JP6803187B2 - Grinding wheel dressing method - Google Patents

Description

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

A grinding device for grinding a plate-shaped workpiece such as a semiconductor wafer is provided with a holding table for holding the plate-shaped workpiece and a grinding means equipped with a grinding wheel in which grinding wheels are arranged in an annular shape, and holds a rotating grinding wheel. The plate-shaped work is ground by contacting and pressing the plate-shaped work 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, so that it is necessary to dress the grinding wheel frequently. 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 easily worn. In addition, as the degree of wear increases, the grinding wheel needs to be replaced. Therefore, in grinding difficult-to-cut materials, the frequency of replacing the grinding wheel is high.

After dressing, after the grinding wheel is worn, and after the grinding wheel is replaced, the height position of the grinding surface of the grinding wheel changes. Therefore, in order to finish the plate-shaped work to a predetermined thickness, the grinding surface is used. It is necessary to set up the origin of. Such a 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 with each other (for example, a patent). Reference 2). The amount of wear of the grinding wheel is 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 with each other during setup, and the position of the grinding means at the end of grinding and the finish of the work. Since the calculation is based on the thickness, the setup is indispensable for calculating the amount of wear of the grinding wheel.

Japanese Unexamined Patent Publication No. 2015-178149 Japanese Unexamined Patent Publication No. 2014-024145

However, in the setup, as described above, it is necessary to bring the grinding surface of the grinding wheel into contact with the holding surface of the holding table, so that the setup cannot be performed when the dressing grindstone is held by the holding table. It is possible to set up by removing the dressing grindstone from the holding table, but the work of removing the dressing grindstone must be performed by the operator, which is a factor of reducing productivity.

The present invention is considered to have such a problem, and an object of the present invention is to enable efficient setup and dressing of a grinding wheel without human intervention.

The present invention comprises a holding table having a holding surface for holding the waha, and a grinding means for grinding the waha held on the holding surface of the holding table by using a grinding wheel in which grinding grinds are arranged in an annular shape and can be rotated. 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 move up and down, a detection unit that detects that the reference table has descended by a certain distance, a calculation means having a calculation function, and a value used by the calculation means or a value calculated by the calculation means are stored. A method of dressing a grinding grind using a grinding device provided with a storage means, wherein a dressing grind holding step of holding a plate-shaped dressing grind on the holding surface of the holding table, and a reference plane measured by the height gauge. A table height difference calculation step for calculating the difference (ΔH) between the height and the height of the holding surface measured by the height gauge, and the grinding feed means grinds the grinding means and the grinding surface of the grinding wheel is the reference. The height of the first grinding means that stores the height position (Z1) 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 pushing down the table. The storage step, the height position (Z1) of the grinding means stored in the first grinding means height storage step, and the height of the holding surface measured by the height gauge calculated in the table height difference calculation step. Using the difference (ΔH) from the height of the reference plane measured by the height gauge and the constant distance (ΔZ) when the detection unit detects that the reference table has descended a certain distance from the upper limit position, 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 is Z2 = Z1- (ΔH−ΔZ).
Add the thickness of the dressing grindstone stored in advance to the height position of the grinding means stored in the second grinding means height storage step and the second grinding means height storage step calculated and stored by the formula of. Then, it is calculated by the dressing start height calculation step of calculating the height position of the grinding means recognized by the grinding feed means when the grinding surface comes into contact with the upper surface of the dressing grindstone, and the dressing start height calculation step. The holding table holds the grinding surface, which comprises a dressing step of dressing the ground surface with the dressing grindstone held by the holding table by grinding and feeding from the height of the grinding means recognized by the grinding feed means. The ground surface of the grindstone is dressed with a dressing grindstone.

In the method of dressing a grinding wheel, the grinding device includes i holding tables, and the i holding tables are rotatably supported by a rotatable turntable and centered on the rotation axis of the turntable. In the table height difference calculation step, the difference (ΔHi) between the height of each holding surface of the i holding tables and the height of the reference surface measured by the height gauge is calculated. Then, in the second grinding means height storage step, each 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 set. Z2i = Z1- (ΔHi−ΔZ)
It is calculated by the formula of. 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 determined by a height gauge, and grinding when the grinding surface of the grinding wheel whose height position changes due to wear or replacement comes into contact with 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 ground surface to obtain the height position at which the ground surface starts contact with the dressing grindstone, and grinding is fed from that height position to perform dressing. Since the height position of the grinding wheel when the grinding wheel comes into contact with the holding surface is recognized by the relative relationship with the reference surface of the reference table, even if the dressing wheel is held on the holding table, the dressing wheel can be held from the holding table. The height position of the grinding surface when the grinding wheel comes into contact with the holding surface can be obtained without detaching. Therefore, the setup and the dressing of the grinding wheel can be performed without human intervention.
Further, when there are a plurality of holding tables, even if the height position of the holding surface of each holding table is different, the height at which the grinding wheel contacts each holding surface is determined from the relative relationship with the height of the reference table. Each can be obtained.

It is a perspective view which shows the 1st Embodiment of a grinding apparatus. It is sectional drawing which shows typically the dressing grindstone holding process. It is sectional drawing which shows typically the process of measuring the height of a holding surface. It is sectional drawing which shows typically the reference plane height measurement process. It is sectional drawing which shows typically the 1st grinding means height memory process and 2nd grinding means height memory 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 process and 4th grinding means height memory process. It is sectional drawing which shows typically the state at the time of the start of grinding in a grinding process. It is a perspective view which shows the 2nd Embodiment of a grinding apparatus. It is a schematic diagram which shows the height position of each grinding means which a grinding feed means recognizes when a grinding surface comes into contact with a plurality of holding surfaces.

1 First Embodiment The grinding device 1 shown in FIG. 1 is a device that grinds a wafer held on a holding table 2 by a grinding means 3. The holding table 2 is driven by a feeding means (not shown) and can move on the base 10 in the front-rear direction (Y-axis direction) and can rotate. The holding table 2 includes a suction portion 20 formed of a porous member and a frame body 21 that supports the suction portion 20. The suction unit 20 communicates with a suction source (not shown). The upper surface of the suction portion 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 substantially vertical (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 detachably connected to the lower surface of the mount 33 are provided. The grinding wheel 34 includes a wheel base 341 and a plurality of substantially rectangular parallelepiped grinding wheels 340 arranged in an annular shape on the bottom surface of the wheel base 341. The grinding wheel 340 is formed by fixing diamond abrasive grains or the like with, for example, a resin bond or a metal bond, and the lower surface thereof is a grinding surface 340a for grinding a wafer. The grinding wheel 340 may be formed in an annular shape and integrally.

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 an axial center in a substantially vertical direction (Z-axis direction), a pair of guide rails 41 arranged in parallel with the ball screw 40, and the upper end of the ball screw 40 to rotate the ball screw 40. It includes a moving motor 42, an elevating plate 43 in which an internal nut is screwed into a ball screw 40 and a side portion is in sliding contact with a guide rail 41, and a holder 44 connected to the elevating plate 43 to hold the grinding means 4. When the motor 42 rotates the ball screw 40, the elevating plate 43 is guided by the guide rail 41 and reciprocates in the Z-axis direction, and the grinding means 3 held by the holder 44 is grounded and fed in the Z-axis direction. To. The motor 42 is controlled by the control means 7.

The elevating plate 43 is provided with a height measuring unit 45 for measuring the height position of the grinding means 3 in the Z-axis direction. Further, the guide rail 41 is provided with a scale 46 read by the height measuring unit 45, and the reading value read by the height measuring unit 45 is controlled as the height position of the grinding means 3 in the Z-axis direction. Recognized in 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 by 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 unit 5 includes a cylinder 51, a reference table 50 whose lower portion is housed in the cylinder 51 and whose upper portion protrudes upward from the cylinder 51, and a reference table 50 which is arranged inside the cylinder 51 and the reference table 50 is lowered by a certain distance. It is provided with a detection unit 52 for detecting this. The reference table 50 is provided with a flatly formed reference surface 500 on its upper surface. The reference table 50 is urged in the + Z direction by the cylinder 51, and is located at the upper limit position when no pressing force is applied from above.

A surface height measuring unit 6 for measuring 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 on the base 10. There is. The surface height measuring 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 depending on the position of the height gauge 60 in the Z-axis direction. Can be done.

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

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

(1) Dressing grindstone holding process As shown in FIG. 1, the dressing grindstone 8 is fixed to the support plate 80 with an adhesive or the like. The support plate 80 is formed to have the same diameter as the suction portion 20 of the holding table 2 or a slightly larger diameter than the suction portion 20. On the other hand, the dressing grindstone 8 is formed to have 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, and 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 340a of the grinding wheel 340 does not come into contact with the reference surface 500 of the reference table 50 and the upper surface 800 of the dressing grindstone 80.

(2) Holding Surface Height Measuring 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 of the holding surface 200 recognized by the height gauge 60 in the Z-axis direction is measured. Here, the axis in the substantially vertical direction seen from the height gauge 60 is defined as the Zg axis, and the 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 21 of the holding surface 200, the measurement can be performed even when the dressing grindstone 80 is held by the holding table 2.

(3) Reference surface height measurement step Next, as shown in FIG. 4, in a 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 is moved. The height position of the reference surface 500 to be recognized in the Z-axis direction, 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 means 71 determines 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 means 70. The value at position Zg2 is read out, and the difference (ΔH) between Zg2 and Zg1 shown in FIG. 5 is calculated. This difference is calculated by the formula (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 Storage Step Next, the reference table 50 is positioned below the grinding wheel 340, and the grinding feeding means 4 grinds the grinding means 3 and lowers without rotating the grinding wheel 34. Then, as shown in FIG. 5, by pressing the reference table 50 downward with the grinding wheel 340, the grinding surface 340a pushes down the reference table 50 and lowers it. Then, when the reference table 50 descends 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 descended by a certain distance is detected. The control means 7 is notified from the unit 52. Upon receiving this notification, the control means 7 sends a signal instructing the motor 42 shown in FIG. 1 constituting the grinding feed means 4 to stop driving. Then, the lowering of the grinding means 3 is stopped. The grinding feed means 4 recognizes the value (Z1) of the scale 46 read by the height measuring unit 45 at the moment when the lowering of the grinding means 3 is stopped, notifies the storage means 70 of the value, and notifies the storage means 70 of the value. Remember. The value of Z1 at this time is the value of the height position of the grinding means 3 recognized by the grinding feed means 4, that is, the value of the height position when the axis in the substantially vertical direction seen from the grinding feed means 4 is the Z axis. Yes, this Z-axis is a coordinate system different from the Z1 axis seen from the height gauge 60.

The amount of descent (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 this ΔZ is stored in the storage means 70 in advance. There is. Further, 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 come into contact with the upper surface 800 of the dressing grindstone 8.

(6) Second Grinding Means Height Storage Step Next, the calculation means 71 determines 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. ), The difference (ΔH) between the height Zg1 of the holding surface 200 measured by the height gauge 60 calculated in the table height difference calculation step shown in FIG. 4 and the height Zg2 of the reference surface measured by the height gauge 60, and the reference. Grinding means recognized by the grinding feed means 4 when the grinding surface 340a comes into contact with the 200 holding surface using the constant distance (ΔZ) when the detection unit detects that the table 50 has descended from the upper limit position by a certain distance. The height position of 3 is obtained by the following (Equation 1) as the height Z2 of the second grinding means on the Z axis.
Z2 = Z1- (ΔH- (ΔZ)) ... (Equation 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. Therefore, the relationship between the Z axis and the Zg axis is conscious. It is not necessary, and the positions of the reference surface 500 and the holding surface 200 on the Z axis can be obtained without directly measuring the positions on the Z axis.

This step corresponds to a so-called setup step of setting the origin of the height position of the grinding means 3 in the Z-axis direction as seen from the grinding feed means 4, and the obtained value of Z2 is the grinding surface of the grinding wheel 340. When dressing the 340a with the dressing grindstone 8, the grinding feed means 4 is used to control the height position of the grinding means 3. Further, when grinding the wafer held on the holding table 2, this Z2 serves as a reference.

(7) Dressing Start Height Calculation Step Next, the calculation means 71 determines the height position Z2 of the grinding means 3 stored in the second grinding means height storage step and the dressing grindstone 8 stored in the storage means 70 in advance. FIG. 6 which the grinding feed means 4 recognizes when the grinding surface 340a comes into contact with the upper surface 800 of the dressing grindstone 8 by adding the thickness T which is the sum of the thickness and the thickness of the support plate 80 and the following (Equation 2). The height position Z3 of the grinding means 3 shown in the above is calculated.
Z3 = Z2 + T ... (Equation 2)

(8) Dressing process The motor 32 shown in FIG. 1 rotates the grinding wheel 34, and the grinding feed means 4 grinds the grinding means 3 downward in the Z-axis direction, and as shown in FIG. 6, the grinding wheel The ground surface 340a of the 340 is brought into contact with the upper surface 800 of the dressing wheel 8 to dress the ground surface 340a. When the grinding feed means 4 grinds the grinding means 3, the grinding means 3 is lowered at a high speed until the height position of the grinding means 3 approaches the Z3, and immediately before the height position of the grinding means 3 reaches Z3. Switch the grinding feed speed to low speed. Then, at the height of the grinding means 3 calculated in the dressing start height calculation step, the grinding surface 340a is brought into contact with the upper surface 800 of the dressing grindstone 8, and the grinding feeding means 4 further grinds the grinding means 3 from there to grind the grinding surface. Dressing of 340a is performed. During dressing, the reference table 50 is lowered so that the reference surface 500 of the reference table 50 is located lower than the upper surface 800 of the dressing grindstone 8.

(9) Third Grinding Means Height Memory Step When dressing is performed as described above, the abrasive grains contained in the grinding wheel 340 fall off. Therefore, as shown in FIG. 7, the ground surface 340b after dressing is formed. 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 a so-called setup after dressing. Therefore, first, as in the first grinding means height storage step, the reference table 50 is positioned below the grinding wheel 340, and the grinding feeding 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. Then, when the reference table 50 descends 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 sent to the detection unit 52. Notifies the control means 7. Upon receiving this notification, the control means 7 sends a signal instructing the motor 42 shown in FIG. 1 constituting the grinding feed means 4 to stop driving. Then, the lowering of the grinding means 3 is stopped. The grinding feed means 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 means 3 is stopped, notifies the storage means 70 of the value, and notifies the storage means 70 of the value. 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 amount of descent (ΔZ) of the reference table 50 until the detection unit 52 detects the reference table 50 is constant, and the value of this ΔZ is stored in the storage means 70 in advance. Further, 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 come into contact with the upper surface 800 of the dressing grindstone 8.

(10) Fourth Grinding Means Height Storage Step Next, the calculation means 71 determines 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. ), The difference (ΔH) between the height Zg1 of the holding surface 200 measured by the height gauge 60 calculated in the table height difference calculation step shown in FIG. 4 and the height Zg2 of the reference surface measured by the height gauge 60, and the reference. Grinding means recognized by the grinding feed means 4 when the grinding surface 340b comes into contact with the holding surface 200 by using the constant distance (ΔZ) when the detection unit detects that the table 50 has descended from the upper limit position by a certain distance. The height position of 3, that is, the height position on the Z axis is determined by the following (Equation 3) as the height Z5 of the fourth grinding means.
Z5 = Z4- (ΔH- (ΔZ)) ... (Equation 3)

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

(11) Grinding Start Height Calculation Step Next, the dressing grindstone 8 and the support plate 80 are separated from the holding table 2, and as shown in FIG. 8, the protective member P of the wafer W to which the protective member P is attached to the surface Wa is attached. The P side is placed on the holding surface 200, and a suction force is applied to the suction portion 20 to hold the suction portion 20. Then, when 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 storage 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 recognized by the grinding feed means 4 when the grinding surface 340b of the grinding wheel 340 comes into contact with the back surface Wb of the wafer W by adding the thickness T1 which is the sum of the thicknesses and the following (Equation 4). The height position Z6 of the means 3 is calculated.
Z6 = Z5 + T1 ... (Equation 4)
The dressing grindstone 8 and the support plate 80 are separated from the holding table 2, and the protective member P side of the wafer W on which the protective member P is attached to the surface Wa is placed on the holding surface 200 to apply a suction force to the suction portion 20. The work of acting and adsorbing and holding may be performed after obtaining the above Z6.

(12) Grinding Step Next, the motor 32 shown in FIG. 1 rotates the grinding wheel 34, and the grinding feeding means 4 grinds the grinding means 3 downward. When the grinding feed means 4 grinds the grinding means 3, the grinding means 3 is lowered at a high speed until the height position of the grinding means 3 approaches the Z6, and immediately before the height position of the grinding means 3 reaches the Z6. Switch 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 contacts the back surface Wb, and another height gauge 60 contacts the upper surface of the frame 21, and the height difference between the two height gauges 60 causes the wafer W to be ground. A value obtained by adding the thickness of the material and the thickness of the protective member P is calculated, and when the calculated value reaches a predetermined value, the grinding feed means 4 raises the grinding means 3 to end the 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 located 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. Then, depending on the degree of wear, it may be necessary to replace the grinding wheel 34. When the grinding wheel 34 is replaced, the position of the grinding surface 340a of the grinding wheel 340 changes, so it is necessary to perform the setup in the same manner as described above. In such a case, the value of the height position of the grinding means 3 recognized by the grinding feed means 4 when the grinding surface 340a comes into contact with the holding surface 200 is set by the same method as the second grinding means height storage step. Ask. When performing this setup, the wafer is held in the holding table 2, but the setup can be performed without removing the wafer by performing the calculation using the reference table 50.

2 Second Embodiment The grinding apparatus 1A shown in FIG. 9 includes three holding tables 2a, 2b, and 2c, and grinding means 3a, 3b with respect to the workpieces held by these holding tables 2a, 2b, and 2c. Is a device that performs grinding. In the following, the parts configured in the same manner as the grinding device 1 of the first embodiment are designated by the same reference numerals as those of the grinding device 1, and the description thereof will be omitted.

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

The turntable 81 is provided with at least one relative height reference portion 5. The configuration of the relative height reference unit 5 is the same as that of the grinding device 1 of the first embodiment.

On the base 10a, the surface height measuring unit 6a for measuring the height position of the holding surfaces 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 depending on the position of the height gauge 60 in the Z-axis direction. it can.

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

A first cassette mounting portion 82a and a second cassette mounting portion 82b are provided on the front side of the base 10a, and the wafer before processing is housed in the first cassette mounting portion 82a. The first cassette 820a is mounted, and the second cassette 820b for accommodating the processed plate-shaped work W is mounted on the second cassette mounting portion 82b.

Behind the first cassette 820a and the second cassette 820a, a robot that carries out the plate-shaped work W before processing from the first cassette 820a and also carries the plate-shaped work 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 an alignment means 840 is arranged in the temporary placement area 84. The alignment means 840 aligns the wafer carried out from the first cassette 820a and placed on the temporary storage area 84 at a predetermined position.

At a position adjacent to the temporary placement region 84, a first transport means 85a that swivels while holding the plate-shaped work W is arranged. The first transport means 85a holds the wafer aligned with the alignment means 840, and transports the wafer to any of the holding tables positioned in the carry-in / out area 101.

Next to the first transport means 85a, a second transport means 85b that swivels while holding the processed plate-shaped work W is provided. A spinner cleaning means 86 for cleaning the machined plate-shaped work transported by the second transporting means 85b is arranged at a position close to the second transporting 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 and 4b is controlled by the control means 7. Further, the control means 7 recognizes the height position of the grinding means 3a and 3b in the Z-axis direction by the output of the encoder 47 provided in the motor 42.

The grinding means 3a and the grinding means 3b are similarly configured except for the grinding wheel. The grinding wheel 342 provided in the grinding means 3a is a grinding wheel for rough grinding, 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 size than the grinding wheel 342 for rough grinding.

In the grinding apparatus 1A configured as described above, the same steps as in the first embodiment are carried out for each of the grinding means 3a and 3b.

(1) Dressing grindstone holding step In this step, the dressing grindstone 8 shown in FIG. 1 is held on any of the holding tables 2a, 2b, and 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 portions 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 holding surface 200, and the height gauge 60 recognizes each holding surface 200. Measure the height. The measurement in this step can also be performed on a holding table holding the dressing grindstone 8.

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

(3) Reference Surface Height Measuring Step Next, as in the first embodiment, in a 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 of the reference surface 500 recognized by the user in the Z-axis direction 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 means 71 has the values of the height positions of the plurality of holding surfaces 200 stored in the storage means 70 and the height of the reference surface 500. The value of the vertical position is read out, and the difference (ΔH1, ΔH2, ΔH3) obtained by subtracting the value of the height position of each holding surface 200 from the value of the height position 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 all have positive values.

(5) First Grinding Means Height Storage 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 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 with the grinding wheel 342. Then, when the reference table 50 descends 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 sent to the detection unit 52. Notifies the control means 7. Upon receiving this notification, the control means 7 sends a signal instructing the motor 42 shown in FIG. 9 constituting the grinding feed means 4a to stop driving. Then, the lowering of the grinding means 3a is stopped. 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 is stopped is stored in the storage means 70. Notify and store in 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 includes 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 difference calculation step and the height of the reference surface measured by the height gauge 60, and the reference table 50 descended 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 comes into contact with the holding surfaces 200 of the holding tables 2a, 2b, and 2c by using the constant distance (ΔZ) when the detection unit detects this. The height position of the grinding means 3a to be used is determined by the following (Equation 5) as the heights Z21, Z22, and Z23 of the second grinding means.
Z2i = Z1- (ΔHi−ΔZ) ・ ・ ・ (Equation 5)
Here, i takes a value from 1 to 3 (the number of holding tables).

This step corresponds to a so-called setup step of setting the origin of the height position of the grinding means 3a in the Z-axis direction as seen from the grinding feed means 4a, 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 the grinding surface 342a is brought into contact with the wafer to grind, the grinding feed means 4a is used to control 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 comes into contact with the holding surfaces 200 of the holding tables 2a, 2b and 2c. Is also obtained by the same method.

(7) Dressing Start Height Calculation Step Next, the calculation means 71 determines the height position Z2 of the grinding means 3a stored in the second grinding means height storage step and the dressing grindstone 8 stored in the storage means 70 in advance. The grinding means recognized by the grinding feed means 4a when the grinding surface 342a comes into contact with the upper surface 800 of the dressing grindstone 8 by adding the thickness T which is the sum of the thickness and the thickness of the support plate 80 and the following (Equation 6). The height position Z3 of 3a is calculated.
Z3 = Z2j + T ... (Equation 6)
Here, j is any value of 1-3. For example, when the dressing grindstone 8 is held on the holding table 2a, the sum of Z21 and T is the height position of the grinding means 3a. , J = 1.
Further, the above calculation is the same for 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 wheel 3b comes into contact with the upper surface 800 of the dressing grindstone 8. It is done by the method.

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

(9) Third Grinding Means Height Memory 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 before dressing. It will be located at a height position different from that of the ground surface 342a. Therefore, in order to finish the wafer to a predetermined thickness by grinding, it is necessary to perform a so-called setup after dressing. The setup method is the same as that of the first embodiment. 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 the reference table 50 is lowered by pressing the reference table 50 downward with the grinding wheel 342. Then, when the reference table 50 descends 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 sent to the detection unit 52. The control means 7 is notified from the above, and after receiving the notification, the control means 7 stops the lowering of the grinding means 3a, and then the height of the grinding means 3a recognized by the grinding feed means 4a based on the information from the encoder 47. The value of the position is stored in the storage means 70. When the grinding wheel 343 constituting the grinding means 3b is dressed, the grinding surface 343a of the grinding wheel 343 is also set up in the same manner.

(10) Fourth Grinding Means Height Storage Step Next, the calculation means 71 determines the value of the height position 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 calculation process and the height of the reference surface measured by the height gauge 60, and the fact that the reference table 50 has descended a certain distance from the upper limit position. When the ground surface of the grinding wheel 342 after dressing comes into contact with the holding surfaces 200 of the holding tables 2a, 2b, and 2c using the constant distance (ΔZ) when the detection unit detects the above, the grinding feeding means 4a 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 height of the fourth grinding means. The value obtained here is a reference height when grinding is performed by bringing the dressed grinding surface of the grinding wheel 342 into contact with the wafers held on the respective holding tables. The obtained value is stored in the storage means 70. When the grinding wheel 343 constituting the grinding means 3b is dressed, the ground surface after dressing of the grinding wheel 343 of the grinding wheel 343 comes into contact with the holding surfaces 200 of the holding tables 2a, 2b, and 2c 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 carries out the wafer before processing from the first cassette 820a, aligns it with the temporary placement area 84, and then uses the first transport means 85a to carry in and out the area 101. The wafer is conveyed to any holding table located in, specifically, a holding table in which the dressing grindstone 8 is not held, and a suction force is applied to the suction unit 20 to hold the wafer. Then, as in the first embodiment, the thickness of the wafer and the thickness of the protective member stored in the storage means 70 in advance are added to the value of the height of the grinding means 3a obtained in the fourth grinding means height storage step. The height position of the grinding means 3a as seen from the grinding feed means 4 when the ground surface of the grinding wheel 342 after dressing comes into contact with the back surface of the wafer is calculated. Further, the same calculation is performed for the grinding means 3b.

(12) Grinding Step Next, the grinding feed means 4a grinds the grinding means 3a to the height position obtained in the grinding start height calculation step. Then, the ground surface of the rotating grinding wheel 342 after dressing comes into contact with the back surface of the wafer, and the back surface is roughly ground. Further, after rotating the turntable 81 by a required angle, the grinding feed means 4b grinds and feeds the grinding means 3b to the height position obtained in the grinding start height calculation process to finish grind the rough-ground back surface of the wafer. To do.

The finish-ground wafer is conveyed to the spinner cleaning means by the second conveying 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. In addition, after cleaning, the wafer rotates to remove the cleaning water.

The washed and dried wafers are housed in the second cassette 820b by the robot 83.

In the example shown in FIG. 9, the relative height reference portion 5 is arranged 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 unit 5 may be arranged at another position, for example, between the holding table 2b and the holding table 2c, or between the holding table 2a and the holding table 2c, as long as it is possible. .. Further, the relative height reference portion 5 may not be arranged on the turntable 81 but may be independently moved below the grinding wheels 342 and 343.

Further, the number of holding tables may be two or four or more, or two or more relative height reference portions may be arranged. For example, when four holding tables are arranged and two relative height reference portions are arranged, the grinding feed means recognizes when the holding surfaces of the two holding tables come into contact with the grinding surface of the grinding wheel. The height position of the grinding means to be used is calculated using one of the relative height reference parts, and the grinding means recognized by the grinding feed means when the holding surfaces of the other two holding tables come into contact with the grinding surface of the grinding wheel. The height position can be calculated by using the other relative height reference unit. 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. Further, 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 have a one-to-one correspondence.

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: Elevating plate 44: Holder 45: Height measuring unit 46: Scale 47: Encoder 5: Relative height reference unit 50: Reference table 500: Reference surface 51: Cylinder 52: Detection unit 6: Surface height measuring unit 60: Height gauge 7 : Control means 70: Storage means 71: Calculation means 8: Dressing wheel 80: Support plate 800: Top surface 81: Turntable 82a: First cassette mounting portion 82b: Second cassette mounting portion 820a: First cassette 820b: Second cassette 83: Robot 84: Temporary storage area 840: Alignment means 85a: First transport means 85b: Second transport means 86: Spinner cleaning means 101: Carry-in / out area 102: Processing area

Claims (2)

A holding table having a holding surface for holding a weight, a grinding means for grinding a wafer held on the holding surface of the holding table by using a grinding wheel in which a grinding wheel is arranged in an annular shape and a rotatable grinding wheel, and the grinding means. Is provided with a 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, which can be moved up and down. A reference table, a detection unit that detects that the reference table has descended by a certain distance, a calculation means having a calculation function, and a storage means for storing the value used by the calculation means or the value calculated by the calculation means. It is a dressing method of a grinding grind using a provided grinding device.
A dressing grindstone holding step of holding a plate-shaped dressing grindstone on the holding surface of the holding table, and
A table height difference calculation step for calculating the 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 recognizes when the detection unit detects that the reference table has been lowered by a certain distance by the grinding feed means grinding the grinding means and the grinding surface of the grinding wheel pushing down the reference table. A first grinding means height storage step of storing the height position (Z1) of the grinding means in the storage means, and
The height position (Z1) of the grinding means stored in the first grinding means height storage step, the height of the holding surface measured by the height gauge calculated in the table height difference calculation step, and the height gauge are measured. Using the difference (ΔH) from the height of the reference surface and the constant distance (ΔZ) when the detection unit detects that the reference table has descended from the upper limit position by a certain distance, the ground surface is formed. The height position Z2 of the grinding means recognized by the grinding feed means when it comes into contact with the holding surface is Z2 = Z1- (ΔH−ΔZ).
The second grinding means height storage process, which is calculated and stored by the formula of
The thickness of the dressing grindstone stored in advance is added to the height position of the grinding means stored in the second grinding means height storage step, and the grinding feed when the grinding surface comes into contact with the upper surface of the dressing grindstone. A dressing start height calculation step for calculating the height position of the grinding means recognized by the means, and
A dressing step of grinding and feeding from the height of the grinding means recognized by the grinding feed means calculated in the dressing start height calculation step and dressing the ground surface with the dressing grindstone held by the holding table .
With
A method for dressing a grinding wheel, in which the grinding surface of the grinding wheel is dressed 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 the rotation axis of the turntable.
In the table height difference calculation step, the 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 storage step, Z2i = Z1-Z2i = Z1-is 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. (ΔHi−ΔZ)
The dressing method for a grinding wheel according to claim 1, which is calculated by the formula of.

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