JP2001018163A - Polishing pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly generate polishing material slurry by providing a direction of a spiral, toward the center part from a pad external peripheral part of a spiral groove connecting the pad center part and external peripheral part, in a reverse direction to a rotational direction of a level block at polishing time. SOLUTION: Polishing material slurry 6 supplied to the center of a level block 4 radially flows in its external peripheral direction by action of centrifugal force due to rotation of the level block 4, while flowing in a groove 2 and overflowing it, traverses the groove 2, reaches an external periphery of the level block, and flows out to the outside. Since a direction of a spiral of the groove 2, that is, a direction of a spiral toward the center part from an external peripheral part of the level block 4 is in a reverse direction to a rotational direction R of the level block 4, partly the slurry flowing in the groove 2 flows toward the center of the level block 4 in the groove 2 by action of centripetal force. Partly the slurry overflows the groove 2 in the halfway, but the rest of slurry, after flowing in a hollow 3, overflows in the periphery, to form again a flow of the slurry together with the newly supplied slurry 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing pad which is used for polishing a work by attaching it to a surface of a surface plate, and more particularly to a polishing pad used for chemical mechanical polishing (CMP) of a semiconductor wafer. It relates to a suitable polishing pad.

[0002]

2. Description of the Related Art For example, one of the techniques for flattening the surface of a semiconductor wafer is chemical mechanical polishing (CMP). In this method, the wafer is pressed against a polishing pad attached to a rotating platen, and the surface of the wafer is polished with the polishing pad while supplying an abrasive slurry.

A grid or concentric groove is formed on the surface of the polishing pad for the purpose of uniformly dispersing the supplied abrasive slurry throughout the pad or retaining the slurry on the pad as long as possible. (See, for example, JP-A-10-249710).

[0004] However, when the lattice-shaped grooves are cut, the effect of dispersing the slurry is high, but the abrasive slurry easily flows along the grooves to the outer periphery of the platen due to the action of centrifugal force due to the rotation of the platen. Therefore, the effect of holding the slurry is low.

[0005] On the other hand, in the case of cutting a plurality of concentric grooves, since each groove does not open to the outer periphery of the surface plate, the slurry holding effect is higher than that in the case of cutting a lattice-like groove. Once each groove is filled with the slurry, the newly supplied slurry easily flows out over each groove toward the outer periphery of the platen, so that the old slurry remains in each groove and the slurry is removed. There is a problem that replacement is difficult and sludge or the like easily accumulates in the groove. Moreover, in the cleaning process after the polishing operation is completed, it is difficult to completely wash out the slurry, sludge, and the like remaining in each groove and discharge them to the outside.

[0006]

The technical problem of the present invention is that the polishing step has an excellent effect of dispersing and retaining the abrasive slurry, and the washing step can easily wash off the slurry and sludge in the grooves. An object of the present invention is to provide a polishing pad excellent in usability.

[0007]

According to the present invention, there is provided, in accordance with the present invention, a circular polishing pad which is attached to a surface plate and used for polishing a work, the surface being provided with a central portion of the pad. It has at least one spiral groove connecting the outer peripheral portion, and the direction of the spiral of the groove from the pad outer peripheral portion to the center portion is opposite to the rotation direction of the surface plate during polishing. A polishing pad is provided.

[0008] The pad of the present invention having the above-mentioned structure is affixed to the surface of the surface plate, pressing the work against the pad surface of the rotating surface plate, and supplying the abrasive slurry to the center of the surface plate. Polish the work. At this time, the abrasive slurry supplied to the center of the platen flows in the outer circumferential direction of the platen by the action of centrifugal force due to the rotation of the platen, and flows while flowing into the groove or overflows from the groove. It reaches the outer periphery of the board and flows out therefrom.However, since the direction of the spiral of the groove, that is, the direction of the spiral from the outer peripheral portion of the pad toward the center is opposite to the rotation direction of the surface plate, Some of the slurry that has flowed into the groove flows toward the center of the platen through the groove due to the effect of centripetal force, and mainly spills out of the groove at the center, and then together with the newly supplied slurry. Then, the above-mentioned slurry flow is formed again, and the slurry is used cyclically.

[0009] Therefore, the dispersing effect and the holding effect of the slurry are excellent, and the slurry can be used cyclically and efficiently. In addition, since the slurry flows satisfactorily in the groove and is appropriately replaced with a new one, there is no problem that old slurry remains in the groove or sludge or the like easily accumulates. Furthermore, in the cleaning process after the polishing operation is completed, the platen is rotated in the opposite direction to the processing while supplying the cleaning liquid, so that the slurry or sludge in the groove is moved from the center side of the platen to the outer peripheral side. It can be easily and completely discharged to the outside by flowing.

In the present invention, preferably, the groove width and depth of the groove are formed uniformly over the entire length, and a recess for a liquid reservoir is formed in the center of the pad and connected to the inner end of the groove. The diameter and the depth of the depression are formed to be larger than the groove width and the depth of the groove.

As described above, by making the width and depth of the grooves uniform and forming a depression in the center of the pad, the effect of holding the slurry is improved, and the flow is smoothed and the dispersion effect is also improved. improves.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a polishing pad according to the present invention will be described below with reference to the drawings. 1 and 2 show a first embodiment of the pad of the present invention. This pad 1 is made of a sponge-like material made of a synthetic resin such as polyurethane, a felt-like material impregnated with a polyurethane resin, or the like. And has a uniform thickness.

On the surface of the pad 1, there is formed a spiral groove 2 connecting the central portion and the outer peripheral portion of the pad. The groove 2 has a function of uniformly dispersing the abrasive slurry on the surface of the surface plate during polishing and a function of efficiently retaining and holding the slurry. The spiral direction of the groove 2, that is, the outer peripheral portion of the pad 1 The direction of the spiral from the outer end 2a of the groove opening to the inner end 2b of the groove on the center side of the pad depends on the surface plate 3 during polishing.
(See FIG. 6). It is desirable that the groove width and depth of the groove 2 be formed substantially uniformly over the entire length.

The cross-sectional shape of the groove 2 may be a concave shape or a U-shape having a uniform width as shown in FIG. 3, or a dovetail shape having a wide groove width at the groove bottom side as shown in FIG. 5, a V-shape as shown in FIG. 5, or other shapes.

In the center of the pad 1, there is formed a circular depression 3 connected to the inner end 2b of the groove 2. The recess 3 functions as a slurry receiver for supplying the abrasive slurry, and also functions as a liquid reservoir for temporarily retaining the supplied slurry. 2 groove width d and depth h
It is formed larger. The preferred size of the diameter D of the depression 3 varies depending on the size of the pad 1 (therefore, the platen 4), but generally, 1/5 to 1/6 of the pad diameter.
Desirably.

As shown in FIG. 6, the pad 1 is
The workpiece W is pressed against the rotating surface of the surface plate 4 by a pressure plate or the like, and the abrasive slurry 6 is supplied from the nozzle 5 to the position of the depression 3 at the center of the surface plate 4. The work W is ground while polishing.

At this time, the abrasive slurry 6 supplied to the center of the platen 4 radially flows toward the outer periphery of the platen 4 by the action of centrifugal force due to the rotation of the platen 4 and flows into the groove 2. While spilling out of the groove 2, it crosses the groove 2 to reach the outer periphery of the surface plate and flows out. However, the direction of the spiral of the groove 2, that is, from the outer periphery of the surface plate 5 toward the center portion. Since the direction of the helix is opposite to the direction of rotation of the platen 4, some of the slurry flowing into the groove 2 moves toward the center of the platen 4 in the groove 2 by the action of centripetal force. While flowing, a part of the slurry overflows from the groove on the way, but the remaining slurry overflows to the surroundings after flowing into the depression 3, and together with the newly supplied slurry 6, forms the above-mentioned slurry flow again. I do.

Therefore, the supplied slurry 6 does not immediately flow in the outer peripheral direction of the platen 4 and does not flow out to the outside at once, but flows slowly while diffusing, and a part of the slurry 6 is reused cyclically. Excellent dispersing and holding effects.
In addition, since the slurry flows well in the groove 2 and is appropriately replaced with new slurry, there is no problem that the old slurry remains in the groove 2 or sludge or the like easily accumulates.

Further, in the step of cleaning the platen 4 after the polishing operation is completed, the platen 4 is rotated in a direction opposite to the direction of processing while supplying a cleaning liquid such as water, so that the slurry in the groove 2 is rotated. The sludge and the like can be easily and completely discharged to the outside from the open outer end 2a by flowing from the center of the surface plate 4 to the outer periphery.

Although the pad 1 of the first embodiment has one groove 2, the number of grooves may be two or more than three, and FIG. 7 shows two grooves. 2nd with 2A, 2B
An example pad 1A is shown. When a plurality of grooves are provided in this manner, it is desirable to provide the grooves 2A and 2B symmetrically with respect to the center of the pad 1A as shown. Further, the cross-sectional shapes of the plurality of grooves may be the same or different.

[0021]

As described above, according to the present invention, the polishing step is excellent in the effect of dispersing and retaining the abrasive slurry, and in the cleaning step, the slurry and sludge in the groove can be easily washed away. An excellent polishing pad can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of a pad according to the present invention.

FIG. 2 is an enlarged sectional view of the pad of FIG.

FIG. 3 is an enlarged sectional view of a main part of a pad showing an example of a sectional shape of a groove.

FIG. 4 is an enlarged sectional view of a main part of a pad showing another example of a sectional shape of a groove.

FIG. 5 is an enlarged sectional view of a main part of a pad showing still another example of a sectional shape of a groove.

FIG. 6 is a side view conceptually showing a use state of the pad.

FIG. 7 is a plan view showing a second embodiment of the pad according to the present invention.

[Explanation of symbols]

 1, 1A pad 2, 2A, 2B groove 2a outer end 2b inner end 3 depression 4 surface plate 6 slurry W work R surface direction of rotation D direction of depression H depth of depression d groove width h depth of groove

Claims (2)

[Claims] 1. A circular polishing pad which is attached to a surface plate and used for polishing a work, the surface of the polishing pad having at least one spiral groove connecting a center portion and an outer peripheral portion of the pad. A polishing pad, wherein a direction of a spiral from a pad outer peripheral portion to a central portion of the groove is opposite to a rotation direction of a surface plate during polishing. 2. The polishing pad according to claim 1, wherein
The groove width and depth of the groove are formed uniformly over the entire length, and a recess for a liquid reservoir is formed in the center of the pad and connected to the inner end of the groove. Characterized by being formed to be larger than the groove width and depth.