JP2021058952A - Grinding device - Google Patents

Abstract

To easily confirm whether or not a shaft of a linear gauge is supported in a non-contact manner.SOLUTION: A value in a scale 250a read out when a shaft 70 at a stand-by position is being supported in a non-contact manner is memorized as a reference value. For instance, during processing, an operation of confirming whether or not the shaft 70 is being supported in a non-contact manner is executed. In the operation of confirming, when a difference between a measured value which is a value in the scale 250a read out when the shaft 70 is at the stand-by position and the reference value is equal to or above a threshold, it is determined that the shaft 70 is not being supported in a non-contact manner. Thus, it is determined whether or not the shaft 70 is being supported in a non-contact manner, on the basis of the read-out value in the scale 250a at the time when the shaft 70 is at the stand-by position. This can easily determine whether or not the shaft 70 is being supported in a non-contact manner.SELECTED DRAWING: Figure 3

Description

The present invention relates to a grinding device.

There is a grinding device that holds the work piece by the holding surface of the chuck table and grinds the work piece with a grinding wheel. In such a grinding device, the height of the holding surface and the height of the upper surface of the work piece are measured, and the difference between the height of the holding surface and the upper surface height of the work piece is calculated as the thickness of the work piece. The workpiece is ground until the calculated value reaches a preset finish thickness.

As a top surface height measuring device for measuring the height of the top surface of the work piece, a linear gauge as disclosed in Patent Document 1 may be used.

The linear gauge includes a shaft with a stylus at the tip. Further, a support surface for supporting the shaft so as to be movable in the axial direction is provided. This support surface surrounds the shaft so as to form a gap at equal intervals from the side surface of the shaft. In this linear gauge, air is injected into the gap between the shaft and the support surface, and the gap is filled with air. As a result, the shaft is supported by the support surface in a non-contact manner. The height of the upper surface of the workpiece is measured by bringing such a shaft into contact with the upper surface of the workpiece and reading the position of the shaft on a scale.

Japanese Unexamined Patent Publication No. 2015-175758

In the linear gauge described above, accurate values can be read by supporting the shaft in a non-contact manner using air. Therefore, in order to confirm whether or not air is being supplied, the supply flow rate or pressure of the air injected from the injection port is monitored.

However, mechanisms for monitoring the air supply flow rate or pressure increase the cost of the top height measuring instrument. Also, despite the air being supplied, the shaft is non-contact and unsupported, which can lead to inaccurate measurements.

Therefore, an object of the present invention is to easily confirm whether or not the shaft of the linear gauge is supported in a non-contact manner.

The grinding device (the present grinding device) of the present invention includes a chuck table that holds a work piece by a holding surface, a grinding means that grinds a work piece held by the chuck table with a grinding wheel, and a holding surface. A grinding device including an upper surface or a holding surface of a work piece to be measured and a linear gauge for measuring the height of the surface to be measured, and the linear gauge comes into contact with the surface to be measured. A shaft in which the stylus is arranged at the lower end, a support means that surrounds the side surface of the shaft and supports it in a non-contact manner and enables vertical movement along the axial direction of the shaft, and a support means connected to the upper end of the shaft. An arm extending in a direction orthogonal to the axial direction, a pushing means for pushing up the arm and moving the shaft upward to position it in a standby position, and a base for arranging the supporting means and the pushing means. And a scale provided with a scale hanging from the arm, and a reading unit arranged on the base and reading the scale of the scale which moves up and down with the vertical movement of the shaft, and the shaft is not made by the supporting means. A storage unit that stores a reference value that is a value read by the reading unit of the scale when it is supported by contact and is located at the standby position, and a storage unit that stores the shaft when it is located at the standby position. The difference between the measured value, which is the value read by the reading unit on the scale, and the reference value stored in the storage unit is obtained, and when the difference is equal to or greater than a preset threshold value, the shaft supports the support. It is provided with a judgment unit that determines that it is not non-contactly supported by means.

In this grinding device, the value of the scale read when the shaft in the standby position is supported in a non-contact manner is stored as a reference value. Then, for example, before measuring the height of the surface to be measured during machining, a confirmation operation of whether or not the shaft is supported in a non-contact manner is performed. In this confirmation operation, when the difference between the measured value, which is the reading value of the scale when the shaft is in the standby position, and the reference value is equal to or greater than the threshold value, it is determined that the shaft is not supported in a non-contact manner. To do.

As described above, in this grinding apparatus, the operation of confirming whether or not the shaft is supported in a non-contact manner is performed based on the reading value of the scale when the shaft is in the standby position. Therefore, it can be easily determined whether or not the shaft is supported in a non-contact manner. Further, since the confirmation operation is performed on the shaft in the standby position, the confirmation operation lowers the shaft only when the shaft is supported in a non-contact manner, so that it is possible to avoid applying a load to the shaft and the supporting means. it can.

It is a perspective view of the grinding apparatus which concerns on embodiment. It is a perspective view of a linear gauge. It is sectional drawing of a linear gauge. It is sectional drawing of a linear gauge. It is explanatory drawing which shows the inclination of the shaft of a linear gauge. It is explanatory drawing which shows the neighborhood of a reading part when a shaft is tilted. It is a graph about the difference between a reference value and a measured value. It is a graph which shows the result of the measurement performed before processing of each wafer.

The grinding device 1 shown in FIG. 1 is a device for performing a grinding process on a wafer W as a workpiece. The wafer W shown in FIG. 1 is, for example, a circular semiconductor wafer.

A device (not shown) is formed on the surface Wa of the wafer W. The surface Wa faces downward in FIG. 1 and is protected by attaching the protective tape T. The back surface Wb of the wafer W is the surface to be ground to be ground.

The grinding apparatus 1 includes a base 10 extending in the Y-axis direction and a column 15 standing on the base 10 on the + Y direction side.
A rectangular opening 10a extending in the X-axis direction is formed on the upper surface of the base 10. The opening 10a is covered with a moving plate 11 and a bellows-shaped waterproof cover 12.

A chuck table 20 is provided on the moving plate 11. The chuck table 20 is a disk-shaped table for holding the wafer W, and includes a holding surface 21. The holding surface 21 contains a porous porous material. With the wafer W placed on the holding surface 21, the suction force exerted by a suction source (not shown) is transmitted to the holding surface 21, so that the wafer W is sucked and held by the holding surface 21. That is, the chuck table 20 holds the wafer W by the holding surface 21.

A waterproof cover 12 is stretchably connected to the moving plate 11. The chuck table 20 and the moving plate 11 are integrally reciprocated in the Y-axis direction by a Y-axis direction moving means (not shown) arranged inside the base 10 when grinding the wafer W. To do. The waterproof cover 12 expands and contracts as the moving plate 11 moves in the Y-axis direction.

In the present embodiment, roughly speaking, the chuck table 20 has a front wafer mounting position (−Y direction side) for mounting the wafer W on the holding surface 21 and a rear (+ Y) where the wafer W is ground. Move to and from the grinding area (on the directional side). Further, when the wafer W is ground by the grinding wheel 48 of the grinding means 40, the chuck table 20 having the holding surface 21 moves in the grinding region.

On the front surface of the column 15 on the base 10, a grinding means 40 for grinding the wafer W and a grinding feeding means 30 for moving the grinding means 40 in the Z-axis direction, which is the grinding feed direction, are provided.

The grinding feed means 30 includes a pair of guide rails 31 parallel to the Z-axis direction, a moving table 32 sliding on the guide rails 31, a ball screw 33 parallel to the guide rails 31, a motor 34, and a front surface of the moving table 32. It has a holder 35 attached to the surface). The holder 35 holds the grinding means 40.

The moving table 32 is slidably installed on the guide rail 31. A nut portion (not shown) is fixed to the rear surface side (rear surface side) of the moving table 32. A ball screw 33 is screwed into this nut portion. The motor 34 is connected to one end of the ball screw 33.

In the grinding feed means 30, the moving table 32 moves in the Z-axis direction along the guide rail 31 by rotating the ball screw 33 by the motor 34. As a result, the holder 35 attached to the moving table 32 and the grinding means 40 held by the holder 35 also move in the Z-axis direction together with the moving table 32.

The grinding means 40 includes a spindle housing 41 fixed to a holder 35, a spindle 42 rotatably held by the spindle housing 41, a motor 43 for rotationally driving the spindle 42, a wheel mount 45 attached to the lower end of the spindle 42, and a wheel mount 45. , A grinding wheel 46 supported by a wheel mount 45 is provided.

The spindle housing 41 is held by the holder 35 so as to extend in the Z-axis direction. The spindle 42 extends in the Z-axis direction so as to be orthogonal to the holding surface 21 of the chuck table 20, and is rotatably supported by the spindle housing 41.
The motor 43 is connected to the upper end side of the spindle 42. The motor 43 causes the spindle 42 to rotate about a rotation axis extending in the Z-axis direction.

The wheel mount 45 is formed in a disk shape and is fixed to the lower end (tip) of the spindle 42. The wheel mount 45 supports the grinding wheel 46.

The grinding wheel 46 is formed so as to have substantially the same diameter as the wheel mount 45. The grinding wheel 46 includes an annular wheel base (annular base) 47 formed of a metal material such as stainless steel. A plurality of grinding wheels 48 arranged in an annular shape are fixed to the lower surface of the wheel base 47 over the entire circumference. The grinding wheel 48 grinds the back surface Wb of the wafer W held on the chuck table 20 arranged in the grinding region. In this way, the grinding means 40 grinds the wafer W held by the chuck table 20 with the grinding wheel 48.

A thickness measuring instrument 55 is arranged at a position adjacent to the chuck table 20. The thickness measuring device 55 can measure the thickness of the wafer W by a contact method during grinding.

That is, the thickness measuring instrument 55 includes a first linear gauge 56 and a second linear gauge 57. The first linear gauge 56 comes into contact with the holding surface 21 of the chuck table 20 and measures its height. The second linear gauge 57 comes into contact with the back surface (upper surface) Wb of the wafer W held by the holding surface 21 and measures the height thereof. As a result, the thickness measuring device 55 can measure the thickness of the wafer W based on the difference between the height of the holding surface 21 of the chuck table 20 and the height of the back surface Wb of the wafer W.

Next, the configuration of the thickness measuring instrument 55 and the second linear gauge 57 will be described.
As shown in FIGS. 2 and 3, the second linear gauge 57 includes a shaft 70 having a stylus 71 at the lower end, a support means 130 for supporting the shaft 70, a rotation regulating means 140 for restricting the rotation of the shaft 70, and a shaft 70. The arm 81 connected to the upper end of the wafer, the pushing means 150 for pushing up the arm 81, the base 83 arranged below the pushing means 150, and the height position reading means 25 for reading the height position of the back surface Wb of the wafer W are provided. ing.

The base 83 extends in the XY plane. The base 83 is a bottom plate for arranging the support means 130, the rotation control means 140, the push-up means 150, and the reading unit 251 of the height position reading means 25. The base 83 is attached to a support base 100 (see FIG. 3) which is a part of the thickness measuring instrument 55. Further, a housing 85 that covers other members of the second linear gauge 57 is attached to the base 83. Further, a substantially circular opening 84 is provided in a substantially central portion of the base 83.

The arm 81 is connected to the upper end of the shaft 70 and extends in a direction orthogonal to the axial direction of the shaft 70.

The shaft 70 extends in the vertical direction (Z-axis direction). The shaft 70 is formed in a columnar shape and is inserted through the opening 84 of the base 83. The upper end of the shaft 70 is connected to the lower surface side at substantially the center of the rectangular flat plate-shaped arm 81 by a fixing nut 82 (see FIG. 2). A stylus 71 is attached to the lower end of the shaft 70. Therefore, the shaft 70 and the stylus 71 are configured to move integrally.

The stylus 71 projects downward from the lower surface of the base 83 through the opening 84. The stylus 71 comes into contact with the back surface Wb of the wafer W when measuring the height of the back surface Wb of the wafer W.

The support means 130 arranged on the base 83 surrounds the side surface 70a of the shaft 70 and supports it in a non-contact manner, enabling vertical movement along the axial direction (Z-axis direction) of the shaft 70.

As shown in FIG. 3, the support means 130 is arranged on the upper surface of the base 83 and supports the periphery of the shaft 70. The support means 130 is formed with a cylindrical support surface 131 for accommodating the shaft 70, corresponding to the cylindrical shaft 70. The support surface 131 faces the side surface 70a of the shaft 70.

Further, the support means 130 includes a plurality of outlets 132 provided on the support surface 131, an air inlet 133 connected to the air supply source 60, and an air flow that communicates the air inlet 133 with each outlet 132. It has a road 134. The air inlet 133 and the air supply source 60 are connected by an air supply pipe 600 such as a metal pipe or a flexible resin tube.

The support surface 131 has a substantially cylindrical inner surface shape, and is provided so as to surround the shaft 70. From the ejection port 132 provided on the support surface 131, the air that has flowed in from the air inlet 133 and has passed through the air flow path 134 is ejected substantially perpendicular to the side surface 70a of the shaft 70. With such air, the support means 130 (support surface 131) can give the shaft 70 a force to maintain a posture parallel to the Z-axis direction. That is, the supporting means 130 can support the shaft 70 in a non-contact state so as to be parallel to the Z-axis direction.

The rotation regulating means 140 regulates the movement of the shaft 70 supported by the supporting means 130 in the rotation direction about the extending direction thereof. The rotation regulating means 140 includes a guide rod 141 having a block-shaped first magnet 142, and two second magnets 143.

The guide rod 141 is connected to the arm 81 and extends parallel to the extending direction of the shaft 70. A first magnet 142 is connected to the tip of the guide rod 141. The second magnet 143 is provided on the base 83 so as to sandwich the first magnet 142 (guide rod 141). The side surface of the second magnet 143 facing the first magnet 142 is magnetized so as to repel the first magnet 142.

In the rotation regulating means 140, the first magnet 142 and the second magnet 143 repel each other so that the guide rod 141 approaches the second magnet 143, that is, the movement (rotation) of the guide rod 141 in the XY plane. ) Is suppressed. Further, the guide rod 141 is connected to the shaft 70 via the arm 81. Therefore, the rotation regulating means 140 suppresses the movement (rotation) of the shaft 70 in the XY plane.

The pushing means 150 moves the shaft 70 linearly along the Z-axis direction. For example, the pushing means 150 pushes up the arm 81 and moves the shaft 70 in the upward + Z direction to position the shaft 70 in the standby position.
Further, the pushing means 150 lowers the shaft 70 in the downward direction (−Z direction) so as to approach the back surface Wb of the wafer W.
The pushing means 150 is fixed to the arm 81 apart from the shaft 70 in the extending direction (X-axis direction) of the arm 81.

As shown in FIGS. 2 and 3, the pushing-up means 150 is a piston cylinder, and the cylinder tube 151 fixed to the upper surface of the base 83, the piston 152 arranged inside the cylinder tube 151, and the piston 152. It includes a connected piston rod 153 and air inlets 154 and 155.

The piston rod 153 is inserted into the cylinder tube 151. The upper end of the piston rod 153 can come into contact with the lower surface of the arm 81 on one end side. The lower end of the piston rod 153 is attached to the piston 152.

A spring member 158 is provided between the lower surface of the piston 152 and the bottom surface of the cylinder tube 151. The spring member 158 urges the piston 152 upward.

The air inlets 154 and 155 are for inflowing air into the cylinder tube 151. Air flow paths 156 and 157 are communicated with the air inlets 154 and 155, respectively. The air flow paths 156 and 157 are selectively connected to the air supply source 60 via the solenoid valve 603.

The height position reading means 25 is arranged on the side opposite to the piston rod 153 with the shaft 70 of the arm 81 interposed therebetween. The height position reading means 25 includes a scale 250 that hangs downward from the arm 81, and a reading unit 251 that reads the scale 250a of the scale 250.

The upper end of the scale 250 is fixed to the lower surface of the arm 81. Therefore, the scale 250 is connected to the shaft 70 via the arm 81. The scale 250 extends in the −Z direction in parallel with the extending direction (Z-axis direction) of the shaft 70. The scale 250 moves up and down as the shaft 70 moves up and down.
Further, the scale 250 has a scale 250a extending in a direction parallel to the axial direction of the shaft 70. The scales 250a are formed on the side surface of the scale 250 at equal intervals along the Z-axis direction.
The scale 250 is fixed to the arm 81 apart from the shaft 70 in the extending direction (X-axis direction) of the arm 81.
The reading unit 251 may be fixed to the lower surface of the arm 81, and the scale 250 may be fixed to the base 83.
Further, the height position reading means 25 may be arranged in the vicinity of the push-up means 150.

The reading unit 251 includes a support column 252 and a sensor 253, and is arranged on the base 83. The reading unit 251 reads the scale 250a of the scale 250 of the scale 250 that moves up and down.

The support pillar 252 is fixed to the side surface of the base 83 and extends in the + Z direction. The sensor 253 is fixed to the side surface of the support column 252 and faces the scale 250a of the scale 250. The sensor 253 is, for example, an optical sensor that reads the reflected light from the scale 250a of the scale 250.

In the grinding apparatus 1, when the stylus 71 of the shaft 70 comes into contact with the back surface Wb of the wafer W, the value of the scale 250a of the scale 250 that moves along the Z-axis direction together with the shaft 70 is read by the reading unit 251. , The height position of the back surface Wb of the wafer W can be measured.

Further, as shown in FIG. 1, the grinding device 1 includes a control means 50 for controlling each component of the grinding device 1. The control means 50 controls each component of the above-mentioned grinding apparatus 1 to perform the processing desired by the operator on the wafer W.

As shown in FIG. 1, the control means 50 includes a determination unit 51 and a storage unit 53. Hereinafter, the functions of the control means 50 including the determination unit 51 and the storage unit 53 will be described together with the operation of the second linear gauge 57.

As shown in FIG. 3, the second linear gauge 57 is positioned above the wafer W during the grinding process of the wafer W. Further, the control means 50 controls the air supply source 60 to supply air to the air inlet 133, thereby supporting the shaft 70 in a non-contact state by the support means 130 (support surface 131). There is.

Further, the control means 50 measures the height position of the back surface Wb of the wafer W at an arbitrary timing by using the second linear gauge 57 during the grinding process.

When the control means 50 does not measure the height of the back surface Wb of the wafer W by the second linear gauge 57, the shaft 70 of the second linear gauge 57 is moved from the back surface Wb of the wafer W as shown in FIG. Set to a remote standby position.

That is, the control means 50 moves the shaft 70 in the upward direction (+ Z direction) by the push-up means 150. Specifically, the control means 50 controls the solenoid valve 603 so that the air supply source 60 communicates with the air flow path 157. As a result, a predetermined amount of air is supplied from the air supply source 60 below the piston 152 in the cylinder tube 151 via the air flow path 157 and the air inflow port 155. At this time, the air above the piston 152 in the cylinder tube 151 can be discharged from the air inflow port 154.

Due to the air supplied from the air inlet 155 and the urging force of the spring member 158, the piston 152 rises inside the cylinder tube 151, and the piston rod 153 rises at the same time. By raising the piston rod 153 in this way, the piston rod 153 comes into contact with the lower surface of the arm 81, and the arm 81 and the shaft 70 connected to the arm 81 are raised. As a result, the stylus 71 of the shaft 70 is separated from the back surface Wb of the wafer W by a predetermined distance. That is, the shaft 70 is set to the standby position in a state where it is supported by the support means 130 in a non-contact manner.

Further, when the control means 50 measures the height of the back surface Wb of the wafer W by the second linear gauge 57, the push-up means 150 brings the shaft 70 closer to the wafer W as shown in FIG. Lower in the Z direction.

Specifically, the control means 50 controls the solenoid valve 603 so that the air supply source 60 communicates with the air flow path 156. As a result, a predetermined amount of air is supplied from the air supply source 60 to the upper part of the piston 152 in the cylinder tube 151 via the air flow path 156 and the air inflow port 154. At this time, the air below the piston 152 in the cylinder tube 151 can be discharged from the air inflow port 155.

The air supplied from the air inlet 154 pushes the piston 152 downward against the urging force of the spring member 158. As a result, the piston 152 is lowered inside the cylinder tube 151, and at the same time, the piston rod 153 in contact with the lower surface of the arm 81 is lowered. As a result, the arm 81 and the shaft 70 are lowered along the −Z direction by their own weight. In this way, the shaft 70 is lowered while being supported by the supporting means 130 in a non-contact manner until the stylus 71 comes into contact with the back surface Wb of the wafer W.

When the stylus 71 comes into contact with the back surface Wb of the wafer W, the control means 50 controls the reading unit 251 (sensor 253) to read the scale 250a of the scale 250. Then, the control means 50 measures the height position of the back surface Wb of the wafer W based on the read value of the scale 250a.
After that, the control means 50 returns the shaft 70 to the standby position by the above-mentioned procedure.

Here, if a problem occurs in the air supply source 60, the air inlet 133 of the support means 130, the air flow path 134, or the like, it is sufficient for the side surface 70a of the shaft 70 from the ejection port 132 of the support means 130. The amount of air may not blow out. In this case, the force (supporting force) for keeping the posture of the shaft 70 parallel to the Z-axis direction becomes weak. Therefore, the shaft 70 tilts in the cylindrical space created by the support surface 131 in the support means 130 and comes into contact with the support surface 131. That is, the shaft 70 cannot be supported by the supporting means 130 in a non-contact manner. This makes the result of height measurement of the back surface Wb of the wafer W inaccurate.

That is, in the present embodiment, the arm 81 is supported by the shaft 70, and the posture of the shaft 70 is maintained parallel to the Z-axis by the supporting means 130, so that the arm 81 extends in the direction perpendicular to the Z-axis. doing. When the supporting force of the supporting means 130 with respect to the shaft 70 is weakened, the arm 81 is tilted so that the shaft 70 is tilted and is not supported in a non-contact manner, and the position of the scale 250 arranged on the arm 81 in the Z-axis direction fluctuates. To do. As a result, when measuring the height of the back surface Wb of the wafer W, the value of the scale 250a of the scale 250 read by the reading unit 251 fluctuates from an appropriate value.

In this regard, in the present embodiment, the control means 50 performs a confirmation operation for confirming whether or not the shaft 70 is non-contactly supported by the support means 130.

That is, when the shaft 70 is in the standby position, one end of the arm 81 is pushed upward together with the shaft 70 by the piston rod 153. In this state, if a sufficient amount of air is not blown out from the ejection port 132 of the supporting means 130, the supporting force of the supporting means 130 with respect to the shaft 70 becomes weak, and the shaft 70 in the arm 81 supported by the shaft 70 is sandwiched. The side opposite to the piston rod 153 (the side on which the scale 250 is arranged) is lowered along the −Z direction by the weight of the arm 81 and the scale 250, as shown by the arrow A, as shown in FIG.

As a result, the shaft 70 in the standby position is inclined between the support surfaces 131 of the support means 130 by an angle θ from the Z-axis direction and comes into contact with the support surface 131.
At this time, as shown in FIG. 6, the value of the scale 250a of the scale 250 read by the sensor 253 of the reading unit 251 fluctuates from the value Va at the time of non-contact (normal time) by ΔV to become the value Vb. ..

Therefore, the control means 50 controls the reading unit 251 when the shaft 70 is non-contactly supported by the support means 130 and is located at the standby position, and the value of the scale 250a of the scale 250 (shown in FIG. 6). Read Va). Then, the control means 50 stores the read value as a reference value in the storage unit 53.

Then, the control means 50 controls the reading unit 251 when the shaft 70 is in the standby position during the grinding process of the wafer W, and the value of the scale 250a of the scale 250 (for example, shown in FIG. 6). Vb) is read as a measured value.

Further, the determination unit 51 of the control means 50 obtains the difference between the measured value Vb and the reference value Va stored in the storage unit 53 (for example, ΔV shown in FIG. 6). Then, the determination unit 51 determines that the shaft 70 is not non-contactly supported by the support means 130 when the obtained difference is equal to or more than a preset threshold value (for example, 2 μm).

FIG. 7 is a graph of the difference (ΔV) between the reference value Va and the measured value Vb when the amount of air supplied from the ejection port 132 of the support means 130 to the side surface 70a of the shaft 70 is insufficient at time T1. Is shown. In this example, the difference between the reference value Va and the measured value Vb sharply increases at time T1 and exceeds the threshold value Vs.
Further, the value of the shaft 70 does not have to be constantly measured. For example, the control means 50 may perform measurement immediately before lowering the shaft 70 before processing each wafer W, and the determination unit 51 may calculate the difference based on the measured values at that time. That is, as shown in FIG. 8, the control means 50 may measure the value of the scale 250a of the scale 250 immediately before lowering the shaft 70 before processing the wafer W. In the example shown in FIG. 8, the result of the measurement (measurement 1) performed before the processing of one wafer W and the result of the measurement (measurement 2) performed before the processing of another wafer W to be processed next are shown. Shown. Then, the determination unit 51 of the control means 50 calculates the difference (ΔV) between the reference value Va and the measured value Vb in each measurement, and when the difference ΔV is equal to or greater than the threshold value Vs as in measurement 2, the shaft 70 May be determined to be non-contact and unsupported.

As described above, in the present embodiment, the value of the scale 250a read when the shaft 70 in the standby position is supported in a non-contact manner is stored as the reference value Va. Then, for example, before measuring the height of the upper surface of the wafer W during processing, a confirmation operation of whether or not the shaft 70 is supported in a non-contact manner is performed. In this confirmation operation, the shaft 70 is non-contact when the difference ΔV between the measured value Vb, which is the reading value of the scale 250a when the shaft 70 is located at the standby position, and the reference value Va is equal to or greater than the threshold value Vs. Judge that it is not supported by.

As described above, in the present embodiment, the operation of confirming whether or not the shaft 70 is supported in a non-contact manner is performed based on the reading value of the scale 250a when the shaft 70 is in the standby position. Therefore, it can be easily determined whether or not the shaft 70 is supported in a non-contact manner. Further, since the confirmation operation is performed on the shaft 70 in the standby position, the confirmation operation lowers the shaft 70 only when the shaft 70 is supported in a non-contact manner, so that a load is applied to the shaft 70 and the supporting means 130. Can be avoided.

The shape of the shaft 70 is not limited to a columnar shape, and may be a shape such as a square columnar shape that is difficult to rotate with respect to the supporting means 130. In this case, the second linear gauge 57 does not have to include the rotation regulating means 140.

Further, the urging force of the spring member 158 raises the piston rod 153 via the piston 152 when air is not supplied to both the air inlet 154 and the air inlet 155, and sets the shaft 70 as the standby position. It may be as strong as possible. In this case, for example, when the second linear gauge 57 is turned off at a timing different from the intention of the operator, the shaft 70 can be retracted to the standby position. Further, in this case, it is not necessary to provide the air flow path 157 and the air inflow port 155 for supplying the air for raising the piston 152 to the cylinder tube 151.

Further, in the present embodiment, the configuration of the second linear gauge 57 for measuring the height of the back surface Wb with the back surface Wb of the wafer W as the surface to be measured is described. In this regard, the holding surface 21 of the chuck table 20 may be used as the surface to be measured, and the first linear gauge 56 for measuring the height of the holding surface 21 may have the same configuration as the second linear gauge 57. Alternatively, either one of the first linear gauge 56 and the second linear gauge 57 may have the configuration of the linear gauge of the present embodiment shown with reference to FIGS. 2 to 4 and the like.
That is, in the linear gauge according to the present embodiment, the back surface Wb or the holding surface 21 of the wafer W held on the holding surface 21 of the chuck table 20 is used as the surface to be measured, and the height of the surface to be measured is measured. Just do it.
Further, the grinding device 1 does not have to include a linear gauge for measuring the height of the holding surface 21 of the chuck table 20.

1: Grinding device, 10: Base, 15: Column,
20: Chuck table, 21: Holding surface,
25: Height position reading means,
30: Grinding feed means, 40: Grinding means,
50: Control means, 51: Judgment unit, 53: Storage unit,
55: Thickness measuring instrument, 56: 1st linear gauge, 57: 2nd linear gauge,
60: Air supply source,
70: shaft, 70a: side surface, 71: stylus,
81: Arm, 83: Base, 84: Aperture, 85: Housing, 100: Support,
130: Support means, 131: Support surface,
132: Outlet, 133: Air inlet, 134: Air flow path,
140: Rotation control means, 141: Guide rod,
142: 1st magnet, 143: 2nd magnet,
150: Push-up means, 151: Cylinder tube, 152: Piston,
153: Piston rod, 154: Air inlet, 155: Air inlet,
158: Spring member,
250: Scale, 250a: Scale, 251: Reader, 252: Support pillar,
253: Sensor,
600: Air supply pipe, 603: Solenoid valve,
W: Wafer, Wb: Back side,

Claims (1)

A chuck table that holds the work piece by the holding surface, a grinding means that grinds the work piece held by the chuck table with a grinding wheel, and an upper surface or the holding surface of the work piece held by the holding surface. A grinding device provided with a surface to be measured and a linear gauge for measuring the height of the surface to be measured.
The linear gauge
A shaft having a stylus in contact with the surface to be measured at the lower end,
Supporting means that surrounds and supports the side surface of the shaft in a non-contact manner and enables vertical movement of the shaft along the axial direction.
An arm connected to the upper end of the shaft and extending in a direction orthogonal to the axial direction,
A push-up means for pushing up the arm and moving the shaft upward to position it in a standby position.
A base for arranging the support means and the push-up means,
A scale with a scale hanging from the arm,
A reading unit, which is arranged on the base and reads the scale of the scale which moves up and down with the vertical movement of the shaft, is provided.
A storage unit that stores a reference value, which is a value read by the reading unit, when the shaft is non-contactly supported by the supporting means and is located at the standby position.
The difference between the measured value, which is the value read by the reading unit on the scale when the shaft is located at the standby position, and the reference value stored in the storage unit is obtained, and the difference is obtained in advance. A determination unit that determines that the shaft is not non-contactly supported by the support means when the value is equal to or higher than the set threshold value.
Grinding device equipped with.

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