JP2009095903A - Grinder and scratch detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wafer scratch detection device, and to provide a grinder equipped with the scratch detection device. <P>SOLUTION: This grinder comprises a chuck table for holding a wafer and a grinding means, having a grinding wheel for grinding the wafer held on the chuck table. The grinder further comprises the scratch detection means for detecting the scratches produced on the ground surface of the wafer. The scratch detection means comprises a light beam irradiation means for making a light beam irradiated to the wafer 11; a photodetector 108, disposed on the upper side of the area to which the light beam is radiated a light-collecting means for collecting the reflected light from the region to which the light beam is radiated and guiding the collected light to the photodetector; and a scratch determination means 110 for determining that there are scratches, when the light quantity detected by the photodetector exceeds a predetermined threshold. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a scratch detection device capable of detecting a scratch on a wafer grinding surface and a grinding device provided with the scratch detection device.

  A semiconductor wafer in which a number of devices such as IC and LSI are formed on the surface, and each device is partitioned by a line to be divided (street), the back surface is ground by a grinding machine and processed to a predetermined thickness. The division line is cut by a dicing machine and divided into individual devices, which are used for electric devices such as mobile phones and personal computers.

  A grinding apparatus for grinding a back surface of a wafer includes a chuck table for holding a wafer, a grinding means for rotatably supporting a grinding wheel provided with a grinding wheel for grinding the wafer held by the chuck table, and a grinding region And a grinding water supply means for supplying the grinding water to the wafer, and the wafer can be processed to a predetermined thickness.

  By the way, when the thickness of the wafer is reduced to 100 μm or less, and further to 50 μm or less, grinding distortion generated on the back surface of the wafer may cause a decrease in the bending strength of the device, and etching or the like may be performed to improve the bending strength. When the distortion is removed, the gettering effect for holding the heavy metal floating inside the wafer on the back surface side is lost, and the quality of the device is remarkably deteriorated.

In view of this, the present applicant has proposed a vitrified bond grindstone in Japanese Patent Application Laid-Open No. 2006-1007, which mainly suppresses grinding distortion and maintains the bending strength while maintaining the gettering effect as a grindstone for finish grinding.
JP 2006-1007 A

  However, when the grinding surface of the wafer ground using the vitrified bond grindstone disclosed in Patent Document 1 is observed, there may be a wafer containing scratches at a ratio of 1 to 40 to 50 wafers. However, there is a problem that the bending strength at the scratched portion is lowered.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a scratch detection device capable of detecting a scratch generated on a grinding surface of a wafer, and a grinding device equipped with the scratch detection device. That is.

  According to the first aspect of the present invention, there is provided a grinding apparatus comprising a chuck table for holding a wafer and a grinding means having a grinding wheel for grinding the wafer held by the chuck table, which is generated on a grinding surface of the wafer. It further comprises scratch detecting means for detecting scratches, the scratch detecting means comprising: a light beam irradiating means for irradiating the wafer with a light beam; and a photodetector disposed on the upper part of the region irradiated with the light beam; Condensing means for condensing reflected light from the region irradiated with the light beam and guiding it to the photodetector, and scratch determining means for determining that there is a scratch when the amount of light detected by the photodetector exceeds a predetermined threshold value. There is provided a grinding apparatus including the above-described grinding device.

  Preferably, the chuck table is movable between an attachment / detachment position where the wafer is attached / detached and a grinding position where the wafer is ground by the grinding means, and the scratch detection means is disposed at either the attachment / detachment position or the grinding position. .

  According to a third aspect of the present invention, there is provided a scratch detection device for detecting a scratch generated on a ground surface of a wafer, a chuck table for holding the wafer, and a light beam irradiation means for irradiating the wafer with a light beam, A photo detector disposed above the region irradiated with the light beam, a condensing means for condensing the reflected light from the region irradiated with the light beam and guiding it to the photo detector, and an amount of light detected by the photo detector There is provided a scratch detection device comprising scratch determination means for determining that there is a scratch when a predetermined threshold is exceeded.

  Preferably, the condensing unit includes an objective lens, a condensing lens that condenses the reflected light captured by the objective lens, and a pinhole mask in which a pinhole is positioned at a focal point of the condensing lens, The photodetector is arranged to capture the light beam that has passed through the pinhole.

  As an alternative, it is preferable that the light beam irradiation means includes a laser diode and a half mirror that reflects a part of the laser beam emitted from the laser diode toward a grinding surface of the wafer. The means includes: the half mirror that transmits a part of the reflected light reflected by the grinding surface of the wafer; a condensing lens that collects the reflected light transmitted through the half mirror; and a focal position of the condensing lens. And a pinhole mask on which the pinhole is positioned, and the photodetector is disposed so as to capture the light beam that has passed through the pinhole.

  Preferably, the frame further includes a frame having a transmission window through which the laser beam reflected by the half mirror is transmitted and opened to the wafer side, and water supply means for supplying water to the frame. The space partitioned by the wafer is filled with water.

  According to the grinding device of the present invention, the grinding device is provided with a scratch detection means to detect scratches from the grinding surface of the wafer, and if there is a scratch, the grinding is continued or the scratch removal grinding is performed to perform the scratch-free wafer. Is transferred to the next process, so that a wafer without scratches can be produced efficiently.

  Further, according to the submerged scratch detection device in which the detection area is submerged at the time of scratch detection, the scratch detection device can be positioned at the wafer grinding position to detect the presence or absence of scratch in real time when the wafer is ground.

  Hereinafter, a wafer grinding method and a grinding apparatus according to embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of a semiconductor wafer before being processed to a predetermined thickness. A semiconductor wafer 11 shown in FIG. 1 is made of, for example, a silicon wafer having a thickness of 700 μm, and a plurality of streets 13 are formed in a lattice shape on the surface 11a, and a plurality of streets partitioned by the plurality of streets 13 are formed. A device 15 such as an IC or LSI is formed in the region.

  The semiconductor wafer 11 configured as described above includes a device region 17 in which the device 15 is formed, and an outer peripheral surplus region 19 that surrounds the device region 17. A notch 21 is formed on the outer periphery of the semiconductor wafer 11 as a mark indicating the crystal orientation of the silicon wafer.

  A protective tape 23 is attached to the surface 11a of the semiconductor wafer 11 by a protective tape attaching process. Therefore, the front surface 11a of the semiconductor wafer 11 is protected by the protective tape 23, and the back surface 11b is exposed as shown in FIG.

  Hereinafter, a grinding apparatus 2 for grinding the back surface 11b of the semiconductor wafer 11 thus configured to a predetermined thickness will be described with reference to FIG. The housing 4 of the grinding device 2 is composed of a horizontal housing part 6 and a vertical housing part 8.

  A pair of guide rails 12 and 14 extending in the vertical direction are fixed to the vertical housing portion 8. A grinding means (grinding unit) 16 is mounted along the pair of guide rails 12 and 14 so as to be movable in the vertical direction. The grinding unit 16 is attached to a moving base 18 that moves up and down along a pair of guide rails 12 and 14 via a support portion 20.

  The grinding unit 16 includes a spindle housing 22 attached to the support portion 20, a spindle 24 rotatably accommodated in the spindle housing 22, and a servo motor 26 that rotationally drives the spindle 24.

  As best shown in FIG. 6, a mounter 28 is fixed to the tip of the spindle 24, and a grinding wheel 30 is screwed to the mounter 28. For example, the grinding wheel 30 is configured by affixing a plurality of grinding wheels 34 in which diamond abrasive grains having a grain size of 0.3 to 1.0 μm are hardened by vitrified bonds to a free end portion of a wheel base 32. Therefore, the grinding surface is a mirror surface.

  Grinding water is supplied to the grinding means (grinding unit) 16 via a hose 36. Preferably, pure water is used as the grinding water. As shown in FIG. 6, the grinding water supplied from the hose 36 is formed in the grinding water supply hole 38 formed in the spindle 24, the space 40 formed in the mounter 28, and the wheel base 32 of the grinding wheel 30. It is supplied to the wafer 11 held on the grinding wheel 34 and the chuck table 54 via a plurality of grinding water supply nozzles 42.

  Referring back to FIG. 3, the grinding apparatus 2 includes a grinding unit feed mechanism 44 that moves the grinding unit 16 in the vertical direction along the pair of guide rails 12 and 14. The grinding unit feed mechanism 44 includes a ball screw 46 and a pulse motor 48 fixed to one end of the ball screw 46. When the pulse motor 48 is pulse-driven, the ball screw 46 rotates and the moving base 18 is moved in the vertical direction via the nut of the ball screw 46 fixed inside the moving base 18.

  A chuck table unit 50 is disposed in the recess 10 of the horizontal housing portion 6. As shown in FIG. 4, the chuck table unit 50 includes a support base 52 and a chuck table 54 that is rotatably disposed on the support base 52. The chuck table unit 50 further includes a cover 56 having a hole through which the chuck table 54 is inserted.

  The chuck table unit 50 is moved in the front-rear direction of the grinding apparatus 2 by the chuck table moving mechanism 58. The chuck table moving mechanism 58 includes a ball screw 60 and a pulse motor 64 connected to one end of a screw shaft 62 of the ball screw 60.

  When the pulse motor 64 is pulse-driven, the screw shaft 62 of the ball screw 60 rotates, and the support base 52 having a nut screwed to the screw shaft 62 moves in the front-rear direction of the grinding device 2. Therefore, the chuck table 54 also moves in the front-rear direction according to the rotation direction of the pulse motor 64.

  As shown in FIG. 3, the pair of guide rails 66 and 68 and the chuck table moving mechanism 58 shown in FIG. 4 are covered with bellows 70 and 72. That is, the front end portion of the bellows 70 is fixed to the front wall that defines the recess 10, and the rear end portion is fixed to the front end surface of the cover 56. The rear end of the bellows 72 is fixed to the vertical housing portion 8, and the front end thereof is fixed to the rear end surface of the cover 56.

  In the horizontal housing portion 6 of the housing 4, a first wafer cassette 74, a second wafer cassette 76, a wafer transfer means 78, a wafer temporary mounting means 80, a wafer carry-in means 82, and a wafer carry-out means 84 are provided. A cleaning means 86 is provided. Further, an operation means 88 is provided in front of the housing 4 for an operator to input grinding conditions and the like.

  Further, a cleaning water spray nozzle 90 for cleaning the chuck table 54 is provided at the approximate center of the horizontal housing portion 6. The cleaning water jet nozzle 90 ejects cleaning water toward the wafer after grinding held by the chuck table 54 in a state where the chuck table unit 54 is positioned in the wafer carry-in / carry-out region.

  The chuck table unit 50 pulse-drives the pulse motor 64 of the chuck table moving mechanism 58 to receive the wafer from the grinding area on the back side of the apparatus and the wafer carry-in means 82 shown in FIG. It is moved to and from the wafer loading / unloading area on the near side.

  A scratch detection device 94 is disposed above the wafer carry-in / out region (wafer attach / detach region). As shown in FIG. 7, the scratch detection device 94 includes a housing 96, a laser diode (LD) 98 attached to the tip of the housing 96, an objective lens 100 that converts the reflected light from the wafer 11 into a collimated beam, The condenser lens 102 includes a pinhole mask 106 in which the pinhole 104 is positioned at the focal position of the condenser lens 102, a photodetector 108, and a scratch determination unit 110 connected to the photodetector 108.

  The LD 98 is attached to the housing 96 so that the laser beam emitted from the LD 98 is irradiated onto the wafer 11 directly below the objective lens 100. In the illustrated embodiment, two LDs 98 are provided, but one LD 98 or three or more LDs 98 may be provided.

  The grinding operation of the grinding device 2 configured as described above will be described below. The wafer housed in the first wafer cassette 74 is a semiconductor wafer having a protective tape mounted on the front surface side (surface on which the circuit is formed), and therefore the wafer is positioned with the back surface positioned on the upper side. Housed in the first cassette 74. As described above, the first wafer cassette 74 that accommodates a plurality of semiconductor wafers is mounted with a predetermined cassette of the housing 4 in the carry-in area.

  When all of the unprocessed semiconductor wafers contained in the first wafer cassette 74 placed in the cassette carry-in area are carried out, a plurality of semiconductor wafers are accommodated in place of the empty wafer cassette 74. A new first wafer cassette 74 is manually placed in the cassette loading area.

  On the other hand, when a predetermined number of ground semiconductor wafers are loaded into the second wafer cassette 76 placed in the predetermined cassette unloading area of the housing 4, the second wafer cassette 76 is manually unloaded. A new empty second wafer cassette 76 is placed in the cassette unloading area.

  The semiconductor wafer accommodated in the first wafer cassette 74 is conveyed by the vertical movement and forward / backward movement of the wafer conveyance means 78 and is placed on the wafer temporary placement means 80. The wafer placed on the temporary wafer placement means 80 is centered here, and then the chuck table of the chuck table unit 50 positioned in the wafer carry-in / out area by the turning operation of the wafer carry-in means 82. 54 and is sucked and held by the chuck table 54.

  When the chuck table 54 sucks and holds the wafer in this way, the chuck table moving mechanism 58 is operated to move the chuck table unit 54 and position it in the grinding area behind the apparatus.

  When the chuck table unit 50 is positioned in the grinding area, the center of the wafer held by the chuck table 54 is positioned slightly beyond the outer circumference circle of the grinding wheel 30.

  Next, the chuck table 54 is rotated at, for example, about 100 to 300 rpm, the servo motor 26 is driven to rotate the grinding wheel 30 at 4000 to 7000 rpm, and the pulse motor 48 of the grinding unit feed mechanism 44 is driven to rotate forward. The grinding unit 16 is lowered.

  Then, as shown in FIG. 6, the back surface of the wafer 11 is ground by pressing the grinding wheel 34 of the grinding wheel 30 against the back surface (surface to be ground) of the wafer 11 on the chuck table 54 with a predetermined load. By grinding in this way for a predetermined time, the wafer 11 is ground to a predetermined thickness.

  When grinding is completed, the chuck table moving mechanism 58 is driven to position the chuck table 54 in the wafer loading / unloading area on the front side of the apparatus. If the chuck table 54 is positioned in the wafer loading / unloading area, the cleaning water is sprayed from the cleaning water spray nozzle 90 and the ground surface (back surface) of the ground wafer 11 held by the chuck table 54 is held. Wash.

  After the surface to be ground (back surface) of the wafer 11 is cleaned in this way, the LD 98 is driven while rotating the chuck table 54 to irradiate the wafer 11 with a laser beam. Since the ground surface of the wafer 11 is a mirror surface, most of the reflected light is reflected by the mirror-finished wafer 11 and does not enter the objective lens 100. However, as shown in FIG. 100, and is converted into a collimated beam by the objective lens 100.

  The collimated beam is condensed by the condenser lens 102 and input to the photodetector 108 through the pinhole 104 of the pinhole mask 106, converted into a current value according to the input light amount, and output to the scratch determination unit 110. .

  In the scratch determination unit 110, this scattered light is detected as a background current 114 as shown in FIG. 8. When the laser beam emitted from the LD 98 detects a scratch, the laser beam is greatly scattered by the scratch and input to the objective lens 100.

  Therefore, the scratch determination unit 110 detects the spike currents 118 and 120. Reference numeral 116 denotes a predetermined threshold for determining whether or not there is a scratch. If the current value is larger than this, it is determined that there is a scratch, and if it is smaller, it is determined that there is no scratch.

  When the scratch determination unit 110 determines that there is no scratch as shown in block 122, the wafer cleaning process shown in block 124 is performed. In other words, after the wafer held by the chuck table 54 is released, the wafer is transferred to the cleaning means 86 by the wafer unloading means 84.

  The wafer conveyed to the cleaning means 86 is cleaned and spin-dried here. Next, the wafer is stored in a predetermined position of the second wafer cassette 76 by the wafer transport means 78.

  When the scratch determination unit 110 determines that there is a scratch as indicated by block 126, the scratch removal grinding process of block 128 is performed. That is, the chuck table moving mechanism 58 is driven to position the chuck table 54 in the grinding region again, and grinding with a grinding wheel 30 of about 1 μm is performed.

  After the grinding, the wafer is positioned again in the wafer loading / unloading area by the chuck table moving mechanism 58, and the scratch detection process of the block 130 is performed. That is, the wafer 11 is irradiated with a laser beam from the LD 98 while rotating the wafer 11 by the chuck table 54, and the scratch determination unit 110 determines again whether or not there is a scratch. When it is finally determined that there is no scratch, a wafer cleaning process of block 124 is performed.

  Referring to FIG. 9, there is shown a longitudinal sectional view of a scratch detection device 94A according to the second embodiment of the present invention. In the present embodiment, the laser beam emitted from the laser diode (LD) 98 is reflected by the half mirror 132 and is incident on the wafer 11 rotated by the chuck table 54.

  Since the ground surface (back surface) of the wafer 11 is mirror-finished, most of the laser beam is reflected by the wafer 11, and approximately half of the reflected light amount passes through the half mirror 132 and is collected by the condenser lens 102. Then, it is input to the photodetector 108 through the pinhole 104 of the pinhole mask 106, converted into a current value by the photodetector 108, and input to the scratch determination unit 110 ′.

  In the scratch determination unit 110 ′ shown in FIG. 10, since most of the laser beam irradiated on the wafer 11 is reflected, it is observed as a background current 134 having a relatively high current value.

  When the laser beam is applied to the scratch formed on the ground surface of the wafer 11, the laser beam is scattered by the scratch, so that the return light reflected by the wafer 11 and input to the photodetector 108 is reduced. Therefore, the scratch determination unit 136 detects the valleys 138 and 140 of the current value.

  136 is a predetermined threshold value for detecting a scratch. If the current value is larger than this, it is determined that there is no scratch, and if it is smaller, it is determined that there is a scratch. Since the subsequent operation of this embodiment is the same as that of the first embodiment described with reference to FIG. 8, the description thereof is omitted.

  Referring to FIG. 11, a longitudinal sectional view of a scratch detection device 94B according to a third embodiment of the present invention is shown. The scratch detection device 94B of the present embodiment detects the presence or absence of scratches in real time while the wafer 11 is positioned in the grinding region by the chuck table 54 and grinding the wafer 11.

  The lower part of the housing 96 ′ of the scratch detection device 94 B is formed in a small diameter housing 97, and a water filling chamber 146 is defined between the wafer 11 and the small diameter housing 97 by a partition wall 142 having a laser beam transmission window 144 made of glass or the like. It is made.

  One end 148 a of the conduit 148 is connected to the water source 150, and the other end 148 b opens to the water filling chamber 146. 152 is a switching valve, and 154 is a water pressure gauge. The distance between the tip 97a of the small diameter housing 97 and the wafer 11 is preferably maintained at about 0.5 to 1 mm.

  The partition wall 142 and the tip 97a of the small-diameter housing 97 may be arranged on the same surface so that the concept of the water filling chamber is eliminated and water is continuously supplied between the wafer 11 and the partition wall 142.

  In order to detect a scratch formed on the wafer 11 by the scratch detection device 94B of the present embodiment, first, water is supplied from the water source 150 to the water filling chamber 146, and the water filling chamber 146 is filled with water.

  Since there is a slight gap between the wafer 11 and the tip 97a of the small-diameter housing 97, a constant amount of water is always supplied from the water source 150 to the water filling chamber 146 in order to constantly replenish the water flowing out from the gap.

  In this state, the laser beam is emitted from the LD 98 while rotating the wafer 11 by the chuck table 54. A part of this laser beam is reflected by the half mirror 132 and irradiated to the wafer 11 through the water in the window 144 and the water filling chamber 146.

  Since the grinding of the wafer 11 is performed while supplying the grinding water, the grinding surface of the wafer 11 is contaminated when the grinding is performed. In this embodiment, however, the water filling chamber 146 is always filled with water to detect the scratch. To do so, the water filled in the water filling chamber 146 is clean water that is not very contaminated.

  Therefore, since the wafer 11 is mirror-finished, most of the laser beam irradiated to the wafer 11 is reflected in the same optical path as the incident beam, and after passing through the window 144, part of it is transmitted through the half mirror 132. The light is condensed by the condenser lens 102 and input to the photodetector 108 through the pinhole 104 of the pinhole mask 106. Incident light is converted into a current value according to the amount of light by the photodetector 108 and input to the scratch determination unit 110 ′ shown in FIG. 10.

  If there is a scratch on the wafer 11, the irradiated laser beam is greatly scattered by the scratch and the reflected light input to the photodetector 108 is reduced as in the second embodiment described above. As in the parts 138 and 140, the current value decreases rapidly. Therefore, it is determined that there is a scratch due to the rapid decrease in the current value.

  If it is determined that there is no scratch, a wafer cleaning process indicated by block 124 in FIG. 10 is performed. That is, after the chuck table 54 is positioned in the wafer loading / unloading area, the suction and holding of the wafer held by the chuck table 54 is released, and the wafer is conveyed to the cleaning unit 86 by the wafer unloading unit 84.

  The wafer conveyed to the cleaning means 86 is cleaned and spin-dried here. Next, the wafer is stored in a predetermined position of the second wafer cassette 76 by the wafer transport means 78.

  If it is determined that there is a scratch, the grinding of the wafer 11 is continued until it is determined that no scratch has been detected. When it is finally determined that there is no scratch, the grinding is finished and the wafer cleaning process is performed.

  Incidentally, the detection of the scratch of the wafer by the scratch detection device 94B of the present embodiment does not always have to be performed during the grinding of the wafer 11, and may be performed in the finishing process of the wafer grinding.

It is a front side perspective view of a semiconductor wafer. It is a back surface side perspective view of the semiconductor wafer where the protective tape was stuck. 1 is an external perspective view of a grinding apparatus according to an embodiment of the present invention. It is a perspective view of a chuck table unit and a chuck table feed mechanism. It is a perspective view of the grinding wheel seen from the lower side. It is a longitudinal cross-sectional view of a grinding wheel. It is a longitudinal cross-sectional view of the scratch detection apparatus which concerns on 1st Embodiment of this invention. It is a block diagram which shows the process after the scratch determination part and scratch determination of 1st Embodiment. It is a longitudinal cross-sectional view of the scratch detection apparatus of 2nd Embodiment of this invention. It is a block diagram which shows the process after the scratch determination part and scratch determination of 2nd Embodiment. It is a longitudinal cross-sectional view of the scratch detection apparatus of 3rd Embodiment of this invention.

Explanation of symbols

2 Grinding machine 11 Semiconductor wafer 16 Grinding means (grinding unit)
24 Spindle 26 Servo motor 30 Grinding wheel 34 Grinding wheel 50 Chuck table unit 54 Chuck table 94, 94A, 94B Scratch detector 96 Laser diode (LD)
DESCRIPTION OF SYMBOLS 100 Objective lens 102 Condensing lens 106 Pinhole mask 108 Photo detector 110,110 'Scratch determination part 132 Half mirror 142 Partition 144 Laser beam transmission window 146 Water filling chamber

Claims (7)

A grinding apparatus comprising a chuck table for holding a wafer and a grinding means having a grinding wheel for grinding a wafer held on the chuck table,
It further comprises a scratch detection means for detecting a scratch generated on the ground surface of the wafer,
The scratch detection means includes a light beam irradiation means for irradiating the wafer with a light beam,
A photo detector disposed above the region irradiated with the light beam, a condensing means for condensing the reflected light from the region irradiated with the light beam and guiding it to the photo detector, and an amount of light detected by the photo detector And a scratch determining means for determining that there is a scratch when a predetermined threshold value is exceeded. The chuck table is movable between an attachment / detachment position for attaching / detaching a wafer and a grinding position for grinding the wafer by the grinding means,
2. The grinding apparatus according to claim 1, wherein the scratch detection means is disposed at either the attaching / detaching position or the grinding position. A scratch detection device for detecting a scratch generated on a ground surface of a wafer,
A chuck table for holding the wafer;
A light beam irradiation means for irradiating the wafer with a light beam;
A photodetector disposed above the area irradiated with the light beam;
Condensing means for condensing the reflected light from the region irradiated with the light beam and guiding it to the photodetector;
Scratch determining means for determining that there is a scratch when the amount of light detected by the photodetector exceeds a predetermined threshold;
A scratch detection apparatus comprising: The condensing means includes an objective lens, a condensing lens that condenses the reflected light captured by the objective lens, and a pinhole mask in which a pinhole is positioned at the focal point of the condensing lens,
The scratch detector according to claim 3, wherein the photodetector captures a light beam that has passed through the pinhole. The light beam irradiation means includes a laser diode and a half mirror that reflects a part of the laser beam emitted from the laser diode toward the ground surface of the wafer.
The condensing means includes: the half mirror that transmits a part of the reflected light reflected by the grinding surface of the wafer; a condensing lens that condenses the reflected light that has transmitted the half mirror; and It consists of a pinhole mask with a pinhole positioned at the focal point,
The scratch detector according to claim 3, wherein the photodetector captures a light beam that has passed through the pinhole. A frame body having a transmission window through which the laser beam reflected by the half mirror is transmitted and opened to the wafer side; and water supply means for supplying water into the frame body,
The scratch detection device according to claim 5, wherein a space partitioned by the frame body and the wafer is filled with water. A frame having a transmission window through which the laser beam reflected by the half mirror passes, and water supply means for supplying water between the frame and the wafer;
6. The scratch detection apparatus according to claim 5, wherein a space between the frame body and the wafer is filled with water.

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