JP6574373B2 - Disc-shaped workpiece grinding method - Google Patents

Description

  The present invention relates to a method for grinding a disk-shaped workpiece used in semiconductor manufacturing.

  Disc-shaped workpieces used in semiconductor manufacturing are, for example, ground by a grinding machine and formed to a predetermined thickness, and then divided by a cutting machine or the like into individual devices, which are used in various electronic equipments. . Here, the disc-shaped workpiece to be ground is made of, for example, a hard material having high Mohs hardness such as sapphire or SiC, and the orientation flat ( Some have an orientation flat). For example, Patent Document 1 describes a method of grinding such a disk-shaped workpiece using a grindstone. During grinding, the disc-shaped workpiece and the grindstone rotate, and the grindstone always passes through the rotation center of the disc-shaped workpiece and contacts the range of the rotation center from the outer periphery of the disc-shaped workpiece.

JP 2011-212820 A

  Here, when the disk-shaped workpiece as described above is ground, there is a problem that a part of the outer peripheral region where the orientation flat is formed may be thinner than the other part. When the inventor of the present invention examined, this problem was presumed to be based on the following phenomenon. That is, for example, if the center of the workpiece determined with reference to the arc portion in the outer periphery of the disk-shaped workpiece is matched with the rotation center of the chuck table, the distance from the center of the workpiece to the orientation flat and the arc from the center of the workpiece Since this is different from the distance to the part, the range (distance) of the workpiece with which the grindstone contacts the disc-shaped workpiece is different. Therefore, a part of the outer peripheral region where the orientation flat is formed in the disk-shaped workpiece is reduced in the area in contact with the grindstone and is easily ground (the force with which the grindstone is pressed is further increased), so that the thickness of the workpiece is reduced It was inferred that it would be thinner than the part.

  Therefore, even when grinding a disk-shaped workpiece made of a hard material such as sapphire or SiC and having an orientation flat, it is possible to prevent variation in the grinding thickness of the workpiece after grinding, and to reduce the grinding thickness of the entire workpiece. There is a problem of increasing accuracy.

In order to solve the above problems, the present invention provides a chuck table that can rotate while holding a disk-shaped workpiece having an orientation flat that indicates a crystal orientation in an outer peripheral region, a rotating shaft that serves as a rotation center of the chuck table, and a grindstone Is rotated from the outer periphery of the disc-shaped workpiece held on the chuck table by rotating the grinding wheel around the center of the grinding wheel and passing on the rotating shaft of the chuck table. A disk-shaped workpiece is ground with the grindstone using a grinding device comprising grinding means for bringing the grindstone into contact with the center range for grinding and a carry-in means for carrying the disc-shaped workpiece into the chuck table. In this grinding method, the distance from the center of rotation of the disc-shaped workpiece to the arc portion of the outer periphery of the disc-shaped workpiece during grinding is such that the distance from the arc portion of the outer periphery of the disc-shaped workpiece to the disc-shaped workpiece The midpoint and outer circumference of a line segment that is shorter than the distance to the center of the outer circumference circle, passes through the center of the outer circumference of the disk-shaped workpiece, one end is orthogonal to the midpoint of the orientation flat, and the other end contacts the outer circumference circle The midpoint of the line connecting the midpoint of the line and the center of the outer circumference of the disk-shaped work is used as the center of rotation of the disk-shaped work during grinding so that it is longer than the distance from the arc of the circle. A position detecting step for detecting the reference position of the disk, a loading step for loading the disk-shaped workpiece into the chuck table with the reference position detected in the position detecting step being coincident with the rotation center of the chuck table, and the loading And a grinding step of grinding the disk-shaped workpiece by bringing the grinding wheel of the grinding wheel into contact with the disk-shaped workpiece carried in the process.

  In the position detecting step, it is preferable that the midpoint of the line connecting the midpoint of the line and the center of the outer circumference of the disc-shaped work is detected on the disc-shaped work as the reference position.

In the grinding method according to the present invention, which is performed when a disk-shaped workpiece on which an orientation flat is formed is ground by a grinding device, the arc portion of the outer periphery of the disk-shaped workpiece from the center of rotation of the disk-shaped workpiece during grinding. Is shorter than the distance from the arc on the outer periphery of the disk-shaped workpiece to the center of the outer circle of the disk-shaped workpiece, and passes through the center of the outer circle of the disk-shaped workpiece, and one end is the midpoint of the orientation flat Connect the midpoint of the line segment and the center of the outer circle of the disc-shaped workpiece so that it is longer than the distance between the midpoint of the line segment perpendicular to A position detection step of detecting the midpoint of the line segment as a reference position as the center of rotation of the disk-shaped workpiece during grinding, and a reference position detected in the position detection step of the disk-shaped workpiece and the rotation center of the chuck table Match The grinding wheel comes into contact with the disk-shaped workpiece by comprising a carrying-in process for loading into the back table and a grinding process for grinding the disk-shaped workpiece by bringing the grinding wheel of the grinding wheel into contact with the disk-shaped workpiece carried in the loading process. Since grinding is performed without causing a difference in distance and a difference in contact area, the grinding thickness of the disc-shaped workpiece after grinding does not vary, and the accuracy of the grinding thickness can be increased.

  Further, in the position detection step, by detecting on the disk-shaped workpiece, the middle point of the line segment connecting the midpoint of the line segment and the center of the outer circumferential circle of the disk-shaped workpiece is detected on the disk-shaped workpiece. Grinding is performed without causing a difference in distance and contact area between the grinding stone and the workpiece, so that there is no variation due to the grinding thickness of the disc-shaped workpiece after grinding, and the accuracy of the grinding thickness is increased. be able to.

It is a typical top view which shows an example of a grinding device. It is a side view which shows an example of a carrying-in means. It is a side view which shows the structure of a grinding means and a chuck table. It is explanatory drawing which shows the example of the image imaged with the camera in the position detection process. It is explanatory drawing which shows the example of the image imaged with the camera in the position detection process. FIG. 6A is a cross-sectional view with reference to the a-a ′ line in FIG. 5 showing the relationship between the rotation center of the chuck table and the reference position of the disc-shaped workpiece. FIG. 6B is a cross-sectional view with reference to the line b-b ′ in FIG. 5 showing the relationship between the rotation center of the chuck table and the reference position of the disk-shaped workpiece. It is explanatory drawing which shows the example of the image of a disk shaped workpiece | work provided with the 1st orientation flat imaged with the camera in the position detection process, and a 2nd orientation flat.

  A grinding apparatus 1 shown in FIG. 1 is an example of a grinding apparatus that holds a disk-shaped workpiece W to be ground by a chuck table 3 and grinds the disk-shaped workpiece W by at least a grinding means 5. The front (−Y direction side) on the base 10 of the grinding apparatus 1 is an attachment / detachment area A that is an area where the disk-shaped workpiece W is attached / detached to / from the chuck table 3. The + Y direction side) is a processing region B that is a region where the disc-like workpiece W is ground by the grinding means 5.

  On the front side (−Y direction side) of the base 10 in the attachment / detachment region A, for example, a first cassette 18a in which a disk-shaped workpiece W before processing is accommodated is disposed, and the first cassette 18a is disposed. In parallel with the second cassette 18b, a second cassette 18b for accommodating the processed disc-shaped workpiece W is disposed.

  Behind the first cassette 18a (on the + Y direction side), the disk-shaped workpiece W before processing is unloaded from the first cassette 18a, and the disk-shaped workpiece W after processing is loaded into the second cassette 18b. A transfer robot 17 is provided. The transfer robot 17 includes a bendable arm 17a and a robot hand 17b attached to the tip of the arm 17a so that the robot hand 17b can reach each of the first cassette 18a and the second cassette 18b. It has become. Further, the transfer robot 17 is supported by a moving mechanism 17c and can freely move in the X-axis direction.

  In the vicinity of the transfer robot 17, a loading means 4 for loading the disk-shaped workpiece W into the chuck table 3 is provided. The carry-in means 4 is, for example, a temporary placement means 40 having functions such as temporarily placing the disk-shaped workpiece W and detecting the center thereof, and the disk-shaped workpiece W positioned in the attachment / detachment area A from the temporary placement means 40. And a conveying means 42 for conveying the chuck table 3 to the chuck table 3.

  The temporary placing means 40 is located in a range where the robot hand 17b of the transfer robot 17 can reach. The temporary placement means 40 includes, for example, a rotatable temporary placement table 400 that temporarily places the disk-shaped workpiece W, a camera 401 that images the disk-shaped workpiece W temporarily placed on the temporary placement table 400, at least a CPU, And an image processing unit 402 that includes a storage element such as a memory and performs image processing based on an image captured by the camera 401.

  As shown in FIGS. 1 and 2, the temporary placement table 400 is formed in a disk shape, and the upper surface thereof is a work placement surface having a smaller diameter than the outer diameter of the disk-like work W. The temporary placement table 400 is supported by a rotation shaft 400a, and a rotating means 400b for rotating the temporary placement table 400 is connected to the lower portion of the rotation shaft 400a. The rotation center of the workpiece placement surface of the temporary placement table 400 is located on a straight line passing through the axis center of the rotation shaft 400a. The temporary table 400 is connected to a suction source (not shown) that generates a suction force for sucking the disk-shaped workpiece W.

  The transport means 42 includes a suction pad 420 for sucking and holding the disk-shaped workpiece W, a transport arm 421, a vertical operation shaft 422 for moving the suction pad 420 up and down, and a suction pad 420 from the temporary placement table 400 to the chuck table. 3, and a linear motion shaft 423 that allows the disk-shaped workpiece W to be conveyed by moving it straight to 3.

  A suction pad 420 is attached to the tip of the vertical operation shaft 422. The suction pad 420 is formed in a disk shape, and the lower surface thereof becomes a suction surface made of, for example, a porous member. Inside the transfer arm 421, a communication path 425 is provided that connects a suction source (not shown) and the suction surface of the suction pad 420. And the suction pad 420 can adsorb | suck the disk-shaped workpiece | work W because the attraction | suction force which the attraction | suction source which is not shown in figure transmits to an attraction | suction surface. The vertical movement shaft 422 is accommodated in the transfer arm 421 so as to be vertically movable, and moves the suction pad 420 up and down.

  The transfer arm 421 is attached to the carry-in base 424 and supported by the linear motion shaft 423 via the carry-in base 424. The linear motion shaft 423 extends in the Y-axis direction from above the temporary table 400 to above the chuck table 3. The carry-in base 424 is slidable on the side surface of the linear movement shaft 423 in the Y-axis direction, and the transfer arm 421 can also move freely in the Y-axis direction as the carry-in base 424 slides. .

  The camera 401 of the temporary placement means 40 is attached to the side surface of the linear movement shaft 423 and is disposed above the temporary placement table 400 so as to be movable. The image data captured by the camera 401 is transferred to the image processing unit 402 connected to the camera 401. In this embodiment, the camera 401 is attached to the side surface of the linear movement shaft 423, but the attachment position is not limited to this. In addition, the conveyance means 42 is not limited to the structure in this embodiment, For example, it is good also as a thing provided with the turning arm provided rotatably in the horizontal surface on the base 10. FIG.

  As shown in FIG. 1, in the movable range of the transfer robot 17, a cleaning means 19 for cleaning the disk-shaped workpiece W after processing is disposed. The cleaning unit 19 is, for example, a single-wafer spin type cleaning unit, and includes a spinner table 190 that can rotate at high speed, a nozzle 191 that ejects cleaning liquid, and an arm 192 that controls a cleaning position by a swiveling motion. I have. A cleaning liquid spout is formed at the end of the nozzle 191, and the position of the cleaning liquid spout when the cleaning water is spouted, that is, the operating position of the cleaning means 19 can be moved by turning the arm 192.

  Behind the cleaning means 19 (+ Y direction side) is a transfer robot 13 for transferring the ground disk-shaped workpiece W held on the chuck table 3 positioned in the attachment / detachment area A to the cleaning device 19. It is arranged. The transfer robot 13 includes a pivotable arm 130 and a suction pad 131 that is attached to the tip of the arm 130 and can suck the disk-shaped workpiece W. The transfer robot 13 is disposed on a rail 132 extending in the Y-axis direction, and can freely move on the rail 132 in the Y-axis direction.

  As shown in FIG. 1, a turntable 14 is disposed at a substantially central portion on the base 10, and a plurality of chuck tables 3 are arranged on the upper surface of the turntable 14 at equal intervals in the circumferential direction (example shown in the figure). 4) are arranged. A rotation shaft (not shown) for rotating the turntable 14 is disposed at the center of the turntable 14, and the turntable 14 can be rotated about the rotation shaft. When the turntable 14 rotates, the chuck table 3 can be revolved and moved between the attachment / detachment region A and the processing region B. The movement of the chuck table 3 from the attachment / detachment region A to the processing region B is not limited to that in the present embodiment. For example, the chuck table 3 is configured on the base 10 by a motor, a ball screw, and the like in the Y-axis direction. You may make it carry out by providing the Y-axis direction sending means which can be reciprocated.

  The chuck table 3 shown in FIGS. 1 and 3 has, for example, a circular outer shape, and includes a suction portion 30 that is made of a porous member or the like and sucks the disk-shaped workpiece W, and a frame body 31 that supports the suction portion 30. It is equipped and can be rotated. The suction unit 30 communicates with a suction source (not shown), and the suction force generated by the suction of the suction source is transmitted to the holding surface 30a, which is the exposed surface of the suction unit 30, so that the chuck table 3 has a holding surface. The disk-like workpiece W is sucked and held on 30a. As shown in FIG. 3, the holding surface 30a is formed in, for example, a conical surface having the center 30o of the holding surface 30a as a vertex.

  Further, as shown in FIG. 3, the chuck table 3 is arranged on the bottom surface side of the chuck table 3, and a center 30 o of the holding surface 30 a is provided by a rotating shaft 32 (chuck table rotating shaft 32) serving as the center of rotation of the chuck table 3. It can be rotated around the axis. The axial direction of the chuck table rotation shaft 32 is a direction (Z-axis direction) perpendicular to the vertical direction with respect to the X-axis direction, and one end of the chuck table rotation shaft 32 is connected to the center of the bottom surface side of the chuck table 3. In addition, a motor 33 that rotationally drives the chuck table rotation shaft 32 is connected to the chuck table rotation shaft 32. An inclination adjusting portion (not shown) is disposed on the bottom surface side of the chuck table 3, and when the disk-shaped workpiece W is ground, the inclination adjusting portion is attached to the disk-shaped workpiece W held on the holding surface 30 a. On the other hand, the inclination of the holding surface 30a of the chuck table 3 is adjusted so that the grinding means 5 can abut horizontally (that is, the chuck table rotating shaft 32 is inclined by a predetermined angle).

  As shown in FIG. 1, a column 11 is erected on the rear side (+ Y direction side) on the base 10, and a grinding feed means 12 is disposed on a side surface of the column 11 on the −Y direction side. The grinding feed means 12 shown in FIG. 3 is connected to a ball screw 120 having a substantially vertical (Z-axis direction) axis, a pair of guide rails 121 arranged in parallel to the ball screw 120, and the ball screw 120. , And a holder 123 whose side part is in sliding contact with the guide rail 121. When the motor 122 rotates the ball screw 120, the holder 123 is guided. The grinding means 5 guided by the rail 121 reciprocates in the Z-axis direction and supported by the holder 123 is ground and fed in the Z-axis direction.

  The grinding means 5 includes, for example, a spindle 50 whose axial direction is the vertical direction (Z-axis direction), a motor 51 that rotationally drives the spindle 50, a circular mount 52 disposed at the lower end of the spindle 50, a mount And a grinding wheel 53 detachably connected to the lower surface of 52. The grinding wheel 53 includes a wheel base 53a and a substantially rectangular parallelepiped-shaped grindstone 53b arranged in a ring shape on the bottom surface of the wheel base 53a. The center of the grinding wheel 53 is located on the extension line of the spindle center of the spindle 50. As the motor 51 rotates the spindle 50, the grinding wheel 53 also rotates around the spindle 50, and the grindstone 53b becomes a circle. Grinding is performed by contacting the plate-like workpiece W. In addition, the 2nd grinding means 6 is arrange | positioned adjacent to the grinding means 5, This 2nd grinding means 6 is equipped with the grindstone which has an abrasive grain with a particle size smaller than the grindstone 53b which comprises the grinding means 5. FIG. Then, the disk-shaped workpiece W is finish ground. Further, a polishing means 7 is disposed adjacent to the second grinding means 6, and this polishing means 7 includes a polishing pad for polishing the ground surface that has been finish-ground, and polishes the disk-shaped workpiece W. To remove grinding distortion.

  The disk-shaped workpiece W whose outer shape shown in FIG. 1 has a substantially disk shape is made of, for example, sapphire, which is a hard material, and an orientation flat OF showing a crystal orientation cuts a part of the outer peripheral region Wc into a flat shape. Is formed. The disk-shaped workpiece W is not limited to a sapphire plate, and the number of orientation flats OF formed is not limited to one. For example, the disk-shaped workpiece W may be a SiC plate, for example. And when the disk-shaped workpiece W is a SiC plate, since there are two types of surfaces, the Si surface and the C surface, due to the crystal structure of the SiC plate, in addition to the first orientation flat, A second orientation flat in a direction perpendicular to the one orientation flat is formed.

  1 to 6, each step in the grinding method and the grinding device when the grinding method according to the present invention is performed using the grinding device 1 shown in FIG. 1 to grind the disk-shaped workpiece W. The operation of No. 1 will be described.

  First, the transfer robot 17 pivots and moves the arm 17a, and the robotic hand 17b carries out the disk-shaped workpiece W accommodated in the first cassette 18a. Next, the transfer mechanism 17 is moved in the X-axis direction by the moving mechanism 17 c to a position in front of the temporary placement table 400 of the temporary placement means 40.

  After the disc-shaped workpiece W has moved to a position before the temporary placement means 40, the transfer robot 17 turns the arm 17a to position the robot hand 17b above the temporary placement table 400. The transfer robot 17 is adjusted so that the center of the temporary placement table 400 and the center of the robot hand 17b are positioned approximately at the same position when viewed from above. Then, the disk-shaped workpiece W is temporarily placed on the upper surface of the temporary placement table 400. At this time, the disc-shaped workpiece W is set such that the back surface Wb side to be ground becomes the upper surface, for example. Moreover, the approximate center of the disk-shaped workpiece W should just be located in the approximate center of the temporary placement table 400, for example. Then, a suction force generated by suction by a suction source (not shown) is transmitted to the upper surface of the temporary placement table 400, and the temporary placement table 400 sucks and holds the disk-shaped workpiece W.

(1) Position Detection Step In the position detection step, for example, first, the camera 401 moves on the temporary placement table 400 that sucks and holds the disk-shaped workpiece W, and the disk-shaped workpiece W is moved within the imaging area of the camera 401. The camera 401 is positioned so that the whole is accommodated. An image Ga in which the entire disc-shaped workpiece W shown in FIG. 4 is captured is captured by the camera 401, and the captured image Ga is transferred to the image processing unit 402 connected to the camera 401. For example, the image processing unit 402 recognizes the circular arc portion We in the outer periphery Wd in the image Ga by using pixels having unique color information included in the outer periphery Wd of the disk-shaped workpiece W in the image Ga. Here, the arc portion We is a portion of the outer periphery Wd of the disc-like workpiece W excluding the orientation flat OF.

  Furthermore, the image processing unit 402 detects points P1, P2, and P3, which are arbitrarily spaced three points on the recognized arc portion We, and performs arc processing by arithmetic processing based on the detected coordinates of these three points. The center Pa of the disc-like workpiece W determined with the part We as a reference is detected. That is, for example, a vertical bisector L1 connecting a line segment connecting the points P1 and P2 is drawn, and a vertical bisector L2 connecting a line segment connecting the points P2 and P3 is drawn so that the vertical bisector L2 is drawn. The intersection Pa between the bisector L1 and the vertical bisector L2 is detected as the center Pa of the disc-like workpiece W (the center Pa of the outer circumference of the disc-like workpiece W) defined with respect to the arc portion We. . The detected coordinates of the center Pa are stored in the memory of the image processing unit 402.

  If one point is added in addition to the upper points P1 to P3, four combinations of three points are obtained. Therefore, the intersection of the perpendicular bisectors can be obtained for each of the combinations of the three points, and a more accurate center Pa can be detected based on the arc portion We of the disk-like workpiece W from the average value of these intersections. .

  Next, for example, the image processing unit 402 detects the midpoint M1 of the orientation flat OF. That is, for example, the image processing unit 402 recognizes the orientation flat OF in the outer periphery Wd in the image Ga by using pixels having unique color information included in the outer periphery Wd of the disk-shaped workpiece W in the image Ga. The image processing unit 402 detects the midpoint M1 of the orientation flat OF from the coordinates of both ends of the recognized orientation flat OF.

  A straight line connecting the detected midpoint M1 of the orientation flat OF and the center Pa of the disc-like workpiece W defined with the circular arc portion We as a reference is drawn, and further, an intersection P4 where the line extending the straight line and the circular arc portion We intersect. Is detected. Then, the image processing unit 402 sets a line segment connecting the midpoint M1 of the orientation flat OF and the intersection point P4 to the center Pa of the outer circumference of the disc-like workpiece W (that is, the disc-like workpiece defined with reference to the arc portion We. W is detected as a line segment L3 passing through the center Pa of W, one end of which is orthogonal to the midpoint of the orientation flat OF, and the other end is in contact with the outer circumference circle (arc portion We) of the disk-like workpiece W.

  Further, the image processing unit 402 performs, for example, calculation of the number of pixels between the midpoint M1 of the orientation flat OF and the intersection point P4 or arithmetic processing based on the coordinates of the midpoint M1 of the orientation flat OF and the coordinates of the intersection point P4. The middle point M2 of the line segment L3 shown in FIG. 5 is detected.

  Here, when the grindstone 53b (shown schematically in FIG. 5) shown in FIG. 1 abuts on the disk-shaped workpiece W held on the chuck table 3, from the arc portion We of the outer periphery Wd to the center of rotation. Is the longest when the center of rotation of the disc-shaped workpiece W is the center Pa of the disc-shaped workpiece W with respect to the arc portion We (that is, the holding surface of the chuck table 3 shown in FIG. 3). And the center 30o of 30a and the center Pa of the disk-shaped workpiece W coincide with each other and the disk-shaped workpiece W is sucked and held by the chuck table 3, and the chuck table 3 is rotated. At this time, the distance from the circular arc portion We of the outer periphery Wd to the center Pa of the disk-shaped workpiece W serving as the rotation center is the radius R of the disk-shaped workpiece W. Therefore, the distance from the reference position serving as the rotation center of the disk-shaped workpiece W during grinding to be detected to the arc portion We of the outer periphery Wd of the disk-shaped workpiece W is shorter than the radius R of the disk-shaped workpiece W. Become.

  Further, a line segment L3 passing through the center Pa of the outer circumference circle (arc portion We) of the disk-shaped workpiece W, one end being orthogonal to the midpoint of the orientation flat OF and the other end contacting the outer circumference circle (arc portion We). The grindstone 53b passes over a line segment L4 connecting the midpoint M2 and the center Pa of the outer circumference circle, and the grindstone 53b comes into contact with the disk-shaped workpiece W, and the distance from the arc portion We of the outer circumference Wd to the rotation center is the shortest When the rotation center is the midpoint M2 of the line segment L3 (that is, the center 30o of the holding surface 30a of the chuck table 3 shown in FIG. 3 is aligned with the midpoint M2 of the line segment L3 to form a disk shape. (When the chuck table 3 is rotated while the workpiece W is sucked and held by the chuck table 3). At this time, the distance from the arc portion We of the outer periphery Wd to the midpoint M2 serving as the center of rotation is (the length of the line segment L3) / 2. Therefore, the distance from the reference position serving as the center of rotation of the disk-shaped workpiece W to be detected to the arc portion We of the outer periphery Wd of the disk-shaped workpiece W is (the length of the line segment L3) / 2. Also gets longer.

  For example, in the present embodiment, the image processing unit 402 detects a reference position on the disk-shaped workpiece W where the radius R of the disk-shaped workpiece W is equal to (the length of the line segment L3) / 2. That is, the image processing unit 402 calculates the number of pixels between the midpoint M2 of the line segment L3 and the center Pa of the outer circumference circle of the disc-shaped work W or the coordinates of the midpoint M2 of the line segment L3 and the disc-shaped work. By performing arithmetic processing based on the coordinates of the center Pa of the outer circumference circle of W, the coordinates of the midpoint M3 of the line segment L4 (enlarged in FIG. 4) are detected. The detected midpoint M3 is stored in the memory of the image processing unit 402 as a reference position. This reference position becomes the rotation center of the disk-shaped workpiece W in the subsequent grinding process. The method for obtaining the reference position M3 is not limited to the above method. For example, even if the radius R of the disk-shaped workpiece W is not equal to (the length of the line segment L3) / 2, at least the outer circumference Wd of the disk-shaped workpiece W from the rotation center of the disk-shaped workpiece W during grinding. The distance to the circular arc portion We is shorter than the distance from the circular arc portion We of the outer circumference Wd of the disc-shaped workpiece W to the center Pa of the outer circumferential circle of the disc-shaped workpiece W, and the center of the outer circumferential circle of the disc-shaped workpiece W is A position where one end is longer than the distance from the midpoint M2 of the line segment L3 where one end is perpendicular to the midpoint M1 of the orientation flat OF and the other end is in contact with the outer circumference circle to the circular arc portion We of the outer circumference circle during grinding. What is necessary is just to detect as the rotation center of the plate-shaped workpiece W.

(2) Carrying-in process After the position detection process is completed, a carrying-in process is carried out in which the disk-shaped workpiece W is carried into the chuck table 3 by matching the reference position M3 detected in the position detecting process with the rotation center 30o of the chuck table 3. .

  In the carry-in process, for example, first, the rotating means 400b shown in FIG. 2 rotates the placement surface of the temporary placement table 400 by a predetermined angle. Thus, the disc-shaped workpiece W is positioned on the placement surface of the temporary placement table 400 so that the orientation flat OF of the disc-shaped workpiece W is perpendicular to the moving direction (Y-axis direction) of the transfer arm 421. It is done. Here, it passes through the center Pa of the outer circumferential circle of the disk-shaped workpiece W shown in FIG. 5, one end is orthogonal to the midpoint M1 of the orientation flat OF, and the other end contacts the outer circumferential circle of the disk-shaped workpiece W. 2 in the X-axis direction (direction perpendicular to the moving direction of the transfer arm 421) between the line segment L3 and the extension line of the axis of the rotary shaft 400a of the temporary table 400 shown in FIG. If there is, for example, the transfer robot 17 moves the disc-shaped workpiece W by a predetermined distance in the X-axis direction so that the line segment L3 and the extension line of the axis center of the rotary shaft 400a intersect perpendicularly. , To correct the deviation.

  Next, the transport means 42 shown in FIG. 2 is operated to slide the carry-in base 424 in the Y-axis direction and move the transport arm 421 so that the transport arm 421 is positioned above the temporary placement table 400. After the transfer arm 421 is moved above the temporary table 400 and the suction pad 420 is positioned so that the reference position M3 of the disk-shaped workpiece W overlaps the extension center of the vertical movement axis 422, the vertical movement axis 422 descends toward the upper surface of the temporary placement table 400. Then, the suction pad 420 is brought into contact with the back surface Wb of the disk-shaped workpiece W held on the temporary placement table 400, and the disk-shaped workpiece W is sucked onto the suction surface of the suction pad 420 by the suction force generated by the suction source. To do.

  The disk-shaped workpiece W is sucked and held on the suction pad 420 and the suction of the disk-shaped workpiece W by the temporary placement table 400 is released. The vertical operation shaft 422 is raised, the carry-in base 424 is slid by a predetermined distance in the Y-axis direction, and the transfer arm 421 is positioned above the chuck table 3. After positioning the suction pad 420 so that the center 30o of the holding surface 30a of the chuck table 3 is positioned on the extension line of the axis center of the vertical movement shaft 422, the vertical movement shaft 422 is lowered to the holding surface 30a of the chuck table 3, The operation of the suction source (not shown) is stopped, and the disc-shaped workpiece W is detached from the suction pad 420. Then, as shown in FIGS. 6 (A) and 6 (B), the disk-shaped workpiece W is placed on the chuck table 3 with the reference position M3 on the disk-shaped workpiece W aligned with the center 30o of the holding surface 30a. Placed. Then, a suction source (not shown) communicating with the holding surface 30 a is operated, and the disk-shaped workpiece W is sucked and held on the holding surface 30 a of the chuck table 3. In addition, as shown in FIG. 3, the inclination adjusting part (not shown) disposed on the bottom surface side of the chuck table 3 causes the grindstone 53b of the grinding means 5 to the disc-shaped workpiece W held on the holding surface 30a. The inclination of the holding surface 30a of the chuck table 3 is adjusted so that it can contact in parallel.

(3) Grinding process After the carry-in process is completed, a grinding process for grinding the disk-shaped workpiece W by bringing the grinding wheel 53b of the grinding wheel 53 into contact with the disk-shaped workpiece W carried in the carry-in process is performed.

  In the grinding process, first, the turntable 14 shown in FIG. 1 rotates, whereby the chuck table 3 that sucks and holds the disk-shaped workpiece W revolves, and the chuck table 3 moves to below the grinding means 5. Then, for example, as shown in FIG. 5, the grinding means 5 is positioned with respect to the chuck table 3 so that the rotation trajectory of the grindstone 53 b passes over the rotation center 30 o of the chuck table 3.

  As the motor 51 rotates the spindle 50, the grinding wheel 53 rotates. Further, the grinding means 5 is sent in the −Z direction by the grinding feed means 12, the grinding wheel 53 descends in the −Z direction, and the grindstone 53 b comes into contact with the back surface Wb of the workpiece W on the disk in parallel. Grinding is performed. Further, during grinding, as the chuck table 3 rotates, the on-disk workpiece W held on the holding surface 30a also rotates, so that the rotation center (reference position M3) from the outer periphery Wd of the disk-shaped workpiece W is also rotated. ) And the grinding wheel 53b performs grinding of the entire back surface Wb of the workpiece W on the disk. Thereafter, the disk-shaped workpiece W is sequentially processed by the second grinding means 6 and the polishing means 7 while rotating the turntable 14. After the processed disk-shaped workpiece W is cleaned by the cleaning means 19, 2 cassette 18b.

  In the grinding method according to the present invention, the distance from the center of rotation of the disk-like workpiece W during grinding to the arc portion We of the outer circumference Wd of the disc-like workpiece W is the arc portion We of the outer circumference Wd of the disc-like workpiece W. Is shorter than the distance from the center Pa of the outer circumferential circle of the disk-shaped workpiece W, passes through the center of the outer circumferential circle of the disk-shaped workpiece W, one end is orthogonal to the midpoint M1 of the orientation flat OF, and the other end is the outer circle. A position detecting step for determining the center of rotation of the disk-shaped workpiece W during grinding, that is, the reference position M3, so as to be longer than the distance between the midpoint M2 of the line segment L3 to be contacted and the arc portion We of the outer circumferential circle; A carrying-in process in which the reference position M3 detected on the chuck table 3 in the position detecting process and the rotation center 30o of the chuck table 3 are brought into alignment with each other and the disc-like work W carried in in the carrying-in process is transferred to the grinding wheel. In order to perform grinding while suppressing the change in the contact area when the grindstone 53b contacts the disc-shaped workpiece W, the grinding process is performed by grinding the disc-shaped workpiece W by bringing the grindstone 53b of 53 into contact. The grinding thickness accuracy of the subsequent disk-shaped workpiece W can be increased.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the carry-in process in the present embodiment, the detected reference position M3 and the rotation center 30o of the chuck table 3 are not shifted at the stage where the disk-like workpiece W is sucked and held on the temporary placement table 400. Although the position of the disk-shaped workpiece W is corrected, the temporary table 400 is rotated to adjust the orientation of the orientation flat OF, and then the disk-shaped workpiece W is carried into the chuck table 3 by the transfer arm 421. In this step, position correction may be performed to eliminate the deviation between the detected reference position M3 and the rotation center 30o of the chuck table 3. Further, for example, in the case where the conveying means 42 includes a turning arm that is rotatably provided in a horizontal plane on the base 10, the detected reference position M3 and the rotation center 30o of the chuck table 3 are made to coincide. Then, the rotation angle of the swing arm is adjusted by a pulse motor or the like.

  Further, the detection of the reference position in the position detection process is not always performed in the grinding apparatus. For example, when a unit is formed in which a disk-shaped workpiece having an orientation flat is fixed to a substrate (support substrate) via wax, and the disk-shaped workpiece constituting the unit is to be ground, the position detection step is The substrate and the disk-shaped work may be performed in a support substrate sticking apparatus that fixes the wax. That is, the reference position of the disk-shaped workpiece is detected before the disk-shaped workpiece is attached to the support substrate. In this case, the disk-shaped workpiece is wax-fixed to the substrate so that the detected reference position coincides with the center of the substrate by the support substrate pasting device. Then, in the carrying-in process in which the disk-shaped workpiece fixed with wax on the substrate is carried into the grinding device from the support substrate sticking device, the center of the substrate is aligned with the center of rotation of the chuck table of the grinding device. Thus, by carrying out suction holding by the chuck table, the carry-in process can be performed with the center of rotation of the chuck table and the detected reference position being coincident, and then the process proceeds to the grinding process.

  Furthermore, as shown in FIG. 7, for example, a disk-shaped workpiece to be ground is formed with a first orientation flat OF1 and a second orientation flat OF2 in a direction orthogonal to the first orientation flat OF1. In the case of the SiC plate (disk-shaped workpiece W1), the reference position is detected as follows in the position detection step. In addition, after the image Gb shown in FIG. 7 in which the entire disc-shaped workpiece W is accommodated by the camera 401 is captured, the process until the center Pa1 of the disc-shaped workpiece W1 defined on the basis of the arc portion W1e is detected. Is performed in the same manner as before until the center Pa is detected in the disk-shaped workpiece W described above.

  After the image processing unit 402 detects the center Pa1 of the disc-like workpiece W1 defined with the arc portion W1e as a reference, for example, the image processing unit 402 recognizes each of both ends of the first orientation flat OF1 recognized in the image Gb. From the coordinates, the middle point M11 of the first orientation flat OF1 is detected. Further, the middle point M12 of the second orientation flat OF2 is detected from the coordinates of both ends of the second orientation flat OF2 recognized in the image Gb.

  A straight line connecting the detected midpoint M11 of the first orientation flat OF1 and the center Pa1 of the disc-like workpiece W1 defined with the circular arc portion W1e as a reference is drawn, and a line extending the straight line and the circular arc portion W1e are further drawn. An intersecting point P41 is detected. The line segment connecting the middle point M11 of the first orientation flat OF1 and the intersection point P41 is the center Pa1 of the outer circumference of the disc-like workpiece W1 (that is, the center of the disc-like workpiece W1 defined with the arc portion We1 as a reference). Pa1) is detected as a line segment L31 whose one end is perpendicular to the middle point M11 of the first orientation flat OF1 and whose other end is in contact with the outer circumference circle (arc portion W1e) of the disc-like workpiece W1.

  Further, a straight line is drawn connecting the detected center point M12 of the second orientation flat OF2 and the center Pa1 of the disc-like workpiece W1 defined with the circular arc part W1e as a reference, and further, a line extending this straight line and the circular arc part W1e. Is detected at intersection point P42. The line segment connecting the middle point M12 of the second orientation flat OF2 and the intersection point P42 is the center Pa1 of the outer circumference of the disk-shaped workpiece W1 (that is, the center of the disk-shaped workpiece W1 defined with the arc portion W1e as a reference). It is detected as a line segment L32 passing through Pa1) and having one end perpendicular to the midpoint M12 of the second orientation flat OF2 and the other end contacting the outer circumference circle (arc portion W1e) of the disc-like workpiece W1.

  Further, for example, the image processing unit 402 calculates the number of pixels between the middle point M11 of the first orientation flat OF1 and the intersection point P41 or based on the coordinates of the middle point M11 of the first orientation flat OF1 and the coordinates of the intersection point P41. By performing arithmetic processing, the midpoint M21 of the line segment L31 is detected. In addition, the image processing unit 402 is based on, for example, calculating the number of pixels between the middle point M12 of the second orientation flat OF2 and the intersection point P42, or the coordinates of the middle point M12 of the second orientation flat OF2 and the coordinates of the intersection point P42. By performing arithmetic processing, the midpoint M22 of the line segment L32 is detected.

Next, for example, the image processing unit 402 detects the coordinates of the midpoint M31 of the line segment connecting the midpoint M21 of the line segment L31 and the center Pa1 of the outer circumferential circle of the disk-shaped workpiece W1. In addition, the image processing unit 402 detects the coordinates of the midpoint M32 of the line segment that connects the midpoint M22 of the line segment L32 and the center Pa1 of the outer circumferential circle of the disk-shaped workpiece W1. The midpoint Pb of the straight line L53 connecting M31 and M32 is calculated as the reference position.
Since the second orientation flat OF2 is formed to be approximately half the length of the first orientation flat OF1, the distance from the center Pa1 to M32 is slight (according to the single crystal silicon wafer semi standard). Therefore, it is possible to detect only M21 without detecting the midpoint M22 and use M31 as a reference position.

  In the above description, the rotation center L4 (reference position L4) for rotating the wafer with reference to the center Pa of the outer circumference circle and the midpoint M2 of the line segment L3 is shown. However, the perpendicular from the orientation flat OF is missing due to the orientation flat OF. The position moved in the direction of the intersection point P4 along the line segment L3 from the center Pa of the outer circumference circle at a half distance of the line segment that contacts the arc portion becomes the reference position L4.

1: Grinding device 10: Base 11: Column A: Detachable area B: Processing area 18a: First cassette 18b: Second cassette
17: Transfer robot 17a: Arm 17b: Robot hand 17c: Moving mechanism 4: Loading means
40: Temporary placement means 400: Temporary placement table 400a: Rotating shaft 400b: Rotating means 401: Camera 402: Image processing unit
42: Transfer means 420: Suction pad 421: Transfer arm 422: Vertical movement axis
423: linear motion shaft 424: carry-in base 425: communication path 19: cleaning means 190: spinner table 191: nozzle 192: arm 13: transport robot 130: arm 131: suction pad 132: rail 14: turntable 3: chuck table 30: Adsorption part 30a: Holding surface 30o: Center of holding surface
31: Frame 32: Chuck table rotating shaft 11: Column 12: Grinding feed means 120: Ball screw 121: Guide rail 122: Motor 123: Holder 5: Grinding means 50: Spindle 51: Motor 52: Mount 53: Grinding wheel 53a: Wheel base 53b: Grinding wheel 6: Second grinding means 7: Polishing means W: Disk-like workpiece Wa: Workpiece surface Wb: Workpiece back surface Wc: Workpiece outer peripheral area OF: Orientation flat (orientation flat)
OF1: First orientation flat OF2: Second orientation flat

Claims (1)

A chuck table capable of rotating while holding a disk-shaped workpiece having an orientation flat indicating a crystal orientation in an outer peripheral region, a rotation shaft serving as a rotation center of the chuck table, a grinding wheel in which a grindstone is arranged in an annular shape, The grinding wheel is rotated about the center of the grinding wheel, passed over the rotation shaft of the chuck table, and the grinding stone is brought into contact with the rotation center from the outer periphery of the disc-shaped workpiece held on the chuck table. A grinding method for grinding a disk-shaped workpiece with the grindstone using a grinding device comprising grinding means for grinding and a loading means for loading the disk-shaped workpiece into the chuck table,
The distance from the center of rotation of the disk-shaped workpiece to the arc of the outer periphery of the disk-shaped workpiece during grinding is shorter than the distance from the arc of the outer periphery of the disk-shaped workpiece to the center of the outer circumference of the disk-shaped workpiece. , Longer than the distance between the midpoint of a line segment passing through the center of the outer circumference of the disk-shaped workpiece, one end orthogonal to the midpoint of the orientation flat and the other end contacting the outer circumference, and the arc of the outer circumference A position detection step of detecting the midpoint of the line segment connecting the midpoint of the line segment and the center of the outer circumferential circle of the disc-shaped workpiece as a reference position as the rotation center of the disc-shaped workpiece during grinding; ,
A loading step of loading the disc-shaped workpiece into the chuck table with the reference position detected in the position detection step and the center of rotation of the chuck table being matched,
A grinding step of grinding the disc-shaped workpiece by bringing the grinding wheel of the grinding wheel into contact with the disc-shaped workpiece carried in the carrying-in step;
A method for grinding a disk-shaped workpiece comprising:

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