JP2018058160A - Dressing method of grinding grindstone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently execute dressing of a grinding grindstone without using manpower.SOLUTION: A height difference ΔH between a reference surface 500 of a reference table 50 and a holding surface 200 of a holding table 2, is determined by a height gage, and a height position Z2 of a grinding surface when the grinding surface 340a of a grinding grindstone 340 for changing a height position by abrasion and replacement, contacts with the holding surface 200, is grasped as a relative position with the reference surface 500 as a reference. A thickness T of a dressing grindstone 8 is added to the height position of the grinding surface 340a, and dressing is executed by grinding-feeding from the height position Z3 by determining the height position Z3 where the grinding surface 340a starts contact with the dressing grindstone 8.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a method for dressing a grinding wheel.

  A grinding apparatus for grinding a plate-like workpiece such as a semiconductor wafer has a holding table for holding the plate-like workpiece and a grinding means having a grinding wheel in which a grinding wheel is arranged in an annular shape, and holds a rotating grinding wheel. The plate-like workpiece is ground by contacting and pressing the plate-like workpiece held on the table.

  When a difficult-to-cut material such as sapphire or SiC is ground using a grinding wheel, the ground surface of the grinding wheel is likely to be crushed, and therefore it is necessary to frequently dress the grinding wheel. The dressing of the grinding wheel is performed, for example, by holding the dressing wheel on a holding table and bringing the rotating grinding wheel into contact with the dressing wheel (see, for example, Patent Document 1).

  Further, when a difficult-to-cut material is ground, the grinding wheel is likely to be worn. Furthermore, if the degree of wear increases, it is necessary to replace the grinding wheel. Therefore, in grinding difficult-to-cut materials, the frequency of exchanging the grinding wheel increases.

  After dressing, after the grinding wheel is worn out, and after changing the grinding wheel, the height of the grinding surface of the grinding wheel changes. It is necessary to perform the origin search (setup). Such setup is performed by gradually lowering the grinding means and recognizing the position of the grinding means in the Z-axis direction when the grinding surface of the grinding wheel and the holding surface of the holding table come into contact (for example, patents). Reference 2). The amount of wear of the grinding wheel is determined based on the height of the grinding means when the grinding surface of the grinding wheel and the holding surface of the holding table come into contact during setup. Since the calculation is based on the thickness, setup is essential for calculating the wear amount of the grinding wheel.

JP2015-178149A JP 2014-024145 A

  However, in the setup, since it is necessary to bring the grinding surface of the grinding wheel and the holding surface of the holding table into contact as described above, the setup cannot be performed in a state where the dressing wheel is held by the holding table. Although the setup can be performed by removing the dressing grindstone from the holding table, the operator needs to perform the work of detaching the dressing grindstone, which causes a reduction in productivity.

  The present invention has been considered in view of such a problem, and an object thereof is to enable efficient setup and dressing of a grinding wheel without manual intervention.

The present invention relates to a holding table having a holding surface for holding a wafer, and a grinding means for grinding the wafer held on the holding surface of the holding table using a grinding wheel in which a grinding wheel is annularly arranged and rotatable. A grinding feed means for grinding and feeding the grinding means in a direction perpendicular to the holding surface; a height gauge for measuring the height of the holding surface of the holding table; and a reference surface provided on the upper surface of the holding table. A reference table that can be moved up and down, a detection unit that detects that the reference table has been lowered by a certain distance, a calculation unit having a calculation function, and a value used by the calculation unit or a value calculated by the calculation unit is stored. A method for dressing a grinding wheel using a grinding device comprising a storage means, wherein the dressing stone is held by holding the plate-shaped dressing wheel on the holding surface of the holding table A table height difference calculating step for calculating a difference (ΔH) between the height of the reference surface measured by the height gauge and the height of the holding surface measured by the height gauge, and the grinding feed means The height position of the grinding means recognized by the grinding feed means when the detection unit detects that the reference table has been lowered by a certain distance by the grinding feed and the grinding surface of the grinding wheel pushing down the reference table ( Z1) is stored in the first grinding means height storage step, the grinding means height position (Z1) stored in the first grinding means height storage step, and the table height difference calculation step is calculated. When the detection unit detects that the difference between the height of the holding surface measured by the height gauge and the height of the reference surface measured by the height gauge (ΔH) and that the reference table has been lowered a certain distance from the upper limit position. The constant distance (ΔZ ) To determine the height position Z2 of the grinding means recognized by the grinding feed means when the grinding surface comes into contact with the holding surface. Z2 = Z1− (ΔH−ΔZ)
The second grinding means height storing step calculated and stored according to the formula, and the dressing stone thickness stored in advance in the height position of the grinding means stored in the second grinding means height storing step are added. The dressing start height calculating step for calculating the height position of the grinding means recognized by the grinding feed means when the grinding surface contacts the upper surface of the dressing grindstone, and the dressing start height calculating step Dressing step of dressing the ground surface with the dressing grindstone held by the holding means after being fed from the height of the grinding means recognized by the grinding feed means, and held by the holding table Dressing the grinding surface of the grinding wheel with a dressing wheel.

In the above grinding wheel dressing method, the grinding apparatus includes i holding tables, and the i holding tables are rotatably supported by a rotatable turntable and centered on a rotation axis of the turntable. In the table height difference calculating step, the difference (ΔHi) between the height of the holding surface of each of the i holding tables and the height of the reference surface measured by the height gauge. In the second grinding means height storing step, each height position of the grinding means recognized by the grinding feed means when the grinding surface comes into contact with each of the i holding tables ( Z2i) Z2i = Z1− (ΔHi−ΔZ)
It is calculated by the following formula. Here, i takes a value from 1 to i.

In the present invention, the height difference between the reference surface of the reference table and the holding surface of the holding table is obtained by a height gauge, and grinding is performed when the grinding surface of the grinding wheel whose height position changes due to wear or replacement contacts the holding surface. The height position of the surface is grasped as a relative position with respect to the reference surface. Then, the thickness of the dressing grindstone is added to the height position of the grinding surface to obtain a height position at which the grinding surface starts to contact the dressing grindstone, and dressing is performed by feeding from the height position. Since the height position of the grinding surface when the grinding wheel contacts the holding surface is recognized by the relative relationship with the reference surface of the reference table, the dressing wheel is removed from the holding table even if the dressing wheel is held on the holding table. Without separating, the height position of the grinding surface when the grinding wheel contacts the holding surface can be obtained. Therefore, setup and dressing of the grinding wheel can be performed without human intervention.
In addition, when there are multiple holding tables, the height at which the grinding wheel contacts each holding surface is determined from the relative relationship with the height of the reference table even if the holding surface height position of each holding table is different. Each can be requested.

1 is a perspective view showing a first embodiment of a grinding apparatus. It is sectional drawing which shows a dressing grindstone holding process typically. It is sectional drawing which shows a holding surface height measurement process typically. It is sectional drawing which shows a reference surface height measurement process typically. It is sectional drawing which shows typically the 1st grinding means height memory | storage process and the 2nd grinding means height memory | storage process. It is sectional drawing which shows typically the state at the time of the dressing start in a dressing process. It is sectional drawing which shows typically the 3rd grinding means height memory | storage process and the 4th grinding means height memory | storage process. It is sectional drawing which shows typically the state at the time of the grinding start in a grinding process. It is a perspective view which shows 2nd Embodiment of a grinding device. It is a schematic diagram which shows the height position of each grinding means which a grinding feed means recognizes when a grinding surface contacts a some holding surface.

1 First Embodiment A grinding apparatus 1 shown in FIG. 1 is an apparatus for grinding a wafer held on a holding table 2 by a grinding means 3. The holding table 2 is driven by feeding means (not shown) and can move on the base 10 in the front-rear direction (Y-axis direction) and is rotatable. The holding table 2 includes an adsorption portion 20 formed of a porous member and a frame body 21 that supports the adsorption portion 20. The suction unit 20 communicates with a suction source (not shown). The upper surface of the suction part 20 and the upper surface of the frame body 21 are formed flush with each other, and the surface constitutes the holding surface 200. The periphery of the holding table 20 is covered with a cover 22.

  The grinding means 3 includes a rotating shaft 30 whose axial direction is a substantially vertical direction (Z-axis direction), a housing 31 that rotatably supports the rotating shaft 30, a motor 32 that rotationally drives the rotating shaft 30, and a rotating shaft 30. An annular mount 33 connected to the lower end of the mount 33 and a grinding wheel 34 removably coupled to the lower surface of the mount 33 are provided. The grinding wheel 34 includes a wheel base 341 and a plurality of grinding wheels 340 having a substantially rectangular parallelepiped shape arranged annularly on the bottom surface of the wheel base 341. The grinding wheel 340 is formed by, for example, a diamond bond or the like being fixed by a resin bond, a metal bond, or the like, and its lower surface is a grinding surface 340a for grinding the wafer. Note that the grinding wheel 340 may be formed integrally in a ring.

  The grinding means 3 is driven by the grinding feed means 4 and is ground and fed in a direction perpendicular to the holding surface 200. The grinding feed means 4 is connected to a ball screw 40 having a substantially vertical (Z-axis direction) axis center, a pair of guide rails 41 arranged in parallel to the ball screw 40, and an upper end of the ball screw 40, and rotates the ball screw 40. A motor 42 to be moved, an elevating plate 43 whose inner nut is screwed into the ball screw 40 and whose side portion is in sliding contact with the guide rail 41, and a holder 44 that is connected to the elevating plate 43 and holds the grinding means 4. When the motor 42 rotates the ball screw 40, the lifting plate 43 is guided by the guide rail 41 and reciprocated in the Z-axis direction, and the grinding means 3 held by the holder 44 is ground and fed in the Z-axis direction. The The motor 42 is controlled by the control means 7.

  The lift plate 43 is provided with a height measuring unit 45 that measures the height position of the grinding means 3 in the Z-axis direction. The guide rail 41 is provided with a scale 46 that is read by the height measuring unit 45, and the reading value obtained by the height measuring unit 45 reading the scale 46 is controlled as the height position of the grinding means 3 in the Z-axis direction. Recognized by means 7. The motor 42 may be provided with an encoder 47, and the control means 7 may recognize the height position of the grinding means 3 in the Z-axis direction based on the output of the encoder 47.

  The cover 22 of the holding table 2 is provided with a relative height reference portion 5 that functions as a reference when measuring the height position of the grinding means 3 in the Z-axis direction. The relative height reference part 5 includes a cylinder 51, a reference table 50 whose lower part is accommodated in the cylinder 51 and whose upper part protrudes upward from the cylinder 51, and a reference table 50 disposed inside the cylinder 51 and lowered by a certain distance. And a detecting unit 52 for detecting this. The reference table 50 includes a reference surface 500 formed flat on the upper surface thereof. The reference table 50 is biased in the + Z direction by the cylinder 51, and is located at the upper limit position when no pressing force is applied from above.

  On the base 10, a surface height measuring unit 6 that measures the height position of the holding surface 200 of the holding table 2 in the Z-axis direction and the height position of the reference surface 500 of the reference table 50 in the Z-axis direction is provided. Yes. The surface height measurement unit 6 includes two height gauges 60 that can move up and down, and measures the height position of the holding surface 200 or the reference surface 500 in the Z-axis direction based on the position of the height gauge 60 in the Z-axis direction. Can do.

  The height measuring unit 45 is connected to the storage unit 70, and the value measured by the height measuring unit 45 is stored in the storage unit 70. The storage unit 70 is connected to a calculation unit 71 having a calculation function. The calculation unit 71 includes a CPU and a storage element, calculates a position in the Z-axis direction where the grinding unit 3 should be located using a value stored in the storage unit 70, and stores the calculation result in the storage unit 70. .

  Next, a method of dressing the grinding wheel 340 using the dressing wheel 8 by holding the dressing wheel 8 shown in FIG. 1 on the holding table 2 in the grinding apparatus 1 will be described.

(1) Dressing whetstone holding process As shown in FIG. 1, the dressing whetstone 8 is fixed to the support plate 80 with an adhesive agent or the like. The support plate 80 is formed to have the same diameter as the suction part 20 of the holding table 2 or a slightly larger diameter than the suction part 20. On the other hand, the dressing grindstone 8 has a smaller diameter than the support plate 80.

  In this step, as shown in FIG. 2, the support plate 80 to which the dressing grindstone 8 is fixed is sucked and held on the holding surface 200 of the holding table 2 so that the upper surface 800 of the dressing grindstone 80 is exposed upward. At this time, the reference table 50 is located at the upper limit position. Further, the grinding means 3 is retracted to a position where the grinding surface 340 a of the grinding wheel 340 does not contact the reference surface 500 of the reference table 50 and the upper surface 800 of the dressing wheel 80.

(2) Holding surface height measurement step As shown in FIG. 3, the tip of the height gauge 60 is brought into contact with the holding surface 200, and the height position in the Z-axis direction of the holding surface 200 recognized by the height gauge 60 is measured. Here, a substantially vertical axis viewed from the height gauge 60 is defined as a Zg axis, and a height position of the holding surface 200 on the Zg axis is defined as Zg1. The value of Zg1 is stored in the storage means 70 shown in FIG. In this measurement, since the tip of the height gauge 60 may be brought into contact with the upper surface of the frame body 21 in the holding surface 200, the measurement can be performed even when the dressing grindstone 80 is held on the holding table 2.

(3) Reference Surface Height Measurement Step Next, as shown in FIG. 4, with the reference table 50 positioned at the upper limit position, the tip of the height gauge 60 is brought into contact with the reference surface 500 of the reference table 50, and the height gauge 60 is The height position in the Z-axis direction of the reference surface 500 to be recognized, that is, the height position Zg2 of the reference surface 500 on the Zg axis is measured. The value of Zg2 is stored in the storage means 70 shown in FIG. This step can also be measured in a state where the dressing grindstone 8 is held on the holding table 2.

(4) Table Height Difference Calculation Step Next, the calculation unit 71 stores the value of the height position Zg1 of the holding surface 200 on the Zg axis and the height of the reference surface 500 on the Zg axis stored in the storage unit 70. The value of the position Zg2 is read and the difference (ΔH) between Zg2 and Zg1 shown in FIG. 5 is calculated. This difference is calculated by the equation (Zg2-Zg1). Here, since the reference surface 500 is located higher than the holding surface 200, the calculation result of ΔH = Zg2−Zg1 is a positive value.

(5) First grinding means height storing step Next, the reference table 50 is positioned below the grinding wheel 340, and the grinding feed means 4 feeds the grinding means 3 and lowers without rotating the grinding wheel 34. Then, as shown in FIG. 5, when the reference table 50 is pressed downward by the grinding wheel 340, the grinding surface 340 a pushes down the reference table 50 and descends. When the reference table 50 is lowered by a certain distance (ΔZ) and the detection unit 52 constituting the relative height reference unit 5 detects the lower end of the reference table 50, a signal indicating that the reference table 50 has been lowered by a certain distance is detected. The control unit 7 is notified from the unit 52. Upon receiving this notification, the control means 7 sends a signal instructing to stop driving to the motor 42 shown in FIG. Then, the descent of the grinding means 3 stops. The grinding feed unit 4 recognizes the value (Z1) of the scale 46 read by the height measuring unit 45 at the moment when the descent of the grinding unit 3 stops, notifies the storage unit 70 of the value, and stores the value in the storage unit 70. Remember me. The value of Z1 at this time is the height position of the grinding means 3 recognized by the grinding feed means 4, that is, the height position value when the substantially vertical axis viewed from the grinding feed means 4 is the Z axis. The Z axis is a coordinate system different from the Z1 axis as viewed from the height gauge 60.

  Note that the descent amount (ΔZ) of the reference table 50 until the detection unit 52 detects the reference table 50 is adjusted in advance so as to be constant, and the value of ΔZ is stored in the storage unit 70 in advance. Yes. In addition, since the reference surface 500 when the detection unit 52 detects the reference table 50 is located above the upper surface 800 of the dressing grindstone 8, grinding is performed until the detection unit 52 detects the reference table 50. The grinding surface 340 of the grindstone 34 does not contact the upper surface 800 of the dressing grindstone 8.

(6) Second grinding means height storage step Next, the calculation means 71 calculates the height position (Z1) of the grinding means 3 stored in the storage means 70 in the first grinding means height storage step shown in FIG. ) And the difference (ΔH) between the height Zg1 of the holding surface 200 measured by the height gauge 60 and the height Zg2 of the reference surface measured by the height gauge 60 calculated in the table height difference calculating step shown in FIG. Grinding means that the grinding feed means 4 recognizes when the grinding surface 340a contacts the 200 holding surface by using the constant distance (ΔZ) when the detection unit detects that the table 50 is lowered by a certain distance from the upper limit position. 3 is obtained by the following (Equation 1) as the second grinding means height Z2 on the Z-axis.
Z2 = Z1− (ΔH− (ΔZ)) (Formula 1)
In the above (Equation 1), the value of the height position on the Zg axis is not used, but only the distance between the two positions on the Zg axis is used, so the relationship between the Z axis and the Zg axis is conscious. The position on the Z axis can be obtained without directly measuring the positions on the Z axis of the reference surface 500 and the holding surface 200.

  This process corresponds to a so-called setup process in which the origin of the height position in the Z-axis direction of the grinding means 3 as viewed from the grinding feed means 4 is found, and the obtained value of Z2 is the grinding surface of the grinding wheel 340. When dressing 340 a with the dressing grindstone 8, the grinding feed means 4 is used when the height position of the grinding means 3 is controlled. Also, when grinding the wafer held on the holding table 2, this Z2 becomes a reference.

(7) Dressing start height calculating step Next, the calculating unit 71 calculates the height position Z2 of the grinding unit 3 stored in the second grinding unit height storing step and the dressing grindstone 8 stored in the storage unit 70 in advance. The thickness T obtained by adding the thickness and the thickness of the support plate 80 is added, and the grinding feed unit 4 recognizes when the grinding surface 340a contacts the upper surface 800 of the dressing grindstone 8 according to the following (Equation 2). The height position Z3 of the grinding means 3 shown in FIG.
Z3 = Z2 + T (Formula 2)

(8) Dressing process The motor 32 shown in FIG. 1 rotates the grinding wheel 34, and the grinding feed means 4 feeds the grinding means 3 downward in the Z-axis direction. As shown in FIG. The grinding surface 340a of 340 is brought into contact with the upper surface 800 of the dressing grindstone 8, and the grinding surface 340a is dressed. When the grinding feed means 4 feeds the grinding means 3, it is lowered at a high speed until the height position of the grinding means 3 approaches Z3 and immediately before the height position of the grinding means 3 reaches Z3. Change the grinding feed speed to low speed. Then, the grinding surface 340a is brought into contact with the upper surface 800 of the dressing grindstone 8 at the height of the grinding means 3 calculated in the dressing start height calculating step, and the grinding feed means 4 further feeds the grinding means 3 from there. Perform dressing 340a. During dressing, the reference table 50 is lowered so that the reference surface 500 of the reference table 50 is positioned lower than the upper surface 800 of the dressing grindstone 8.

(9) Third grinding means height storage step When dressing is performed as described above, since the abrasive grains contained in the grinding wheel 340 fall off, as shown in FIG. It will be located above the ground surface 340a before dressing. Therefore, in order to finish the wafer to a predetermined thickness by grinding, it is necessary to perform so-called setup after dressing. Therefore, first, as in the first grinding means height storing step, the reference table 50 is positioned below the grinding wheel 340, and the grinding feed means 4 lowers the grinding means 3 without rotating the grinding wheel 34. Then, as shown in FIG. 7, the reference table 50 is lowered by pressing the reference table 50 downward with the grinding wheel 340. When the reference table 50 is lowered by a certain distance (ΔZ) and the detection unit 52 constituting the relative height reference unit 5 detects the lower end of the reference table 50, a signal indicating that the reference table 50 has been detected is detected. Is notified to the control means 7. Upon receiving this notification, the control means 7 sends a signal instructing to stop driving to the motor 42 shown in FIG. Then, the descent of the grinding means 3 stops. The grinding feed unit 4 recognizes the value (Z4) of the scale 46 read by the height measuring unit 45 at the moment when the lowering of the grinding unit 3 stops, notifies the storage unit 70 of the value, and stores the value in the storage unit 70. Remember. The value of Z4 at this time is the height position of the grinding means 3 recognized by the grinding feed means 4. The descending amount (ΔZ) of the reference table 50 until the detection unit 52 detects the reference table 50 is constant, and the value of ΔZ is stored in the storage unit 70 in advance. In addition, since the reference surface 500 when the detection unit 52 detects the reference table 50 is located above the upper surface 800 of the dressing grindstone 8, grinding is performed until the detection unit 52 detects the reference table 50. The grinding surface 340 of the grindstone 34 does not contact the upper surface 800 of the dressing grindstone 8.

(10) Fourth grinding means height storage step Next, the calculation means 71 calculates the height position (Z4) of the grinding means 3 stored in the storage means 70 in the third grinding means height storage step shown in FIG. ) And the difference (ΔH) between the height Zg1 of the holding surface 200 measured by the height gauge 60 and the height Zg2 of the reference surface measured by the height gauge 60 calculated in the table height difference calculating step shown in FIG. Grinding means recognized by the grinding feed means 4 when the grinding surface 340b contacts the holding surface 200 using the constant distance (ΔZ) when the detection unit detects that the table 50 has been lowered by a certain distance from the upper limit position. The height position of 3, ie, the height position on the Z-axis, is obtained as the fourth grinding means height Z5 by the following (Equation 3).
Z5 = Z4− (ΔH− (ΔZ)) (Formula 3)

  This process is a so-called setup process, and the obtained value of Z5 is a height that serves as a reference when the grinding surface 340a of the grinding wheel 340 is brought into contact with the wafer held on the holding table 2 for grinding. is there.

(11) Grinding start height calculation step Next, the dressing grindstone 8 and the support plate 80 are detached from the holding table 2, and the protective member for the wafer W in which the protective member P is adhered to the surface Wa as shown in FIG. The P side is placed on the holding surface 200, and suction force is applied to the suction unit 20 to hold it by suction. In grinding the back surface Wb of the wafer W, the height position Z5 of the grinding means 3 stored in the fourth grinding means height storing step, the thickness of the wafer W stored in the storage means 70 in advance, and the protective member P Grinding shown in FIG. 8 is recognized by the grinding feed means 4 when the grinding surface 340b of the grinding wheel 340 is in contact with the back surface Wb of the wafer W according to the following (Equation 4). The height position Z6 of the means 3 is calculated.
Z6 = Z5 + T1 (Formula 4)
The dressing grindstone 8 and the support plate 80 are detached from the holding table 2, and the protective member P side of the wafer W having the protective member P attached to the surface Wa is placed on the holding surface 200, and suction force is applied to the suction unit 20. You may perform the operation | work which makes it act and adsorb | suck-hold after calculating | requiring said Z6.

(12) Grinding Step Next, the motor 32 shown in FIG. 1 rotates the grinding wheel 34, and the grinding feed means 4 feeds the grinding means 3 downward. When the grinding means 4 feeds the grinding means 3, it is lowered at high speed until the height position of the grinding means 3 approaches Z6, and immediately before the height position of the grinding means 3 reaches Z6. Change the grinding feed speed to low speed. Then, the grinding surface 340b of the rotating grinding wheel 340 comes into contact with the back surface Wb of the wafer W, and grinding of the back surface Wb is started. During grinding, the height gauge 60 shown in FIG. 1 is in contact with the back surface Wb, and another height gauge 60 is in contact with the upper surface of the frame body 21, and the wafer W is being ground due to the height difference between the two height gauges 60. The sum of the thickness of the protective member P and the thickness of the protective member P is calculated. When the calculated value reaches a predetermined value, the grinding feed means 4 raises the grinding means 3 to finish grinding. During grinding of the wafer W, the reference table 50 is lowered so that the reference surface 500 of the reference table 50 is positioned at a position lower than the back surface Wb of the wafer W after grinding.

  When the wafer is ground using the grinding wheel 340 in this way, the grinding wheel 340 is worn. Depending on the degree of wear, the grinding wheel 34 needs to be replaced. When the grinding wheel 34 is replaced, the position of the grinding surface 340a of the grinding wheel 340 changes, so that it is necessary to perform setup in the same manner as described above. In such a case, the height position value of the grinding means 3 recognized by the grinding feed means 4 when the grinding surface 340a contacts the holding surface 200 is determined by the same method as in the second grinding means height storing step. Ask. When performing this setup, the wafer is held in the holding table 2, but by performing a calculation using the reference table 50, the setup can be performed without removing the wafer.

2 Second Embodiment A grinding apparatus 1A shown in FIG. 9 includes three holding tables 2a, 2b, and 2c, and grinding means 3a and 3b with respect to a workpiece held on these holding tables 2a, 2b, and 2c. Is a device for grinding. In addition, below, about the site | part comprised similarly to the grinding apparatus 1 of 1st Embodiment, the code | symbol same as the grinding apparatus 1 is attached | subjected and the description is abbreviate | omitted.

  These holding tables 2a, 2b, and 2c are rotatably supported by a turntable 81 that can rotate, and can revolve around a rotation axis of the turntable 81. Each holding table 2a, 2b, 2c is configured such that the suction portion 20 is supported by a frame body 21 in the same manner as the holding table 2 constituting the grinding apparatus 1 of the first embodiment.

  At least one relative height reference portion 5 is disposed on the turntable 81. The configuration of the relative height reference portion 5 is the same as that of the grinding device 1 of the first embodiment.

  The base 10a includes a surface height measurement unit 6a that measures the height position of the holding surface 200 of the holding tables 2a, 2b, and 2c in the Z-axis direction and the height position of the reference surface 500 of the reference table 50 in the Z-axis direction. , 6b. The surface height measuring units 6a and 6b are configured in the same manner as the grinding device 1, and can measure the height position of the holding surface 200 or the reference surface 500 in the Z-axis direction based on the position of the height gauge 60 in the Z-axis direction. it can.

  The front portion in the Y-axis direction on the base 10a is a carry-in / out region 101, which is a region in which the wafer is carried into and out of the holding table 30, and the rear in the Y-axis direction on the base 10a is a grinding means. A processing region 102 is a region where the wafers held on the holding tables 2a, 2b, and 2c are ground by 3a and 3b.

  A first cassette mounting portion 82a and a second cassette mounting portion 82b are provided on the front side of the base 10a, and a wafer before processing is accommodated in the first cassette mounting portion 82a. The first cassette 820a is placed, and the second cassette 820b that houses the processed plate-like workpiece W is placed on the second cassette placement portion 82b.

  Behind the first cassette 820a and the second cassette 820a, a robot that unloads the plate-shaped workpiece W before processing from the first cassette 820a and loads the plate-shaped workpiece W after processing into the second cassette 820b. 83 is arranged. A temporary placement area 84 is provided at a position adjacent to the robot 83, and positioning means 840 is disposed in the temporary placement area 84. The alignment means 840 aligns the wafer carried out from the first cassette 820a and placed in the temporary placement area 84 at a predetermined position.

  At a position adjacent to the temporary placement region 84, a first transport unit 85a that turns while holding the plate-like workpiece W is disposed. The first transport unit 85 a holds the wafer aligned by the alignment unit 840 and transports the wafer to any holding table positioned in the carry-in / out area 101.

  Next to the first transport unit 85a, a second transport unit 85b that rotates while holding the processed plate-like workpiece W is provided. A spinner cleaning means 86 for cleaning the processed plate-shaped workpiece conveyed by the second conveyance means 85b is disposed at a position close to the second conveyance means 85b. The wafer cleaned by the spinner cleaning means 86 is carried into the second cassette 820b by the robot 83.

  The grinding means 3a and 3b are driven by the grinding feed means 4a and 4b, respectively, and are ground and fed in a direction perpendicular to the holding surface 200. The motor 42 constituting the grinding feed means 4a, 4b is controlled by the control means 7. Further, the control means 7 recognizes the height position of the grinding means 3a, 3b in the Z-axis direction based on the output of the encoder 47 provided in the motor 42.

  The grinding means 3a and the grinding means 3b are configured similarly except for the grinding wheel. The grinding wheel 342 provided in the grinding means 3a is a rough grinding wheel and has abrasive grains having a relatively large particle size. On the other hand, the grinding wheel 343 provided in the grinding means 3b is a grinding wheel for finish grinding, and has abrasive grains having a smaller particle diameter than the grinding wheel 342 for rough grinding.

  In the grinding apparatus 1A configured as described above, the same processes as those of the first embodiment are performed for the respective grinding means 3a and 3b.

(1) Dressing whetstone holding process In this process, the dressing whetstone 8 shown in FIG. 1 is hold | maintained in either of holding table 2a, 2b, 2c.

(2) Holding surface height measuring step In this step, as in the first embodiment, the height gauge 60 of any of the surface height measuring units 6a and 6b is brought into contact with the reference surface 500 of the reference table 50, and the height gauge 60 Measure the height of the reference plane 500 recognized by. Further, for all of the three holding tables 2a, 2b, and 2c, the height gauge 60 of any of the surface height measuring units 6a and 6b is brought into contact with the respective holding surfaces 200, and the respective holding surfaces 200 recognized by the height gauge 60 are detected. Measure height. Measurement in this step can also be performed on a holding table holding the dressing grindstone 8.

  The same surface height measurement unit is used for measuring the height position of the reference surface 500 and for measuring the height position of the holding surface 200 of the holding tables 2a, 2b, and 2c. For example, when the surface height measuring unit 6a is used for measuring the height position of the reference surface 500, the surface height measuring unit 6a is also used for measuring the height position of the holding surface 200 of the holding tables 2a, 2b, and 2c. use.

(3) Reference surface height measurement step Next, as in the first embodiment, in the state where the reference table 50 is located at the upper limit position, the tip of the height gauge 60 is brought into contact with the reference surface 500 of the reference table 50, and the height gauge 60 The height position in the Z-axis direction of the reference surface 500 recognized by is measured and stored in the storage means 70. This step can also be measured in a state where the dressing grindstone 80 is held on the holding table 2.

(4) Table Height Difference Calculation Step Next, as in the first embodiment, the calculation unit 71 calculates the height position values of the plurality of holding surfaces 200 and the height of the reference surface 500 stored in the storage unit 70. The height value is read out, and the difference (ΔH1, ΔH2, ΔH3) obtained by subtracting the height position value of each holding surface 200 from the height position value of the reference surface 500 shown in FIG. 10 is calculated. Here, since the reference surface 500 is located higher than the holding surface 200, ΔH1, ΔH2, and ΔH3 are all positive values.

(5) First grinding means height storing step Next, as shown in FIG. 10, the reference table 50 is positioned below the grinding wheel 342, and the grinding feed means 4a is operated by the grinding means without rotating the grinding wheel 34. 3a is lowered, and the reference table 50 is lowered by pressing the reference table 50 downward by the grinding wheel 342. When the reference table 50 is lowered by a certain distance (ΔZ) and the detection unit 52 constituting the relative height reference unit 5 detects the lower end of the reference table 50, a signal indicating that the reference table 50 has been detected is detected. Is notified to the control means 7. Upon receiving this notification, the control means 7 sends a signal instructing to stop driving to the motor 42 shown in FIG. 9 constituting the grinding feed means 4a. Then, the descent of the grinding means 3a stops. In the grinding feed means 4a, the value of the height position Z1 of the grinding means 3a recognized by the grinding feed means 4a based on the information of the encoder 47 shown in FIG. 9 at the moment when the lowering of the grinding means 3a stops is stored in the storage means 70. Notification is made and stored in the storage means 70. The value of Z1 at this time is the value of the height position of the grinding means 3a recognized by the grinding feed means 4a.

(6) Second grinding means height storage step Next, the calculation means 71 calculates the height position (Z1) of the grinding means 3a stored in the storage means 70 in the first grinding means height storage step, and the table height. The difference (ΔH1, ΔH2, ΔH3) between the height of the holding surface 200 measured by the height gauge 60 calculated in the height difference calculating step and the height of the reference surface measured by the height gauge 60, and the reference table 50 is lowered by a certain distance from the upper limit position. The grinding feed means 4a recognizes when the grinding surface 342a of the grinding wheel 342 contacts each holding surface 200 of the holding tables 2a, 2b, 2c using the fixed distance (ΔZ) when the detection unit detects this. The height position of the grinding means 3a to be obtained is obtained as the second grinding means height Z21, Z22, Z23 by the following (Equation 5).
Z2i = Z1− (ΔHi−ΔZ) (Formula 5)
Here, i takes a value from 1 to 3 (the number of holding tables).

This process corresponds to a so-called setup process in which the origin of the height position of the grinding means 3a in the Z-axis direction as viewed from the grinding feed means 4a is found, and the obtained values of Z21, Z22, and Z23 are the grinding wheels. When the grinding surface 342a of 342 is dressed by the dressing grindstone 8 or when the grinding surface 342a is brought into contact with the wafer for grinding, the grinding feed means 4a is used when controlling the height position of the grinding means 3a.
Further, in this step, the height position of the grinding means 3b recognized by the grinding feed means 4b when the grinding surface 343a of the grinding wheel 343 constituting the grinding means 3b contacts each holding surface 200 of the holding tables 2a, 2b, 2c. Is obtained by the same method.

(7) Dressing start height calculating step Next, the calculating unit 71 calculates the height position Z2 of the grinding unit 3a stored in the second grinding unit height storing step and the dressing grindstone 8 stored in the storage unit 70 in advance. Grinding means that the grinding feed means 4a recognizes when the grinding surface 342a comes into contact with the upper surface 800 of the dressing grindstone 8 by the following (Equation 6) by adding the thickness T and the total thickness T of the support plate 80 The height position Z3 of 3a is calculated.
Z3 = Z2j + T (Formula 6)
Here, j is any value of 1-3. For example, when the dressing grindstone 8 is held in the holding table 2a, the sum of Z21 and T is the height position of the grinding means 3a. , J = 1.
The above calculation also applies to the height position of the grinding means 3b recognized by the grinding feed means 4b when the grinding surface 343a of the grinding wheel 343 constituting the grinding means 3b contacts the upper surface 800 of the dressing grindstone 8. It is done by the method.

(8) Dressing Step The motor 32 shown in FIG. 9 rotates the grinding wheel 34, and the grinding feed means 4a feeds the grinding means 3a downward in the Z-axis direction to dress the grinding surface 342a of the grinding wheel 342. The grinding surface 342a is dressed by making contact with the upper surface 800 of the grindstone 8. The same applies when dressing the grinding surface 343a of the grinding wheel 343 constituting the grinding means 3b.

(9) Third grinding means height storage step When dressing is performed as described above, the abrasive grains contained in the grinding wheel 342 fall off, so that the grinding surface 342 of the grinding wheel 342 after dressing is It is located at a different height from the grinding surface 342a. Therefore, in order to finish the wafer to a predetermined thickness by grinding, it is necessary to perform so-called setup after dressing. The setup method is the same as in the first embodiment, and in this step, the reference table 50 is positioned below the grinding wheel 342 and the grinding wheel 34 is rotated, as in the first grinding means height storage step. Instead, the grinding feed means 4a lowers the grinding means 3a and presses the reference table 50 downward by the grinding wheel 342, thereby lowering the reference table 50. When the reference table 50 is lowered by a certain distance (ΔZ) and the detection unit 52 constituting the relative height reference unit 5 detects the lower end of the reference table 50, a signal indicating that the reference table 50 has been detected is detected. The control means 7 that has received this notice stops the descent of the grinding means 3a and then determines the height of the grinding means 3a recognized by the grinding feed means 4a based on the information from the encoder 47. The position value is stored in the storage means 70. When the grinding wheel 343 constituting the grinding means 3b is dressed, the setup is similarly performed for the grinding surface 343a of the grinding wheel 343.

(10) Fourth grinding means height storage step Next, the calculation means 71 calculates the height position value of the grinding means 3 stored in the storage means 70 in the third grinding means height storage step and the table height. The difference (ΔH1, ΔH2, ΔH3) between the height of the holding surface 200 measured by the height gauge 60 calculated in the difference calculating step and the height of the reference surface measured by the height gauge 60, and that the reference table 50 is lowered by a certain distance from the upper limit position. And the fixed distance (ΔZ) when the detection unit detects the grinding feed means 4a when the ground surface after dressing of the grinding stone 342 contacts each holding surface 200 of the holding tables 2a, 2b, 2c. The height position of the grinding means 3a recognized by the above, that is, the height position on the Z axis is obtained as the fourth grinding means height. The value obtained here becomes a reference height when grinding is performed by bringing the ground surface after dressing of the grinding wheel 342 into contact with the wafer held on each holding table. The obtained value is stored in the storage means 70. Even when dressing the grinding wheel 343 constituting the grinding means 3b, the ground surface after dressing comes into contact with the holding surfaces 200 of the holding tables 2a, 2b, and 2c with respect to the grinding surface 343a of the grinding wheel 343 by the same method. The height position of the grinding means 3b recognized by the grinding feed means 4b at the time, that is, the height position on the Z-axis is obtained as the height of the fourth grinding means.

(11) Grinding start height calculation step Next, the robot 83 unloads the unprocessed wafer from the first cassette 820a, and after alignment by the temporary placement region 84, the first transfer means 85a causes the load / unload region 101 to move. The wafer is transported to any one of the holding tables, specifically the holding table on which the dressing grindstone 8 is not held, and a suction force is applied to the suction portion 20 to hold the wafer. Then, as in the first embodiment, the wafer thickness and the protective member thickness previously stored in the storage means 70 are added to the height value of the grinding means 3a obtained in the fourth grinding means height storage step. The height of the grinding means 3a as viewed from the grinding feed means 4 when the ground surface after dressing of the grinding wheel 342 contacts the back surface of the wafer is calculated. The same calculation is performed for the grinding means 3b.

(12) Grinding process Next, the grinding means 3a feeds the grinding means 3a to the height position obtained in the grinding start height calculation step. The ground surface after dressing of the rotating grinding wheel 342 contacts the back surface of the wafer, and the back surface is roughly ground. In addition, after the turntable 81 is rotated by a required angle, the grinding feed means 4b feeds the grinding means 3b to the height position obtained in the grinding start height calculation step, and finish-grinds the rough ground back surface of the wafer. To do.

  The finish ground wafer is transported to the spinner cleaning means by the second transport means 85b, where the wafer rotates and high pressure water is sprayed onto the back surface of the wafer to clean the ground back surface. Further, after the cleaning, the wafer is rotated and the cleaning water is removed.

  The cleaned and dried wafer is accommodated in the second cassette 820b by the robot 83.

  In the example shown in FIG. 9, the relative height reference portion 5 is disposed between the holding table 2a and the holding table 2b, but moves below the grinding wheels 342 and 343 constituting the grinding means 3a and 3b. The relative height reference part 5 may be disposed at other positions, for example, between the holding table 2b and the holding table 2c, or between the holding table 2a and the holding table 2c. . Moreover, the relative height reference | standard part 5 is good also as a structure which is not arrange | positioned on the turntable 81 and moves below the grinding stones 342 and 343 independently.

  Further, the number of holding tables may be two or four or more, and two or more relative height reference portions may be provided. For example, when four holding tables are arranged and two relative height reference parts are arranged, the grinding feed means recognizes when the holding surfaces of the two holding tables and the grinding surface of the grinding wheel come into contact with each other. The height position of the grinding means to be calculated is calculated using one of the relative height reference portions, and the grinding means that the grinding feed means recognizes when the holding surface of the other two holding tables and the grinding surface of the grinding wheel come into contact with each other. The height position can be properly used by calculating using the other relative height reference portion. Also, when the number of grinding means and the number of relative height reference parts are the same, and each grinding means uses a dedicated relative height reference part, the grinding surface comes into contact with the holding surface of each holding table. The height position may be obtained. Furthermore, the number of holding tables and the number of relative height reference parts may be the same, and one holding table and one relative height reference part may be made to correspond one-to-one.

DESCRIPTION OF SYMBOLS 1, 1A: Grinding device 2, 2a, 2b, 2c: Holding table 20: Adsorption part 21: Frame body 200: Holding surface 22: Cover 3, 3a, 3b: Grinding means 30: Rotating shaft 31: Housing 32: Motor 33 : Mount 34: grinding wheel 341: wheel base 340, 342, 343: grinding wheel 340a, 340b, 342a, 343a: grinding surface 4, 4a, 4b: grinding feed means 40: ball screw 41: guide rail 42: motor 43: Lift plate 44: Holder 45: Height measurement unit 46: Scale 47: Encoder 5: Relative height reference unit 50: Reference table 500: Reference surface 51: Cylinder 52: Detection unit 6: Surface height measurement unit 60: Height gauge 7 : Control means 70: storage means 71: calculation means 8: dressing grindstone 80: support plate 800: upper surface 81: turn tape Table 82a: First cassette placement unit 82b: Second cassette placement unit 820a: First cassette 820b: Second cassette 83: Robot 84: Temporary placement area 840: Positioning means 85a: First transport means 85b: Second transfer means 86: Spinner cleaning means 101: Loading / unloading area 102: Processing area

Claims (2)

A holding table having a holding surface for holding a wafer, a grinding means for grinding a wafer held on the holding surface of the holding table using a rotatable grinding wheel in which a grinding wheel is annularly arranged, and the grinding means Grinding feed means for grinding and feeding in a direction perpendicular to the holding surface, a height gauge for measuring the height of the holding surface of the holding table, and a reference surface on the upper surface provided on the holding table and capable of moving up and down A reference table, a detection unit for detecting that the reference table has been lowered by a certain distance, a calculation unit having a calculation function, and a storage unit for storing a value used by the calculation unit or a value calculated by the calculation unit A grinding wheel dressing method using a grinding apparatus comprising:
A dressing grindstone holding step for holding a plate-shaped dressing grindstone on the holding surface of the holding table;
A table height difference calculating step for calculating a difference (ΔH) between the height of the reference surface measured by the height gauge and the height of the holding surface measured by the height gauge;
The grinding feed means recognizes when the detection unit detects that the reference table is lowered by a certain distance by the grinding feed means grinding and feeding the grinding means, and the grinding surface of the grinding wheel pushes down the reference table. A first grinding means height storing step for storing the height position (Z1) of the grinding means in the storage means;
The height position (Z1) of the grinding means stored in the first grinding means height storing step, the height of the holding surface measured by the height gauge calculated in the table height difference calculating step, and the height gauge are measured. Using the difference (ΔH) between the height of the reference surface and the constant distance (ΔZ) when the detection unit detects that the reference table has been lowered by a certain distance from the upper limit position, The height position Z2 of the grinding means recognized by the grinding feed means when contacting the holding surface is expressed as Z2 = Z1− (ΔH−ΔZ).
A second grinding means height storing step which is calculated and stored according to the formula:
The grinding feed when the grinding surface comes into contact with the upper surface of the dressing wheel by adding the thickness of the dressing wheel stored in advance to the height position of the grinding device stored in the second grinding device height storing step Dressing start height calculating step for calculating the height position of the grinding means recognized by the means;
A dressing step of dressing the ground surface with the dressing grindstone that is ground and fed from the height of the grinding means recognized by the grinding feed means calculated in the dressing start height calculating step;
With
A grinding wheel dressing method for dressing a grinding surface of the grinding wheel with the dressing wheel held by the holding table. The grinding device includes a plurality of the holding tables, and the plurality of holding tables are rotatably supported by a rotatable turntable and can revolve around a rotation axis of the turntable,
In the table height difference calculating step, a difference ΔHi between the height of each holding surface of the plurality of holding tables and the height of the reference surface measured by the height gauge is calculated,
In the second grinding means height storing step, the height position Z2i of the grinding means recognized by the grinding feed means when the grinding surface comes into contact with each of the i holding tables is determined as Z2i = Z1−. (ΔHi−ΔZ)
The grinding wheel dressing method according to claim 1, which is calculated by the following formula.

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