JP2022047868A - Grinding device - Google Patents

Abstract

To optimize a distance in escape-cut processing.SOLUTION: Escape-cut processing is executed until a height of a holding surface 32 gauged with a first gauge 61 becomes equal to an original height of the surface not yet ground. An optimal movement distance of a grinding stone 77 in the escape-cut processing is a distance by which the grinding stone 77 does not contact a wafer 100 on the holding surface 32, which is in other words the distance by which the grinding stone 77 separates from the wafer 100. The fact that the height of the holding surface 32 becomes equal to the original height of the surface not yet ground means that the grinding stone 77 has separated from the wafer 100. This can optimize the movement distance (movement time) of the grinding stone 77 in the escape-cut processing.SELECTED DRAWING: Figure 1

Description

The present invention relates to a grinding device.

In the grinding apparatus disclosed in Patent Documents 1 to 3, the wafer held on the holding surface is in-feed ground by an annular grinding wheel. In this grinding device, the grinding means is grounded downward close to the holding surface, and the grinding wheel is pressed against the wafer held on the holding surface to grind the wafer. When the wafer reaches a predetermined thickness, a spark-out process is performed in which the grinding wheel is rotated for a predetermined time with the grinding feed stopped to grind the wafer. After that, an escape cut process is performed in which the wafer is ground while the grinding wheel is slowly moved upward away from the wafer.

By performing such an escape cut process, when the grinding wheel is separated from the wafer, the formation of irregularities on the surface to be ground of the wafer due to the rotation locus of the grinding wheel is suppressed.

Japanese Unexamined Patent Publication No. 2017-054872 Japanese Patent Application Laid-Open No. 2003-236736 Japanese Unexamined Patent Publication No. 2009-012134

In recent years, in order to shorten the grinding time, a grinding wheel is pressed against a wafer with a large pressing force to perform grinding. Therefore, the chuck table holding the wafer sinks due to the pressing force. Further, the grinding means receives the reaction force of the pressing force and is fanned upward.

As described above, when the pressing force of the grinding wheel is large, the chuck table and the grinding means are displaced in the direction away from each other, so that it is necessary to lengthen the escape cut processing distance (time).

On the other hand, under the machining conditions when the force for pressing the grinding wheel against the wafer is small, the amount of displacement in the chuck table and the grinding means in the direction away from each other is small. Therefore, the escape cut processing distance (time) may be short.

Therefore, an object of the present invention is to optimize the distance (time) of escape cut processing in a grinding device for grinding a wafer.

The first grinding device of the present invention grinds the workpiece held on the holding surface by a chuck table for holding the workpiece by the holding surface and an annular grinding wheel mounted on the lower end of the spindle. Means, a grinding feed means for moving the grinding means in a direction perpendicular to the holding surface, a holding surface height measuring device for measuring the height of the holding surface, and a thickness measurement for measuring the thickness of the workpiece. A storage device including at least means, which stores the holding surface height measured by the holding surface height measuring device before the grinding wheel comes into contact with the workpiece held on the holding surface. After the workpiece is ground to a predetermined thickness by the portion and the grinding wheel, the holding surface height measured by the holding surface height measuring instrument is the height stored in the storage portion. It is provided with a control unit that escape-cuts the workpiece by the grinding wheel by moving the grinding wheel upward at a preset escape cut processing speed.

The second grinding device of the present invention is held on the holding surface by a chuck table that holds the workpiece by the holding surface and an annular grinding wheel mounted on the lower surface of the mount arranged at the lower end of the spindle. A grinding means for grinding a workpiece, a grinding feed means for moving the grinding means in a direction perpendicular to the holding surface, a holding surface height measuring device for measuring the height of the holding surface, and the workpiece. A grindstone having at least a thickness measuring means for measuring the thickness of a grindstone, the holding surface is provided by extending a vertically expandable expansion / contraction unit interposed between the holding surface and the lower surface of the mount. A predetermined load value is applied to the holding surface and the lower surface of the mount so as to push down the mount and push the mount upward, and the amount of downward displacement of the holding surface and the upward direction of the lower surface of the mount are applied. A storage unit that measures the amount of displacement and stores a data table showing the relationship between the amount of downward displacement and the amount of upward displacement with respect to an applied predetermined load value, and a workpiece held on the holding surface. After the first holding surface height, which is the holding surface height measured by the holding surface height measuring instrument before the grinding wheel is brought into contact with the object, and the work piece being ground to a predetermined thickness by the grinding wheel. Immediately before the start of the escape cut process in which the grinding wheel is ground while being separated from the workpiece, the difference from the second holding surface height, which is the holding surface height measured by the holding surface height measuring instrument, is set. The data table is referred to by using the first calculation unit that calculates the downward displacement amount of the holding surface as the machining downward displacement amount and the machining downward displacement amount, and the downward displacement amount having the same value as the machining downward displacement amount is referred to. An extraction unit that extracts the upward displacement amount according to the displacement amount as the machining upward displacement amount of the grinding wheel immediately before the start of the escape cut machining, the machining downward displacement amount, and the machining upward displacement. The value obtained by adding the amount is set in advance in the second calculation unit that calculates the upward movement distance of the grinding wheel in the escape cut process and until the moving distance of the grinding wheel becomes the upward moving distance. It is provided with a control unit that escape-cuts the workpiece by the grindstone by moving the grindstone upward at the escape cut processing speed.

The height of the holding surface during the grinding process is lowered by the grinding wheel pressing the holding surface through the workpiece. Then, in the first grinding apparatus, the escape cut process is performed until the height of the holding surface measured by the holding surface height measuring device becomes the height before the grinding process. Here, the optimum moving distance of the grinding wheel in the escape cut process is the distance until the grinding wheel does not come into contact with the workpiece on the holding surface, that is, until the grinding wheel separates from the workpiece. The fact that the height of the holding surface becomes the height before the grinding process means that the holding surface is no longer pressed by the grinding wheel, that is, the grinding wheel is separated from the workpiece. Therefore, in this configuration, it is possible to optimize the moving distance (moving time) of the grinding wheel in the escape cut processing.

Further, in the second grinding device, the escape cut process is performed until the moving distance of the grinding wheel becomes the upward moving distance. This upward movement distance is the sum of the amount of upward displacement of the grinding wheel and the amount of downward displacement of the holding surface due to the grinding wheel pressing the holding surface when the thickness of the workpiece reaches a predetermined value. Is. Therefore, the fact that the grinding wheel rises by the upward moving distance means that the holding surface is not pressed by the grinding wheel, that is, the grinding wheel is separated from the workpiece. Therefore, even with this configuration, it is possible to optimize the moving distance (moving time) of the grinding wheel in the escape cut processing.

It is explanatory drawing which shows the structure of the grinding apparatus which concerns on one Embodiment. It is a graph which shows the time change of the height of the grinding wheel and the time change of the height of the holding surface of a chuck table at the time of grinding a wafer. It is explanatory drawing which shows the structure of the grinding apparatus which concerns on other embodiment.

As shown in FIG. 1, the grinding device 1 according to the present embodiment is a device for grinding a wafer 100 as a workpiece, and includes a control unit 90 that controls each member of the grinding device 1.

The wafer 100 is, for example, a circular semiconductor wafer. In FIG. 1, the surface 101 of the wafer 100 facing downward holds a plurality of devices and is protected by attaching a protective tape 103. The back surface 102 of the wafer 100 is a surface to be ground to be ground.

The grinding device 1 includes a holding means 30 for holding the workpiece. The holding means 30 includes a chuck table 31, a support member 33 for supporting the chuck table 31, and a rotating means 34 for rotating the chuck table 31.

The chuck table 31 includes a holding surface 32 for holding the wafer 100 and a frame body 36 surrounding the holding surface 32. In the present embodiment, the upper surface of the frame body 36 is formed substantially flush with the holding surface 32 and has the same height as the holding surface 32.

The holding surface 32 of the chuck table 31 communicates with a suction source (not shown) and sucks and holds the wafer 100 via the protective tape 103. That is, the chuck table 31 holds the wafer 100 by the holding surface 32.

Further, the chuck table 31 can rotate about the central axis extending in the Z-axis direction passing through the center of the holding surface 32 while the wafer 100 is held by the holding surface 32 by the rotating means 34 provided below. Is. Therefore, the wafer 100 is held by the holding surface 32 and rotated about the center of the holding surface 32.

Further, below the holding means 30, a Y-axis direction moving means 40 is arranged.
The Y-axis direction moving means 40 moves the holding means 30 and the grinding means 70 in the Y-axis direction relatively parallel to the holding surface 32. In the present embodiment, the Y-axis direction moving means 40 is configured to move the holding means 30 in the Y-axis direction with respect to the grinding means 70.
The grinding device 1 may have a turntable having a plurality of holding means 30 as the horizontal moving means instead of the Y-axis direction moving means 40.

The Y-axis direction moving means 40 includes a Y-axis guide rail 42 parallel to the Y-axis direction, a Y-axis moving table 45 sliding on the Y-axis guide rail 42, a Y-axis ball screw 43 parallel to the Y-axis guide rail 42, and Y. It includes a Y-axis motor 44 connected to the shaft ball screw 43, and a holding base 41 for holding the Y-axis motor 44.

The Y-axis moving table 45 is slidably installed on the Y-axis guide rail 42 via the slide member 451. A nut portion 401 is fixed to the lower surface of the Y-axis moving table 45. A Y-axis ball screw 43 is screwed into the nut portion 401. The Y-axis motor 44 is connected to one end of the Y-axis ball screw 43.

In the Y-axis direction moving means 40, the Y-axis moving table 45 moves in the Y-axis direction along the Y-axis guide rail 42 by rotating the Y-axis ball screw 43 by the Y-axis motor 44. The support member 33 of the holding means 30 is placed on the Y-axis moving table 45 via the support pillar 35. Therefore, as the Y-axis moving table 45 moves in the Y-axis direction, the holding means 30 including the chuck table 31 moves in the Y-axis direction.

Further, as shown in FIG. 1, a column 11 is erected behind the holding means 30 (on the + Y direction side). A grinding means 70 for grinding the wafer 100 and a grinding feed means 50 are provided on the front surface of the column 11.

The grinding feed means 50 moves the holding means 30 and the grinding means 70 relatively in the Z-axis direction (grinding feed direction) perpendicular to the holding surface 32. In the present embodiment, the grinding feed means 50 is configured to move the grinding means 70 with respect to the holding means 30 in the Z-axis direction perpendicular to the holding surface 32.

The grinding feed means 50 includes a Z-axis guide rail 51 parallel to the Z-axis direction, a Z-axis moving table 53 sliding on the Z-axis guide rail 51, a Z-axis ball screw 52 parallel to the Z-axis guide rail 51, and a Z-axis motor. 54, a Z-axis encoder 55 for detecting the rotation angle of the Z-axis motor 54, and a holder 56 attached to the front surface (front surface) of the Z-axis moving table 53 are provided. The holder 56 holds the grinding means 70.

The Z-axis moving table 53 is slidably installed on the Z-axis guide rail 51 via the slide member 531. A nut portion 501 is fixed to the rear surface side (rear surface side) of the Z-axis moving table 53. A Z-axis ball screw 52 is screwed into the nut portion 501. The Z-axis motor 54 is connected to one end of the Z-axis ball screw 52.

In the grinding feed means 50, the Z-axis motor 54 rotates the Z-axis ball screw 52, so that the Z-axis moving table 53 moves along the Z-axis guide rail 51 in the Z-axis direction. As a result, the holder 56 attached to the Z-axis moving table 53 and the grinding means 70 held by the holder 56 also move in the Z-axis direction together with the Z-axis moving table 53.

The grinding means 70 includes a spindle housing 71 fixed to the holder 56, a spindle 72 rotatably held in the spindle housing 71, a rotary motor 73 for rotationally driving the spindle 72, and a wheel mount 74 attached to the lower end of the spindle 72. It also includes a grinding wheel 75 supported by a wheel mount 74.

The spindle housing 71 is held by the holder 56 so as to extend in the Z-axis direction. The spindle 72 extends in the Z-axis direction so as to be orthogonal to the holding surface 32 of the chuck table 31, and is rotatably supported by the spindle housing 71.

The rotary motor 73 is connected to the upper end side of the spindle 72. The rotary motor 73 causes the spindle 72 to rotate about a rotary axis extending in the Z-axis direction.

The wheel mount 74 is formed in a disk shape and is fixed to the lower end (tip) of the spindle 72. The wheel mount 74 supports the grinding wheel 75.

The grinding wheel 75 is formed so that the outer diameter has substantially the same diameter as the outer diameter of the wheel mount 74. The grinding wheel 75 includes an annular wheel base 76 formed of a metal material. Inside the wheel base 76, a processing channel 761 for supplying processing water from a water source (not shown) to the grinding wheel 77 is formed.

A plurality of grinding wheels 77 arranged in an annular shape are fixed to the lower surface of the wheel base 76 over the entire circumference. That is, a grinding wheel 77 is mounted on the lower end of the spindle 72.

The annularly arranged grinding wheel 77 is rotated around the center thereof by a rotary motor 73 via a spindle 72, a wheel mount 74, and a wheel base 76, and is held on the back surface of the wafer 100 on the chuck table 31. 102 is ground.
As described above, the grinding means 70 holds the wafer 100 on the holding surface 32 by the annular grinding wheel 77 mounted on the lower end of the spindle 72, that is, the lower surface of the wheel mount 74 arranged at the lower end of the spindle 72. Grind.

Further, the grinding device 1 includes a thickness measuring means 60 for measuring the thickness of the wafer 100. The thickness measuring means 60 can measure the thickness of the wafer 100 held on the holding surface 32 by a contact method. The thickness measuring means 60 includes a first gauge 61 as a holding surface height measuring device for measuring the height of the holding surface 32, and a top surface height measuring device for measuring the height of the upper surface (back surface 102) of the wafer 100. It has a second gauge 62 of.

The thickness measuring means 60 brings the first gauge 61 and the second gauge 62 into contact with the upper surface of the frame body 36 of the chuck table 31 and the back surface 102 of the wafer 100, respectively. Thereby, the thickness measuring means 60 can measure the height of the holding surface 32 of the chuck table 31 and the height (upper surface height) of the back surface 102 of the wafer 100. The measured height of the holding surface 32 and the height of the back surface 102 of the wafer 100 are sent to the thickness calculation unit 63. The thickness calculation unit 63 can calculate the thickness of the wafer 100 based on the difference between the height of the holding surface 32 and the height of the back surface 102 of the wafer 100.

The thickness measuring means 60 replaces the first gauge 61 and the second gauge 62 with a non-contact distance measuring device, for example, a laser distance measuring device, as a holding surface height measuring device and a top surface height measuring device. May be provided. For example, this distance measuring instrument irradiates the wafer 100 with a laser beam, receives the reflected light from the holding surface 32 and the reflected light from the back surface 102 of the wafer 100, and based on these, the height of the holding surface 32 and the wafer. The height of the back surface 102 of the 100 and the thickness of the wafer 100 are measured.

The control unit 90 controls each member of the grinding device 1 to perform grinding on the wafer 100. Further, the grinding device 1 includes a storage unit 92. Hereinafter, the grinding process of the wafer 100 in the grinding apparatus 1 controlled by the control unit 90 will be described together with the function of the storage unit 92.

In the present embodiment, first, the operator holds the wafer 100 on the holding surface 32 of the chuck table 31 so that the back surface 102 faces upward.

Next, the control unit 90 controls the Y-axis direction moving means 40 and holds the grinding wheel 77 until it is positioned at the rotation center of the wafer 100 held on the holding surface 32 of the chuck table 31 in the holding means 30. The means 30 is moved in the Y-axis direction.

Further, the control unit 90 controls the rotary motor 73 of the grinding means 70 to rotate the grinding wheel 75 (grinding grindstone 77) together with the spindle 72. Further, the control unit 90 rotates the holding surface 32 (wafer 100) of the chuck table 31 by the rotating means 34.

Next, the control unit 90 uses the grinding feed means 50 to bring the grinding means 70 at the origin height position closer to the holding means 30.

FIG. 2 shows the time change of the height of the grinding wheel 77 (the height of the lower surface (grinding surface) of the grinding wheel 77) by a broken line. As shown in FIG. 2, the control unit 90 first holds the grinding means 70 at a relatively high initial speed V1 until the height of the grinding wheel 77 reaches a predetermined air cut start height H1. It is lowered so as to approach the means 30 (time range T1).

Further, the control unit 90 starts measuring the height of the holding surface 32 of the chuck table 31 by the first gauge 61 at the same time as the descent of the grinding wheel 77 starts.

Then, the storage unit 92 measures the height of the holding surface 32 measured by the first gauge 61 before the grinding wheel 77 comes into contact with the back surface 102 of the wafer 100 held by the holding surface 32 of the chuck table 31, that is, grinding. The height of the holding surface 32 before processing is stored.

The height of the holding surface 32 at the time of grinding is lowered because the holding surface 32 is pressed downward by the grinding wheel 77 when the grinding wheel 77 comes into contact with the wafer 100 on the holding surface 32. FIG. 2 shows the time change of the measured height of the holding surface 32 by a solid line.

In the time range T1, the grinding wheel 77 is not in contact with the wafer 100 on the holding surface 32. Therefore, as shown in FIG. 2, the height of the holding surface 32 is maintained at the height (h1) before grinding.

After the grinding wheel 77 reaches the air cut start height H1, the control unit 90 uses the grinding feed means 50 to reduce the descent speed of the grinding means 70 to the first grinding, which is a machining feed rate slower than the initial speed V1. The speed is set to V2 and the grinding means 70 is brought closer to the holding means 30 (time range T2). That is, the control unit 90 slows down the descending speed of the grinding means 70 from the initial speed V1 to the first grinding speed V2.

In the time range T2, the grinding wheel 77 is not yet in contact with the wafer 100 and is air-cut. Then, after the grinding wheel 77 comes into contact with the back surface 102 of the wafer 100 (time t1), the control unit 90 grinds the back surface 102 of the wafer 100 with the grinding wheel 77 at the first grinding speed V2 (time range). T3; 1st grinding process). When the first grinding process is started, the height (h2) of the holding surface 32 measured by the first gauge 61 is gradually lowered because the holding surface 32 is pressed downward by the grinding wheel 77. Going.

After that, the control unit 90 measures the thickness of the wafer 100 being ground by appropriately using the thickness measuring means 60 and the thickness calculating unit 63. Then, when the thickness of the wafer 100 approaches a predetermined value (target value), the control unit 90 uses the grinding feed means 50 to use the grinding means 70 at the second grinding speed V3, which is slower than the first grinding speed V2. It is brought closer to the holding means 30 (time range T4). That is, the control unit 90 further slows the descent speed of the grinding means 70 from the first grinding speed V2 to the second grinding speed V3, and continues the grinding process (second grinding process). In this second grinding process, the damage caused to the wafer 100 in the first grinding process is reduced.

Further, in the second grinding process, the lowering speed of the grinding means 70 becomes slower, so that the downward pressing force of the grinding wheel 77 against the wafer 100 becomes smaller. Therefore, the height (h3) of the holding surface 32 measured by the first gauge 61 gradually increases as compared with the end of the first grinding process.

After the time t2 when the thickness of the wafer 100 reaches a predetermined value, the control unit 90 performs a so-called spark-out process (time range T5). In the spark-out, the control unit 90 stops the descent of the grinding means 70 by the grinding feed means 50, maintains the height of the rotating grindstone 77 for a predetermined time, and removes the uncut portion on the back surface 102 of the wafer 100. ..

In this spark-out, the lowering of the grinding means 70 is stopped, so that the downward pressing force of the grinding wheel 77 against the wafer 100 is further reduced. Therefore, the height (h4) of the holding surface 32 measured by the first gauge 61 gradually increases as compared with the end of the second grinding process.

After that, the control unit 90 performs escape cut processing (time range T6). In the escape cut processing, the control unit 90 uses the grinding feed means 50 to suppress the adverse effect of the grinding wheel 77 on the back surface 102 of the wafer 100, and sets the grinding means 70 at a preset escape cut processing speed. The wafer 100 is escape-cut by the grinding wheel 77 by slowly moving it upward in V4.

In this escape cut process, the grinding means 70 is slowly raised, so that the downward pressing force of the grinding wheel 77 against the wafer 100 is further reduced. Therefore, the height (h5) of the holding surface 32 measured by the first gauge 61 becomes higher than that at the time of spark-out.

When the escape cut process is proceeded, the grinding wheel 77 finally separates from the back surface 102 of the wafer 100, and the grinding wheel 77 does not grind the back surface 102 of the wafer 100. At this time, the holding surface 32 is not subjected to the pressing force of the grinding wheel 77. Therefore, the height (h5) of the holding surface 32 in the escape cut process is the height (h1) before the grinding process.

Then, in the present embodiment, the control unit 90 until the height (h5) of the holding surface 32 measured by the first gauge 61 becomes the height (h1) before grinding that is stored in the storage unit 92. , Escape cut processing is performed to raise the grinding wheel 77 at the escape cut processing speed V4.

After the escape cut is completed, the control unit 90 retracts the grinding means 70 to the origin height position at a relatively high evacuation speed V5 by using the grinding feed means 50 (time range T7).

As described above, in the present embodiment, the escape cut process is performed until the height of the holding surface 32 pressed by the grinding wheel 77 becomes the height before the grinding process.

Here, the escape cut process is performed in order to prevent the back surface 102 of the wafer 100 from being formed with irregularities by the grinding wheel 77 that is about to move away from the wafer 100. Therefore, the optimum moving distance (climbing distance) of the grinding wheel 77 in the escape cut processing is the distance until the grinding wheel 77 does not come into contact with the wafer 100 of the holding surface 32, that is, until the grinding wheel 77 separates from the wafer 100. ..

The height of the holding surface 32 before the grinding process means that the holding surface 32 is no longer pressed by the grinding wheel 77, that is, the grinding wheel 77 is separated from the wafer 100. Therefore, in the present embodiment, it is possible to optimize the moving distance (moving time) of the grinding wheel 77 in the escape cut processing.

The grinding device according to the present embodiment may be the grinding device 2 as shown in FIG. The grinding device 2 is a device for grinding a wafer 100 as a workpiece, similar to the grinding device 1 shown in FIG. The grinding device 2 further includes a displacement meter 80 in the configuration of the grinding device 1.

The displacement meter 80 includes a support base 84 provided on a base (not shown) of the grinding device 1, an arm 85 extending horizontally from the tip of the support base 84, and an upper displacement meter 81 extending horizontally from the arm 85. And a lower displacement meter 82.

The support base 84 is provided on the base of the grinding device 1 so as to be rotatable with respect to the base. Therefore, the upper displacement meter 81 and the lower displacement meter 82 supported by the support base 84 via the arm 85 can also rotate with the rotation of the support base 84. By this turning, the tips of the upper displacement meter 81 and the lower displacement meter 82 can be arranged below the wheel mount 74 and above the holding surface 32, respectively.

The upper displacement meter 81 is used to measure the amount of upward displacement of the mount lower surface 741, which is the lower surface of the wheel mount 74. The amount of upward displacement of the mount lower surface 741 is an amount of upward displacement of the mount lower surface 741 when an upward load that pushes up the wheel mount 74 upward is applied to the lower surface of the mount lower surface 741.

The lower displacement meter 82 is used to measure the amount of downward displacement of the holding surface 32 of the chuck table 31. The downward displacement amount of the holding surface 32 is an amount of downward displacement of the holding surface 32 when a downward load that pushes the holding surface 32 downward is applied to the holding surface 32.

Note that FIG. 3 shows the state of the grinding device 2 at the time of the data table storage process described later. Although not shown in FIG. 3, when the grinding device 2 also grinds the wafer 100, the grinding means 70 has a grinding wheel 75 having a grinding wheel 77 supported by a wheel mount 74 at the lower end of the spindle 72. (See FIG. 1).

Further, although not shown in FIG. 3, the grinding device 2 includes a thickness measuring means 60 including a first gauge 61 and a second gauge 62, similar to those shown in FIG. 1.

Further, in the grinding device 2, the control unit 90 includes a first calculation unit 93, an extraction unit 94, and a second calculation unit 95. Hereinafter, the operation of the grinding device 2 controlled by the control unit 90 will be described together with the functions of the first calculation unit 93, the extraction unit 94, and the second calculation unit 95.

In the grinding apparatus 2, a data table storage step is carried out as a preparatory step for grinding to grind the wafer 100.

In this step, the operator removes the grinding wheel 75 from the grinding means 70 of the grinding device 2 to expose the mount lower surface 741 of the wheel mount 74. Then, as shown in FIG. 3, the control unit 90 or the operator puts the tips of the upper displacement meter 81 and the lower displacement meter 82 in the displacement meter 80 below the wheel mount 74 and above the holding surface 32, respectively. Deploy.

Further, the operator arranges and intervenes the telescopic unit 110 that can be expanded and contracted in the vertical direction (Z-axis direction) between the lower surface 741 of the mount and the holding surface 32 of the chuck table 31 arranged below the lower surface of the mount.

The telescopic unit 110 includes a cylinder 112 and a piston 111 that is movable within the cylinder 112. The cylinder 112 communicates with the air source 116 via the regulator 115.

When the expansion / contraction unit 110 is interposed between the holding surface 32 and the mount lower surface 741 and the air from the air source 116 is introduced into the cylinder 112 by the regulator 115, the piston 111 is moved into the cylinder 112. It moves in the + Z direction, and the expansion / contraction unit 110 extends. By extending in this way, the expansion / contraction unit 110 can apply a downward load and an upward load to the holding surface 32 and the mount lower surface 741, respectively.

On the other hand, when the air in the piston 111 is exhausted by the regulator 115, the piston 111 moves in the −Z direction in the cylinder 112, and the expansion / contraction unit 110 contracts.

Then, the control unit 90 pushes down the holding surface 32 by extending the expansion / contraction unit interposed between the holding surface 32 and the lower surface of the mount 741, and pushes up the holding surface 32 and the wheel mount 74 upward. A load having a predetermined load value (downward load and upward load) is applied to the lower surface 741 of the mount.

Further, the control unit 90 measures the downward displacement amount of the holding surface 32 and the upward displacement amount of the mount lower surface 741 at this time by using the displacement meter 80. Then, the control unit 90 measures, for example, the downward displacement amount of the holding surface 32 and the upward displacement amount of the mount lower surface 741 while changing the load (downward load and upward load) of a predetermined load value.

Then, the control unit 90 acquires the relationship between the downward displacement amount of the holding surface 32 and the upward displacement amount of the mount lower surface 741 with respect to the given predetermined load value, and generates a data table 921 showing this relationship. do. Then, the storage unit 92 stores the data table 921.
The storage unit 92 may perform the control of applying the downward load and the upward load and generating the data table 921 instead of the control unit 90.

Next, the operator and the storage unit 92 perform grinding on the wafer 100 as described with reference to FIG. 2 for the grinding device 1.

That is, the operator removes the expansion / contraction unit 110 from between the lower surface of the mount 741 and the holding surface 32, and attaches the grinding wheel 75 (see FIG. 1) including the grinding wheel 77 to the wheel mount 74. Further, the control unit 90 or the operator rotates the support base 84 so that the tips of the upper displacement meter 81 and the lower displacement meter 82 in the displacement meter 80 are separated from the lower part of the wheel mount 74 and the upper part of the holding surface 32. Let me.

Further, the operator causes the holding surface 32 of the chuck table 31 to hold the wafer 100. Then, the control unit 90 aligns the positions of the grinding means 70 and the holding means 30 in the Y-axis direction, and rotates the holding surface 32 and the grinding wheel 77. Then, the control unit 90 lowers the grinding means 70 at the initial speed V1 by using the grinding feed means 50 (FIG. 2; time range T1), and holds the chuck table 31 by the first gauge 61 (see FIG. 1). The measurement of the height of the surface 32 is started.

Then, the storage unit 92 measures the height of the holding surface 32 measured by the first gauge 61 before the grinding wheel 77 comes into contact with the back surface 102 of the wafer 100 held by the holding surface 32, that is, the holding before grinding. The height of the surface 32 is stored as the height of the first holding surface.

Further, the control unit 90 has an air cut (time range T2), a first grinding process (time range T3), a second grinding process (time range T4), and a spark-out process (time range) shown with reference to FIG. T5) is carried out.

Further, the storage unit 92 is after the thickness of the wafer 100 reaches a predetermined value, and before the start of the escape cut process (time range T6) in which the grinding wheel 77 is separated from the back surface 102 of the wafer 100 (that is,). , Immediately before the start of the escape cut process), the height of the holding surface 32 measured by the first gauge 61 is stored as the height of the second holding surface.
Then, the first calculation unit 93 shown in FIG. 3 calculates the difference between the height of the first holding surface and the height of the second holding surface as the amount of downward displacement of the holding surface 32 during machining.

After that, the extraction unit 94 refers to the data table 921 stored in the storage unit 92 by using the downward displacement amount of the holding surface 32 during processing, and the downward displacement having the same value as the downward displacement amount during processing. The amount of upward displacement according to the amount is extracted as the amount of upward displacement during processing in the grinding wheel 77 immediately before the start of escape cut processing.

Further, the second calculation unit 95 moves the value obtained by adding the amount of downward displacement of the holding surface 32 during machining and the amount of upward displacement of the grinding wheel 77 during machining upwards of the grinding wheel 77 during escape cut machining. Calculated as a distance.

After that, the control unit 90 performs the above-mentioned escape cut processing (time range T6 in FIG. 2). Then, in the grinding device 2, the control unit 90 uses the grinding feed means 50 to grind at a preset escape cut processing speed V4 until the moving distance of the grinding wheel 77 reaches the above-mentioned upward moving distance. By moving the grindstone 77 upward, the wafer 100 is escape-cut by the grinding grindstone 77.

After the escape cut is completed, the control unit 90 retracts the grinding means 70 to the origin height position at a relatively high evacuation speed V5 by using the grinding feed means 50 (time range T7).

As described above, in the present embodiment, in the grinding device 2, the escape cut process is performed until the moving distance of the grinding wheel 77 becomes the above-mentioned upward moving distance.

As described above, the optimum moving distance (climbing distance) of the grinding wheel 77 in the escape cut processing is until the grinding wheel 77 does not come into contact with the wafer 100 of the holding surface 32, that is, until the grinding wheel 77 separates from the wafer 100. The distance.

The upward movement distance of the grinding wheel 77 is the amount of upward displacement of the grinding wheel 77 due to the grinding wheel 77 pressing the holding surface 32 when the thickness of the wafer 100 reaches a predetermined value. It is the sum of the downward displacement amounts of the holding surface 32. Therefore, the fact that the grinding wheel 77 rises by the upward moving distance means that the holding surface 32 is not pressed by the grinding wheel 77, that is, the grinding wheel 77 is separated from the wafer 100. Therefore, in the present embodiment, it is possible to optimize the moving distance (moving time) of the grinding wheel 77 in the escape cut processing.

Further, in the grinding apparatus 2, the moving distance of the grinding wheel 77 in the escape cut processing can be optimized without measuring the height of the holding surface 32 during the grinding process. Therefore, it is possible to simplify the control of grinding.

1: Grinding device 2: Grinding device, 11: Column,
30: Holding means, 31: Chuck table, 32: Holding surface, 36: Frame body,
33: Support member, 34: Rotating means, 35: Support pillar,
40: Y-axis direction moving means, 41: holding base, 42: Y-axis guide rail,
43: Y-axis ball screw, 44: Y-axis motor, 45: Y-axis moving table,
50: Grinding feed means, 51: Z-axis guide rail,
52: Z-axis ball screw, 53: Z-axis moving table, 54: Z-axis motor,
55: Z-axis encoder, 56: Holder 60: Thickness measuring means, 61: 1st gauge, 62: 2nd gauge, 63: Thickness calculation unit,
70: Grinding means, 71: Spindle housing, 72: Spindle,
73: Rotating motor, 74: Wheel mount, 741: Underside of mount,
75: Grinding wheel, 76: Wheel base, 77: Grinding wheel,
80: Displacement meter, 81: Upper displacement meter, 82: Lower displacement meter, 84: Support base, 85: Arm,
90: control unit, 92: storage unit, 921: data table 93: first calculation unit, 94: extraction unit, 95: second calculation unit,
100: Wafer, 101: Front side, 102: Back side, 103: Protective tape,
110: Telescopic unit, 111: Piston, 112: Cylinder,
115: Regulator, 116: Air source

Claims (2)

A chuck table that holds the workpiece by the holding surface, a grinding means that grinds the workpiece held on the holding surface by an annular grinding wheel mounted on the lower end of the spindle, and a direction perpendicular to the holding surface. A grinding device including at least a grinding feed means for moving the grinding means, a holding surface height measuring device for measuring the height of the holding surface, and a thickness measuring means for measuring the thickness of the workpiece. hand,
A storage unit that stores the holding surface height measured by the holding surface height measuring device before the grinding wheel comes into contact with the workpiece held on the holding surface.
After the workpiece is ground to a predetermined thickness by the grinding wheel, the grinding wheel is operated until the holding surface height measured by the holding surface height measuring device becomes the height stored in the storage unit. A control unit that performs escape cut processing on the workpiece by the grinding wheel by moving it upward at a preset escape cut processing speed.
A grinding device equipped with. A chuck table that holds the workpiece by the holding surface, and a grinding means that grinds the workpiece held on the holding surface by an annular grinding wheel mounted on the lower surface of the mount arranged at the lower end of the spindle. A grinding feed means for moving the grinding means in a direction perpendicular to the holding surface, a holding surface height measuring device for measuring the height of the holding surface, and a thickness measuring means for measuring the thickness of the workpiece. It is a grinding device equipped with at least
The holding surface and the holding surface and the mounting surface so as to push down the holding surface and push up the mount by extending a vertically expandable telescopic unit interposed between the holding surface and the lower surface of the mount. A load of a predetermined load value is applied to the lower surface of the mount, the amount of downward displacement of the holding surface and the amount of upward displacement of the lower surface of the mount are measured, and the downward direction with respect to the applied predetermined load value. A storage unit that stores a data table showing the relationship between the displacement amount and the upward displacement amount,
The first holding surface height, which is the holding surface height measured by the holding surface height measuring instrument before the grinding wheel is brought into contact with the workpiece held on the holding surface, and the workpiece by the grinding wheel. Is the holding surface height measured by the holding surface height measuring instrument immediately before the start of the escape cut process in which the grinding wheel is ground to a predetermined thickness and then the grinding wheel is ground while being separated from the workpiece. 2 The first calculation unit that calculates the difference from the height of the holding surface as the amount of downward displacement of the holding surface during machining,
The data table is referred to using the downward displacement amount during machining, and the upward displacement amount corresponding to the downward displacement amount having the same value as the machining downward displacement amount is obtained immediately before the start of escape cut machining. An extraction unit that extracts as an upward displacement amount during processing of the grinding means,
A second calculation unit that calculates the sum of the downward displacement amount during machining and the upward displacement amount during machining as the upward movement distance of the grinding wheel during escape cut machining.
By moving the grinding wheel upward at a preset escape cut processing speed until the moving distance of the grinding wheel reaches the upward moving distance, the workpiece is escape-cut by the grinding wheel. , Control unit,
A grinding device equipped with.

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