JP2007175825A - Polishing equipment - Google Patents

Abstract

In a grinding wheel in which a polishing portion is formed of a flexible member, a contact state between a dressing tool and a polishing portion is made suitable for dressing when dressing the polishing portion.
A dressing tool 11 for dressing a polishing unit 341 is disposed at a position adjacent to a holding unit 2, and the dressing tool 34 contacts the polishing unit 341 to dress the polishing unit 341, and a dressing. An immersion suppression unit 112 that sets an amount of immersion of the unit 110 into the polishing unit 341 is provided. Since the dressing unit 110 is always immersed in the polishing unit 341 by the same amount by the immersion control unit 112, excessive dressing is performed to shorten the life of the polishing unit 341, or the dressing is insufficient and the polishing resistance is reduced. The surface is not raised and surface burn is not generated.
[Selection] Figure 9

Description

  The present invention relates to a polishing apparatus for polishing a plate-like object.

  A semiconductor wafer having a device such as an IC or LSI formed on the front surface is ground to a desired thickness by grinding with a grinding device. A ground strain layer is formed on the back surface by grinding, and this ground strain layer. However, this is a factor that reduces the bending strength of each device. Therefore, in order to remove the grinding strain layer, wet etching, dry etching, polishing using slurry, and the like are performed.

  However, each method has a problem that productivity is low and waste liquid causes environmental pollution. Therefore, the present applicant impregnates a flexible member such as felt with abrasive grains made of zirconia or the like to bond. A technology that removes the grinding strain layer by polishing the backside of a semiconductor wafer in a dry manner using a polishing wheel mounted on a polishing machine with a polishing wheel composed of a polishing part fixed with a material fixed to a base. developed. In such a polishing apparatus, when clogging occurs in the polishing part, the dressing part having a configuration in which diamond abrasive grains are hardened by nickel plating or the like has a diameter of about 1 to 2 cm is brought into contact with the polishing surface of the polishing part. To prevent clogging (see, for example, Patent Document 1).

JP 2003-305543 A

  However, when the dressing part is brought into contact with the polishing part formed of a flexible member, the dressing part is immersed from the lower surface of the polishing part, so that the contact state between the dressing part and the polishing part is appropriate for dressing. I can't control it. Therefore, every time dressing is performed, the contact state between the dressing part and the polishing part is different, which causes excessive dressing to shorten the life of the polishing part, and insufficient dressing results in poor polishing resistance. There is a problem that it rises and causes surface burns to the object to be polished.

  Therefore, the problem to be solved by the present invention is to make the contact state between the dressing tool and the polishing part suitable for dressing when dressing a polishing wheel in which the polishing part is formed of a flexible member. is there.

  The present invention relates to a holding unit having a holding surface for holding a wafer, a polishing unit for polishing the surface of the wafer held by the holding unit, and a direction parallel to the holding surface of the holding unit. In a polishing apparatus comprising at least a parallel direction driving means that moves relative to the holding direction, and a vertical direction driving means that moves the holding means and the polishing means in a direction perpendicular to the holding surface of the holding means, The polishing means comprises a polishing wheel having a polishing portion configured by including abrasive grains in a flexible material, and a spindle that can rotate while supporting the polishing wheel, and a dressing tool for dressing the polishing portion is adjacent to the holding means The dressing tool is placed at the position where the dressing tool comes into contact with the polishing part and dresses the polishing part, and the immersion control that sets the amount of the dressing part to be immersed in the polishing part. Characterized in that it comprises and.

  It is desirable that the immersion suppression unit is a contact surface whose upper surface is in contact with the polishing unit, the contact surface is formed in a flat shape, and the upper surface of the dressing unit is configured to protrude from the contact surface of the immersion suppression unit. Further, it is desirable that the corner portion of the immersion suppression portion is chamfered. The dressing portion is preferably configured by fixing diamond abrasive grains with a bond, and the immersion suppression portion is preferably configured by a ceramic plate surrounding the dressing portion.

  For example, the upper surface of the dressing portion is disposed in a state of protruding from 100 to 150 μm from the upper surface of the immersion suppression portion.

  Since the polishing apparatus according to the present invention includes an immersion suppression unit that sets an amount by which the dressing unit is immersed in the polishing unit, the dressing unit is always immersed in the polishing unit by the same amount during dressing. Therefore, the dressing is not excessively performed and the life of the polishing portion is shortened, and the dressing becomes insufficient, so that the polishing resistance is not increased and the surface to be polished is not burned.

  A polishing apparatus 1 shown in FIG. 1 includes a holding unit 2 having a holding surface 20 that holds a wafer W that is an object to be polished, and a polishing unit 3 that polishes the wafer W held by the holding unit 2.

  The holding means 2 is configured to be rotatably supported by a support base 21. A bellows 22 is fixed to a side portion of the support base 21.

  The polishing means 3 includes a spindle 30 having a vertical axis, a housing 31 that rotatably supports the spindle 30, a motor 32 that rotationally drives the spindle 30, and a wheel mount 33 that is formed at the lower end of the spindle 30. And a polishing grindstone 34 attached to the wheel mount 33. As shown in FIGS. 2 and 3, the polishing grindstone 34 is configured by a polishing portion 341 being fixed to a circular support member 340. A plurality of screw holes 340 a are formed in the support member 340, and the polishing grindstone 34 is fixed to the wheel mount 33 by screws screwed into the screw holes 340 a. The polishing unit 341 has a configuration in which a flexible member such as felt is impregnated with abrasive grains such as zirconia and is hardened by a bond material such as glue.

  Returning to FIG. 1, the polishing means 3 can be moved in the vertical direction by the vertical driving means 4. The vertical direction driving means 4 includes a ball screw 40 arranged in the vertical direction, a pair of guide rails 41 arranged in parallel with the ball screw 40, a pulse motor 42 for rotationally driving the ball screw 40, and an internal nut made up of the ball screw. The vertical movement base 43 is engaged with the guide rail 41 and is slidably contacted with the guide rail 41, and the support portion 44 is connected to the vertical movement base 43 and supports the housing 31. As the ball screw 40 is rotated by being driven by the pulse motor 42, the vertical movement base 43 and the support portion 44 are guided by the guide rail 41 and moved up and down, and the housing 31 supported by the support portion 44 is moved up and down accordingly. The entire polishing means 3 is vertically moved up and down.

  As shown in FIG. 1, on the front side of the polishing apparatus 1, a wafer cassette 5a for storing a wafer W to be polished and a wafer cassette 5b for storing a polished wafer are placed. In the vicinity of the wafer cassettes 5a and 5b, a loading / unloading means 6 for carrying out the wafer W from the wafer cassette 5a and loading the wafer W into the wafer cassette 5b is provided.

  The carry-in / out means 6 includes a holding unit 60 that holds the wafer W, and an arm unit 61 that is connected to the leading end of the holding unit 60 and rotates and expands and contracts. Positioning means 7 for performing the above positioning and cleaning means 8 for cleaning the polished wafer are disposed.

  In the vicinity of the alignment means 7, a first transfer means 9 a for transferring the wafer W placed on the alignment means 7 to the holding means 2 is disposed. On the other hand, in the vicinity of the cleaning unit 8, a second transfer unit 9 b that transfers the wafer W held by the holding unit 2 to the cleaning unit 8 is disposed.

  The holding means 2 can be moved in the parallel direction by the parallel direction driving means 10 shown in FIG. The parallel direction driving means 10 includes a ball screw 100 disposed in a direction parallel to the holding surface 20, a pair of guide rails 101 disposed in parallel to the ball screw 100, and a pulse motor 102 that rotationally drives the ball screw 100. A parallel movement base 103 whose inner nut is screwed to the ball screw 100 and whose lower part is in sliding contact with the guide rail 101; a holding means rotation drive unit 104 which is fixed to the parallel movement base 103 and rotates the holding means 2; Consists of As the ball screw 100 is rotated by being driven by the pulse motor 102, the parallel movement base 103 and the holding unit rotation driving unit 104 are guided by the guide rail 101 and moved in the horizontal direction, and are connected to the holding unit rotation driving unit 104. The held holding means 2 and the support base 21 are also configured to move in the horizontal direction. Although not shown in FIG. 4, the bellows 22 shown in FIG. 1 is attached to the side portion of the support base 21.

  As shown in FIG. 4, a dressing tool 11 for dressing the polishing unit 341 shown in FIGS. 2 and 3 is disposed at a position adjacent to the holding means 2. As shown in FIG. 5, the dressing tool 11 is disposed on the parallel movement base 103 and can be moved in the parallel direction by the parallel direction driving means 10.

  As shown in FIGS. 5 and 6, the dressing tool 11 includes a dressing unit 110 that contacts the polishing unit 341 shown in FIGS. 2 and 3 and dresses the polishing unit 341. The dressing unit 110 is configured by bonding abrasive grains such as diamond abrasive grains by bonding, and is formed in a disk shape having a diameter of about 1 to 2 cm and is fixed to the circular substrate 111. In addition, the shape of the dressing part 110 is not limited to the example of illustration, For example, a rectangular shape may be sufficient.

  The dressing unit 110 is surrounded by an immersion suppression unit 112. The immersion suppression unit 112 is formed, for example, in a ring shape from a ceramic plate, has an upper surface formed in a flat shape, and is fixed to the circular substrate 111 by screwing. The immersion suppression unit 112 is desirably formed in a circular shape as in the illustrated example, but is not necessarily circular. However, in the case of a shape having a corner such as a rectangle, it is desirable to chamfer the corner.

  The dressing tool 11 can be moved up and down by being driven by the dressing tool lifting means 12. The dressing tool lifting / lowering means 12 is connected to the support plate 120 for supporting the circular substrate 111 from below, the levelness adjusting means 121 for adjusting the level of the support plate 120, and the levelness adjusting means 121 and arranged in the vertical direction. A ball screw 122, a pulse motor 123 for rotating the ball screw 122, and four guide rods 124 provided upright in the vertical direction. The level adjustment means 121 includes a lifting plate 121a that moves up and down with the rotation of the ball screw 122, two pulse motors 121b and 121c disposed on the lifting plate 121a, and a pulse motor 121b and 121c that are connected to each other (not shown). It is composed of a ball screw, and the level of the support plate 120 can be finely adjusted by driving with pulse motors 121b and 121c. In addition, through holes 125 are formed in the four corners of the elevating plate 121a so as to penetrate the four guide rods 124 erected in the vertical direction. The four guide rods 124 serve as guides when the elevating plate 121a is raised and lowered. It becomes.

  As shown in FIG. 7, the upper surface of the dressing unit 110 protrudes upward by H from the upper surface of the immersion suppression unit 112. The protrusion amount H is, for example, about 100 μm to 150 μm.

  Next, the operation of the polishing apparatus 1 will be described with reference to FIG. 1. The wafer W accommodated in the wafer cassette 5 a is unloaded by the loading / unloading means 6 and placed on the alignment means 7. The center position of the wafer W is aligned at a fixed position. Then, after being driven by the parallel driving means 10 shown in FIG. 4 and the holding means 2 being translated to the movable range of the first transfer means 9a along with the expansion and contraction of the bellows 22, the wafer is transferred by the first transfer means 9a. W is transferred to the holding means 2, and the wafer W is held on the holding surface 20.

  Next, the holding means 2 is positioned immediately below the polishing means 3 by the parallel driving means 10 shown in FIG. Then, the holding means 2 is rotated to rotate the wafer W, and the polishing means 34 is driven and lowered by the vertical driving means 4 while the polishing grindstone 34 is driven by the motor 32 and the holding means 2 is rotated. While moving in the horizontal direction, the polishing unit 341 constituting the polishing grindstone 34 comes into contact with the upper surface of the wafer W, and the upper surface front surface of the wafer W is polished in a dry manner. During normal polishing of the wafer W, as shown in FIG. 8, the dressing tool 11 is lowered so as to be positioned at a retracted position where it does not come into contact with the polishing unit 341.

  On the other hand, when performing dressing of the polishing unit 341, the dressing tool 11 is raised and the upper surface of the dressing unit 110 is positioned higher than the upper surface of the wafer W as shown in FIG. 9. The lowering and raising of the dressing tool 11 is controlled by the dressing tool lifting / lowering means 12 shown in FIG.

  As shown in FIG. 9, the dressing unit 110 contacts the rotating flexible polishing unit 341 while the dressing tool 11 moves in parallel with the holding unit 2 by being driven by the parallel driving unit 10 shown in FIG. 4. By applying pressure, the entire surface of the polishing portion 341 is dressed. Since the polishing unit 341 is flexible, the dressing unit 110 is immersed in the polishing unit 341 during dressing, but since the dressing unit 110 is surrounded by the immersion suppression unit 112, The upper surface is in contact with the polishing unit 341, the immersion suppressing unit 112 suppresses the immersing of the dressing unit 110, and the amount of the dressing unit 110 immersing into the polishing unit 341 is determined by the upper surface of the dressing unit 110 and the upper surface of the immersing suppressing unit 112 (polishing The height difference between the contact surface and the portion 341), that is, the height difference H shown in FIG. Since the dressing unit 110 is always immersed in the polishing unit 341 by a certain amount, the dressing is excessively performed and the life of the polishing unit is shortened, or the dressing is insufficient and the polishing resistance is increased to increase the surface of the wafer. There will be no surface burn. In particular, when the upper surface of the immersion suppression unit 112 that contacts the polishing unit 341 is formed in a flat shape and the upper surface of the dressing unit 110 is configured to protrude from the contact surface of the immersion suppression unit 112, the dressing unit 112 is stable. Immerse the fixed amount polishing unit 341.

  Moreover, since the immersion suppression part 112 is formed circularly, the grinding | polishing part 341 does not get caught. Even when the immersion suppression portion is not circular, the polishing portion 341 will not be caught as long as it is chamfered.

  In the example of FIG. 9, the case where the dressing is performed without polishing the wafer W has been described. However, the polishing unit 341 can be dressed during the polishing of the polished wafer W. In this case, the vertical driving means 4 controls the height of the polishing means 4 so that the lower surface of the polishing unit 341 contacts the upper surface of the wafer W and also contacts the dressing unit 110, and the dressing unit lifting / lowering unit 12. To control the height of the dressing unit 110.

  Returning to FIG. 1, when the dressing of the polishing unit 341 is appropriately performed and the polishing of the wafer W is completed, the holding unit 2 moves in the parallel direction and is positioned in the vicinity of the second transfer unit 9b. Then, the polished wafer W is transferred to the cleaning unit 8 by the second transfer unit 9b, and after the polishing dust and the like are removed, the wafer W is accommodated in the wafer cassette 5b by the transfer-in / out unit 6.

  In the above example, the holding means 2 and the polishing means 3 move relative to each other in a direction parallel to the holding surface 20 when the holding means 2 moves in the parallel direction. It is good also as a structure which moves to. In that case, the means for moving the polishing means 3 in the parallel direction becomes the parallel direction driving means.

  In the above example, the holding means 2 and the polishing means 3 are moved in the vertical direction relative to the holding surface 20 when the polishing means 3 moves in the vertical direction. It is good also as a structure which moves to a direction. In that case, the means for moving the holding means 2 in the vertical direction becomes the vertical direction driving means.

It is a perspective view which shows an example of a grinding | polishing apparatus. It is a perspective view which shows the state which looked at an example of the grinding stone from the upper side. It is a perspective view which shows the state which looked at an example of the grinding stone from the lower side. It is a perspective view which shows a parallel direction drive means, a holding means, and a dressing tool. It is a disassembled perspective view which shows an example of a dressing tool. It is a perspective view which shows an example of a dressing tool. It is sectional drawing which shows the dressing part and immersion suppression part which comprise a dressing tool. It is explanatory drawing which shows the state which grind | polishes a wafer. It is explanatory drawing which shows the state which dresses a grinding | polishing part.

Explanation of symbols

1: Polishing device 2: Holding means 20: Holding surface 21: Support base 22: Bellows 3: Polishing means 30: Spindle 31: Housing 32: Motor 33: Wheel mount 34: Polishing grindstone 340: Support member 341: Polishing section 4 : Vertical direction drive means 40: Ball screw 41: Guide rail 42: Pulse motor 43: Vertical movement base 44: Support part 5a, 5b: Wafer cassette 6: Loading / unloading means 60: Holding part 61: Arm part 7: Positioning means 8: Cleaning means 9a: First conveying means 9b: Second conveying means 10: Parallel direction driving means 100: Ball screw 101: Guide rail 102: Pulse motor 103: Parallel movement base 104: Holding means rotation driving unit 11: Dressing tool 110: Dressing part 111: Circular substrate 112: Immersion suppression part 12: Dressing Immediately lifting means 120: support plate 121: Horizontal adjustment means 121a: lift plate 121b, 121c: pulse motor 122: ball screw 123: Pulse motor 124: guide rod

Claims (5)

A holding means having a holding surface for holding the wafer, a polishing means for polishing the surface of the wafer held by the holding means, and a direction parallel to the holding surface of the holding means for holding the holding means and the polishing means Polishing comprising at least a parallel direction driving means for moving the holding means and the polishing means in a direction perpendicular to a holding surface of the holding means. In the device
The polishing means includes a polishing grindstone having a polishing portion configured by including abrasive grains in a flexible material, and a spindle that can rotate while supporting the polishing grindstone,
A dressing tool for dressing the polishing part is disposed at a position adjacent to the holding means;
The dressing tool includes a dressing unit that contacts the polishing unit to dress the polishing unit, and an immersion suppression unit that sets an amount of the dressing unit to be immersed in the polishing unit. The immersion suppression portion is a contact surface whose upper surface is in contact with the polishing portion, and the contact surface is formed in a flat shape,
The upper surface of the said dressing part is a grinding | polishing apparatus of Claim 1 comprised from the contact surface of this immersion suppression part.   The polishing apparatus according to claim 2, wherein a corner portion of the immersion suppression portion is formed by chamfering.   4. The polishing apparatus according to claim 2, wherein the dressing unit is configured by fixing diamond abrasive grains with a bond, and the immersion suppression unit is configured by a ceramic plate surrounding the dressing unit.   The polishing apparatus according to claim 2, 3 or 4, wherein an upper surface of the dressing portion is disposed in a state of projecting by 100 to 150 µm from an upper surface of the immersion suppression portion.

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