TW201813769A - Dressing method for grinding stone capable of dressing a grinding stone efficiently without manual operation - Google Patents

Abstract

The object of the present invention is to dress a grinding stone efficiently without manual operation. The solution is to pre-calculate a height difference between a reference surface of a reference table and a holding surface of a holding table by a height gauge. The height position of the grinding surface where the grinding surface of the grinding stone is contacted with the holding surface is grasped as a relative position with the reference surface, wherein the height position of the grinding surface is changed due to abrasion or replacement. Then the thickness of the dressing-grinding stone is added to the height position of the grinding surface to obtain a height position at which the grinding surface starts to contact with the dressing-grinding stone and dressing is performed by grind-feeding from this height position.

Description

Dressing method of grinding stone

FIELD OF THE INVENTION The present invention relates to a method for dressing a grinding stone.

BACKGROUND OF THE INVENTION A grinding device for grinding a plate-like workpiece such as a semiconductor wafer includes a holding table that holds the plate-like workpiece, and a grinding mechanism having a grinding wheel in which grinding grinding stones are annularly arranged. The rotating grinding stone is brought into contact with and pressed against the plate-like workpiece held on the holding table to grind the plate-like workpiece.

When grinding grinding stones are used to grind difficult-to-cut materials such as sapphire or SiC, it is easy to cause passivation on the grinding surface of the grinding stones, so it is necessary to frequently dress the grinding stones. The dressing of the grinding stone is performed by, for example, holding the dressing stone on a holding table and bringing the rotating grinding stone into contact with the dressing stone (see, for example, Patent Document 1).

In addition, when grinding difficult-to-cut materials, the grinding stones are easily worn. In addition, when the degree of wear becomes high, the grinding wheel must be replaced. Therefore, in the grinding of difficult-to-cut materials, the frequency of replacement of the grinding wheel becomes high.

After dressing, after the grinding stone is worn out, and after the grinding wheel has been replaced, the height position of the grinding surface of the grinding stone is changed. Therefore, in order to process the plate-like workpiece to a predetermined thickness, it is necessary to perform Origin search (set up) of the grinding surface. The setting is performed by gradually lowering the grinding mechanism gradually, and identifying the position in the Z-axis direction of the grinding mechanism when the grinding surface of the grinding stone is in contact with the holding surface of the holding table (see, for example, Patent Document 2). The wear amount of the grinding stone is based on the height of the grinding mechanism when the grinding surface of the grinding stone is in contact with the holding surface of the holding table at the time of setting, and is based on the grinding mechanism at the end of grinding. And the thickness of the workpiece are calculated, so even in order to calculate the amount of wear of the grinding stone, the setting becomes necessary. Prior Art Literature Patent Literature

Patent Document 1: Japanese Patent Laid-Open Publication No. 2015-178149 Patent Document 2: Japanese Patent Laid-Open Publication No. 2014-024145

SUMMARY OF THE INVENTION Problems to be Solved by the Invention However, in the setting, as described above, since the grinding surface of the grinding stone must be brought into contact with the holding surface of the holding table, the dressing stone is not held on the holding table. , You cannot set it. Although the setting can be performed by removing the dressing grindstone from the holding table, the operation of removing the dressing grindstone must be performed by an operator, which has become a cause of reduced productivity.

The present invention has been made in view of such a problem, and an object thereof is to make it possible to efficiently perform setting and dressing of a grinding stone without using a human hand. Means to solve the problem

The present invention is a dressing method for a grinding stone using a grinding device. The grinding device includes a holding table having a holding surface for holding a wafer, and a grinding mechanism provided with the grinding stones in a ring shape. And a rotatable grinding wheel for grinding the wafer held on the holding surface of the holding table; a grinding feed mechanism for grinding and feeding the grinding mechanism in a vertical direction with respect to the holding surface; height Gauge, measuring the height of the holding surface of the holding table; a reference table, which is provided on the holding table and has a reference surface on the upper surface and can be moved up and down; a detection section that detects that the reference table has descended a certain distance; a calculation mechanism, It has a computing function; and a storage mechanism that stores the value used by the calculation mechanism or the value calculated by the calculation mechanism. The dressing method of the grinding stone has: a dressing stone holding step to make the plate-shaped dressing and grinding The stone is held on the holding surface of the holding platform; the platform height difference calculation step calculates 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; Grinder The height storage step is stored in the detecting unit and detects that the grinding surface of the grinding stone is pressed down by the grinding feed mechanism to feed the grinding mechanism to the grinding table to lower the reference table. The height position (Z1) of the grinding mechanism identified by the grinding feed mechanism at a certain distance; The second grinding mechanism height storage step uses the stored position in the first grinding mechanism height storage step. The height position (Z1) of the grinding mechanism, the difference (ΔH) between the height of the holding surface measured by the height gauge and the height of the reference surface measured by the height gauge calculated in the platform height difference calculation step. And the certain distance (ΔZ) when the detection unit detects that the reference table has descended a certain distance from the upper limit position to identify the grinding feed mechanism when the grinding surface contacts the holding surface. The height position Z2 of the grinding mechanism is calculated and stored by the mathematical formula of Z2 = Z1- (ΔH-ΔZ); the dressing start height calculation step will store the value stored in the second grinding mechanism height storage step. The height position of the grinding mechanism plus the Adjust the thickness of the grinding stone to calculate the height position of the grinding mechanism identified by the grinding feed mechanism when the grinding surface contacts the upper surface of the grinding stone; and the dressing step is calculated from the height at the beginning of the dressing The height of the grinding mechanism identified by the grinding feed mechanism calculated in the step starts the grinding feed, and the grinding surface is trimmed by the trimming grinding stone held by the holding mechanism, so that The dressing stone held by the holding table dresses the grinding surface of the grinding stone.

In the above-mentioned dressing method of a grinding stone, the grinding device is provided with the i holding table, and the i holding table is supported by a rotatable turntable in a rotatable manner, and a rotating shaft of the turntable can be supported. When revolving as the center, in the aforementioned platform height difference calculation 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, and In the above-mentioned second grinding mechanism height storage step, when the grinding surface is in contact with each of the i holding tables, the height position (Z2i) of each of the grinding mechanisms identified by the grinding feed mechanism, It is calculated by the mathematical formula of Z2i = Z1- (ΔHi-ΔZ). Here, i is a value from 1 to i. Invention effect

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 in advance by using a height gauge, and the grinding surface of the grinding stone that changes in height due to wear or replacement is in contact with the holding surface. The height position of the grinding surface is grasped as the relative position based on the reference surface. Then, the thickness of the dressing grindstone is added to the height position of the grinding surface, and the height position at which the grinding surface comes into contact with the dressing grindstone is obtained, and grinding is performed from the height position to perform dressing. Since the height position of the grinding surface when the grinding stone is brought into contact with the holding surface is identified by the relative relationship with the reference surface of the reference table, even if the dressing stone is held on the holding table, When the dressing grindstone is detached from the holding table, the height position of the grinding surface when the grinding grindstone is in contact with the holding surface is obtained. Therefore, the setting and dressing of the grinding stone can be performed without using a human hand. In addition, when there are a plurality of holding tables, even if the height positions of the holding surfaces of the holding tables are different, the relative relationship between the height of the reference table and the reference table can be used to determine the contact between the grinding stone and each holding surface. height.

Form 1 for Implementing the Invention 1 First Embodiment The grinding apparatus 1 shown in FIG. 1 is a device for grinding a wafer held on a holding table 2 by a grinding mechanism 3. The holding table 2 is driven by a feed mechanism (not shown) to move on the base table 10 in the front-rear direction (Y-axis direction) and is rotatable. The holding table 2 includes an adsorption section 20 formed of a porous member, and a frame 21 that supports the adsorption section 20. The suction unit 20 is a suction source (not shown) that communicates. The upper surface of the suction part 20 and the upper surface of the frame body 21 are formed flush, and this surface constitutes the holding surface 200. The periphery of the holding table 20 is covered by a cover 22.

The grinding mechanism 3 includes a rotation shaft 30 whose axis direction is substantially vertical (Z-axis direction), a housing 31 that rotatably supports the rotation shaft 30, a motor 32 that rotationally drives the rotation shaft 30, and a lower end connected to the rotation shaft 30. An annular mounting base 33 and a grinding wheel 34 detachably connected to the lower surface of the mounting base 33. The grinding wheel 34 includes a wheel base 341 and a plurality of grinding stones 340 having a substantially rectangular parallelepiped shape and arranged annularly on the bottom surface of the wheel base 341. The grinding stone 340 is formed by, for example, fixing diamond abrasive grains such as a resin adhesive or a metal adhesive, and the lower surface thereof is formed as a grinding surface 340 a for grinding a wafer. The grinding stone 340 may be a grinding stone formed integrally in a ring shape.

The grinding mechanism 3 is driven by the grinding feed mechanism 4 and grinds the feed in the vertical direction with respect to the holding surface 200. The grinding feed mechanism 4 includes 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 an upper end of the ball screw 40 is connected to the ball screw 40. The rotating motor 42, the inner nut is screwed to the ball screw 40 and the lifting plate 43 is slidably connected to the guide rail 41 on the side, and the bracket 44 is connected to the lifting plate 43 and holds the grinding mechanism 4. When the ball screw 40 rotates, the lifting plate 43 is guided by the guide rail 41 and reciprocates in the Z-axis direction along with this, and the grinding mechanism 3 held on the holder 44 is ground and fed in the Z-axis direction. . The motor 42 is controlled by the control mechanism 7.

The lifting plate 43 is provided with a height measuring unit 45 that measures the height position in the Z-axis direction of the grinding mechanism 3. The guide rail 41 is provided with a scale 46 that can be read by the height measuring unit 45, and the control mechanism 7 uses the reading value of the scale 46 read by the height measuring unit 45 as one of the grinding mechanisms 3. It can identify the height position in the Z-axis direction. Alternatively, the motor 42 may be provided with an encoder 47, and the output of the encoder 47 may cause the control mechanism 7 to recognize the height position in the Z-axis direction of the grinding mechanism 3.

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 in the Z-axis direction of the grinding mechanism 3. The relative height reference section 5 includes a cylinder 51, a reference table 50 whose lower portion is housed in the cylinder 51 and the upper portion projects upward from the cylinder 51, and a detection section which is disposed inside the cylinder 51 and detects that the reference table 50 has descended a certain distance. 52. The reference table 50 includes a reference surface 500 formed flat on the upper surface. The reference stage 50 is provided with potential energy in the + Z direction by the cylinder 51, and can be positioned at the upper limit position in a state where no pressing force is applied from above.

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

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

Next, in the above-mentioned grinding apparatus 1, a method of holding the dressing grindstone 8 shown in FIG. 1 on the holding table 2 and using the dressing grindstone 8 to dress the grindstone 340 will be described.

(1) Step of holding dressing grindstone As shown in FIG. 1, the dressing grindstone 8 is fixed to the support plate 80 by an adhesive or the like. The support plate 80 may be formed to have the same diameter as or slightly larger than the suction portion 20 of the holding table 2. 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 attracted and held on the holding surface 200 of the holding table 2, and the upper surface 800 of the dressing grindstone 80 is exposed above. status. At this time, the reference stage 50 is located at the upper limit position. In addition, the grinding mechanism 3 is retracted to a position where the grinding surface 340 a of the grinding stone 340 does not contact the reference surface 500 of the reference table 50 and the upper surface 800 of the dressing stone 80.

(2) Measuring procedure for holding surface height 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 identified by the height gauge 60 is measured. Here, the substantially vertical axis seen from the height gauge 60 is the Zg axis, and the height position of the holding surface 200 on the Zg axis is Zg1. The value of Zg1 is stored in the storage mechanism 70 shown in FIG. 2. In this measurement, the tip of the height gauge 60 only needs to be brought into contact with the upper surface of the frame 21 in the holding surface 200, so 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, 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 reference for the identification of the height gauge 60 is measured. The height position of the plane 500 in the Z-axis direction, that is, the height position Zg2 of the reference plane 500 on the Zg axis. The value of Zg2 is stored in the storage mechanism 70 shown in FIG. 1. In this step, the measurement can be performed while the dressing grindstone 8 is held on the holding table 2.

(4) Platform height difference calculation step Next, the calculation mechanism 71 reads the value of the height position Zg1 of the holding surface 200 on the Zg axis stored in the storage mechanism 70 and the height position Zg2 of the reference surface 500 on the Zg axis. The difference (ΔH) between Zg2 and Zg1 shown in FIG. 5 is calculated. This difference is calculated by the formula of (Zg2-Zg1). Here, since the reference surface 500 is located higher than the holding surface 200, the calculation result of ΔH = Zg2-Zg1 becomes a positive value.

(5) First grinding mechanism height storage step Next, the reference table 50 is positioned below the grinding stone 340, and the grinding feed mechanism 4 grinds the grinding mechanism 3 without rotating the grinding wheel 34. The cutting feed is gradually lowered, and as shown in FIG. 5, the reference surface 50 is pressed downward by the grinding stone 340, so that the reference surface 50 is pressed down by the grinding surface 340 a and gradually lowered. In addition, when the reference stage 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 stage 50, a signal indicating that the reference stage 50 has been lowered by a certain distance from the detection unit 52 Notification to control agency 7. Upon receiving this notification, the control mechanism 7 sends a signal to the motor 42 shown in FIG. 1 constituting the grinding feed mechanism 4 to instruct the stop of the driving. In this way, the lowering of the grinding mechanism 3 is stopped. In the grinding feed mechanism 4, the value (Z1) of the scale 46 read by the height measuring unit 45 is recognized at the moment when the descent of the grinding mechanism 3 is stopped, and the value is notified to the storage mechanism 70, and Make it stored in the storage mechanism 70. The value of Z1 at this time is the height position of the grinding mechanism 3 identified by the grinding feed mechanism 4, that is, the value of the height position when the substantially vertical axis seen from the grinding feed mechanism 4 is set to the Z axis. This Z axis is a different coordinate system from the Z1 axis seen from the height gauge 60.

In addition, the amount of fall (ΔZ) of the reference table 50 until the detection section 52 detects the reference table 50 has been adjusted and formed in advance, and the value of this ΔZ has been stored in the storage mechanism 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 stone 8, there is no grinding during the period until the detection unit 52 detects the reference table 50. The grinding surface 340 of the grindstone 34 is in contact with the upper surface 800 of the dresser 8.

(6) Second grinding mechanism height storage step Next, the calculation mechanism 71 uses the height position (Z1) of the grinding mechanism 3 stored in the storage mechanism 70 in the first grinding mechanism height storage step as shown in FIG. 5. The difference (ΔH) between the height Zg1 of the holding surface 200 measured by the height gauge 60 calculated in the platform height difference calculation step shown in FIG. 4 and the height Zg2 of the reference surface determined by the height gauge 60 side, and the detection section detection When the reference table 50 has descended from the upper limit position by a certain distance (ΔZ), the height position of the grinding mechanism 3 identified by the grinding feed mechanism 4 when the grinding surface 340a contacts the 200 holding surface is taken as The height Z2 of the second grinding mechanism on the Z axis is obtained by the following (Mathematical Formula 1). Z2 = Z1- (ΔH- (ΔZ)) ... (Mathematical formula 1) In the above (Mathematical formula 1), since the value of the height position on the Zg axis is not used, only the position between the two positions on the Zg axis is used. Distance, so there is no need to pay attention to the relationship between the Z axis and the Zg axis, and the positions 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 step is a step corresponding to a so-called setting step of searching for the origin of the height position in the Z-axis direction of the grinding mechanism 3 as seen from the grinding feed mechanism 4. The value of Z2 obtained is a value obtained by grinding The grinding surface 340 a of the grinding stone 340 is used when the grinding feed 8 controls the height position of the grinding mechanism 3 when the grinding surface 8 is being adjusted by the dressing grinding stone 8. When grinding a wafer already held on the holding table 2, this Z2 is also used as a reference.

(7) Dressing start height calculation step Next, the calculation mechanism 71 will set the height position Z2 of the grinding mechanism 3 stored in the second grinding mechanism height storage step and the height of the dressing stone 8 stored in the storage mechanism 70 in advance. The thickness T after the thickness is added to the total thickness of the support plate 80 is calculated by the following (Mathematical Formula 2), which is calculated by the grinding feed mechanism 4 when the grinding surface 340 a contacts the upper surface 800 of the dressing stone 8. The height position Z3 of the grinding mechanism 3 shown in FIG. 6. Z3 = Z2 + T ... (Mathematical formula 2)

(8) Dressing step The motor 32 shown in FIG. 1 causes the grinding wheel 34 to rotate, and the grinding feed mechanism 4 moves the grinding mechanism 3 toward the downward direction of the Z axis to perform the grinding feed, as shown in FIG. 6. The grinding surface 340 a of the grinding stone 340 is brought into contact with the upper surface 800 of the dressing stone 8 to dress the grinding surface 340 a. When the grinding feed mechanism 4 feeds the grinding mechanism 3, the grinding mechanism 3 is gradually lowered at a high speed before the height of the grinding mechanism 3 approaches the above Z3, and immediately before the height of the grinding mechanism 3 reaches Z3 The grinding feed speed is switched to a low speed. Then, in the height of the grinding mechanism 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 feed mechanism 4 is further configured to grind the surface The grinding mechanism 3 grinds the feed, and trims the grinding surface 340a. In addition, during the trimming, the reference surface 50 is formed in advance so that the reference surface 500 of the reference table 50 is positioned lower than the upper surface 800 of the dressing stone 8.

(9) The third grinding mechanism height storage step When the trimming is performed as described above, the abrasive grains included in the grinding stone 340 fall off, and as shown in FIG. 7, the trimmed grinding surface 340b becomes It is higher than the grinding surface 340a before trimming. Therefore, in order to process the wafer to a predetermined thickness by grinding, it is necessary to perform a so-called setting after the trimming. Therefore, first, similar to the first grinding mechanism height storage step, the grinding feed mechanism 4 enables the reference table 50 to be positioned below the grinding stone 340 without rotating the grinding wheel 34. The grinding mechanism 3 is gradually lowered. As shown in FIG. 7, the reference table 50 is gradually lowered by pressing the reference table 50 downward with the grinding stone 340. In addition, when the reference stage 50 is lowered by a certain distance (ΔZ) to cause the detection unit 52 constituting the relative height reference unit 5 to detect the lower end of the reference stage 50, the detection unit 52 will notify the signal indicating that the reference stage 50 is detected to Control mechanism 7. Upon receiving this notification, the control mechanism 7 sends a signal to the motor 42 shown in FIG. 1 constituting the grinding feed mechanism 4 to instruct the stop of the driving. In this way, the lowering of the grinding mechanism 3 is stopped. In the grinding feed mechanism 4, the value (Z4) of the scale 46 read by the height measuring unit 45 is recognized at the moment when the descent of the grinding mechanism 3 is stopped, and the value is notified to the storage mechanism 70, and Make it stored in the storage mechanism 70. The value of Z4 at this time is the height position of the grinding mechanism 3 identified by the grinding feed mechanism 4. The detection unit 52 detects that the amount of fall (ΔZ) of the reference stage 50 before the reference stage 50 is constant, and the value of this ΔZ is stored in the storage mechanism 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 stone 8, there is no grinding stone during the period before the detection unit 52 detects the reference table 50. The grinding surface 340 of 34 is in contact with the upper surface 800 of the grinding stone 8.

(10) 4th grinding mechanism height storage step Next, the calculation mechanism 71 uses the height position (Z4) of the grinding mechanism 3 stored in the storage mechanism 70 in the third grinding mechanism height storage step as shown in FIG. The difference (ΔH) between the height Zg1 of the holding surface 200 measured by the height gauge 60 calculated in the platform height difference calculation step shown in FIG. 4 and the height Zg2 of the reference surface measured by the height gauge 60, and the detection by the detection unit When the reference table 50 has descended from the upper limit position by a certain distance (ΔZ), the height position of the grinding mechanism 3 identified by the grinding feed mechanism 4 when the grinding surface 340b contacts the holding surface 200, That is, the height position on the Z axis is determined as the fourth grinding mechanism height Z5 by the following (Equation 3). Z5 = Z4- (ΔH- (ΔZ)) ... (Mathematical formula 3)

This step is a so-called setting step, and the value of Z5 obtained is a reference height when the grinding surface 340a of the grinding stone 340 is brought into contact with the wafer held on the holding table 2 for grinding. .

(11) Step of calculating grinding start height Next, the dressing grindstone 8 and the support plate 80 are detached from the holding table 2, and as shown in FIG. 8, the protective member P side of the wafer W to which the protective member P is attached is attached to the front surface Wa. It is placed on the holding surface 200, and suction force is applied to the suction unit 20 to perform suction holding. When the back surface Wb of the wafer W is ground, the height position Z5 of the grinding mechanism 3 stored in the fourth grinding mechanism height storage step and the thickness of the wafer W stored in the storage mechanism 70 in advance and The thickness T1 after the total thickness of the protective member P is added, and the grinding feed mechanism 4 when the grinding surface 340b of the grinding stone 340 contacts the back surface Wb of the wafer W is calculated by the following (Mathematical Formula 4). The height position Z6 of the grinding mechanism 3 shown in FIG. 8 is identified. Z6 = Z5 + T1 (Equation 4) Further, 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 with the protective member P attached to the front Wa is placed on The operation of performing suction adsorption on the holding surface 200 by applying a suction force to the suction portion 20 may be performed after the above-mentioned Z6 is obtained.

(12) Grinding step Next, the motor 32 shown in FIG. 1 rotates the grinding wheel 34, and the grinding feed mechanism 4 feeds the grinding mechanism 3 downward. When the grinding feed mechanism 4 feeds the grinding mechanism 3, the grinding mechanism 3 gradually lowers at a high speed before the height of the grinding mechanism 3 approaches the above-mentioned Z6, and immediately before the height of the grinding mechanism 3 reaches Z6 The grinding feed speed is switched to a low speed. Then, the grinding surface 340b of the rotating grinding stone 340 contacts 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 brought into contact with the back surface Wb, and the other height gauge 60 is brought into contact with the upper surface of the frame body 21. The wafer can be calculated from the height difference between the two height gauges 60. The value obtained by adding the thickness during the grinding of W and the thickness of the protective member P. When the calculated value reaches a predetermined value, the grinding mechanism 3 is raised by the grinding feed mechanism 4 to end the grinding. . In addition, during the grinding of the wafer W, the reference surface 500 is formed in advance so that the reference surface 500 is lower than the back surface Wb of the wafer W after the grinding by lowering the reference table 50.

When the wafer is ground in this manner and the grinding stone 340 is used for grinding, the grinding stone 340 is worn. In addition, depending on the degree of wear, the necessity of replacing the grinding wheel 34 occurs. When the grinding wheel 34 is replaced, since the position of the grinding surface 340a of the grinding stone 340 is changed, it must be set in the same manner as described above. In this case, the height position of the grinding mechanism 3 identified by the grinding feed mechanism 4 when the grinding surface 340a contacts the holding surface 200 is determined by the same method as the second grinding mechanism height storage step. Value. When such a setting is performed, although the wafer is held on the holding table 2, the calculation can be performed without removing the wafer by performing calculations using the reference table 50.

2 Second Embodiment The grinding device 1A shown in FIG. 9 includes three holding tables 2a, 2b, and 2c, and executes grinding mechanisms 3a and 3b on the workpieces held on the holding tables 2a, 2b, and 2c. Grinding device. In the following, the same components as those of the grinding apparatus 1 will be assigned to the parts configured in the same manner as the grinding apparatus 1 of the first embodiment, and the description will be omitted.

These holding tables 2a, 2b, and 2c are formed so as to be rotatably supported by a rotatable turntable 81, and are formed to revolve around the rotation axis of the turntable 81 as a center. Each of the holding tables 2a, 2b, and 2c is configured similarly to the holding table 2 constituting the grinding apparatus 1 of the first embodiment, and is configured to support the suction unit 20 by a frame body 21.

The turntable 81 is provided with at least one relative height reference portion 5. 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 table 10a includes a surface height measuring section 6a for measuring the height position in the Z-axis direction of the holding surface 200 of the holding tables 2a, 2b, and 2c, and the height position in the Z-axis direction of the reference surface 500 of the reference table 50. 6b. The surface height measuring sections 6 a and 6 b are configured similarly to the grinding device 1 and can measure the height position in the Z axis direction of the holding surface 200 or the reference surface 500 from the position in the Z axis direction of the height gauge 60.

The front part in the Y-axis direction on the base 10a is formed as a region for carrying wafers in and out of the holding table 30, that is, the carry-in / out area 101, and the Y-axis rear on the base 10a is formed by a grinding mechanism 3a, 3b is a processing area 102, which is a region where the wafers held on the holding tables 2a, 2b, and 2c are ground.

The first cassette mounting portion 82a and the second cassette mounting portion 82b are provided on the front side of the base 10a, and the first cassette mounting portion 82a can mount a first cassette storing wafer before processing. In the cassette 820a, a second cassette 820b for storing the processed plate-like workpiece W can be placed on the second cassette mounting portion 82b.

Behind the first cassette 820a and the second cassette 820a, a robot 83 is arranged to carry out the plate-like workpiece W before processing from the first cassette 820a and carry the plate-like workpiece W after processing into the second cassette 820b. . A temporary area 84 is provided at a position adjacent to the robot 83, and an alignment mechanism 840 is disposed on the temporary area 84. The alignment mechanism 840 aligns the wafer carried out from the first cassette 820a and placed in the temporary area 84 to a predetermined position.

At a position adjacent to the temporary area 84, a first conveyance mechanism 85a that is wound while holding the plate-like workpiece W is arranged. The first transfer mechanism 85 a holds the wafer that has been aligned in the alignment mechanism 840, and transfers the wafer to any of the holding tables positioned in the loading / unloading area 101.

A second conveying mechanism 85b is provided in the vicinity of the first conveying mechanism 85a while being wound while holding the processed plate-like workpiece W. A rotator cleaning mechanism 86 is disposed near the second conveyance mechanism 85b. The rotator cleaning mechanism 86 cleans the processed plate-shaped workpieces conveyed by the second conveyance mechanism 85b. The wafer that has been cleaned by the spinner cleaning mechanism 86 is carried into the second cassette 820b by the robot 83.

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

The grinding mechanism 3a and the grinding mechanism 3b are configured similarly except that the grinding stone is ground. The grinding stone 342 included in the grinding mechanism 3a is a grinding stone for rough grinding, and has abrasive grains having a large particle diameter. On the other hand, the grinding stone 343 included in the grinding mechanism 3b is a grinding stone for fine grinding, and has abrasive grains having a smaller particle size than the grinding stone 342 for rough grinding.

In the grinding device 1A configured as described above, the same steps as those of the first embodiment are performed on the respective grinding mechanisms 3a and 3b.

(1) Dressing stone holding step In this step, the dressing stone 8 shown in FIG. 1 is held on any of the holding tables 2a, 2b, and 2c.

(2) Step of measuring the height of the holding surface In this step, as in the first embodiment, any one of the height gauges 60 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 measurement height gauge 60 is identified The height of the reference plane 500. For all three holding tables 2a, 2b, and 2c, any one of the height gauges 60 of the surface height measuring sections 6a, 6b is brought into contact with the respective holding surface 200, and the heights of the respective holding surfaces 200 identified by the height gauge 60 are measured. . The measurement in this step can be performed even on a holding table on which the dressing grindstone 8 is held.

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

(3) Reference Level Height Measurement Step Next, as in the first embodiment, the tip of the height gauge 60 is brought into contact with the reference surface 500 of the reference stage 50 in a state where the reference stage 50 is located at the upper limit position, and the height of the gauge 60 is identified. The height position in the Z-axis direction of the reference surface 500 is stored in the storage mechanism 70. In this step, the measurement can be performed while the dressing grindstone 80 is held on the holding table 2.

(4) Platform height difference calculation step Next, as in the first embodiment, the calculation mechanism 71 reads the values of the height positions of the plurality of holding surfaces 200 stored in the storage mechanism 70 and the values of the height positions of the reference surface 500 to calculate 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. Here, since the reference surface 500 is located higher than the holding surface 200, all of ΔH1, ΔH2, and ΔH3 have positive values.

(5) Step of storing first grinding mechanism height Next, as shown in FIG. 10, the reference table 50 is positioned below the grinding stone 342, and the grinding feed mechanism is rotated without rotating the grinding wheel 34. 4a, the grinding mechanism 3a is gradually lowered, and the reference table 50 is pressed downward by the grinding stone 342, thereby gradually lowering the reference table 50. In addition, when the reference stage 50 is lowered by a certain distance (ΔZ) to cause the detection unit 52 constituting the relative height reference unit 5 to detect the lower end of the reference stage 50, the detection unit 52 will notify the signal indicating that the reference stage 50 is detected to Control mechanism 7. Upon receiving this notification, the control mechanism 7 sends a signal instructing the stop of the drive to the motor 42 shown in FIG. 9 constituting the grinding feed mechanism 4a. In this way, the lowering of the grinding mechanism 3a is stopped. In the grinding feed mechanism 4a, the height position Z1 of the grinding mechanism 3a identified by the grinding feed mechanism 4a will be based on the information of the encoder 47 shown in FIG. 9 at the moment when the falling of the grinding mechanism 3a is stopped. The value is notified to the storage mechanism 70 and stored in the storage mechanism 70. The value of Z1 at this time is a value of the height position of the grinding mechanism 3a identified by the grinding feed mechanism 4a.

(6) Second grinding mechanism height storage step Next, the calculation mechanism 71 uses the height position (Z1) of the grinding mechanism 3a stored in the storage mechanism 70 in the first grinding mechanism height storage step, and calculates the height difference at the platform. The difference (ΔH1, ΔH2, ΔH3) between the height of the holding surface 200 measured by the height gauge 60 and the height of the reference surface measured by the height gauge 60 calculated in the step, and the detection unit detects that the reference stage 50 has moved from the upper limit position When the fixed distance (ΔZ) is lowered for a certain distance, when the grinding surface 342a of the grinding stone 342 contacts the holding surfaces 200 of the holding tables 2a, 2b, and 2c, the grinding is recognized by the grinding feed mechanism 4a. The height position of the grinding mechanism 3a is determined as the second grinding mechanism heights Z21, Z22, and Z23 by the following (Equation 5). Z2i = Z1- (ΔHi-ΔZ) (Expression 5) where i is a value from 1 to 3 (the number of holding tables).

This step is equivalent to the so-called setting step of searching for the origin of the height position in the Z-axis direction of the grinding mechanism 3a seen from the grinding feed mechanism 4a. The values of Z21, Z22, and Z23 obtained are When the grinding surface 342a of the grinding stone 342 is trimmed by the dressing stone 8 or the grinding surface 342a is brought into contact with the wafer, the grinding feed mechanism 4a controls the height position of the grinding mechanism 3a. When using. In this step, the grinding mechanism identified by the grinding feed mechanism 4b when the grinding surface 343a of the grinding grindstone 343 constituting the grinding mechanism 3b contacts each of the holding surfaces 200 of the holding tables 2a, 2b, and 2c. The height position of 3b can also be obtained by the same method.

(7) Dressing start height calculation step Next, the calculation mechanism 71 will set the height position Z2 of the grinding mechanism 3a stored in the second grinding mechanism height storage step, and the height of the grinding stone 8 stored in the storage mechanism 70 in advance. The thickness T after adding the thickness to the total thickness of the support plate 80 is calculated, and the grinding feed mechanism 4a when the grinding surface 342a contacts the upper surface 800 of the dressing grindstone 8 is calculated by the following (Mathematical Formula 6). The height position Z3 of the identified grinding mechanism 3a. Z3 = Z2j + T (mathematical formula 6) where j is any value from 1-3. For example, when the dressing grindstone 8 is held on the holding table 2a, the sum of Z21 and T becomes grinding. The height position of the mechanism 3a will be j = 1. In addition, the above calculation is also the height position of the grinding mechanism 3b identified by the grinding feed mechanism 4b when the grinding surface 343a of the grinding stone 343 constituting the grinding mechanism 3b contacts the upper surface 800 of the dressing stone 8 This is done by peers.

(8) Dressing step The motor 32 shown in FIG. 9 rotates the grinding wheel 34, and the grinding feed mechanism 4a turns the grinding mechanism 3a downward toward the Z-axis direction to feed the grinding, so that the grinding stone 342 is ground. The cut surface 342a is in contact with the upper surface 800 of the dressing stone 8 and the dressing surface 342a is dressed. The same applies when the grinding surface 343a of the grinding stone 343 constituting the grinding mechanism 3b is trimmed.

(9) The third grinding mechanism height storage step When the dressing is performed as described above, the abrasive grains included in the grinding stone 342 fall off, forming a grinding surface of the grinding stone 342 after the dressing. 342 is formed so that it may be located in a height position different from the grinding surface 342a before dressing. Therefore, in order to process the wafer to a predetermined thickness by grinding, it is necessary to perform a so-called setting after the trimming. The setting method is the same as that of the first embodiment. In this step, it is the same as the height storage step of the first grinding mechanism, and the reference table 50 is positioned below the grinding stone 342 without grinding. When the wheel 34 rotates, the grinding feed mechanism 4a gradually lowers the grinding mechanism 3a, and the reference stage 50 is gradually lowered by pressing the reference stage 50 downward with the grinding stone 342, thereby gradually lowering the reference stage 50. In addition, when the reference stage 50 is lowered by a certain distance (ΔZ) to cause the detection unit 52 constituting the relative height reference unit 5 to detect the lower end of the reference stage 50, the detection unit 52 will notify the signal indicating that the reference stage 50 is detected to The control mechanism 7 stops the descent of the grinding mechanism 3a after receiving the notification, and stores the value of the height position of the grinding mechanism 3a identified by the grinding feed mechanism 4a based on the information from the encoder 47.于 Storage mechanism 70. When the grinding stone 343 constituting the grinding mechanism 3b is trimmed, the grinding surface 343a of the grinding stone 343 is also set in the same manner.

(10) Fourth grinding mechanism height storage step Next, the calculation mechanism 71 uses the value of the height position of the grinding mechanism 3 stored in the storage mechanism 70 in the third grinding mechanism height storage step, and calculates the height difference in the platform. The difference between the height of the holding surface 200 measured by the height gauge 60 and the height of the reference plane measured by the height gauge 60 (ΔH1, ΔH2, ΔH3), and the detection unit detected that the reference stage 50 has fallen from the upper limit position. The fixed distance (ΔZ) in the case of a certain distance is used to identify the grinding feed mechanism 4a when the adjusted grinding surface of the grinding stone 342 contacts the holding surfaces 200 of the holding tables 2a, 2b, and 2c. The height position of the grinding mechanism 3a, that is, the height position on the Z axis, is obtained as the height of the fourth grinding mechanism. The value obtained here will be the reference height when the grinding surface of the grinding stone 342 is brought into contact with the wafers already held on the respective holding tables for grinding. The calculated value is stored in the storage mechanism 70. In the case where the grinding grindstone 343 constituting the grinding mechanism 3b has been trimmed, the grinding surface 343a of the grinding grindstone 343 is brought into contact with the holding table 2a by the same method. The height position of the grinding mechanism 3b identified by the grinding feed mechanism 4b at the time of each of the holding surfaces 200, 2b, and 2c, that is, the height position on the Z axis, is determined as the height of the fourth grinding mechanism and obtained separately.

(11) Grinding start height calculation step Next, the robot 83 removes the wafer before processing from the first cassette 820a, passes through the alignment by the temporary area 84, and uses the first transfer mechanism 85a to The wafer is transferred to a holding table located in any one of the loading / unloading areas 101, specifically, a holding table on which the dressing grindstone 8 is not held, and an attractive force is applied to the suction unit 20 to hold the wafer. As in the first embodiment, the height of the grinding mechanism 3a obtained in the fourth grinding mechanism height storage step is added to the thickness of the wafer stored in the storage mechanism 70 in advance and the value of the protective member The total thickness is calculated as the height of the grinding mechanism 3a as seen from the grinding feed mechanism 4 when the grinding surface of the grinding grindstone 342 is in contact with the back surface of the wafer. The same calculation is performed for the grinding mechanism 3b.

(12) Grinding step Next, the grinding feed mechanism 4a gradually feeds the grinding mechanism 3a toward the height position obtained in the grinding start height calculation step. In addition, the grinding surface of the rotating grinding stone 342 is brought into contact with the back surface of the wafer, and the back surface is roughly ground. After rotating the turntable 81 by a predetermined angle, the grinding feed mechanism 4b feeds the grinding mechanism 3b to the height position obtained in the grinding start height calculation step, and rough-grinds the wafer. The sharpened back is ground.

The polished wafer is transferred to the rotator cleaning mechanism by the second transfer mechanism 85b, where the wafer is rotated and high-pressure water is sprayed on the rear surface of the wafer to clean the ground surface. After the cleaning, the wafer is rotated to remove the cleaning water.

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

In the example shown in FIG. 9, although the relative height reference portion 5 is disposed between the holding table 2 a and the holding table 2 b, as long as it can be moved to the grinding stones 342 and 343 constituting the grinding mechanisms 3 a and 3 b. The lower position is sufficient, and the relative height reference portion 5 may be disposed 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. Further, the relative height reference portion 5 may be configured to be moved below the grinding stones 342 and 343 independently without being disposed on the turntable 81.

In addition, the number of holding tables may be two or more, and two or more relative height reference sections may be arranged. For example, when four holding tables are provided and two relative height reference portions are provided, they can be used separately as follows: for the holding surfaces of the two holding tables and the grinding surface of the grinding stone The height position of the grinding mechanism identified by the grinding feed mechanism at the time of contact is calculated using one of the relative height reference portions. For the contact between the holding surface of the other two holding tables and the grinding surface of the grinding stone The height position of the grinding mechanism identified by the grinding feed mechanism is calculated using another relative height reference. In addition, the number of the grinding mechanisms and the number of the relative height reference portions may be set to be the same number, and each of the grinding mechanisms may use a dedicated relative height reference portion to obtain the holding of the grinding surfaces in contact with each other. The height position when the table is held. In addition, the number of holding bases and the number of relative height reference portions may be set to the same number, and one holding base and one relative height reference portion may correspond to one to one.

1.1A‧‧‧Grinding device

10, 10a‧‧‧ abutment

2, 2a, 2b, 2c‧‧‧

20‧‧‧ Adsorption Department

200‧‧‧ keep face

21‧‧‧Frame

22‧‧‧ Cover

3, 3a, 3b ‧‧‧ grinding mechanism

30‧‧‧rotation axis

31‧‧‧shell

32‧‧‧ Motor

33‧‧‧Mount

34‧‧‧Grinding Wheel

340, 342, 343‧‧‧ Grinding stone

340a, 340b, 342a, 343a

341‧‧‧ round abutment

4, 4a, 4b ‧‧‧ grinding feed mechanism

40‧‧‧ball screw

41‧‧‧rail

42‧‧‧ Motor

43‧‧‧Lifting plate

44‧‧‧ bracket

45‧‧‧ Altitude Measurement Department

46‧‧‧ scale

47‧‧‧ Encoder

5‧‧‧ Relative Height Reference Section

50‧‧‧ Bench

500‧‧‧ datum

51‧‧‧cylinder

52‧‧‧Testing Department

6, 6a, 6b ‧‧‧ Surface Height Measurement Department

60‧‧‧ Altitude gauge

7‧‧‧Control agency

70‧‧‧Memory

71‧‧‧Computing Agency

8‧‧‧ Trimming Millstone

80‧‧‧ support plate

800‧‧‧ Top surface

81‧‧‧ turntable

82a‧‧‧1st cassette loading section

82b‧‧‧ 2nd cassette loading section

820a‧‧‧1st cassette

820b‧‧‧2nd cassette

83‧‧‧ Robot

84‧‧‧Temporary area

840‧‧‧ Counterpart

85a‧‧‧The first transfer agency

85b‧‧‧ 2nd transfer agency

86‧‧‧Rotator cleaning mechanism

101‧‧‧ Moved in and out of the area

102‧‧‧Processing area

P‧‧‧Protective member

T, T1‧‧‧thickness

W‧‧‧ wafer (plate-like workpiece)

Wa‧‧‧ front

Wb‧‧‧ back

X, Y, Z‧‧‧ directions

Z1, Z2, Z3, Z4, Z5, Z6, Zg1, Zg2, Z2i, Z21, Z22, Z23

Zg‧‧‧axis

ΔH, ΔHi‧‧‧height difference

ΔZ‧‧‧fall distance

FIG. 1 is a perspective view showing a first embodiment of the grinding apparatus. FIG. 2 is a cross-sectional view schematically showing a dressing stone holding step. FIG. 3 is a cross-sectional view schematically showing a step of measuring a holding surface height. FIG. 4 is a cross-sectional view schematically showing a reference surface height measurement procedure. Fig. 5 is a cross-sectional view schematically showing a first grinding mechanism height storage step and a second grinding mechanism height storage step. FIG. 6 is a cross-sectional view schematically showing a state at the start of trimming in the trimming step. Fig. 7 is a cross-sectional view schematically showing a third grinding mechanism height storing step and a fourth grinding mechanism height storing step. FIG. 8 is a cross-sectional view schematically showing a state at the start of grinding in the grinding step. Fig. 9 is a perspective view showing a second embodiment of the grinding apparatus. FIG. 10 is a schematic diagram showing the height positions of the respective grinding mechanisms identified by the grinding feed mechanism when the grinding surface is in contact with the plurality of holding surfaces.

Claims (2)

A dressing method for a grinding grindstone uses a grinding device. The grinding device includes: a holding table having a holding surface for holding a wafer; and a grinding mechanism that is provided with the grinding grindstone in a ring shape and can be A rotating grinding wheel to grind the wafer held on the holding surface of the holding table; a grinding feed mechanism, which grinds the grinding mechanism in a vertical direction with respect to the holding surface; a height gauge, Measuring the height of the holding surface of the holding table; a reference table, which is provided on the holding table and has a reference surface on the upper surface and can be moved up and down; a detection unit that detects that the reference table has fallen a certain distance; A function; and a storage mechanism that stores a value used by the calculation mechanism or a value calculated by the calculation mechanism, and the dressing method of the grinding stone has: a dressing stone holding step, so that the plate-shaped dressing stone is maintained On the holding surface of the holding table; the platform height difference calculation step, 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; 1st grinding Institution height In the storing step, it is detected in the detecting unit that the grinding surface of the grinding stone is pressed down by the grinding feed mechanism to feed the grinding mechanism to the grinding table to lower the reference table to a certain level. The height position (Z1) of the grinding mechanism identified by the grinding feed mechanism in the case of distance is stored in the storage mechanism; the second grinding mechanism height storage step is used in the first grinding mechanism height storage step The stored height position of the grinding mechanism (Z1), the height of the holding surface measured by the height gauge calculated in the platform height difference calculation step, and the height of the reference surface measured by the height gauge Difference (ΔH), and the certain distance (ΔZ) when the detection unit detects that the reference table has descended a certain distance from the upper limit position, the grinding feed mechanism when the grinding surface contacts the holding surface The identified height position Z2 of the grinding mechanism is calculated and stored by the mathematical formula Z2 = Z1- (ΔH-ΔZ); the dressing start height calculation step will be used in the second grinding mechanism height storage step. The height position of the grinding mechanism stored plus the pre-stored The thickness of the dressing grindstone to calculate the height position of the grinding mechanism identified by the grinding feed mechanism when the grinding surface contacts the upper surface of the dressing grindstone; and the dressing step starts from the dressing The height of the grinding mechanism identified by the grinding feed mechanism calculated in the height calculation step starts the grinding feed, and the grinding surface is trimmed by the trimming stone held by the holding mechanism, and A dressing surface of the grinding stone is dressed by the dressing stone held by the holding table. The dressing method of a grinding stone according to claim 1, wherein the grinding device is provided with a plurality of the holding tables, and the plurality of holding tables are supported in a rotatable manner by a rotatable turntable and can be rotated. The rotation axis of the turntable is used as the center for revolving. In the aforementioned platform height difference calculation step, the difference between the height of the holding surface of each of the plurality of holding tables and the height of the reference surface measured by the height gauge is calculated separately. ΔHi, and in the above-mentioned second grinding mechanism height storage step, when the grinding surface is in contact with each of the i holding tables, the height position Z2i of each of the grinding mechanisms identified by the grinding feed mechanism , Calculated by the mathematical formula of Z2i = Z1- (ΔHi-ΔZ).