JP2002100592A - Abrasive pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abrasive pad, with which the grade of polishing can be variously changed as designed by forming a stable groove shape without making a wafer fall from a holder by friction during wafer polishing and exchange work can be easily executed. SOLUTION: An abrasive pad 10 is provided which is equipped with an upper layer 2 and a lower layer 1 and forms at least one recessed part 21 by locating the upper layer 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polishing process for a semiconductor wafer or the like.

[0002]

2. Description of the Related Art In recent years, in the semiconductor industry, the degree of integration of ICs has dramatically increased, and 4M, 16M, and even 64M
Is in progress.

[0003] Under such circumstances, demands for improving the quality of the surface of the wafer, which is the base of the IC, and for the cost are increasing. Wafer chemical properties,
Of course, the electrical characteristics are natural, but in order to increase the degree of integration of ICs, the minimum line width of the devices provided on the wafer is becoming smaller and smaller, from 0.5 microns to 0.35 microns. Demands are becoming more sophisticated. Further, the size of the wafer has been rapidly increasing, and the cost per bit has been rapidly decreasing. Recently, 12-inch silicon wafers are on the market, and various types of polishing pads exist to cope with the enlargement of wafers.

For example, when trying to polish a 12-inch or 16-inch wafer using a non-woven fabric pad, the following problems have become apparent. (1) If there is no groove on the surface, the slurry does not reach the center of the semiconductor wafer, so that a large frictional force is generated between the polishing pad and the wafer, and the wafer slides out of the holder during wafer polishing. The wafer may be crushed. In that case, the operation rate of the device is reduced, and the product yield is reduced. (2) In order to supply the slurry to the central portion of the wafer and eliminate the above-mentioned disadvantage, when performing groove processing on the non-woven fabric pad, if a groove is excavated with a diamond cutter, the fibers are loosened and fuzzing of the groove occurs. However, a stable groove shape as designed cannot be obtained. Further, if a groove is to be formed by heating, it is extremely difficult to form a groove by thermal deformation of the surface due to the properties of the nonwoven fabric. Therefore, it is very difficult to design a semiconductor polishing grade by groove processing of a nonwoven fabric pad. (3) When polishing a large-diameter wafer, the diameter of the lower platen of the polishing apparatus is 1800 mm or more, so that it is difficult for one person to replace a polishing pad having the same diameter, and the maintenance time is prolonged. . As a result, the yield of products is reduced, and the operation rate of the device is also reduced. (4) When changing the shape or depth of the groove to change the target film or the processing process (polishing condition), it is necessary to remove the entire pad body from the polishing platen and change to another type of polishing pad. In the experimental and development stages, the target film and processing process need to be changed frequently.Preparing many types of pads and replacing large polishing pads is extremely efficient due to the difficulty of this operation. bad.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is designed so that the wafer does not fall off from the holder due to friction during wafer polishing, and the polishing grade is designed by forming a stable groove shape. It is an object of the present invention to provide a polishing pad that can be changed in various ways as described above and that can easily perform a replacement operation.

[0006]

The polishing pad of the present invention comprises:
By providing an upper layer and a lower layer, and arranging the upper layer on the lower layer, one or more concave portions are formed, thereby achieving the above object.

In one embodiment, the upper layer is formed from two or more pad pieces, and the pad pieces are adhered to the lower layer.

In one embodiment, the recess is a groove.

In one embodiment, the depth of the recess is adjusted by changing the thickness of the at least upper layer.

In one embodiment, the upper layer is releasably attached to the lower layer with a double-sided tape.

A polishing apparatus according to the present invention comprises an upper plate and a lower plate. The upper plate holds an object to be polished, and the lower plate has an upper layer and a lower layer.
A polishing pad having one or more recesses is provided, and a nozzle capable of supplying a polishing slurry between the polishing pad and the surface of the object to be polished is provided, thereby achieving the above object.

Hereinafter, the present invention will be described in detail.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A polishing pad 10 of the present invention is shown in FIG.
And a circular lower layer 1 as shown in FIG.
Has a pad piece 5 releasable by an adhesive layer such as a double-sided tape 7. The upper layer 2 is composed of two or more pad pieces 5, and one or more grooves 4 are formed between adjacent pad pieces 5, 5 by the arrangement of the pad pieces 5, 5. When the upper layer 2 is viewed from the upper surface, the shape of the groove 4 may be radial as shown in FIG. 1, may be annular as shown in FIG. 5, or may be lattice as shown in FIG. Or
As shown in FIG. 9, the pad pieces 5 may be circular, and concavities 21 may be formed between adjacent pad pieces 5, or the concavities 21 may be formed by forming holes such as circles in the upper layer 2. It may be. The depth of the groove 4 or the concave portion 21 is
Has a depth corresponding to the thickness of the substrate. The preferred width of the groove 4 is 0.2 to 5 mm, and the preferred depth of the groove 4 is 0.3 to 5 mm.
1.2 mm.

It is understood that any shape other than those described above is within the scope of the present invention as long as the concave portion is formed by a combination of the molded upper layer 2 and lower layer 1.

Next, a method of manufacturing the polishing pad 10 shown in FIG. 1 will be described. A disk-shaped lower layer 1 and an upper layer 2 having the same shape as the lower layer 1 are prepared, and the upper layer 2 is cut radially, for example, as shown in FIG. Preferably, the width of the notch 3 at that time is cut with a dimension corresponding to the width of the groove 4 to be formed. Then, a pad piece 5 cut into a fan shape is stuck on the lower layer 1 using a general-purpose double-sided tape 7. At this time, preferably, the circumferential portion 6 of the fan-shaped pad piece 5 is made to coincide with the circumferential portion 22 of the lower layer 1, and the adjacent pad pieces 5 are arranged at equal intervals. At this time, a positioning line 19 may be provided in advance on the lower layer 1 so that the position is not shifted. As a result, a radial groove 4 having a width corresponding to the width of the cut 3 can be formed on the polishing pad 10. FIG. 1 shows a pad piece 5.
Is shown, but an arbitrary number (for example, 6, 10, 12, or the like) can be adopted as long as the number of grooves 4 is 1 or more.

The method of manufacturing the polishing pad 10 shown in FIG. 5 will be described. The upper layer 2 is cut into a plurality of concentric annular pad pieces 5 and the pad pieces 5 are attached to the lower layer 1. as a result,
An annular groove 4 having the same width as the width of the cut can be formed on the polishing pad 10. FIG. 5 shows an example having four annular grooves 4, but if there is one or more grooves 4, the upper layer 2 may be composed of an arbitrary number of pad pieces 5.

The polishing pad 10 shown in FIG. 8 is formed by cutting the upper layer 2 into a rectangular shape and attaching the pad pieces 5 to the lower layer 1 to form the lattice-shaped grooves 4.

As shown in FIG. 9, the upper layer 2 is formed into a plurality of circles to form pad pieces 5, and the pad pieces 5 are adhered to the lower layer 1 to provide circular protrusions, thereby providing a fixed width. However, the polishing pad 10 having the concave portion 21 can be formed.

Alternatively, the polishing pad 10 can be formed by forming one or more appropriate holes in the upper layer 2 and attaching the holes to the lower layer 1 to form circular recesses. Here, the holes need not be circular and may be of any shape.

The thickness of the upper layer 2 and the thickness of the lower layer 1 are 2
It is about mm, but the depth of the groove 4 to be formed can be changed by changing the combination of the thickness of the upper layer 2 and the thickness of the lower layer 1. FIG. 6 shows (thickness of upper layer 2)>
4 shows a cross section of the polishing pad 10 in the case of (thickness of the lower layer 1). In this case, a deep groove can be formed. FIG.
Shows a cross section of the polishing pad 10 when (thickness of the upper layer 2) <(thickness of the lower layer 1). In this case, a shallow groove can be formed.

In order to form the groove 4 by cutting and separating the upper layer 2 and performing processing such as sticking,
Unlike a case where a groove is excavated and formed on a single polishing pad with a diamond cutter or the like, the fiber is not loosened or fluffed, and a stable groove shape is obtained. Therefore, various groove shapes can be easily obtained. .

The substrate used for the upper layer 2 and the lower layer 1 of the polishing pad of the present invention is made of a polymer composition selected from polyurethane resin, epoxy resin or vinyl resin (for example, foam), Alternatively, it is composed of a composite comprising the composition and a base material. Examples of the foam include the following.

As the foam, for example, a foam composition can be formed by a wet coagulation method by using a composition containing a urethane polymer and dimethylformamide. Alternatively, a composition containing a urethane polymer, a vinyl polymer such as a vinyl chloride polymer, a vinyl chloride-vinyl acetate copolymer, a vinyl chloride-vinyl acetate-vinyl alcohol terpolymer, and dimethylformamide. By using, the foam composition can be formed by a wet coagulation method. The surface of the foam, particularly the skin layer formed on the surface, is preferably buffed to have a foamed structure on the surface. These foams can be used for both the upper and lower layers.

Examples of the urethane polymer intended for thermosetting include polyether-based urethane resins, polyester-based urethane resins, polyester-ether-based urethane resins,
Any of the polycarbonate urethane resins can be used. Examples of the polyol component used in the production of each urethane resin include polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol, polyethylene adipate, polypropylene adipatere, polyoxytetramethylene adipate, and the like. In addition, examples of the isocyanate component include 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, and the like.

Examples of the chain extender include ethylene glycol, 1,4-butanediol, propylene glycol, and 3,3′-dichloro-4,4′-diaminodiphenylmethane.

The urethane polymer is, for example, polyoxypropylene glycol as a polyol component, 4,4'-diphenylmethane diisocyanate as an isocyanate component, 1,4-butanediol as a chain extender,
A dimethylformamide solution of a urethane polymer polymerized using ethanol as a polymerization terminator and dimethylformamide as a solvent is used.

A filler such as carbon black, a dispersion stabilizer such as a surfactant, and a wet coagulant may be added to the foam composition.

The above-mentioned foam composition is applied on a support having a releasable surface, and a foam can be obtained by, for example, a wet coagulation method described below.

That is, the support coated with the foam composition is immersed in water at a predetermined temperature and then immersed in hot water at a predetermined temperature for a certain period of time. During this immersion, the solvent contained in the foam composition is replaced by permeation of water, whereby the foam composition is desolvated, the foam composition is low foamed, and the elastic foam layer is formed on the support. Formed. Next, this is taken out of the water, dried with hot air at a predetermined temperature and for a predetermined time, and buffed to obtain a foam.

A substrate can be impregnated with the above foam composition, and a composite can be formed by a wet coagulation method in the same manner as described above. As the base material, for example, a nonwoven fabric (Nippon Felt B
S-300) can also be used.

The polishing pad 1 of the present invention having the above configuration
The operation of 0 will now be described with reference to FIG.

The polishing pad 10 of the present invention is set on the lower platen 8 of the semiconductor polishing apparatus 20, and the wafer 14 is mounted on the holder 13 of the upper platen 9. The upper surface plate 9 is pressed against the lower surface plate 8 under a load. The upper surface plate 9 and the lower surface plate 8 face each other and rotate in opposite directions as shown in FIG. A slurry 11 is introduced between the polishing pad 10 and the wafer 14 through a nozzle 12, and the slurry 1 is used by using the polishing pad 10 of the present invention.
1 are uniformly dispersed on the polishing pad 10. The principle is as described below.

As the polishing pad 10 and the wafer 14 rotate, the slurry 11 supplied therebetween is uniformly dispersed on the polishing pad 10. At this time, surplus slurry 1
1 are accumulated in the grooves 4 of the polishing pad 10, and unnecessary slurry 11 is removed from the polishing pad 10. On the other hand, since the lower platen 8 and the upper platen 9 rotate in the opposite directions in the arrangement shown in FIG. 10, in the region 15 near the periphery of the polishing pad 10 and the region 16 near the center, the wafer 14 The relative speed with the polishing pad 10 is different,
If the polishing pad 10 has no groove, in the region near the peripheral portion 10 where the relative speed between the wafer 14 and the polishing pad 10 is high,
Due to the friction, the slurry 11 rapidly decreases from between the wafer 14 and the polishing pad 10. Then, the distribution of the slurry 11 becomes non-uniform with time, and the polishing condition of the wafer 14 also becomes non-uniform. If the polishing pad 10 of the present invention is used, when a region where the slurry 11 is insufficient on the wafer 14 is formed, the slurry 11 accumulated in the groove 4 is supplied, and the insufficient portion is eliminated, so that the uniformity of the wafer 14 is improved. Polishing can be realized.

In the polishing pad 10 shown in FIG. 1 in which the grooves 4 are formed radially, the excess slurry 11 accumulated in the grooves
Is caused by the centrifugal force of the polishing pad 10 as it rotates.
Since the slurry 11 moves from the central portion 17 to the peripheral portion 18 of the polishing pad 10, the slurry 11 accumulated in the groove 4 relatively quickly passes between the polishing pad 10 and the wafer 14. On the other hand, in the polishing pad 10 shown in FIG. 5 in which the grooves are formed concentrically, the excess slurry 11 accumulated in the grooves 4 is less likely to move from the central portion 17 of the polishing pad 10 to the peripheral portion 18. Therefore, the slurry 11 stays in the groove 4 for a relatively long time. As described above, by changing the shape of the groove 4, the time during which the slurry 11 stays in the groove 4 can be changed, so that the speed at which the slurry 11 is supplied from the inside of the groove 4 to the polishing surface also differs. As a result, the degree of polishing can be changed.

By changing the groove shape and the depth of the groove 4 as described above, the polishing grade can be variously changed as designed.

Since the pad piece 5 is attached to the lower layer 1 with the double-sided tape 7, when changing the polishing conditions, the pad piece 5 may be peeled off and a new pad piece 5 may be attached. Since the pad piece 5 is divided into at least two pieces, it can be replaced much more easily than the case where the upper layer having the same size as the lower layer 1 is replaced, and can be sufficiently replaced even by one person. Therefore, the polishing conditions need to be changed much less than the conventional one, and the time during which the polishing apparatus 20 is stopped can be reduced. As a result, the manufacturing efficiency of the semiconductor can be improved.

If several pad pieces 5 having different shapes are prepared, various polishing conditions can be created by replacing the pad pieces 5, and it is not necessary to replace the entire polishing pad at this time. In addition, changes in polishing conditions can be made in a short time, and work can be efficiently performed in experiments and development sites.

[0038]

According to the present invention, the wafer does not fall off from the holder due to friction during the polishing of the wafer, and the polishing grade can be variously changed as designed by forming a stable groove shape, and the replacement operation can be easily performed. A polishing pad can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view of a polishing pad of the present invention in which grooves are radially formed.

FIG. 2 is a plan view of a lower layer of the polishing pad of the present invention.

FIG. 3 is a plan view showing a pad piece of the polishing pad of the present invention in which grooves are radially formed.

FIG. 4 is a cross-sectional view of the polishing pad of the present invention having grooves formed radially, taken along line AA ′ of FIG. 1;

FIG. 5 is a plan view of the polishing pad of the present invention in which grooves are formed concentrically.

FIG. 6 is a cross-sectional view of the polishing pad of the present invention when the thickness of the upper layer is larger than the thickness of the lower layer, taken along the line AA ′ of FIG. 5;

FIG. 7 is a cross-sectional view of the polishing pad of the present invention in which the thickness of the lower layer is larger than the thickness of the upper layer, taken along the line AA ′ in FIG. 5;

FIG. 8 is a plan view of the polishing pad of the present invention in which grooves are formed in a lattice shape.

FIG. 9 is a plan view of the polishing pad of the present invention having a circular projection.

FIG. 10 is a schematic view of a semiconductor polishing apparatus provided with the polishing pad of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lower layer 2 Upper layer 4 Groove 5 Pad piece 7 Double-sided tape 8 Lower surface plate 9 Upper surface plate 10 Polishing pad 11 Slurry 14 Wafer 20 Semiconductor polishing device

Claims (6)

[Claims] 1. A polishing pad comprising an upper layer and a lower layer, wherein one or more recesses are formed by disposing the upper layer on the lower layer. 2. The polishing pad according to claim 1, wherein the upper layer is formed of two or more pad pieces, and the pad pieces are attached to the lower layer. 3. The method according to claim 1, wherein the recess is a groove.
A polishing pad according to item 1. 4. The depth of the concave portion is adjusted by changing a thickness of at least the upper layer.
Item 3. The polishing pad according to any one of Items 3. 5. The polishing pad according to claim 1, wherein the upper layer is detachably attached to the lower layer with a double-sided tape. 6. An upper plate and a lower plate, wherein an object to be polished is held on the upper plate, and the lower plate has an upper layer and a lower layer, and one or more concave portions are formed by the arrangement of the upper layer. A polishing pad, provided with a polishing pad to be polished, and a nozzle capable of supplying a polishing slurry between the polishing pad and the surface of the object to be polished.