TWI769294B - polishing pad - Google Patents

Abstract

A polishing liquid is appropriately supplied between the polishing pad and the workpiece.

A polishing pad, an A disc-shaped polishing unit mounted on a polishing device, the polishing device having: a holding table for holding a workpiece; and the polishing unit for polishing the workpiece held on the holding table; the polishing pad is characterized by being provided with: a polishing liquid supply a 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 plug-shaped member having a plurality of holes penetrating in the thickness direction and arranged to block stop the slurry supply path.

Description

polishing pad

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

In the manufacturing process of component chips used in electronic devices such as mobile phones and computers, first, IC (Integrated Circuit, integrated circuit), LSI (Large Scale Integration, large-scale integrated circuit) are formed on the front surface of the semiconductor wafer. ) and other components. 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 carried out using a grinding apparatus. 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 main shaft; and a grinding wheel attached to the lower end of the main shaft. The grinding wheel includes a grinding stone that contacts the wafer to grind the wafer. For the grinding of wafers, a grinding apparatus is used, which has: a grinding unit for rough grinding, which includes a grinding stone with relatively large abrasive grains; and a grinding unit for fine grinding, which includes grinding with relatively small abrasive grains millstone.

When the back surface side of the wafer is ground, the surface to be ground tends to form minute concavo-convex shapes. Therefore, it is known that after grinding, 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 for holding the workpiece, and a polishing pad for polishing the workpiece. The diameter of the polishing pad is larger than the diameter of the wafer, and the polishing pad is arranged to cover the entire processed surface of the wafer held on the holding table when polishing the wafer. Then, the polishing pad and the holding table holding the wafer are rotated around respective 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 the center of the polishing pad, penetrates the polishing pad in the thickness direction, and when polishing a wafer, the polishing liquid is supplied to the wafer through the polishing liquid supply path. The polishing liquid is, for example, a slurry in which abrasive particles are dispersed. When grinding workpieces, not only chemical and mechanical It acts on the ground to help grinding, and it also helps to discharge the grinding dust generated by grinding. Therefore, it is necessary to appropriately supply the polishing liquid to the entire surface to be processed, so for example, grooves are formed on the polishing surface of the polishing pad.

[Previously known technical literature]

[Patent Literature]

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

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

For example, when the polishing pad is brought into abutment with a workpiece for polishing a relatively large diameter workpiece such as 200 mm in diameter or 300 mm in diameter, since the lower end of the polishing liquid supply path of the polishing pad is blocked by the workpiece, the polishing liquid stay in the polishing liquid supply path. At the time of polishing, the polishing pad forming the groove and the workpiece held by the holding table are brought into contact with each other and rotated around respective axes parallel to each other. Then, the polishing liquid is appropriately supplied between the polishing pad and the surface to be processed.

On the other hand, a workpiece with a relatively small diameter, especially in the case of a workpiece whose diameter is smaller than the radius of the polishing pad, even if the polishing pad is arranged to cover the entire surface of the workpiece, the lower end of the polishing liquid supply path still remains. May not be blocked by the workpiece. Then, even if the polishing liquid is supplied to the polishing liquid supply path, since most of the polishing liquid flows out, the polishing liquid cannot be appropriately supplied to the workpiece surface of the workpiece through the grooves 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 above-mentioned problems, and an object thereof is to provide a polishing pad capable of appropriately supplying a polishing liquid between the polishing pad and the workpiece.

According to an aspect of the present invention, there is provided a polishing pad mounted on a polishing unit of a polishing apparatus and having a disk shape, the polishing apparatus including: a holding table for holding a workpiece; and the polishing unit for polishing a workpiece held by the holding table A workpiece, and the polishing pad is characterized by comprising: a polishing liquid supply path penetrating a central portion in the thickness direction; a groove formed on a surface contacting the workpiece and reaching the polishing liquid supply path; and a plug-shaped member having a thickness of A plurality of holes penetrating in the direction are arranged so as to block the polishing liquid supply path.

A polishing liquid supply path is formed on the polishing pad of one aspect of the present invention, penetrates the polishing pad in the thickness direction, and supplies the polishing liquid to the polishing liquid supply path when polishing a workpiece. 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 to penetrate in the thickness direction. Therefore, the polishing liquid passes through the plug-like member by passing through the hole.

When the polishing liquid passing through the hole of the plug-like 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 the groove that reaches the polishing liquid supply path, and the polishing liquid is supplied to the entire area of the workpiece surface of the workpiece through the groove.

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

1: Workpiece

3: Protective tape

2: Grinding device

4: Abutment

4a: Opening

6a.6b: Cassette stage

8a.8b: Cassette

10: Workpiece conveying robot arm

12: Positioning table

14: Workpiece loading mechanism (loading arm)

16: Workpiece unloading mechanism (unloading arm)

18: X-axis moving table

20: Hold Desk

20a: Keep Faces

20b: Path of Attraction

22: Moving in and out of the area

24: Processing area

26: Grinding unit

28: Support Department

30: Z-axis guide

32: Z-axis moving board

34: Z-axis ball screw

36: Z-axis pulse motor

38: Spindle housing

40: Spindle

42: Mounting pieces

44: Polishing pad

46: Fixtures

48: Grinding fluid supply source

50: Grinding liquid supply path

52: Rotary cleaning device

54: substrate layer

56: abrasive layer

58: screw hole

60: Grinding fluid supply path

62: Groove

64: Bolt-like member

66: Hole

68: Grinding fluid

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 base 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 the polishing pad viewed from the polishing layer side.

3 is a cross-sectional view schematically showing a polishing step using a polishing pad.

Embodiments relating to one aspect of the present invention will be described with reference to the accompanying drawings. The polishing pad of the present example was attached to a polishing apparatus. The workpiece polished by the polishing apparatus and the 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 by the polishing apparatus 2 is, for example, a substantially disk-shaped substrate made of materials such as silicon, SiC (silicon carbide), or other semiconductor materials, or materials such as sapphire, glass, and quartz. The surface of the workpiece 1 is divided into a plurality of regions by a plurality of planned division lines (scribe lines) arranged in a lattice shape, and elements such as ICs are formed in each of the plurality of regions. Finally, the workpiece 1 is divided along the planned dividing line to form individual element wafers.

The workpiece 1 is thinned by grinding the back surface. The back surface of the workpiece 1 to be ground tends to be formed with minute concavo-convex shapes. Therefore, after grinding, the back surface of the workpiece 1 is ground to remove the minute irregularities. When grinding the back side of the workpiece 1 , the protective tape 3 may be pasted on the front surface of the workpiece 1 . The protective tape 3 protects the front side of the workpiece 1 from shocks applied such as when back grinding the workpiece 1 or when the workpiece 1 is transported, and prevents damage to the components.

The protective tape 3 has a film-like 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, polyethylene terephthalate), polyvinyl chloride, or polystyrene, etc. are used as a base material. Then, for the paste layer (adhesive layer), for example, silicone rubber, acrylic material, epoxy resin material or the like is used.

The grinding device 2 has a base 4 that supports each configuration. The upper surface of the front side part of the base 4 is provided with cassette mounting bases 6a, 6b. For example, the cassette 8a is mounted on the cassette mounting table 6a, and the workpiece|work 1 before grinding|polishing is accommodated. The cassette 8b is mounted on the cassette mounting table 8b, for example, and accommodates the workpiece|work 1 after grinding|polishing. The workpiece transfer robot 10 is mounted on the base 4, is adjacent to the cassette mounting tables 6a, 6b, and transfers the workpiece 1. As shown in FIG.

The upper surface of the front side part 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 carrying mechanism (loading arm) 14 for placing the workpiece 1 on the holding table 20; the workpiece A carry-out mechanism (unloading arm) 16 carries out the workpiece 1 from the holding table 20 ; and a rotary cleaning device 52 cleans and spin-dries the polished workpiece 1 .

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

The upper surface of the holding table 20 is the holding surface 20a, and the workpiece 1 is held. The inside of the holding table 20 is provided with a suction path 20b (see FIG. 3 ), one end of which leads to the holding surface 20a of the holding table 20, and the other end is connected to a suction source (not shown). When the suction source is activated, 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 about an axis perpendicular to the holding surface 20a.

A grinding unit 26 is arranged above the processing area 24 to grind the workpiece 1 . A support portion 28 is erected at the rear end portion of the base 4 of the polishing apparatus 2 , and the polishing unit 26 is supported through the support portion 28 . exist A pair of Z-axis guide rails 30 extending in the Z-axis direction are provided on the front surface of the support portion 28 , and the Z-axis moving plate 32 is slidably attached to each of the Z-axis guide rails 30 .

A nut portion (not shown) is mounted on the rear side (rear side) of the Z-axis moving plate 32 , and the 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 rail 30 .

The grinding 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 grinding unit 26 can be moved in the Z-axis direction.

The polishing unit 26 includes a main shaft 40 , which is rotated by a motor connected to the base end side, and a polishing pad 44 in this embodiment, which is fixed to a mounting member 42 through a fixture 46 , and the mounting member 42 is disposed on the distal end side of the main shaft 40 . The motor is provided in the spindle housing 38 , and when the motor is actuated, 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 the polishing liquid supply source 48 , and when polishing the workpiece 1 , the polishing liquid formed in the center portion of the polishing pad 44 is fed from the polishing liquid supply source 48 through the polishing liquid supply path 50 to the polishing liquid supply source 48 . The supply path 60 (refer to FIG. 3 ) supplies the polishing liquid.

When polishing the workpiece 1 held on the holding table 20 positioned in the machining 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 each axis along the Z-axis direction, and the polishing pad 44 is lowered to abut against the workpiece 1 . At this time, in order to supply the polishing liquid between the workpiece 1 and the polishing pad 44 , the polishing liquid supply source 48 is actuated, 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 polish the workpiece 1 having a radius larger than that of the polishing pad 44, since the lower end of the polishing liquid supply path 60 of the polishing pad 44 is blocked via the workpiece 1, the polishing The liquid stays on the workpiece 1 . During polishing, the polishing pad 44 and the workpiece 1 are brought into contact with each other while being rotated around an axis along the Z-axis direction, so that the polishing liquid is appropriately supplied to the polishing pad 44 and the workpiece 1 between the machined surfaces.

On the other hand, when polishing the workpiece 1 whose diameter is smaller than the radius of the polishing pad 44 , even if the polishing pad 44 is brought into contact with the workpiece 1 , the polishing liquid supply path 60 of the polishing pad 44 will not be affected by the workpiece 1 . blocked situation. Then, even if the polishing liquid is supplied to the polishing liquid supply path 60, due to the polishing liquid Since most of the slurries flow out, the polishing liquid cannot be appropriately supplied to the machined surface of the workpiece 1 . If the polishing liquid cannot be appropriately supplied to the workpiece surface, the workpiece 1 cannot be properly polished.

Therefore, even when polishing the workpiece 1 whose diameter is smaller than the radius of the polishing pad 44 , the polishing pad 44 of the present embodiment is used in order to appropriately supply the polishing liquid to the surface to be machined. Next, the polishing pad 44 is described in more detail.

The polishing pad 44 is disc-shaped and has: 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 is used to polish the workpiece 1, touch the workpiece 1. FIG. 2(A) is a perspective view schematically showing the polishing pad 44 viewed from the base 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. 2(C) is a plan view schematically showing the polishing pad 44 viewed from the polishing layer 56 side.

As shown in FIG. 2(A) , screw holes 58 are formed in the base material layer 54 . When the polishing pad 44 is fixed to the mount 42 , the threaded fixture 46 is screwed into the screw hole 58 . Moreover, as shown in FIG.2(B), the groove|channel 62 is formed in the surface of the workpiece|work 1 which contacts this grinding|polishing layer 56. A polishing liquid supply path 60 that penetrates the polishing pad 44 in the thickness direction is formed in the center portion of the polishing pad 44 , and the grooves 62 reach 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 FIGS. 2(A) and 2(C) , a plug-like member 64 is arranged on the polishing liquid supply path so as to block the polishing liquid supply path. A plurality of holes 66 are formed in the plug-shaped member 64 and penetrate the plug-shaped member 64 in the thickness direction. For example, the hole 66 has a diameter of about 4 mm and is formed on the peg member 64 at 4 places. This plug-shaped member 64 is produced by forming a hole 66 in a resin such as disc-shaped vinyl chloride, for example, by a drilling machine or the like.

The abrasive layer 56 is, for example, a nonwoven fabric containing abrasive grains. In the case of using a fixed abrasive pad (which is used for the non-woven fabric in which the polishing layer 56 contains the abrasive grains), a polishing liquid that does not contain abrasive grains is used when polishing the workpiece 1 . This polishing liquid is, for example, an alkaline solution obtained by adding a water-soluble organic substance such as glycerol or ethylene glycol to an alkaline solution in which sodium hydroxide or potassium hydroxide is dissolved. Alternatively, pure water can also be used.

Then, a non-woven fabric that does not contain abrasive grains can also be used for the abrasive 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, etc. are selected according to the content of the predetermined grinding or the type of the workpiece 1 .

Furthermore, the polishing layer 56 may include solid-phase reaction fine particles to induce solid-phase reaction with the workpiece 1 , and fine particles for removing defects, which have a higher Mohs hardness than the workpiece 1 and can be formed on the workpiece 1 . Form a blemish-free layer. When the defect-removing layer is formed, the intrusion of impurity elements into elements formed on the workpiece can be suppressed. The polishing pad 44 having the polishing layer 56 is made by dispersing the solid-phase reaction fine particles and the fine particles for removing defects on a liquid binder, and immersing the liquid binder in a non-woven fabric to dry the non-woven fabric. formed.

Next, the grinding|polishing of the workpiece|work 1 in the grinding|polishing apparatus 2 attached to the grinding|polishing pad 44 is demonstrated. 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 attached to a mount 42 disposed at the lower end of the spindle 40 .

When the polishing pad 44 is attached to the mount 42 , the polishing liquid supply path 50 formed in the polishing unit 26 is connected to the polishing liquid supply path 60 formed in the center of the polishing pad 44 .

First, the suction source of the holding table 20 is actuated, and the workpiece 1 is sucked and held on the holding surface 20a. Then, the holding table 20 is moved in the processing area 24 , and the polishing unit 26 is arranged above the workpiece 1 so as 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. Next, when the polishing pad 44 comes into contact with the workpiece 1, the polishing of the workpiece 1 starts.

When polishing the workpiece 1 , the polishing liquid supply source 48 of the polishing apparatus 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 downward from the hole 66 . 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 , it is also supplied to the groove 62 of 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 machined surface of the workpiece 1 via the groove 62 , the workpiece 1 is properly polished.

When the plug-like member 64 is not arranged 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 reach the groove 62 surely, a large amount of polishing liquid must be supplied to the polishing liquid supply source. On the other hand, since the plug-like member 64 is provided in the polishing pad 44 of the present embodiment, the polishing liquid can be delivered 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 the present embodiment, the 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-described embodiments, and can be implemented with various modifications. For example, in the above-described embodiment, the polishing pad 44 on which the plug-shaped member 64 is arranged has been described, but one aspect of the present invention is not limited to this. For example, the plug-like member 64 incorporated in the polishing liquid supply path 60 of the polishing pad 44 having the polishing liquid supply path 60 is also an aspect of the present invention.

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

In addition, the structures, methods, and the like related to the above-described embodiments can be implemented with appropriate modifications without departing from the scope of the object of the present invention.

1: Workpiece

3: Protective tape

20: Hold Desk

20a: Keep Faces

20b: Path of Attraction

40: Spindle

42: Mounting pieces

46: Fixtures

50: Grinding liquid supply path

54: substrate layer

56: abrasive layer

60: Grinding fluid supply path

62: Groove

64: Bolt-like member

66: Hole

68: Grinding fluid

Claims (2)

A grinding pad is mounted on a grinding unit of a grinding device and is disc-shaped, the grinding device is provided with: a holding table for holding a workpiece; and the grinding unit is used for grinding the workpiece held on the holding table, and the grinding pad is characterized by having : base material layer; grinding layer, contacting the workpiece; grinding fluid supply path, formed in the base material layer and the grinding layer and penetrating the central part in the thickness direction; groove, formed on the surface of the grinding layer contacting the workpiece, and reach the polishing liquid supply path; and a plug-like member having a plurality of holes penetrating in the thickness direction and arranged to block the polishing liquid supply path. The polishing pad of claim 1, wherein when the polishing liquid is supplied to the polishing liquid supply path, the polishing liquid temporarily stays above the plug-like member, and flows downward from the hole, through the hole formed in the polishing liquid. The inner wall surface of the polishing liquid supply path of the base material layer and the polishing layer flows downward, is supplied to the groove of the polishing layer, and is supplied to the entire area of the workpiece surface of the workpiece.

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