TW201912303A - Abrasive pad - Google Patents

Abstract

This invention provides a grinding liquid between the polishing pad and the workpiece. The grinding pad is placed on the grinding unit of the grinding device and is in a circular plate shape. The grinding pad is provided with a holding table for holding a workpiece; and a grinding unit for grinding the workpiece held by the holding table. The grinding pad is characterized in comprising: a grinding liquid supply path penetrating through the central part in the thickness direction; a groove formed on the surface contacting the workpiece and reaching the grinding liquid supply path; and a bolt-shaped member having a plurality of holes penetrating in the thickness direction, and configured to block the grinding liquid supply path.

Description

Polishing pad

The present invention relates to a polishing pad mounted on a polishing apparatus.

In the manufacture of component wafers for electronic devices such as mobile phones or computers, first, an IC (Integrated Circuit) and an LSI (Large Scale Integration) are formed on the front side of a wafer that is a semiconductor. ) And so on. Next, the wafer is ground from the back side and thinned to a predetermined thickness, and the wafer is divided for each element to form individual element wafers.

The grinding of the wafer is performed by a grinding device. The grinding device includes a holding table for holding a wafer, and a grinding unit for grinding the wafer, and the grinding unit includes a spindle; and a grinding wheel mounted on a lower end of the spindle. The grinding wheel includes a grinding grindstone, which contacts the wafer to grind the wafer. For wafer grinding, a grinding device is used, which has a grinding unit for rough grinding, including a grinding stone with relatively large abrasive grains, and a grinding unit for fine grinding, including grinding with a relatively small abrasive grain Millstone.

When the back side of the wafer is ground, there is a tendency that a minute uneven shape is formed on the surface to be ground. Therefore, it is known that after grinding is performed, for example, the back surface of the wafer is polished by a CMP (Chemical Mechanical Polishing) method to remove the minute irregularities (see Patent Document 2).

A polishing apparatus for polishing a workpiece such as a wafer includes a holding table that holds the workpiece, and a polishing pad that polishes the workpiece. The diameter of the polishing pad is larger than the diameter of the wafer. When polishing the wafer, the polishing pad is arranged to cover the entire processed surface of the wafer held on the holding table. Then, the polishing pad and the holding table holding the wafer are rotated around the rotation axes parallel to each other, and the wafer is polished when the polishing pad is brought into contact with the wafer.

A polishing liquid supply path is formed in a central portion of the polishing pad, and the polishing pad passes through the polishing pad in a thickness direction. When the wafer is polished, the polishing liquid is supplied to the wafer through the polishing liquid supply path. The polishing liquid is, for example, a slurry (a slurry) in which abrasive particles are dispersed. When grinding a workpiece, it not only contributes to the grinding by chemically and mechanically, but also helps to discharge the grinding debris generated by grinding. Therefore, since the polishing liquid needs to be appropriately supplied to the entire surface to be processed, for example, a groove is formed on the polishing surface of the polishing pad. [Habitual technical literature] [patent literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2000-288881 [Patent Document 2] Japanese Patent Laid-Open No. 8-99265

[Problems to be Solved by the Invention] For example, when the polishing pad is abutted against a workpiece to grind a relatively large diameter workpiece such as a diameter of 200 mm or a diameter of 300 mm, the lower end of the polishing liquid supply path of the polishing pad is caused by the workpiece Because it is blocked, the polishing liquid stays in the polishing liquid supply path. During the polishing, the polishing pad forming the groove and the workpiece held on the holding table are rotated while rotating around respective axes parallel to each other while abutting. Then, the polishing liquid is appropriately supplied between the polishing pad and the surface to be processed.

On the other hand, in the case of relatively small diameter workpieces, especially in the case of workpieces having a diameter smaller than the radius of the polishing pad, even if the polishing pad is provided to cover the entire surface of the workpiece, the lower end of the polishing liquid supply path is still May not be blocked by the workpiece. Then, even if the polishing liquid is supplied to the polishing liquid supply path, most of the polishing liquid flows out, so that the polishing liquid cannot be appropriately supplied to the work surface of the workpiece through the groove formed in the polishing surface. If the polishing liquid cannot be appropriately supplied, the workpiece cannot be properly polished.

The present invention has been made in view of the problems described above, and an object thereof is to provide a polishing pad that can appropriately supply a polishing liquid between the polishing pad and a workpiece.

[Technical means to solve the problem] According to an aspect of the present invention, there is provided a polishing pad which is mounted on a polishing unit of a polishing device and has a circular plate shape, and includes a holding table for holding a workpiece, and the polishing unit for polishing and holding The workpiece of the holding table, the polishing pad is characterized by including a polishing liquid supply path penetrating a central portion in a thickness direction; a groove formed on a surface contacting the workpiece and reaching the polishing liquid supply path; and a pin-shaped member, It has a plurality of holes penetrating in the thickness direction, and is arranged to block the polishing liquid supply path.

[Effects of the Invention] A polishing pad supply path is formed on the polishing pad according to one aspect of the present invention, and the polishing pad is penetrated in the thickness direction, and a polishing liquid is supplied to the polishing liquid supply path when the workpiece is being polished. A plug-shaped member is disposed on the polishing pad to block the polishing liquid supply path, and a plurality of holes are formed in the plug-shaped member and penetrate through the thickness direction. Therefore, the polishing liquid passes through the pin-shaped member by passing through the hole.

When the polishing liquid passing through the hole of the plug-shaped member is discharged from below the hole, it is dispersed and distributed to the inner wall surface of the polishing liquid supply path. Then, the polishing liquid is supplied to a groove reaching the polishing liquid supply path, and the polishing liquid is supplied to the entire area of the processed surface of the workpiece through the groove.

Therefore, according to one aspect of the present invention, there is provided a polishing pad which can appropriately supply a polishing liquid between the polishing pad and a workpiece.

One embodiment of the present invention will be described with reference to the drawings. The polishing pad of this embodiment is mounted on a polishing apparatus. A workpiece to be polished by the polishing apparatus and a polishing apparatus for polishing the workpiece will be described with reference to FIG. 1. FIG. 1 is a perspective view schematically showing a polishing apparatus 2 for polishing a workpiece 1 such as a semiconductor wafer.

The workpiece 1 processed in the polishing device 2 is, for example, a substantially disc-shaped substrate made of a material such as silicon, SiC (silicon carbide) or other semiconductors, or a material such as sapphire, glass, or quartz. The surface of the workpiece 1 is divided into a plurality of regions by a plurality of predetermined division lines (cut lines) arranged in a grid pattern, and elements such as ICs are formed in each of the plurality of regions. Finally, the workpiece 1 is divided along the predetermined division line to form individual element wafers.

The work 1 is thinned by grinding the back surface. The back surface of the workpiece 1 to be ground tends to form a minute uneven shape. Therefore, after the grinding is performed, the back surface of the workpiece 1 is polished to remove the minute unevenness. When the back surface of the workpiece 1 is ground, a protective tape 3 may be stuck on the front surface of the workpiece 1. The protective tape 3 protects the front side of the work 1 from being impacted, such as when grinding the back surface of the work 1 or when transporting the work 1, and prevents damage to the components.

The protective tape 3 has a film-shaped base material having flexibility, and a paste layer (adhesive layer) formed on one surface of the base material. For example, PO (polyolefin, polyolefin), PET (polyethylene terephthalate), polyvinyl chloride, or polystyrene are used for the substrate. Then, for the paste layer (adhesive layer), for example, a silicone rubber, an acrylic material, an epoxy resin material, or the like is used.

The polishing apparatus 2 has a base 4 supporting each structure. The upper surface of the front part of the base 4 is provided with the cassette mounting bases 6a and 6b. For example, a cassette 8a is mounted on the cassette mounting table 6a, and the workpiece 1 before grinding is accommodated. The cassette mounting table 8b has, for example, a cassette 8b for accommodating the workpiece 1 after grinding. A workpiece transfer robot arm 10 is mounted on the base 4 and is adjacent to the cassette mounting tables 6 a and 6 b, and the workpiece 1 is transferred.

The upper surface of the front portion of the base 4 is further provided with a positioning table 12 for positioning the position of the workpiece 1 using a plurality of positioning pins; a workpiece moving mechanism (loading arm) 14 for placing the workpiece 1 on the holding table 20; The unloading mechanism (unloading arm) 16 unloads the workpiece 1 from the holding table 20; and the rotary cleaning device 52, which cleans and spin-dryes the ground workpiece 1.

An opening 4 a is provided on the upper surface of the rear side portion of the base 4. An X-axis moving holding table 18 is provided inside the opening 4a, and a holding table (chuck table) 20 for holding and holding the workpiece 1 is placed on the upper surface thereof. The X-axis moving stage 18 can be moved in the X-axis direction by an X-axis direction moving mechanism (not shown). The X-axis moving table 18 is positioned in the loading / unloading area 22 of the workpiece 1 on the holding table 20 through the function of the X-axis direction moving mechanism; and the processing area of the workpiece 1 which is attracted and held on the holding table 20 by grinding. twenty four.

The upper surface of the holding table 20 becomes a holding surface 20 a and holds the workpiece 1. The holding table 20 includes a suction path 20 b (see FIG. 3) inside, one end of which is connected to the holding surface 20 a of the holding table 20, and the other end is connected to a suction source (not shown). When the suction source is actuated, a negative pressure acts on the workpiece 1 placed on the holding surface 20 a, and the workpiece 1 is sucked and held on the holding table 20. Then, the holding table 20 can be rotated around an axis perpendicular to the holding surface 20a.

A grinding unit 26 is disposed above the processing area 24 to grind the workpiece 1. A support portion 28 is erected on the rear end of the base 4 of the polishing apparatus 2, and the polishing unit 26 is supported by the support portion 28. A pair of Z-axis guides 30 elongated in the Z-axis direction are provided in front of the support portion 28, and the Z-axis moving plate 32 is slidably mounted on each of the Z-axis guides 30.

A nut portion (not shown) is mounted on the back side (rear side) of the Z-axis moving plate 32, and a Z-axis ball screw 34 parallel to the Z-axis guide 30 is screwed to the nut portion. A Z-axis pulse motor 36 is connected to one end of the Z-axis ball screw 34. When the Z-axis ball screw 34 is rotated by the Z-axis pulse motor 36, the Z-axis moving plate 32 moves in the Z-axis direction along the Z-axis guide 30.

The polishing unit 26 is fixed to the lower part of the front side of the Z-axis moving plate 32. When the Z-axis moving plate 32 is moved in the Z-axis direction, the polishing unit 26 can be moved in the Z-axis direction.

The polishing unit 26 includes a main shaft 40 that is rotated by a motor connected to the base end side; the polishing pad 44 of this embodiment is fixed to a mount 42 through a fixture 46 that is disposed on a front end side of the main shaft 40. The motor is provided in the spindle housing 38. When the motor is operated, the polishing pad 44 rotates in accordance with the rotation of the spindle 40.

A polishing liquid supply path 50 is formed inside the polishing unit 26 and penetrates the polishing unit 26 in the Z-axis direction. The upper end side of the polishing liquid supply path 50 is connected to a polishing liquid supply source 48. When polishing the workpiece 1, the polishing liquid supply source 48 passes through the polishing liquid supply path 50 to the polishing liquid formed in the center of the polishing pad 44. The supply path 60 (see FIG. 3) supplies a polishing liquid.

When polishing the workpiece 1 held on the holding table 20 positioned in the processing area 24, the polishing pad 44 is arranged above the workpiece 1 so as to cover the entire surface to be polished of the workpiece 1. Then, the polishing pad 44 and the holding table 20 are rotated around respective axes along the Z-axis direction, and the polishing pad 44 is lowered to abut the workpiece 1. At this time, in order to supply a polishing liquid between the workpiece 1 and the polishing pad 44, the polishing liquid supply source 48 is operated, and the polishing liquid is supplied to the polishing liquid supply path 50.

For example, when the polishing pad 44 is brought into contact with the workpiece 1 to grind the workpiece 1 having a larger radius than the polishing pad 44, the lower end of the polishing liquid supply path 60 of the polishing pad 44 is blocked by the workpiece 1. The liquid stays on the workpiece 1. During polishing, the polishing pad 44 and the work 1 are rotated around the axis along the Z-axis while abutting each other, so the polishing liquid is appropriately supplied to the polishing pad 44 and the work 1 Between the processed surfaces.

On the other hand, when the workpiece 1 whose diameter is smaller than the radius of the polishing pad 44 is ground, even if the polishing pad 44 abuts against the workpiece 1, the polishing liquid supply path 60 of the polishing pad 44 is not covered by the workpiece 1 Blocking situation. Then, even if the polishing liquid is supplied to the polishing liquid supply path 60, most of the polishing liquid flows out, so the polishing liquid cannot be appropriately supplied to the work surface of the workpiece 1. If the polishing liquid cannot be properly supplied to the surface to be processed, the workpiece 1 cannot be properly polished.

Therefore, the polishing pad 44 of this embodiment is used in order to appropriately supply a polishing liquid to the surface to be processed even when the workpiece 1 having a diameter smaller than the radius of the polishing pad 44 is polished. Next, the polishing pad 44 is described in more detail.

The polishing pad 44 is disc-shaped and includes a base material layer 54 that contacts the mounting member 42 when the polishing pad 44 is mounted on the mounting member 42 of the polishing unit 26, and a polishing layer 56 that grinds the workpiece. 1 hour, the workpiece 1 is contacted. FIG. 2 (A) is a perspective view schematically showing the polishing pad 44 viewed from the base material layer 54 side, and FIG. 2 (B) is a perspective view schematically showing the polishing pad 44 viewed from the polishing layer 56 side. FIG. 2C is a plan view schematically showing the polishing pad 44 as viewed from the polishing layer 56 side.

As shown in FIG. 2 (A), a screw hole 58 is formed in the base material layer 54. When the polishing pad 44 is fixed to the mounting member 42, a fixing tool 46 having a screw thread is screwed into the screw hole 58. Further, as shown in FIG. 2 (B), a groove 62 is formed on the surface of the workpiece 1 that contacts the polishing layer 56. A polishing liquid supply path 60 passing through the polishing pad 44 in the thickness direction is formed in a central portion of the polishing pad 44, and the groove 62 reaches the polishing liquid supply path 60. The diameter of the polishing liquid supply path 60 is, for example, 20 mm to 30 mm.

As shown in FIG. 2 (A) and FIG. 2 (C), a plug-shaped member 64 is disposed on the polishing liquid supply path to block the polishing liquid supply path. A plurality of holes 66 are formed in the plug-shaped member 64 and penetrate through the plug-shaped member 64 in the thickness direction. For example, the diameter of the hole 66 is about 4 mm, and four positions are formed in the plug-shaped member 64. The plug-shaped member 64 is produced by, for example, forming a hole 66 in a disc-shaped resin such as vinyl chloride using a drill or the like.

The polishing layer 56 is, for example, a non-woven fabric containing abrasive particles. In the case of using a fixed abrasive pad (for a non-woven fabric including the abrasive grains in the abrasive layer 56), when the workpiece 1 is ground, a polishing liquid not containing abrasive grains is used. This polishing solution is an alkaline solution obtained by adding a water-soluble organic substance such as glycerin or ethylene glycol to an alkaline solution such as sodium hydroxide or potassium hydroxide. Alternatively, pure water may be used.

Then, a non-woven fabric containing no abrasive particles may be used for the polishing layer 56. In this case, for example, a slurry in which solid particles are dispersed in a dispersion medium is used in the polishing liquid. The type of the dispersion medium of the slurry, the type of fixed particles, the shape and size of the solid particles, and the like are selected according to the content to be ground or the type of the workpiece 1.

Further, the polishing layer 56 may include solid-phase reaction fine particles to induce a solid-phase reaction with the workpiece 1; and fine particles for removal, having a higher Mohs hardness than the workpiece 1, and a defect-removing layer may be formed on the surface to be processed. When the defect removal layer is formed, it is possible to suppress impurities from invading the element formed on the workpiece. The polishing pad 44 having the polishing layer 56 is obtained by dispersing the solid-phase reaction particles and the defect-removing particles on a liquid bonding material, and immersing the liquid bonding material in a nonwoven fabric to dry the nonwoven fabric And formed.

Next, polishing of the workpiece 1 mounted on the polishing apparatus 2 of the polishing pad 44 will be described. FIG. 3 is a cross-sectional view schematically showing a polishing step using the polishing pad 44. As shown in FIG. 3, the polishing pad 44 is used by being mounted on a mount 42 disposed on the lower end of the spindle 40.

When the polishing pad 44 is mounted on the mounting member 42, a polishing liquid supply path 50 formed inside the polishing unit 26 is connected to a polishing liquid supply path 60 formed at a central portion of the polishing pad 44.

First, the suction source of the holding table 20 is actuated, and the work 1 is sucked and held on the holding surface 20a. Then, the holding table 20 is moved in the processing area 24, and a grinding unit 26 is arranged above the workpiece 1 to cover the surface to be polished of the workpiece 1. Then, the holding table 20 and the polishing pad 44 are rotated around each axis along the Z-axis direction, and the polishing pad 44 is lowered. Then, when the polishing pad 44 comes into contact with the workpiece 1, the polishing of the workpiece 1 is started.

When polishing the workpiece 1, the polishing liquid supply source 48 of the polishing device 2 is operated, and the polishing liquid is supplied to the polishing liquid supply path 50. The polishing liquid supplied to the polishing liquid supply path 50 passes through the plug-shaped member 64 and temporarily stays above the plug-shaped member 64, and then flows out from the hole 66 downward. Since the polishing liquid flowing downward from the hole 66 flows downward through the inner wall surface of the polishing liquid supply path 60 of the polishing pad 44, the polishing liquid is also supplied to the groove 62 reaching the polishing liquid supply path 60.

Therefore, even if the polishing liquid supply path 60 of the polishing pad 44 is not blocked by the workpiece 1, the polishing liquid is supplied to the groove 62. Since the polishing liquid that has reached the groove 62 is supplied to the entire area of the work surface of the workpiece 1 through the groove 62, the workpiece 1 is appropriately polished.

When the plug-shaped member 64 is not disposed on the polishing pad 44, the polishing liquid does not necessarily pass through the inner wall surface of the polishing liquid supply path 60. Therefore, in order for the polishing liquid to reliably reach the tank 62, a large amount of polishing liquid must be supplied to the polishing liquid supply source. On the other hand, since the pin-shaped member 64 is disposed in the polishing pad 44 of the present embodiment, the polishing liquid can be transmitted to the inner wall surface of the polishing liquid supply path 60, so that it is not necessary to supply a large amount of polishing liquid.

As described above, according to the polishing pad 44 of this embodiment, a polishing liquid can be appropriately supplied between the polishing pad 44 and the workpiece 1.

In addition, the present invention is not limited to the description of the above embodiments, and can be implemented with various modifications. For example, in the embodiment described above, the polishing pad 44 provided with the pin-shaped member 64 has been described, but one aspect of the present invention is not limited to this. For example, the plug-shaped member 64 incorporated in the polishing liquid supply path 60 of the polishing pad 44 having the polishing liquid supply path 60 is also one aspect of the present invention.

The pin-shaped member 64 may not be provided in the polishing liquid supply path 60, and may be, for example, a disc-shaped member having a diameter similar to that of the polishing pad. A hole penetrating the disc-shaped member in the thickness direction is provided near the center of the disc-shaped member. Next, when the polishing pad 44 is fixed to the mounting member 42 at the lower end of the main shaft 40, if the disc-shaped member is sandwiched between the polishing pad 44 and the mounting member 42, the polishing liquid supply path 60 is fixed by the The disc-shaped member is blocked, and the polishing liquid flows downward through the hole.

In addition, without departing from the scope of the object of the present invention, the structures, methods, and the like related to the above embodiments can be appropriately changed and implemented.

1‧‧‧Workpiece

3‧‧‧ protective tape

2‧‧‧ grinding device

4‧‧‧ abutment

4a‧‧‧ opening

6a.6b ‧‧‧ Cassette Loading Platform

8a.8b‧‧‧ Cassette

10‧‧‧ Workpiece transfer robot arm

12‧‧‧ positioning table

14‧‧‧ Workpiece moving mechanism (loading arm)

16‧‧‧ Workpiece removal mechanism (unloading arm)

18‧‧‧X-axis mobile stage

20‧‧‧holding table

20a‧‧‧ keep face

20b‧‧‧Attraction path

22‧‧‧ Move in and out area

24‧‧‧ Processing Area

26‧‧‧grinding unit

28‧‧‧ support

30‧‧‧Z-axis guide

32‧‧‧Z axis moving plate

34‧‧‧Z-axis ball screw

36‧‧‧Z-axis pulse motor

38‧‧‧ Spindle housing

40‧‧‧ Spindle

42‧‧‧Mounting parts

44‧‧‧ Abrasive pad

46‧‧‧Fixture

48‧‧‧ grinding fluid supply source

50‧‧‧ polishing liquid supply path

52‧‧‧Rotary cleaning device

54‧‧‧ substrate layer

56‧‧‧ abrasive layer

58‧‧‧Screw holes

60‧‧‧Grinding fluid supply path

62‧‧‧slot

64‧‧‧ bolt-shaped member

66‧‧‧hole

68‧‧‧ abrasive

FIG. 1 is a perspective view schematically showing a polishing apparatus. FIG. 2 (A) is a perspective view schematically showing the polishing pad viewed from the substrate layer side, and FIG. 2 (B) is a perspective view schematically showing the polishing pad viewed from the polishing layer side. FIG. 2 (C) is a plan view schematically showing a polishing pad viewed from the polishing layer side. 3 is a cross-sectional view schematically showing a polishing step using a polishing pad.

Claims (1)

A polishing pad, which is mounted on a polishing unit of a polishing device and has a circular plate shape, is provided with a holding table to hold a workpiece; and the polishing unit to grind a workpiece held on the holding table, and the polishing pad is characterized by comprising: a polishing liquid A supply path penetrating the central portion in the thickness direction; a groove formed on a surface contacting the workpiece and reaching the polishing liquid supply path; and a pin-shaped member having a plurality of holes penetrating in the thickness direction and arranged to The polishing liquid supply path is blocked.