TW202112491A - Grinding apparatus and grinding method in which a grindstone is arranged at a position of not covering an object to be processed so as to prevent the grindstone from contacting the object when the grindstone is lowered down to the height of an upper surface of the object - Google Patents

Abstract

An objective of the present invention is to shorten a processing time while suppressing damage to a processed object. A solution is that, in the instant embodiment, a grindstone (37) is lowered down to the height (H) of an upper surface of a wafer (W) in a condition that the grindstone (37) is arranged at a position of not covering the wafer (W). Consequently, the grindstone (37) is prevented from being brought into contact with the wafer (W) in lowering down the grindstone (37). As such, the grindstone (37) can be lowered down to the height (H) of the upper surface of the wafer (W) at a high lowering-down speed. Therefore, the time that it takes to process the wafer (W) can be shortened.

Description

Grinding device and grinding method

The invention relates to a grinding device and a grinding method.

In the polishing device disclosed in Patent Document 1, the polishing grindstone is lowered close to the wafer held on the holding surface of the chuck, and the thickness of the wafer is measured while reaching a specific thickness. The polishing grindstone is transported through the polishing grindstone. round.

When lowering the grinding grindstone, until it is held near the upper surface of the wafer on the holding surface, the grinding grindstone is lowered at a high speed. After that, the descending speed is changed to a low speed, so that the grinding stone is brought into contact with the wafer. In this way, after changing the descending speed to a low speed, the situation in which the grinding stone is approached to the wafer at a low speed from the vicinity of the upper surface of the wafer to the wafer contacting the polishing grindstone is called gas cutting. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2008-073785 A

[The problem to be solved by the invention]

In gas cutting, when the lowering speed of the grinding stone is too fast, the wafer may be damaged or the grinding stone may be damaged due to the impact of the grinding stone contacting the wafer. On the other hand, when the polishing speed is too slow, the processing time becomes longer and the efficiency deteriorates.

Therefore, the object of the present invention is to reduce the processing time while suppressing the damage of the processed objects such as wafers. [Means to solve the problem]

The polishing device (this polishing device) of the present invention is provided with a holding means for holding a workpiece through a holding surface, and a workpiece that is held on the holding surface and rotated with the center of the holding surface as the axis. A grinding grindstone arranged on a rotating grinding wheel, a grinding means for grinding, and a horizontal moving means that moves the holding means and the grinding means in a horizontal direction parallel to the holding surface, and the grinding means , In the holding surface, the polishing device of the grinding and feeding means that moves in the vertical direction and the control means, the control means is provided with: viewed from the upper side of the holding surface, on the workpiece held on the holding surface , Without covering the grinding stone, using the horizontal movement means, positioning the holding means and the first control part of the polishing means, and measuring the thickness of the workpiece to be held on the holding surface by the thickness measuring means, The second control unit that calculates the height of the upper surface of the workpiece held on the holding surface, and lowers the lower surface of the grinding stone to the height of the upper surface of the workpiece calculated by the second control unit, and controls the grinding progress The third control part of the means and the horizontal movement means are used until the grinding stone is positioned at the center of rotation of the workpiece held on the holding surface of the holding means, and the holding means and the grinding means are moved relative to each other A fourth control unit in the horizontal direction and a fifth control unit that grinds and feeds the grinding means at a predetermined grinding feed rate to grind the workpiece to a specific thickness.

The polishing method of the present invention (this polishing method) includes: a holding means with a holding surface, a holding process for holding a workpiece, the holding means and a polishing means with a grinding stone, viewed from above the holding surface , In the workpiece held on the holding surface, without covering the grinding stone, away from the first step in the horizontal direction, and the second step to calculate the height of the upper surface of the workpiece held on the holding surface, and The lower surface of the grinding grindstone is lowered to the height of the upper surface of the workpiece calculated in the second step, and the third step of grinding and feeding the grinding means in the vertical direction on the holding surface, and until the grinding grindstone is positioned on the workpiece The center of rotation of the object, the fourth step in which the holding means and the polishing means are moved in the horizontal direction relative to each other, and the polishing means is fed to the polishing means at a preset polishing feed rate to grind the workpiece to a specific The thickness of the fifth project. [Effects of the invention]

In the polishing device and the polishing method, the polishing grindstone is lowered to the height of the object to be processed in a state where the polishing grindstone is arranged at a position not covering the object to be processed. For this reason, when the grinding stone is lowered, it is possible to prevent the grinding stone from contacting the workpiece. Therefore, there is no need to perform gas cutting, and the grinding stone can be lowered to the height of the workpiece at a rapid descending speed. Therefore, it is possible to shorten the time taken for the processing of the workpiece.

[For the implementation of the invention]

As shown in FIG. 1, the polishing apparatus 11 of this embodiment is an apparatus for polishing a wafer W as a workpiece, and includes a rectangular parallelepiped base 12, a column 13 extending upward, and one of the control polishing apparatus 11 Control means 70 of each component.

The wafer W is, for example, a circular semiconductor wafer. In FIG. 1, the surface of the wafer W facing downward is held by a plurality of devices, and a protective tape T is attached to protect it. The back surface of the wafer W becomes the surface to be processed by polishing.

On the upper surface side of the base 12, an opening 12a is provided. Then, the holding means 15 is arranged in the opening 12a. The holding means 15 includes a chuck 18 having a holding surface 19 for sucking the wafer W, and a support member 16 that supports the chuck 18.

The holding surface 19 of the chuck 18 is connected to a suction source (not shown), and the wafer W is sucked and held by the protective tape T. That is, the holding means 15 holds the wafer W via the holding surface 19.

In addition, the chuck 18 can be rotated around a central axis extending in the Z-axis direction through the center of the holding surface 19 while holding the wafer W on the holding surface 19 by a rotating means not shown. Therefore, the wafer W is held on the holding surface 19 and is rotated about the center of the holding surface 19 as an axis.

Around the chuck 18, a snake belly cover J that expands and contracts in the Y-axis direction is connected. Then, under the holding means 15, a Y-axis direction moving means 40 is arranged.

The Y-axis direction moving means 40 is an example of a horizontal moving means. The moving means 40 in the Y-axis direction relatively moves the holding means 15 and the polishing means 30 in a horizontal direction parallel to the holding surface 19. The Y-axis direction moving means 40 is provided with a pair of Y-axis guide rails 42 parallel to the Y-axis direction, a Y-axis moving platform 45 sliding on the Y-axis guide rail 42, and a Y-axis ball screw 43 parallel to the Y-axis guide rail 42. And, a Y-axis servo motor 44 connected to the Y-axis ball screw 43, a Y-axis encoder 46 for detecting the rotation speed and position of the Y-axis servo motor 44, and a holding table 41 for holding these.

The Y-axis moving platform 45 is slidably arranged on the Y-axis guide rail 42. On the underside of the Y-axis moving platform 45, a nut portion 45a is fixed (refer to FIG. 3). A Y-axis ball screw 43 is screwed into this nut portion 45a. The Y-axis servo motor 44 is connected to one end of the Y-axis ball screw 43.

As shown in FIG. 1, in the Y-axis direction moving means 40, the Y-axis servo motor 44 rotates the Y-axis ball screw 43, and the Y-axis moving platform 45 moves in the Y-axis direction along the Y-axis guide 42. On the Y-axis moving platform 45, the supporting member 16 of the holding means 15 is placed. Therefore, with the movement of the Y-axis direction of the Y-axis moving platform 45, the holding means 15 including the chuck 18 moves in the Y-axis direction.

However, as shown in FIG. 3, the supporting member 16 is attached to the Y-axis moving platform 45 and is placed by the tilt changing member 17. The inclination changing member 17 is used to change the inclination of the holding surface 19 of the holding means 15.

In the present embodiment, the holding means 15 is generally set on the holding surface 19 at the wafer placement position before the wafer W is placed (-Y direction side), and after the wafer W is polished (+Y direction side) ) In the grinding area, move along the Y-axis direction. Furthermore, when the wafer W is polished by the polishing grindstone 37 of the polishing means 30, the holding means 15 having the holding surface 19 moves in the Y-axis direction in the polishing area.

In addition, as shown in FIG. 1, a column 13 is erected on the back of the base 12 (+Y direction side). On the front surface of the column 13, a polishing means 30 for polishing the wafer W and a polishing and feeding means 14 for moving the polishing means 30 in the Z-axis direction (grinding and feeding means) perpendicular to the holding surface 19 are provided.

The grinding and feeding means 14 is equipped with a pair of Z-axis guide rails 21 parallel to the Z-axis direction, a Z-axis moving platform 23 sliding on the Z-axis guide 21, and Z-axis ball screws 20, Z-axis parallel to the Z-axis guide 21. The axis servo motor 22, a Z axis encoder 25 for detecting the rotation speed and position of the Z axis servo motor 22, and a holder 24 mounted on the front (surface) of the Z axis moving platform 23. The holder 24 is a holding grinding means 30.

The Z-axis moving platform 23 is slidably arranged on the Z-axis guide rail 21. The nut portion 20a is fixed to the rear surface side (rear side) of the Z-axis movement stage 23 (refer to FIG. 3). The Z-axis ball screw 20 is screwed into this nut portion 20a. The Z-axis servo motor 22 is connected to one end of the Z-axis ball screw 20.

As shown in FIG. 1, in the grinding and feeding means 14, the Z-axis servo motor 22 rotates the Z-axis ball screw 20, and the Z-axis moving platform 23 moves in the Z-axis direction along the Z-axis guide 21. Thereby, the holder 24 attached to the Z-axis moving platform 23 and the polishing means 30 held on the holder 24 also move in the Z-axis direction along with the Z-axis moving platform 23.

The grinding means 30 includes: a main shaft housing 31 fixed to the holder 24, a main shaft 32 rotatably held in the main shaft housing 31, a motor 33 that drives the main shaft 32 to rotate, and a wheel frame 34 installed at the lower end of the main shaft 32, and The grinding wheel 35 supported on the wheel frame 34.

The main shaft housing 31 extends in the Z-axis direction and is held by the holder 24. The main shaft 32 is orthogonal to the holding surface 19 of the chuck 18, extends in the Z-axis direction, and is rotatably supported by the main shaft housing 31. The motor 33 is connected to the upper end side of the main shaft 32. Via this motor 33, the main shaft 32 rotates around a rotating shaft extending in the Z-axis direction as the center.

The wheel carrier 34 is formed in a circular plate shape, and is fixed to the lower end (front end) of the main shaft 32. The wheel frame 34 supports the grinding wheel 35.

The grinding wheel 35 is formed to have approximately the same diameter as the wheel frame 34. The grinding wheel 35 includes an annular wheel base (ring base) 36 formed of a metal material such as stainless steel. On the underside of the wheel base 36, a plurality of grinding stones 37 arranged in a ring shape are fixed on the entire circumference. The polishing grindstone 37 grinds the back surface of the wafer W held on the chuck 18 arranged in the polishing area. However, the outer side of the lower end of the grinding stone 37 can be rounded.

In this way, the polishing means 30 grinds the wafer W held on the holding surface 19 of the holding means 15 with the center of the holding surface 19 as an axis, and the polishing grindstone 37 arranged on the rotating polishing wheel 35 in a ring shape.

Moreover, as shown in FIG. 1, the thickness measuring means 51 is arrange|positioned at the side part of the opening part 12a of the base 12. As shown in FIG. The thickness measuring means 51 can measure the thickness of the wafer W, for example, by a contact method.

That is, the thickness measuring means 51 is attached to the holding surface 19 of the chuck 18 and the wafer W, and contacts the contact 54 and the contact 55 respectively. Thus, the thickness measuring means 51 obtains the height of the holding surface 19 of the chuck 18 and the height of the wafer W, and can measure the thickness of the wafer W based on the difference in height.

However, the contact member 54 and the contact member 55 are non-contact distance measuring devices, such as laser distance measuring devices.

As shown in FIG. 2, the control means 70 includes a first control unit 71, a second control unit 72, a third control unit 73, a fourth control unit 74, and a fifth control unit 75. Hereinafter, along with the functions of the five control units 71 to 75, the polishing method of the wafer W of the polishing apparatus 11 will be described.

In this embodiment, first, the control means 70 or the operator attaches to the holding means 15 having the holding surface 19 shown in FIG. 1 to hold the wafer W (holding process).

Next, the first control section 71 of the control means 70 controls the Y-axis direction moving means 40. As shown in FIG. 3, when viewed from above the holding surface 19 of the holding means 15, on the wafer W held on the holding surface 19, The grinding stone 37 of the grinding means 30 is not covered, and the positioning and holding means 15 and the grinding means 30 are positioned. That is, the first control portion 71 is viewed from above the holding surface 19, and the wafer W held on the holding surface 19 is not covered by the polishing grindstone 37, and the holding means 15 and the polishing means 30 are kept away from the horizontal direction (the first 1 Engineering). In this embodiment, the first control unit 71 is viewed from above the holding surface 19. The holding means 15 is positioned on the wafer W held on the holding surface 19 without covering the polishing grindstone 37 via the Y-axis direction moving means 40 .

However, the first control unit 71 does not cover the polishing grindstone 37 with respect to the wafer W. When positioning the holding means 15, it can use the encoding signal from the Y-axis encoder 46 (the number of rotations of the Y-axis servo motor 44). ). That is, the first control unit 71 recognizes the position of the holding means 15 in the Y-axis direction based on the encoder signal.

Next, the second control unit 72 of the control means 70 measures the thickness of the wafer W held on the holding surface 19 via the thickness measurement means 51. Then, the second control unit 72 calculates the upper surface height of the wafer W based on the measured thickness of the wafer W (second process). However, the upper surface height of the wafer W is, for example, the height from the reference position of the polishing apparatus 11 (for example, the upper surface of the base 12) to the upper surface of the wafer W.

Next, as shown in FIG. 3, the third control unit 73 of the control means 70 controls the grinding and feeding means 14 to lower the bottom of the grinding stone 37 of the grinding means 30 in the -Z direction as shown by the arrow A until it passes through the second The height H of the upper surface of the wafer W calculated by the control unit 72. That is, the third control unit 73 lowers the lower surface of the polishing grindstone 37 to the height H of the upper surface of the wafer W, and grinds and feeds the polishing means 30 (third process).

However, when the third control unit 73 sets the height of the lower surface of the grinding stone 37 to the height H of the upper surface of the wafer W, the encoder signal from the Z-axis encoder 25 (the number of rotations of the Z-axis servo motor 22) can be used. .

That is, the third control unit 73 can, for example, make the grinding feed rate of the lowering speed of the grinding means 30 (grindstone 37) a desired speed based on the coded signal, and control the grinding feed means 14 (Z-axis servo motor 22). ). Furthermore, the control means 70 recognizes the height of the bottom of the grinding stone 37 based on the coded signal.

Next, the control means 70 controls the motor 33 and rotates the grinding wheel 35 (grinding stone 37) along with the main shaft 32. Furthermore, the control means 70 rotates the chuck 18 (wafer W) via a rotating means not shown.

In addition, the fourth control section 74 of the control means 70, as shown in FIG. 4, controls the Y-axis direction moving means 40 until the polishing means 30 is positioned at the center of rotation of the wafer W held on the holding surface 19 of the holding means 15 The grinding stone 37 is polished, and the holding means 15 and the polishing means 30 are relatively moved in a horizontal direction. In the present embodiment, the fourth control unit 74 positions the grinding stone 37 of the grinding means 30 at the center of rotation of the wafer W via the Y-axis direction moving means 40, and moves the holding means 15 along the +Y direction indicated by the arrow B. Approach the polishing means 30 (the fourth process).

Next, the fifth control part 75 of the control means 70 is shown in FIG. 5, the preset grinding feed speed is along the grinding feed direction (-Z direction) indicated by the arrow C, while grinding and feeding the grinding means 30, The wafer W is polished to a specific thickness (the fifth process).

As described above, in this embodiment, the polishing grindstone 37 is lowered to the height H of the upper surface of the wafer W in a state where the polishing grindstone 37 is arranged at a position that does not cover the wafer W. For this reason, when the polishing grindstone 37 is lowered, it is possible to prevent the polishing grindstone 37 from contacting the wafer W. As a result, the grinding stone 37 can be lowered to the height H of the upper surface of the wafer W at a rapid lowering speed. Therefore, the time taken for the processing of the wafer W can be shortened.

That is, conventionally, after the polishing grindstone is lowered to the vicinity of the upper surface of the wafer at a high speed, gas cutting is performed in which the polishing grindstone is lowered to the height of the upper surface of the wafer at a slow lowering speed. In this gas cutting, when rough grinding the grindstone, the descending distance is 50-100μm, and the descending speed is 5-6μm/s. When finely grinding the grindstone, the descending distance is 10-20μm, and the descending speed is 0.5-0.6μm/s. Therefore, for gas cutting, it takes up to 30 seconds. In this embodiment, the time for such gas cutting can be saved.

In addition, the first control unit 71 is in the first process, when viewed from above the holding surface 19, when the polishing grindstone 37 is arranged at a position not covering the wafer W, the polishing grindstone 37 and the Y of the wafer W The position of the axis direction can be as close as possible without overlapping these ranges. At this time, in the third step, when the lower surface of the polishing grindstone 37 is lowered to the height H of the upper surface of the wafer W, the distance between the polishing grindstone 37 and the wafer W in the Y-axis direction can be shortened.

Therefore, in the fourth step, when the holding means 15 is moved to position the polishing grindstone 37 at the rotation center of the wafer W, the moving distance of the holding means 15 can be shortened. Therefore, the time spent in processing the wafer W can be further shortened. However, when the distance between the polishing grindstone 37 and the wafer W in the Y-axis direction is shortened, the movement time of the holding means 15 of the fourth process is that the radius of the wafer W is 160 mm, and the Y-axis direction moving means 40 is performed When the moving speed of the holding means 15 is 20-30 mm/s, it is approximately 8 seconds. That is, in the conventional method, gas cutting, which takes about 30 seconds, can be completed in only about 8 seconds.

In addition, the grinding stone 37 of the grinding means 30 corresponds to the purpose of the grinding device 11, and may be either a grinding stone for rough grinding or a grinding stone for fine grinding. That is, when the grinding force of the grinding grindstone is a large rough grinding grindstone, as in the past, the grinding grindstone is lowered to perform gas cutting, and when the grindstone is finely ground, as in the present invention, in the horizontal direction parallel to the holding surface, Move the grinding stone to perform gas cutting. When the fine grinding stone that is easy to be damaged is in contact with the wafer, the impact applied to the fine grinding stone is reduced to prevent the defect of the fine grinding stone.

11: Grinding device 12: Abutment 13: Column 15: Keep the means 16: Supporting components 18: Chuck 19: Keep the noodles 14: Grinding feed means 30: Grinding means 34: Wheel frame 35: Grinding wheel 37: Grinding stone 40: Means of movement in the Y-axis direction 51: Thickness measurement method 70: Control 71: The first control part 72: The second control part 73: 3rd control part 74: 4th control part 75: 5th control part W: Wafer T: Protective tape

[Fig. 1] An explanatory diagram showing the structure of the polishing device. [Figure 2] A block diagram showing the composition of the control means. [Fig. 3] An explanatory diagram showing the polishing operation of the wafer of the polishing device. [Fig. 4] An explanatory diagram showing the polishing operation of the wafer of the polishing device. [Fig. 5] An explanatory diagram showing the polishing operation of the wafer of the polishing device.

13: Column

14: Grinding feed means

15: Keep the means

16: Supporting components

17: Tilt change member

18: Chuck

19: Keep the noodles

20: Z-axis ball screw

20a: Fixed nut part

21: Z axis guide

22: Z-axis servo motor

24: Retainer

25: Z axis encoder

30: Grinding means

31: Spindle housing

32: Spindle

33: Motor

34: Wheel frame

35: Grinding wheel

36: Wheel abutment (ring abutment)

37: Grinding stone

40: Means of movement in the Y-axis direction

41: hold the stage

43: Y-axis ball screw

44: Y-axis servo motor

45: Y-axis mobile platform

45a: Nut part

46: Y axis encoder

51: Thickness measurement method

H: height

W: Wafer

A: Arrow

Claims (2)

A grinding device with: holding means to hold the workpiece through a holding surface, And a grinding means to grind the workpiece held on the holding surface and rotate the center of the holding surface as the axis, and the grinding grindstone arranged on the rotating grinding wheel in a ring shape, And the holding means and the polishing means move relative to the horizontal moving means parallel to the horizontal direction of the holding surface, And the grinding means, the grinding feeding means that moves in the vertical direction on the holding surface, And control means of grinding device, its characteristics are The control method has: When viewed from above the holding surface, the workpiece held on the holding surface is not covered by the grinding stone, and the horizontal movement means is used to position the holding means and the first control part of the grinding means, And the second control unit that measures the thickness of the workpiece held on the holding surface through a thickness measuring means to calculate the height of the upper surface of the workpiece held on the holding surface, And lower the lower surface of the grinding stone to the height of the upper surface of the workpiece calculated by the second control unit to control the third control unit of the grinding feeding means, And using the horizontal moving means until the grinding stone is positioned at the center of rotation of the workpiece held on the holding surface of the holding means, and the holding means and the grinding means are moved relative to the fourth control section in the horizontal direction , And the fifth control unit that grinds and feeds the grinding means at a preset grinding feed rate to grind the workpiece to a specific thickness. A grinding method characterized by: a holding means with a holding surface, a holding process for holding the processed object, The holding means and the polishing means with a polishing grindstone are viewed from above the holding surface, and the workpiece held on the holding surface is not covered by the polishing grindstone, and is away from the horizontal first step, And the second step that calculates the height of the upper surface of the workpiece held on the holding surface, And the third step in which the lower surface of the grinding stone is lowered to the height of the upper surface of the workpiece calculated in the second step, and the polishing means is polished and fed in the vertical direction on the holding surface. And until the grinding stone is positioned at the center of rotation of the workpiece, the holding means and the grinding means are moved relative to the fourth step in the horizontal direction, The fifth process of grinding the workpiece to a specific thickness while grinding and feeding the grinding means at a preset grinding feed rate.

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