribution of light incident on the line sensor 4 at each position shown in FIGS. 6A to 6E. In each figure, the horizontal axis indicates the luminance of light incident on the line sensor 4, and the vertical axis indicates the address (0 to 511) of the light receiving element provided in the line sensor 4.
As shown in FIGS. 7A to 7E, the light incident on the line sensor 4 includes the peripheral area of the wafer W where the position detection light is reflected and the wafer W where the position detection light passes. The brightness is different from the outer area. On the other hand, an inclined surface called a bevel is formed in the vicinity of the end portion of the wafer W, and reflected light is scattered at the bevel portion. For this reason, the luminance of the light incident on the line sensor 4 does not show a step-like change at the edge of the wafer W, and the boundary from the position just before the outer edge of the wafer W is the boundary. A luminance distribution in which the luminance gradually increases over the inner position of the wafer W is obtained.
　そこで本例の位置検出装置２は、ベベル部の影響で輝度が連続的に変化する場合におけるウエハＷの端部位置での輝度が、予備実験などにより予め把握されている。そして、この端部位置での輝度をしきい値として入射光の輝度がしきい値を上回る位置をウエハＷの端部として検出する。 Therefore, in the position detection apparatus 2 of the present example, the luminance at the edge position of the wafer W when the luminance continuously changes due to the influence of the bevel portion is previously grasped by a preliminary experiment or the like. Then, the position where the luminance of the incident light exceeds the threshold value is detected as the edge portion of the wafer W with the luminance at the edge position as a threshold value.
　またマークＭの形成されている領域では、図７（ｂ）～（ｄ）に示すようにドットが形成されている位置にてラインセンサー４に入射する光の輝度が低下する（対応する図６（ｂ）～（ｄ）参照）。また、照射領域（即ち受光領域４０）内にドット列が１列進入した状態（図６（ｂ）、（ｄ））におけるドットの通過位置に比べて（図７（ｂ）、（ｄ））、隣り合って配置された２列分のドット列が進入した状態（図６（ｃ））におけるドット通過位置（図７（ｃ））の方が輝度の低下量が大きくなる。 In the region where the mark M is formed, the luminance of the light incident on the line sensor 4 is lowered at the position where the dot is formed as shown in FIGS. 7B to 7D (corresponding FIG. 6). (Refer to (b) to (d)). Further, as compared with the dot passing position in the state where the dot row has entered the irradiation region (that is, the light receiving region 40) (FIGS. 6B and 6D) (FIGS. 7B and 7D). The amount of decrease in luminance is larger in the dot passing position (FIG. 7C) in the state where the two adjacently arranged dot rows enter (FIG. 6C).
　一方で、後述する実施例に示すように、実際のラインセンサー４で検出される輝度は、受光素子の配置数（解像度）に応じて図７（ｂ）～（ｄ）に示す輝度変化パターンが平滑化される（後述する図１３の（Ａ）～（Ｃ）におけるマーク検出位置の輝度データ参照）。　
　そこで、本例の位置検出装置２においては、マークＭが光の照射領域を通過することにより、入射光の輝度変化が大きくなる位置（マークＭを検出する感度が高い位置）を予めマーク検出位置として設定し、当該位置における輝度変化に基づいてマークＭが形成されている領域を検出する。 On the other hand, as shown in the embodiments described later, the luminance detected by the actual line sensor 4 has the luminance change patterns shown in FIGS. 7B to 7D according to the number of light receiving elements arranged (resolution). Smoothed (refer to the luminance data at the mark detection position in FIGS. 13A to 13C described later).
Therefore, in the position detection device 2 of the present example, a position where the luminance change of incident light is increased by passing the mark M through the light irradiation region (a position where the sensitivity for detecting the mark M is high) is set in advance as the mark detection position. And an area where the mark M is formed is detected based on the luminance change at the position.
　上述の手法により、本例の位置検出装置２は、ラインセンサー４にて検出された輝度データに基づき、ウエハＷの端部の位置と、ウエハＷの裏面におけるマークＭの形成位置とを検出することができる。　
　しかしながら、ウエハＷを１回転させる間に６０００ポイントで取得され、ラインセンサー４にて検出された５１２ｐｉｘｅｌの全ての画素の輝度データ（階調データ）を画像データとして制御部５に出力し、画像解析により上述の手法でウエハＷの端部やマークＭの検出を行うと、３．１ＭＢ（６０００ポイント×５１２ｐｉｘｅｌ×８Ｂｉｔ（２５６階調）≒３．１ＭＢ）もの大きなデータを処理する必要が生じる。この結果、システム構成が複雑になり、装置コストの上昇につながってしまう。 With the above-described method, the position detection device 2 of this example detects the position of the end portion of the wafer W and the formation position of the mark M on the back surface of the wafer W based on the luminance data detected by the line sensor 4. be able to.
However, the brightness data (gradation data) of all the pixels of 512 pixels acquired at 6000 points during one rotation of the wafer W and detected by the line sensor 4 are output as image data to the control unit 5 for image analysis. Thus, when the edge of the wafer W and the mark M are detected by the above-described method, it is necessary to process data as large as 3.1 MB (6000 points × 512 pixels × 8 bits (256 gradations) ≈3.1 MB). As a result, the system configuration becomes complicated and the apparatus cost increases.
　そこで本例の位置検出装置２は、ウエハＷの端部やマークＭの配置位置の特徴を利用して、これら端部やマークＭの検出に必要な情報だけをラインセンサー制御部４０１にて取り出し、制御部５に設けられたメモリ５２に書き込む処理を実行する。この観点において、制御部５やラインセンサー制御部４０１は、位置検出装置２のデータ処理部を構成している。　
　以下、ラインセンサー制御部４０１にて実行される処理の詳細について説明する。 In view of this, the position detection apparatus 2 of the present example uses the line sensor control unit 401 to extract only information necessary for the detection of the edge and the mark M by using the feature of the arrangement position of the edge and the mark M of the wafer W. Then, a process of writing in the memory 52 provided in the control unit 5 is executed. From this viewpoint, the control unit 5 and the line sensor control unit 401 constitute a data processing unit of the position detection device 2.
Details of processing executed by the line sensor control unit 401 will be described below.
　初めに、ウエハＷの端部の位置を特定する手法につき、ラインセンサー制御部４０１は各サンプリングポイントにてウエハＷの径方向外側から内側へ向けてラインセンサー４によるスキャンを行い、各受光素子から取得した輝度データを予め設定しておいたしきい値と比較する。そして、輝度データの大きさがしきい値を超えた（しきい値より明るくなった）位置における受光素子の番地データ（０～５１１番）を９Ｂｉｔの端部位置データとして制御部５のメモリ５２へ書き込む。 First, for the method of specifying the position of the edge of the wafer W, the line sensor control unit 401 performs scanning by the line sensor 4 from the radially outer side to the inner side of the wafer W at each sampling point. The acquired luminance data is compared with a preset threshold value. Then, the address data (0 to 511) of the light receiving element at the position where the magnitude of the luminance data exceeds the threshold value (becomes brighter than the threshold value) is written in the memory 52 of the control unit 5 as 9-bit end position data. .
　制御部５は、各受光素子の番地と、当該受光素子がラインセンサー４のどの位置に配置されているものであるかを示す情報に基づいてウエハＷの端部の位置を特定する。そして、６０００ポイント分の端部位置をウエハＷの回転角度と対応付けて並べることにより、図８に示すように真空チャック２１上に保持されたウエハＷを１回転させたときのウエハＷの端部位置の変位を把握することができる。そして、この端部位置の変位範囲の中央値から、ウエハＷの直径が求められ、前記中央値と最大の変位量との差分から真空チャック２１の回転中心とウエハＷの中心との間の偏心量を求めることができる。このとき、予めラインセンサー制御部４０１にてしきい値判定が行われた端部位置データを利用することにより、６．８ｋＢ（６０００ポイント×９Ｂｉｔ≒６．８ｋＢ）のデータ量でこれらウエハＷの直径や偏心量を特定することができる。 The control unit 5 specifies the position of the end of the wafer W based on the address of each light receiving element and the information indicating where the light receiving element is arranged on the line sensor 4. Then, by aligning the end positions for 6000 points in association with the rotation angle of the wafer W, as shown in FIG. 8, the end of the wafer W when the wafer W held on the vacuum chuck 21 is rotated once. The displacement of the part position can be grasped. Then, the diameter of the wafer W is obtained from the median value of the displacement range of the end position, and the eccentricity between the rotation center of the vacuum chuck 21 and the center of the wafer W is obtained from the difference between the median value and the maximum displacement amount. The amount can be determined. At this time, by using the edge position data for which the threshold determination has been performed in advance by the line sensor control unit 401, the data amount of these wafers W is 6.8 kB (6000 points × 9 bits≈6.8 kB). The diameter and the amount of eccentricity can be specified.
　しかしながら図８に示す端部位置の変位だけでは、真空チャック２１に保持されたウエハＷのずれ方向を特定することができない。そこでマークＭの検出結果を利用した、真空チャック２１上のウエハＷの向きの検出を行う。
　ここで図５、図６を用いて説明したように、位置検出装置２にて位置検出が行われるウエハＷにおいては、その端部からｗ［ｍｍ］だけ離れた位置から内側の領域にマークＭが形成される規格となっている。従って、マークＭの検出が行われるマーク検出位置もウエハＷの端部から所定の距離（ｗ’［ｍｍ］）だけ中央部側に寄った位置となる。このため、図８に示すように真空チャック２１上に保持されたウエハＷの回転に応じてウエハＷの端部が移動すると、既述のマーク検出位置も移動することとなる（図８の破線）。 However, the displacement direction of the wafer W held by the vacuum chuck 21 cannot be specified only by the displacement of the end position shown in FIG. Therefore, the orientation of the wafer W on the vacuum chuck 21 is detected using the detection result of the mark M.
Here, as described with reference to FIGS. 5 and 6, in the wafer W whose position is detected by the position detection device 2, the mark M is marked on the inner region from a position separated by w [mm] from the end. Has become a standard. Accordingly, the mark detection position at which the mark M is detected is also a position that is closer to the center side by a predetermined distance (w ′ [mm]) from the end of the wafer W. For this reason, as shown in FIG. 8, when the end of the wafer W moves in accordance with the rotation of the wafer W held on the vacuum chuck 21, the mark detection position described above also moves (the broken line in FIG. 8). ).
　そこで本例のラインセンサー制御部４０１は、各受光素子から取得した輝度データのうち、既述のしきい値判定に基づいて特定したウエハＷの端部から予め設定した距離（ｗ’［ｍｍ］）だけウエハＷの中央部側へ寄った位置からの反射光が入射した受光素子から得た画素の輝度データ（２５６階調、８Ｂｉｔ）をマーク検出位置における輝度データとして制御部５のメモリ５２へ書き込む。なお、この輝度データは、１個の受光素子から得られたものに限定されるものではなく、例えば隣り合う複数個の受光素子から得られた画素の輝度データの平均値を用いてもよい。 Therefore, the line sensor control unit 401 of this example includes a preset distance (w ′ [mm]) from the edge of the wafer W specified based on the above-described threshold determination among the luminance data acquired from each light receiving element. ), The luminance data (256 gradations, 8 bits) of the pixel obtained from the light receiving element on which the reflected light from the position close to the center side of the wafer W is incident on the memory 52 of the control unit 5 as the luminance data at the mark detection position. Write. The luminance data is not limited to that obtained from one light receiving element, and for example, an average value of luminance data of pixels obtained from a plurality of adjacent light receiving elements may be used.
　制御部５は、６０００ポイント分の輝度データをウエハＷの回転角度（回転方向の位置）と対応付けて並べることにより、図９に示すようにマーク検出位置における反射光の輝度変化を把握することができる。そして反射光の輝度の低下が検出された位置（予め設定された輝度よりも輝度が低くなった位置）をマークＭの形成位置としてウエハＷの向き（例えば結晶方向と、ウエハＷの中心とマークＭ形成位置とを結ぶ方向とが成す角度）を特定することができる。このウエハＷの角度に基づいて、真空チャック２１上に載置されたウエハＷの偏心方向を特定し、前記偏心量のｘ方向成分やｙ方向成分を特定することができる。このとき、予めラインセンサー制御部４０１にて特定したマーク検出位置における輝度データを利用することにより、６ｋＢ（６０００ポイント×８Ｂｉｔ≒６ｋＢ）のデータ量でウエハＷの向きを特定することができる。 The control unit 5 grasps the luminance change of the reflected light at the mark detection position as shown in FIG. 9 by arranging the luminance data for 6000 points in association with the rotation angle (position in the rotation direction) of the wafer W. Can do. Then, the position (for example, the crystal direction, the center of the wafer W, the mark, and the mark) where the mark M is formed is the position where the decrease in the brightness of the reflected light is detected (the position where the brightness is lower than the preset brightness). The angle formed by the direction connecting the M formation position can be specified. Based on the angle of the wafer W, the eccentric direction of the wafer W placed on the vacuum chuck 21 can be specified, and the x direction component and the y direction component of the eccentric amount can be specified. At this time, by using the luminance data at the mark detection position specified in advance by the line sensor control unit 401, the orientation of the wafer W can be specified with a data amount of 6 kB (6000 points × 8 bits≈6 kB).
　マーク検出位置における輝度データのみを選択的に取得することにより、例えばウエハＷの裏面にパーティクルなどが付着していても、パーティクルの付着に起因する輝度データの変化までも取り込んでしまう確率が低く、マークＭとパーティクルの識別の必要性が少ない。また、複数のドットを規則的に配列してマークＭを形成することにより、図９の拡大図中に示すように、特異な輝度変化のパターンを形成させることができる。この結果、パーティクルの付着やデポジット膜などの影響による輝度データの変動の影響を取り除いてマークＭからの反射による輝度データの変化を確実に識別することができる。 By selectively acquiring only the luminance data at the mark detection position, for example, even if particles or the like are attached to the back surface of the wafer W, there is a low probability that even changes in luminance data due to the adhesion of particles will be captured, There is little need to distinguish the mark M from the particles. Further, by forming a mark M by regularly arranging a plurality of dots, a unique luminance change pattern can be formed as shown in the enlarged view of FIG. As a result, it is possible to reliably identify the change in the luminance data due to the reflection from the mark M by removing the influence of the fluctuation of the luminance data due to the influence of particle adhesion, deposit film, and the like.
　上述の手法によれば、ウエハＷの周縁領域及びその外方領域をスキャンして得た３．１ＭＢの輝度データ（階調データ）と比較して、約０．４％相当のデータ量（端部位置データ（６．８ｋＢ）＋マーク検出位置の輝度データ（６ｋＢ）＝１２．８ｋＢ）にて、真空チャック２１上のウエハＷの直径、偏心量、ウエハＷの向きを特定することが可能となる。
　以上に説明した手法を利用してウエハＷの位置検出を行う位置検出装置２の動作について図１０のフロー図を参照しながら説明する。　 According to the above-described method, compared with the 3.1 MB luminance data (gradation data) obtained by scanning the peripheral area and the outer area of the wafer W, the data amount (edge) is about 0.4%. It is possible to specify the diameter, the amount of eccentricity, and the orientation of the wafer W on the vacuum chuck 21 by the position position data (6.8 kB) + the luminance data (6 kB) = 12.8 kB of the mark detection position. Become.
The operation of the position detection apparatus 2 that detects the position of the wafer W using the method described above will be described with reference to the flowchart of FIG.
　初めに、外部のウエハ搬送機構によりウエハＷが位置検出装置２の筐体内に搬送され、ウエハＷがウエハ保持部２０の真空チャック２１上に載置される。このとき、真空チャック２１上の正しい位置にウエハＷが載置された場合には、ウエハＷの中心と真空チャック２１の回転中心とが一致し、ウエハＷの裏面に形成されたマークＭも予め設定された方向を向いた状態となる。しかる後、ウエハ搬送機構が筐体内から退避したらウエハＷの位置検出を開始する（スタート）。 First, the wafer W is transferred into the housing of the position detection device 2 by an external wafer transfer mechanism, and the wafer W is placed on the vacuum chuck 21 of the wafer holder 20. At this time, when the wafer W is placed at the correct position on the vacuum chuck 21, the center of the wafer W and the center of rotation of the vacuum chuck 21 coincide with each other, and the mark M formed on the back surface of the wafer W is also in advance. It will be in the state of facing the set direction. Thereafter, when the wafer transfer mechanism is retracted from the housing, the position detection of the wafer W is started (start).
　次いで、ＬＥＤライト３１を点灯してウエハＷへの投光を開始すると共に、ウエハＷを回転させ、回転速度が設定速度に到達して等速となったら、真空チャック２１が予め設定した方向を向いたタイミングで検出動作を開始する（ステップＳ１０１）。
　はじめにカウンタをリセットし（ステップＳ１０２）、検出開始位置にてラインセンサー４に入射する反射光の輝度をしきい値と比較しウエハＷの端部の位置を特定し（ステップＳ１０３）、特定された端部の位置から予め設定した距離だけ中央部側へ寄ったマーク検出位置における輝度データを取得する（ステップＳ１０４）。 Next, the LED light 31 is turned on to start light projection onto the wafer W, and the wafer W is rotated. When the rotation speed reaches the set speed and becomes constant, the vacuum chuck 21 changes the preset direction. The detection operation is started at the facing timing (step S101).
First, the counter is reset (step S102), the brightness of reflected light incident on the line sensor 4 at the detection start position is compared with a threshold value, and the position of the edge of the wafer W is specified (step S103). Luminance data is acquired at a mark detection position close to the center side by a preset distance from the end position (step S104).
　次に、これらの動作で取得した端部位置データ及び輝度データを、各々ウエハＷの回転角度と対応付けてメモリ５２に記憶する（ステップＳ１０５）。　　次いでカウンタをインクリメントして（ステップＳ１０６）、設定されたサンプリング数との比較を行い（ステップＳ１０７）、全測定点の測定が完了していない場合には（ステップＳ１０７；ＮＯ）、前回の検出動作時から所定時間だけ経過後（ステップＳ１０８）、ステップＳ１０３～１０６の動作を繰り返し、各サンプリングポイントにおける端部位置データ及びマーク検出位置における輝度データを順次、取得する。 Next, the edge position data and the luminance data acquired by these operations are stored in the memory 52 in association with the rotation angle of the wafer W (step S105). Next, the counter is incremented (step S106) and compared with the set sampling number (step S107). When measurement of all measurement points is not completed (step S107; NO), the previous detection operation is performed. After a lapse of a predetermined time from the time (step S108), the operations of steps S103 to S106 are repeated to sequentially acquire the edge position data at each sampling point and the luminance data at the mark detection position.
　ウエハＷが少なくとも１回転し、全てのサンプリングポイントでデータ取得を終えたら（ステップＳ１０７；ＹＥＳ）、ＬＥＤライト３１を消灯し、ウエハＷの回転を停止する。そして、取得した端部位置データ及びマーク検出位置における輝度データに基づき、図８に示した端部位置の変位や、図９に示したマーク検出位置における輝度変化に基づき、ウエハＷの直径や偏心量、ウエハＷの向きを特定する（ステップＳ１０９、エンド）。 When the wafer W has made at least one rotation and data acquisition has been completed at all sampling points (step S107; YES), the LED light 31 is turned off and the rotation of the wafer W is stopped. Based on the acquired edge position data and luminance data at the mark detection position, the diameter and eccentricity of the wafer W are determined based on the displacement of the edge position shown in FIG. 8 and the luminance change at the mark detection position shown in FIG. The amount and the direction of the wafer W are specified (step S109, end).
　本実施の形態に係る位置検出装置２によれば以下の効果がある。裏面に複数のドットからなる位置合わせ用のマークＭが形成されたウエハＷを真空チャック２１に載置して少なくとも１回転させ、ウエハＷの回転方向の位置と、ウエハＷの裏面に照射した光を反射させ、ラインセンサー４で受光して得られた輝度とを対応付けたデータを取得している。従って、このデータに基づいてウエハの向きを検出することができるので、切り欠きを備えないウエハＷの位置を検出することができる。 The position detection device 2 according to the present embodiment has the following effects. The wafer W on which the alignment mark M composed of a plurality of dots is formed on the back surface is placed on the vacuum chuck 21 and rotated at least once, and the position of the wafer W in the rotation direction and the light irradiated on the back surface of the wafer W are irradiated. And the brightness obtained by receiving the light with the line sensor 4 is acquired. Therefore, since the orientation of the wafer can be detected based on this data, the position of the wafer W not having a notch can be detected.
　ここで本例の位置検出装置２は、ウエハＷの裏面にて反射した光を利用してウエハＷの端部の位置、及びウエハＷの裏面に形成されたマークＭを検出する手法について説明した。但し、端部位置の検出については従来のように、ウエハＷを挟んで上下面の一方側にＬＥＤライト３１を配置し、他方側にラインセンサー４を配置して、ＬＥＤライト３１から照射した光がウエハＷにて遮られた位置に基づいて端部位置を検出する透過光方式を採用してもよいし、端部の検出自体を行わなくてもよい。例えば、真空チャック２１上に載置されたウエハＷを側面から押さえつけて、ｘ方向やｙ方向への位置ずれを矯正する治具が位置検出装置２内に設けられている場合などには、マークＭの検出によるウエハＷの向きの特定のみを行えばよい。 Here, the position detection apparatus 2 of the present example has described a method of detecting the position of the edge of the wafer W and the mark M formed on the back surface of the wafer W using light reflected from the back surface of the wafer W. . However, as for detection of the end position, the LED light 31 is arranged on one side of the upper and lower surfaces across the wafer W, and the line sensor 4 is arranged on the other side so that the light emitted from the LED light 31 is detected. May employ a transmitted light system that detects the end position based on the position blocked by the wafer W, or may not detect the end itself. For example, when a jig for pressing the wafer W placed on the vacuum chuck 21 from the side surface and correcting the positional deviation in the x direction or the y direction is provided in the position detection device 2, It is only necessary to specify the orientation of the wafer W by detecting M.
　この場合において、マーク検出位置の特定は、位置ずれの矯正が行われた後のウエハＷの端部が位置すると想定される位置から予め設定された距離だけ内側の位置をマーク検出位置として、既述の手法により輝度データを取得してもよい。また、マークＭの検出を行うだけの場合には、ウエハＷの直径の変化に応じてマークＭの配置位置が変化すると考えられる領域をカバーするようにラインセンサー４の受光領域４０を設定し、当該領域内の輝度データ（階調データ）を全て取得して画像解析によりマークを検出してもよい。ウエハＷの端部を検出する場合に比べて受光領域４０が狭いので、画像データのデータ量の増大を抑えることができる。 In this case, the mark detection position is specified by setting a position that is a predetermined distance from the position where the end portion of the wafer W after the correction of the positional deviation is positioned as a mark detection position. Luminance data may be acquired by the method described above. When only the mark M is detected, the light receiving area 40 of the line sensor 4 is set so as to cover the area where the arrangement position of the mark M is considered to change according to the change in the diameter of the wafer W. The mark may be detected by obtaining all the luminance data (gradation data) in the area and analyzing the image. Since the light receiving region 40 is narrower than when detecting the edge of the wafer W, an increase in the amount of image data can be suppressed.
　ここで、光照射機構３の構成例は図１～図３に例示したものに限られない。例えば円筒平面凸レンズ（第１円筒平面レンズ３４、第２円筒平面レンズ３５）に替えて、ロッドレンズやボールレンズ、ＦＡＣ（Fast-Axis Collimating Lens）レンズなどを採用してもよい。さらに、光照射機構３により形成される光照射領域の形状は、ラインセンサー４の受光領域４０に対応させて直線状とする場合に限定されない。ウエハＷの中央部側から外側に向かって直線状に伸びるように配置された受光領域４０に向けて、ウエハＷからの反射光を反射できるように構成されていれば、例えば光照射領域の形状は円形や矩形であってもよい。
　また、従来の透過光方式のウエハＷの検出法においてもラインセンサー４が用いられていることから、光照射機構３の構成を変更するだけで反射光方式の検出法を実行するシステムに転用することもできる。 Here, the configuration example of the light irradiation mechanism 3 is not limited to that illustrated in FIGS. 1 to 3. For example, a rod lens, a ball lens, a FAC (Fast-Axis Collimating Lens) lens, or the like may be employed instead of the cylindrical planar convex lens (the first cylindrical planar lens 34 and the second cylindrical planar lens 35). Furthermore, the shape of the light irradiation region formed by the light irradiation mechanism 3 is not limited to the case where the light irradiation region is formed in a straight line corresponding to the light receiving region 40 of the line sensor 4. If the light reflected from the wafer W can be reflected toward the light receiving region 40 arranged so as to extend linearly outward from the center side of the wafer W, for example, the shape of the light irradiation region May be circular or rectangular.
In addition, since the line sensor 4 is also used in the conventional detection method of the transmitted light type wafer W, it is diverted to a system that executes the detection method of the reflected light type only by changing the configuration of the light irradiation mechanism 3. You can also
　さらに、ウエハＷの裏面に設けるマークＭの数も１つの場合に限定されるものでなく、ウエハＷの周方向に互いに離れた位置に複数個設けてマークＭ検出の確実性を向上させるようにしてもよい。マークＭ自体の形状についてもドットの配列を種々変化させて、マークＭを文字情報などとして取り扱うことができるようにしてもよい。 Further, the number of marks M provided on the back surface of the wafer W is not limited to one, and a plurality of marks M are provided at positions separated from each other in the circumferential direction of the wafer W to improve the reliability of mark M detection. May be. Regarding the shape of the mark M itself, the dot arrangement may be changed variously so that the mark M can be handled as character information.
　続いて、上述の位置検出装置２を組み込んだ塗布、現像装置の例について図１１、図１２を参照しながら簡単に説明する。　
　処理対象のウエハＷを収容したキャリア１０２が塗布、現像装置のキャリアブロックＳ１に設けられた載置台１０１に載置されると、受け渡しアームＣによってウエハＷが取り出される。取り出されたウエハＷは、処理ブロックＳ２に設けられた棚ユニットＵ２内の受け渡しモジュールＣＰＬ２に受け渡され、搬送アームＡ２によってＢＣＴ層Ｂ２に搬入されて、反射防止膜が形成される。次いで、ウエハＷは、棚ユニットＵ２の受け渡しモジュールＢＦ２に受け渡され、受け渡しモジュールＣＰＬ３及び搬送アームＡ３を介してＣＯＴ層Ｂ３に搬入され、液処理モジュール１０３によりレジスト膜が形成される。 Next, an example of a coating and developing apparatus incorporating the above-described position detection device 2 will be briefly described with reference to FIGS.
When the carrier 102 containing the wafer W to be processed is placed on the placing table 101 provided in the carrier block S1 of the coating and developing apparatus, the wafer W is taken out by the delivery arm C. The taken wafer W is transferred to the transfer module CPL2 in the shelf unit U2 provided in the processing block S2, and transferred into the BCT layer B2 by the transfer arm A2, thereby forming an antireflection film. Next, the wafer W is transferred to the transfer module BF2 of the shelf unit U2, and transferred to the COT layer B3 via the transfer module CPL3 and the transfer arm A3, and a resist film is formed by the liquid processing module 103.
　ＣＯＴ層Ｂ３内には、レジスト膜を現像した際に、ウエハＷのパターン形成領域の外側である周縁部のレジスト膜が残らないようにするため、露光装置に搬入される前に当該周縁部のレジスト膜を予め露光しておく周縁露光モジュール１０４が設けられる。周縁露光モジュール１０４は、図１に示したウエハ保持部２０が筐体内に収容され、ウエハ保持部２０は搬送アームＡ３との間でウエハＷの受け渡しを行う位置と、周縁露光を行う位置との間を横方向に移動自在に構成される。周縁露光が行われる位置まで移動したウエハＷの周縁部の上方側には、紫外ランプなどの露光部が設けられ、ウエハＷを回転させながら紫外線を照射することにより、周縁露光が行われる。 In the COT layer B3, when the resist film is developed, the peripheral edge resist film outside the pattern formation region of the wafer W is not left, so that the peripheral edge portion is not transferred to the exposure apparatus. A peripheral exposure module 104 for exposing the resist film in advance is provided. In the peripheral exposure module 104, the wafer holding unit 20 shown in FIG. 1 is accommodated in a housing, and the wafer holding unit 20 has a position where the wafer W is transferred to and from the transfer arm A3 and a position where the peripheral exposure is performed. It is configured to be movable in the horizontal direction. An exposure unit such as an ultraviolet lamp is provided above the peripheral part of the wafer W moved to the position where the peripheral exposure is performed, and peripheral exposure is performed by irradiating the wafer W with ultraviolet rays.
　この周縁露光モジュール１０４においては、パターン形成領域の外側（周縁部）を正確に露光する必要がある。そこで周縁露光モジュール１０４には本発明の位置検出装置２が組み込まれている。この位置検出装置２を用いて、ウエハＷの直径や真空チャック２１に保持されたウエハＷの偏心量を正しく検出する。そして、真空チャック２１に保持されたウエハＷの回転動作と、ウエハ保持部２０の横方向への移動動作とを組み合わせ、位置検出装置２にて検出された結果に応じてウエハＷ直径の変化やウエハＷの偏心が相殺されるように露光位置を移動させることにより、正しい領域を露光することができる。 In the peripheral edge exposure module 104, it is necessary to accurately expose the outer side (peripheral portion) of the pattern formation region. Therefore, the edge exposure module 104 incorporates the position detection device 2 of the present invention. Using this position detection device 2, the diameter of the wafer W and the amount of eccentricity of the wafer W held on the vacuum chuck 21 are correctly detected. Then, the rotation operation of the wafer W held by the vacuum chuck 21 and the lateral movement operation of the wafer holding unit 20 are combined, and the change in the wafer W diameter according to the result detected by the position detection device 2 By moving the exposure position so that the eccentricity of the wafer W is offset, the correct area can be exposed.
　レジスト膜が形成され、周縁露光が行われた後のウエハＷは、搬送アームＡ３により、棚ユニットＵ２の受け渡しモジュールＢＦ３に受け渡された後、例えば受け渡しモジュールＢＦ３→受け渡しアームＤ１→受け渡しモジュールＣＰＬ４を介して搬送アームＡ４に受け渡され、ＴＣＴ層Ｂ４にてレジスト膜の上に反射防止膜が形成される。しかる後、ウエハＷは、搬送アームＡ４により受け渡しモジュールＴＲＳ４に受け渡される。なおレジスト膜の上の反射防止膜を形成しない場合や、レジスト膜の下の反射防止膜を形成する代わりに、ウエハＷに対して疎水化処理を行う場合もある。 After the resist film is formed and the edge exposure is performed, the wafer W is transferred to the transfer module BF3 of the shelf unit U2 by the transfer arm A3, and then, for example, the transfer module BF3 → the transfer arm D1 → the transfer module CPL4 To the transfer arm A4, and an antireflection film is formed on the resist film in the TCT layer B4. Thereafter, the wafer W is transferred to the transfer module TRS4 by the transfer arm A4. In some cases, the antireflection film is not formed on the resist film, or the wafer W is subjected to a hydrophobic treatment instead of forming the antireflection film below the resist film.
　受け渡しモジュールＴＲＳ４に受け渡された反射防止膜形成後のウエハＷは、さらに受け渡しモジュールＣＰＬ１１に受け渡され、ＤＥＶ層Ｂ１内の上部に設けられた搬送専用のシャトルアームＥにより棚ユニットＵ３の受け渡しモジュールＣＰＬ１２に搬送される。次いで、ウエハＷはインターフェイスブロックＳ３に取り込まれ、インターフェイスアームＦにより露光装置Ｓ４に搬送され、ここで所定の露光処理が行われる。しかる後、ウエハＷは、棚ユニットＵ３の受け渡しモジュールＴＲＳ６に載置されて処理ブロックＳ２に戻される。 The wafer W after the formation of the antireflection film transferred to the transfer module TRS4 is further transferred to the transfer module CPL11, and the transfer module of the shelf unit U3 is provided by the shuttle arm E dedicated for transfer provided in the upper part of the DEV layer B1. It is conveyed to CPL12. Next, the wafer W is taken into the interface block S3 and transferred to the exposure apparatus S4 by the interface arm F, where a predetermined exposure process is performed. Thereafter, the wafer W is placed on the delivery module TRS6 of the shelf unit U3 and returned to the processing block S2.
　処理ブロックＳ２に戻されたウエハＷは、ＤＥＶ層Ｂ１にて現像処理が行われた後、処理モジュール群Ｕ１に設けられた加熱モジュールに搬送され、ここでレジストパターンに残存する溶剤が除去される。この後、例えば搬送アームＡ１により処理モジュール群Ｕ１に設けられた冷却モジュールに搬送されて冷却される。こうして現像処理が行われたウエハＷは、レジスト膜の膜厚、レジストパターンをなす凹部の線幅（ＣＤ）の大きさ、隣り合う一組の凹凸部の幅（ピッチ）などの検査が行われ、各ウエハＷにはこれらの項目の合格、不合格の情報が付加されて、後段の装置における処理を実行するか否かなどの判断材料となる。 The wafer W returned to the processing block S2 is developed in the DEV layer B1, and then transferred to the heating module provided in the processing module group U1, where the solvent remaining in the resist pattern is removed. . Then, for example, it is transported to the cooling module provided in the processing module group U1 by the transport arm A1 and cooled. The wafer W thus developed is inspected for the film thickness of the resist film, the line width (CD) of the recesses forming the resist pattern, and the width (pitch) of a pair of adjacent uneven portions. Each wafer W is added with pass / fail information of these items, and is used as a judgment material for determining whether or not to execute processing in the subsequent apparatus.
　この検査装置においても、ウエハＷ内のどの領域にて膜厚やＣＤなどが規格を外れているのか正確に把握することが重要となる。そこで、この検査装置にも本発明の位置検出装置２が組み込まれ、検査対象のウエハＷの直径や載置位置の偏心量、ウエハＷの向きを検出した結果に基づいて把握した正確な検査位置と対応付けた検査結果の評価などが行われる。検査装置は例えば棚ユニットＵ２内に配置される。　
　検査を終えたウエハＷは、棚ユニットＵ２における受け渡しアームＣのアクセス範囲の受け渡し台に搬送され、受け渡しアームＣを介してキャリア１０２に戻される。 Also in this inspection apparatus, it is important to accurately grasp in which region in the wafer W the film thickness, CD, etc. are out of specification. Therefore, the position detection device 2 of the present invention is also incorporated in this inspection apparatus, and the accurate inspection position grasped based on the result of detecting the diameter of the wafer W to be inspected, the eccentric amount of the mounting position, and the orientation of the wafer W. Evaluation of the inspection result associated with is performed. The inspection device is disposed in the shelf unit U2, for example.
The wafer W that has been inspected is transferred to the transfer table in the access range of the transfer arm C in the shelf unit U2, and returned to the carrier 102 via the transfer arm C.
　以上、本発明の位置検出装置２を塗布、現像装置に組み込んだ例について説明したが、位置検出装置２を設ける装置はこの例に限定されるものではない。例えばスピンチャック上に保持したウエハＷに各種の処理液を供給して液処理を行う枚葉式の液処理装置や、真空容器内に設けられた載置台にウエハＷを載置し、成膜処理やエッチング処理、アッシング処理を行う真空処理装置などに設けられているスピンチャックや載置台に載置されるウエハＷの位置合わせなどに位置検出装置２を利用してもよい。この場合は、スピンチャックや載置台へウエハＷを搬送するウエハ搬送機構にウエハＷを受け渡す前に、位置検出装置２にて位置検出を行い、位置ずれなどを補正してウエハ搬送機構にウエハＷを受け渡す手法などが考えられる。 The example in which the position detection device 2 of the present invention is incorporated in the coating and developing device has been described above, but the device provided with the position detection device 2 is not limited to this example. For example, the wafer W is mounted on a single-wafer type liquid processing apparatus that supplies various processing liquids to the wafer W held on the spin chuck and performs liquid processing, or a mounting table provided in a vacuum vessel to form a film. The position detection device 2 may be used for alignment of a wafer W mounted on a spin chuck or a mounting table provided in a vacuum processing apparatus that performs processing, etching processing, or ashing processing. In this case, before delivering the wafer W to the wafer conveyance mechanism that conveys the wafer W to the spin chuck or the mounting table, the position detection device 2 detects the position and corrects the positional deviation and the like to the wafer conveyance mechanism. A method of delivering W can be considered.
（実施例）　
　図１～図３に示したものと同様の構成の位置検出装置２により、図５に示すウエハＷに形成されたマークＭの検出試験を行った。
Ａ．実験条件　
　直径が３００ｍｍのウエハＷの端部から１．０ｍｍの位置に、図５、図６を用いて説明した構成のマークＭ（０．６ｍｍ×０．４ｍｍ）を形成し、受光領域の長さが６．４ｍｍ、受光素子（ＣＭＯＳ）の数が５１２個（画素数ｐｉｘｅｌ）のラインセンサー４を用いて位置検出を行った。ラインセンサー４は、図６（ａ）～（ｅ）に示すようにウエハＷの端部を挟んで内側のウエハＷの周縁領域、及び端部よりも外方の領域に亘り、ウエハＷの径方向に受光領域４０が位置するように配置した。ウエハＷは、その中心が真空チャック２１の回転中心と一致するように（偏心量＝０）真空チャック２１上に載置し、ラインセンサー４にてマークＭをスキャンし、各受光素子から輝度データを取得した。 (Example)
A detection test of the mark M formed on the wafer W shown in FIG. 5 was performed by the position detection device 2 having the same configuration as that shown in FIGS.
A. Experimental conditions
The mark M (0.6 mm × 0.4 mm) having the structure described with reference to FIGS. 5 and 6 is formed at a position 1.0 mm from the end of the wafer W having a diameter of 300 mm, and the length of the light receiving region is Position detection was performed using a line sensor 4 having 6.4 mm and 512 light receiving elements (CMOS) (pixel number pixel). As shown in FIGS. 6A to 6E, the line sensor 4 has a diameter of the wafer W across the peripheral area of the inner wafer W and the outer area of the end with the end of the wafer W interposed therebetween. It arrange | positioned so that the light reception area | region 40 may be located in the direction. The wafer W is placed on the vacuum chuck 21 so that the center thereof coincides with the rotation center of the vacuum chuck 21 (eccentricity = 0), the mark M is scanned by the line sensor 4, and luminance data is received from each light receiving element. Acquired.
Ｂ．実験結果　
　図１３に併記したマークＭの拡大図中の（Ａ）～（Ｃ）の位置に、ラインセンサー４の受光領域４０の中心が到達したときの各受光素子から取得した輝度データの分布を示す。図中、横軸がラインセンサー４のスキャン位置（受光素子の番地）を示し、縦軸が２５６階調の輝度データの値を示している。拡大図中の（Ａ）の位置のスキャン結果を実線で示し、（Ｂ）、（Ｃ）の位置のスキャン結果を、各々一点鎖線、及び破線で示している。なお、これらの線が重なって見にくくなることを避けるため、各線は上下方向に少しずらして示してある。 B. Experimental result
The distribution of luminance data acquired from each light receiving element when the center of the light receiving region 40 of the line sensor 4 reaches the position (A) to (C) in the enlarged view of the mark M shown in FIG. In the figure, the horizontal axis indicates the scanning position (address of the light receiving element) of the line sensor 4, and the vertical axis indicates the luminance data value of 256 gradations. The scan results at the position (A) in the enlarged view are indicated by solid lines, and the scan results at the positions (B) and (C) are respectively indicated by a one-dot chain line and a broken line. In addition, in order to avoid that these lines overlap and it is hard to see, each line is shown in the up-down direction slightly shifted.
　図１３に示した結果によれば、（Ａ）～（Ｃ）のいずれの場合においても、ウエハＷの端部よりも外方領域側の位置から輝度データの値が上昇し始め、ウエハＷ側に移動するに連れて、（Ａ）～（Ｃ）は同じ傾きで輝度データの値が上昇している。従って、適切なしきい値を設定することにより、ウエハＷの端部の位置を正確に把握することが可能であることが分かる。 According to the results shown in FIG. 13, in any of the cases (A) to (C), the value of the luminance data starts to rise from the position on the outer region side of the edge of the wafer W, and the wafer W side As the value moves to (A) to (C), the value of the luminance data increases with the same inclination in (A) to (C). Therefore, it can be understood that the position of the end portion of the wafer W can be accurately grasped by setting an appropriate threshold value.
　また、マークＭが形成されている領域の輝度データの分布を見ると、マークＭから外れた位置をスキャンした（Ａ）の位置では、ラインセンサー４に入射する反射光の光量を示す輝度データに落ち込みはない。次に、１本目のドット列上をスキャンした（Ｂ）の位置では、マークＭが形成されている位置にて輝度データの値は落ち込んでいる。さらに２本目のドット列上をスキャンした（Ｃ）の位置では（Ｂ）の位置よりも輝度データの値が低下する領域が形成されている。（Ｂ）の位置よりも（Ｃ）の位置の方が、輝度データの値が低下するのは、隣り合って並んだドットの影響を受けてラインセンサー４に入射する反射光の光量が低下したためであると考えられる。 When the distribution of the luminance data in the area where the mark M is formed is seen, the luminance data indicating the amount of reflected light incident on the line sensor 4 is obtained at the position (A) where the position deviated from the mark M is scanned. There is no decline. Next, at the position (B) where the first dot row is scanned, the value of the luminance data drops at the position where the mark M is formed. Further, an area where the value of the luminance data is lower than that of the position (B) is formed at the position (C) scanned on the second dot row. The reason why the value of the brightness data is lower at the position (C) than at the position (B) is that the amount of reflected light incident on the line sensor 4 is reduced due to the influence of adjacent dots. It is thought that.
　このように、マークＭが形成されたウエハＷをスキャンする位置に応じてラインセンサー４にて検出される輝度データが変化することを利用し、適切な位置にマーク検出位置を設定することで、図９に示すようにマーク検出位置における輝度データの変化に基づいてマークＭの形成位置を検出できることが確認できた。 In this way, by using the fact that the luminance data detected by the line sensor 4 changes according to the position where the wafer W on which the mark M is formed is scanned, the mark detection position is set at an appropriate position. As shown in FIG. 9, it was confirmed that the formation position of the mark M can be detected based on the change in the luminance data at the mark detection position.
Ｍ　　　　　マーク
Ｗ　　　　　ウエハ
２　　　　　位置検出装置
２０　　　　ウエハ保持部
２１　　　　真空チャック
２３　　　　回転モーター
３　　　　　光照射機構
３１　　　　ＬＥＤライト
４　　　　　ラインセンサー
４０　　　　受光領域
４０１　　　ラインセンサー制御部
５　　　　　制御部 M Mark W Wafer 2 Position detection device 20 Wafer holding unit 21 Vacuum chuck 23 Rotating motor 3 Light irradiation mechanism 31 LED light 4 Line sensor 40 Light receiving area 401 Line sensor control unit 5 Control unit

Claims (19)

  1. 　裏面に複数のドットからなる位置合わせ用のマークが形成されたウエハを載置するための載置台と、
    　前記載置台を回転させるための回転機構と、
    　投光部を備え、前記載置台を回転させたときに、前記ウエハのマークが通過する領域に、前記投光部から投光された光が照射される光照射領域を形成するための光照射機構と、
    　前記光照射機構により前記光照射領域に照射された光の反射光を受光するために設けられ、前記反射光の受光領域が、ウエハの中央部側から外側に向かって伸びるように設けられたラインセンサーと、
    　前記載置台を少なくとも１回転させたときに、ウエハの回転方向の位置と前記ラインセンサーにより得られた輝度とを対応付けたデータに基づいてウエハの向きを検出するデータ処理部と、を備えたことを特徴とするウエハの位置検出装置。     A mounting table for mounting a wafer on which a positioning mark composed of a plurality of dots is formed on the back surface;
    A rotation mechanism for rotating the mounting table;
    Light irradiation for forming a light irradiation region provided with a light projecting unit and irradiated with light projected from the light projecting unit in a region through which the mark of the wafer passes when the mounting table is rotated. Mechanism,
    A line provided to receive the reflected light of the light irradiated to the light irradiation region by the light irradiation mechanism, and the light receiving region of the reflected light is provided to extend outward from the central portion side of the wafer. A sensor,
    A data processing unit that detects the orientation of the wafer based on data in which the position in the rotation direction of the wafer is associated with the luminance obtained by the line sensor when the mounting table is rotated at least once. A wafer position detecting device.
  2. 　前記マークは、ウエハの中央部から外側に向かって配列された複数のドットを含むことを特徴とする請求項１に記載のウエハの位置検出装置。 2. The wafer position detecting apparatus according to claim 1, wherein the mark includes a plurality of dots arranged from the center of the wafer toward the outside.
  3. 　前記ラインセンサーの受光領域の長さは、前記載置台を回転させたときにウエハの周縁がその光照射領域に位置するように設定されていることを特徴とする請求項１に記載のウエハの位置検出装置。 The length of the light receiving region of the line sensor is set so that the periphery of the wafer is positioned in the light irradiation region when the mounting table is rotated. Position detection device.
  4. 　前記データ処理部は、ラインセンサーにより得られた輝度分布に基づいて、ウエハの回転方向の位置ごとのウエハの周縁の位置を検出するように構成されていることを特徴とする請求項３に記載のウエハの位置検出装置。 The said data processing part is comprised so that the position of the periphery of a wafer for every position of the rotation direction of a wafer may be detected based on the luminance distribution obtained by the line sensor. Wafer position detection device.
  5. 　前記データ処理部は、ウエハの回転方向の位置ごとにウエハの周縁の位置から一定位置だけウエハの中央部に寄った位置に対応する画素の輝度に基づいて前記マークを検出するステップを実行してウエハの向きを検出するように構成されていることを特徴とする請求項４に記載のウエハの位置検出装置。 The data processing unit executes a step of detecting the mark based on a luminance of a pixel corresponding to a position close to a central portion of the wafer by a certain position from a peripheral position of the wafer for each position in the rotation direction of the wafer. 5. The wafer position detection apparatus according to claim 4, wherein the wafer position detection apparatus is configured to detect the orientation of the wafer.
  6. 　前記画素の輝度に基づいて前記マークを検出するステップは、前記輝度と予め設定された輝度との比較結果により前記マークを検出するステップであることを特徴とする請求項５に記載のウエハの位置検出装置。 6. The wafer position according to claim 5, wherein the step of detecting the mark based on the luminance of the pixel is a step of detecting the mark based on a comparison result between the luminance and a preset luminance. Detection device.
  7. 　前記データ処理部は、前記輝度分布に基づいて、ウエハの向きに加えてウエハの中心位置を検出するように構成されていることを特徴とする請求項１に記載のウエハの位置検出装置。 2. The wafer position detection apparatus according to claim 1, wherein the data processing unit is configured to detect a center position of the wafer in addition to the orientation of the wafer based on the luminance distribution.
  8. 　前記データ処理部は、前記輝度分布に基づいて、ウエハの向きに加えてウエハの大きさを検出するように構成されていることを特徴とする請求項１に記載のウエハの位置検出装置。 2. The wafer position detecting apparatus according to claim 1, wherein the data processing unit is configured to detect the size of the wafer in addition to the orientation of the wafer based on the luminance distribution.
  9. 　前記マークを構成するドットの光反射率は、ウエハの裏面の光反射率よりも小さいことを特徴とする請求項１に記載のウエハの位置検出装置。 2. The wafer position detecting apparatus according to claim 1, wherein the light reflectance of the dots constituting the mark is smaller than the light reflectance of the back surface of the wafer.
  10. 　前記ラインセンサーの光照射領域は、載置台の回転中心を中心とする円の径方向に沿って並んでいることを特徴とする請求項１に記載のウエハの位置検出装置。 2. The wafer position detecting device according to claim 1, wherein the light irradiation areas of the line sensor are arranged along a radial direction of a circle centering on a rotation center of the mounting table.
  11. 　裏面に複数のドットからなる位置合わせ用のマークが形成されたウエハを載置台に載置して少なくとも１回転させる工程と、
    　前記回転するウエハに形成されているマークが通過する領域に、光が照射される光照射領域を形成する工程と、
    　前記光照射領域に照射された光の反射光を受光するために設けられ、前記反射光の受光領域が、ウエハの中央部側から外側に向かって伸びるように設けられたラインセンサーを用い、ウエハの回転方向の位置と前記ラインセンサーにより得られた輝度とを対応付けたデータに基づいてウエハの向きを検出する工程と、を含むことを特徴とするウエハの位置検出方法。     Placing the wafer on which the alignment mark composed of a plurality of dots is formed on the back surface and placing the wafer on the mounting table at least once;
    Forming a light irradiation region in which light is irradiated in a region through which a mark formed on the rotating wafer passes;
    Using a line sensor provided to receive the reflected light of the light irradiated to the light irradiation region, the light receiving region of the reflected light extending from the center side of the wafer toward the outside, the wafer Detecting the orientation of the wafer based on data in which the position in the rotation direction of the lens and the brightness obtained by the line sensor are associated with each other.
  12. 　前記マークは、ウエハの中央部から外側に向かって配列された複数のドットを含むことを特徴とする請求項１１に記載のウエハの位置検出方法。 12. The wafer position detecting method according to claim 11, wherein the mark includes a plurality of dots arranged outward from the center of the wafer.
  13. 　前記ラインセンサーの受光領域の長さは、前記載置台を回転させたときにウエハの周縁がその光照射領域に位置するように設定されていることを特徴とする請求項１１に記載のウエハの位置検出方法。 The length of the light receiving region of the line sensor is set so that the periphery of the wafer is positioned in the light irradiation region when the mounting table is rotated. Position detection method.
  14. 　前記ラインセンサーにより得られた輝度分布に基づいて、ウエハの回転方向の位置ごとのウエハの周縁の位置を検出する工程を含むことを特徴とする請求項１３に記載のウエハの位置検出方法。 14. The wafer position detecting method according to claim 13, further comprising a step of detecting the position of the peripheral edge of the wafer for each position in the rotation direction of the wafer based on the luminance distribution obtained by the line sensor.
  15. 　ウエハの回転方向の位置ごとにウエハの周縁の位置から一定位置だけウエハの中央部に寄った位置に対応する画素の輝度に基づいて前記マークを検出する工程を含むことを特徴とする請求項１４に記載のウエハの位置検出方法。 15. The method according to claim 14, further comprising: detecting the mark based on the luminance of a pixel corresponding to a position close to the central portion of the wafer by a certain position from the position of the peripheral edge of the wafer for each position in the rotation direction of the wafer. The wafer position detecting method according to claim 1.
  16. 　前記画素の輝度に基づいて前記マークを検出する工程は、前記輝度と予め設定された輝度との比較結果により前記マークを検出する工程であることを特徴とする請求項１５に記載のウエハの位置検出方法。 The position of the wafer according to claim 15, wherein the step of detecting the mark based on the luminance of the pixel is a step of detecting the mark based on a comparison result between the luminance and a predetermined luminance. Detection method.
  17. 　前記ウエハの周縁の検出結果に基づいて、ウエハの向きに加えてウエハの中心位置を検出する工程を含むことを特徴とする請求項１４に記載のウエハの位置検出方法。 15. The wafer position detecting method according to claim 14, further comprising a step of detecting the center position of the wafer in addition to the orientation of the wafer based on the detection result of the peripheral edge of the wafer.
  18. 　前記マークを構成するドットの光反射率は、ウエハの裏面の光反射率よりも小さいことを特徴とする請求項１１に記載のウエハの位置検出方法。 12. The wafer position detecting method according to claim 11, wherein the light reflectance of the dots constituting the mark is smaller than the light reflectance of the back surface of the wafer.
  19. 　ウエハを載置するための載置台と、前記載置台を回転させるための回転機構と、を備えたウエハの位置検出装置に用いられるコンピュータプログラムを記憶する記憶媒体であって、
    　前記コンピュータプログラムは、請求項１１に記載のウエハの位置検出方法を実行するようにステップ群が組まれていることを特徴とする記憶媒体。     A storage medium for storing a computer program used in a wafer position detection apparatus comprising: a mounting table for mounting a wafer; and a rotation mechanism for rotating the mounting table.
    12. A storage medium in which the computer program includes a set of steps so as to execute the wafer position detection method according to claim 11.
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