JP2021035713A - Abrasive pad - Google Patents

Abstract

To provide an abrasive pad capable of being easily bent in disposal, even in the case of the abrasive pad with high hardness.SOLUTION: An abrasive pad for use comprises at least a circular polishing layer 1 having a polishing surface P for polishing an object to be polished. An opposite polishing surface R opposite to the polishing surface of the polishing layer has at least one first groove G1. Both ends of the first groove do not reach an outer periphery, and its depth is in the range of 5-30% of the thickness of the polishing layer. Thus, even the abrasive pad with high hardness can be easily bent along the first groove.SELECTED DRAWING: Figure 1

Description

The present invention relates to a polishing pad used for CMP (chemical mechanical polishing), specifically, a polishing pad that is bent after use to be compact and easily discarded.

CMP is used as a polishing method used in the step of mirror-processing a semiconductor wafer and the step of flattening the surface of an object to be polished having an insulator film such as an oxide film or a conductor film when forming a circuit on a semiconductor substrate. It has been known. CMP is a method in which a slurry is supplied to the polished surface of a rotating polishing pad, and the surface to be polished is pressed while rotating while rotating to polish the surface.

As the polishing pad for CMP, a non-woven fabric type polishing pad, a polishing pad mainly composed of a polymer foam having a closed cell structure, a polishing pad mainly composed of a non-foamed polymer, and the like are known. The non-woven fabric type polishing pad has an advantage that it has good contact with the base material to be polished because it is flexible, but has a disadvantage that it has a low flatness that flattens the surface to be polished because it is flexible. .. Further, the polishing pad mainly composed of a polymer foam having a closed cell structure has an advantage that it has excellent flatness because it has a higher hardness than a non-woven fabric type polishing pad, while the polishing layer has a higher hardness. There was a disadvantage that it was difficult to achieve high flatness by polishing. On the other hand, a polishing pad mainly composed of a non-foaming polymer can realize high flatness by increasing the hardness of the polishing layer. In addition, the polishing pad mainly composed of non-foamed polymer has higher wear resistance than the polishing pad mainly composed of polymer foam, so that the polishing pad has a longer life and polishing characteristics due to variations in foaming. It also has the advantage that it is difficult to make a difference.

By the way, in order to solve the drawbacks that occur in CMP, it has been proposed to form grooves and recesses on the anti-polished surface which is opposite to the polished surface of the polishing pad.

For example, Patent Document 1 below is based on the finding that the generation of scratches is induced by the generation of excessive pressure near the center of the polishing pad, and is circular or circular or near the center of the polishing pad on the anti-polishing surface side. It is proposed to form a concave portion having a polygonal shape.

Further, for example, Patent Document 2 below has a polishing pad having a plurality of holes for holding a polishing agent for polishing an object to be polished, and has a groove on a surface opposite to the surface for polishing the object to be polished. According to the polishing pad, the area surrounded by the groove is likely to be displaced independently, the semiconductor wafer and the polishing layer are in contact with each other almost flatly, and an excessive load is less likely to occur at the edge portion of the semiconductor wafer. Further, it is disclosed that the semiconductor wafer can be prevented from being deformed into a sucker shape and a negative pressure is generated between the polishing pad and the semiconductor wafer.

Further, for example, Patent Document 3 below discloses a polishing pad having concentric grooves on both the polished surface and the back surface thereof. Then, according to such a polishing pad, the groove formed on the anti-polishing surface appears on the polishing surface due to the polishing of the polishing layer accompanying the execution of the polishing operation, so that the holding power of the slurry is restored during polishing. Disclose what to do.

Japanese Unexamined Patent Publication No. 2004-345048 Japanese Unexamined Patent Publication No. 9-117855 Japanese Unexamined Patent Publication No. 2005-294410

In CMP, the polishing pad is used by being adhered to the rotary surface plate of the polishing apparatus with a double-sided adhesive material. The polishing pad reaches the end of its life when the groove for holding the slurry on the polishing surface becomes too shallow and the polishing rate fluctuates, and after being peeled off from the rotary surface plate, it is bent and discarded. As the polishing pad used for CMP, in recent years, a polishing pad having high hardness has begun to be used in order to achieve high flatness. In the case of the low-hardness polishing pad that has been used in the past, it was easy to bend at the time of disposal, but the high-hardness polishing pad has problems that it is difficult to bend at the time of disposal and that after bending, it repels when it tries to return to its original state due to elasticity. there were.

An object of the present invention is to provide a polishing pad that can be easily bent at the time of disposal even if the polishing pad has a high hardness.

One aspect of the present invention includes at least a circular polishing layer having a polishing surface for polishing an object to be polished, and at least one first groove on the anti-polishing surface opposite to the polishing surface of the polishing layer. The first groove is a polishing pad in which both ends do not reach the outer periphery and the depth is 5 to 30% of the thickness of the polishing layer. According to such a polishing pad, stress is concentrated in the first groove when bending at the time of disposal, so that even a high-hardness polishing pad is easily bent along the first groove. Further, since the slurry does not easily penetrate into the first groove where both ends do not reach the outer periphery, the decrease in the adhesive force of the double-sided adhesive that adheres the polishing layer to the rotary surface plate or the cushion layer is suppressed. .. Further, since the depth of the first groove is 5 to 30% of the thickness of the polishing layer, stress is concentrated on the first groove when bent, and the step due to the formation of the first groove is polished. It is preferable because it does not easily affect the characteristics.

Further, it is preferable that the first groove overlaps 60 to 95% of the length of the chord with respect to the circular shape because it is easy to bend when bent and it becomes appropriately compact when bent.

Further, it is preferable that the string has a circular diameter because the polishing pad is easily bent in half in the vicinity of the center of the circular shape to be compact.

Further, the fact that the first groove is covered with the double-sided adhesive material laminated on the anti-polished surface and closed, and that the cushion layer is laminated with the double-sided adhesive material, the slurry is formed during polishing. It is preferable because it is difficult to penetrate through the first groove.

Further, the polishing pad further has a second groove for holding the slurry, and when the second groove and the first groove are projected onto a two-dimensional surface, they may have a portion where they overlap. It is preferable because the thickness of the polishing layer becomes thinner in the overlapping portion and the polishing layer becomes more easily bent.

Further, when the depth of the first groove is D1 (mm), the depth of the second groove is D2 (mm), and the thickness of the polishing layer is T (mm), D1 <T-D2 is satisfied. This is preferable because the first groove on the anti-polished surface and the second groove on the polished surface are separated and the first groove does not easily affect the polishing characteristics of the polished surface.

Further, it is preferable that the flexural modulus of the polishing layer is 1000 to 40,000 MPa from the viewpoint that the effect of the present invention becomes remarkable because the polishing pad has high elasticity.

According to the present invention, it is possible to obtain a polishing pad that can be easily bent at the time of disposal even if the polishing pad has a high hardness.

FIG. 1 is a schematic view for explaining the polishing pad 10 of the embodiment. FIG. 2 is a schematic plan view of a polishing surface for explaining the polishing pad 20 of another example of the embodiment. FIG. 3 is a schematic plan view of a polishing surface for explaining the polishing pad 30 of another example of the embodiment. FIG. 4 is an explanatory diagram for explaining CMP. FIG. 5 is an explanatory diagram for explaining how the polishing pad is bent at the time of disposal.

An embodiment of the polishing pad according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic view for explaining the polishing pad 10, which is an example of the polishing pad of the present embodiment. In FIG. 1, (a) is a schematic plan view of the polishing pad 10 viewed from the side of the polishing surface P, which is one surface of the polishing layer, and (b) is a partially enlarged schematic view of the polishing surface P of (a), (c). Is a schematic cross-sectional view of the I-I'cross section of (b). The polished surface is one surface of the polishing layer that is in contact with the object to be polished and performs a polishing action in CMP, and the surface that is opposite to the polishing surface of the polishing layer and is not in contact with the object to be polished is the anti-polishing surface.

In FIG. 1, 10 is a circular polishing pad including a polishing layer 1 having a polishing surface P and an anti-polishing surface R. With reference to the schematic cross-sectional view of FIG. 1C, the polishing pad 10 has a laminated structure in which the polishing layer 1 and the cushion layer 2 are adhered to the anti-polishing surface R of the polishing layer 1 via the double-sided adhesive material 3. Have. The cushion layer is a soft layer having a hardness lower than that of the polishing layer, as will be described later. As the double-sided adhesive material, a double-sided adhesive sheet or a double-sided adhesive tape is preferably used. The polishing layer 1 has a thickness T (mm), the first groove G1 has a depth D1 (mm), and the second groove G2 has a depth D2 (mm).

Referring to FIG. 1A, a second groove G2, which is a plurality of concentric grooves for holding the slurry, is formed on the polishing surface P of the polishing layer 1. The shape of the second groove for holding the slurry is not particularly limited, and concentric, spiral, lattice-shaped, and radial grooves for holding the slurry on the polishing surface formed in the conventional polishing pad. Alternatively, a groove or recess composed of a plurality of holes can be adopted without particular limitation. Among these, concentric or spiral grooves are preferable because they are excellent in polishing characteristics such as polishing speed.

The groove pitch, groove width, and groove depth D2 of the second groove are not particularly limited, but for example, the groove pitch is 1.5 to 20.0 mm, further 2.5 to 15.0 mm, and the groove width is The retention of the slurry is 0.1 to 5.0 mm, further 0.3 to 3.5 mm, and the groove depth D2 is 0.3 to 1.7 mm, further 0.5 to 1.5 mm. It is preferable from the viewpoint of ensuring sufficient properties.

On the other hand, the anti-polishing surface R, which is the opposite surface of the polishing layer to the polishing surface P, has one first groove G1 in which the ends T1 and T2 do not reach the outer circumference. The first groove is a groove for facilitating bending when the polishing pad is discarded. In FIGS. 1A and 1B, the second groove G2 formed on the polished surface P is shown by a solid line, and the first groove G1 formed on the anti-polished surface R is a broken line. It is indicated by.

Here, the first groove G1 preferably overlaps any string on the outer circumference of the circle of the polishing layer. The strings have a length of 55-100% of their diameter. The length of the chord, which has a length of 100% relative to the diameter, corresponds to the diameter. In the polishing pad 10, the length of the chord is the diameter. Further, overlapping with 60 to 95% of the length of the chord on the outer circumference of the circle means that the ratio of the length of the first groove G1 overlapping with the chord to the length of the chord is 60 to 95%.

As described above, the polishing pad 10 has a first groove G1 on the anti-polishing surface R of the polishing layer 1 that overlaps the circular outer chords. The first groove has a single line segment shape having both ends as formed on the polishing pad 10, and is discontinuous as if one line segment was interrupted at a plurality of points. It may be a form in which the line segments of are arranged along the strings, or a continuous or discontinuous curve along the strings. By forming the first groove on the anti-polishing surface of the polishing layer in this way, the portion of the polishing layer on which the first groove is formed becomes thinner than the other portions, and the polishing pad is discarded. Since stress is concentrated on the first groove when bent, it becomes easy to bend at that portion. Further, since the first groove is formed on the anti-polished surface R, it is unlikely to affect the polished surface on which the polishing action is performed. Further, referring to FIG. 1, since each of the ends T1 and T2 of the first groove does not reach the outer periphery of the polishing layer, the invasion of the slurry from the outer periphery of the polishing layer into the first groove G1 is suppressed. .. Therefore, the double-sided adhesive material that adheres the polishing layer 1 and the cushion layer 2 is less likely to come off. That is, by forming the first groove as described above on the anti-polished surface, even a high-hardness polishing pad can be easily bent at the time of disposal without affecting the polishing surface.

FIG. 2 is a schematic view for explaining the polishing pad 20, which is another example of the polishing pad of the present embodiment, and is a plan view of the polishing pad 20 as viewed from the side of the polishing surface P. The polishing pad 20 has two first grooves G11 and G12 overlapping two orthogonal diameters instead of the polishing layer 1 in which one first groove G1 overlapping the diameter is formed on the anti-polishing surface R. The structure is the same as that of the polishing pad 10 except that the polishing layer 11 is provided. Neither both ends T11, T12 of the first groove G11 and both ends T13, T14 of the first groove G12 formed in the polishing layer 11 of the polishing pad 20 have reached the outer circumference. According to such a polishing pad 20, it becomes easy to bend along either the first groove G11 or the first groove G12.

Further, FIG. 3 is a schematic view for explaining the polishing pad 30, which is another example of the polishing pad of the present embodiment, and is a plan view of the polishing pad 30 viewed from the side of the polishing surface P. In the polishing pad 30, instead of the polishing layer 1 in which one first groove G1 overlapping the diameter is formed on the anti-polishing surface R, two first grooves G21 and G22 parallel to each other that do not overlap the diameter are formed. It has the same configuration as the polishing pad 10 except that it includes the formed polishing layer 21. Neither both ends T21, T22 of the first groove G21 and both ends T23, T24 of the first groove G22 formed in the polishing layer 21 of the polishing pad 30 have reached the outer circumference. Also, each string has a length of 70% with respect to the circular diameter. According to such a polishing pad 30, it can be folded in three by bending in both the first groove G21 and the first groove G22.

As illustrated with reference to the polishing pad 20 and the polishing pad 30, in the polishing pad of the present embodiment, the first groove may be a plurality of grooves. The number of the first grooves in the polishing pad of the present embodiment is not particularly limited, but the bendability and the first groove are 1 to 6, further 1 to 4, particularly 1 to 2. It is preferable from the viewpoint of the balance with the processing cost of. Further, the position of the first groove to be formed is not particularly limited, and can be appropriately provided along the chord that overlaps the portion to be bent that is assumed in advance.

The ratio of the length of the first groove to the length of the chord is preferably 60 to 95%, more preferably 70 to 90%. If the ratio of the length of the first groove to the length of the chord is too low, it becomes difficult for stress to concentrate along the first groove and it becomes difficult to bend linearly. Further, if the ratio of the length of the first groove to the length of the chord is too high, the slurry may be mixed from the outer periphery of the polishing layer to the inside of the first groove during CMP, and the polishing layer and the polishing layer. The double-sided adhesive that adheres to the cushion layer may easily come off.

The circular diameter of the polishing layer is preferably 600 to 1200 mm, more preferably 700 to 900 mm in diameter, because the effect of compactification by bending at the time of disposal is large.

Further, since the string has a length of 55 to 100%, more preferably 60 to 100% with respect to the circular diameter, it is easy to bend when bent, and it becomes moderately compact when bent. preferable. The length of the chord, which is 100% of the circular diameter, corresponds to the diameter.

Further, the distance from each end of the first groove to the outer circumference of the polishing layer is 10 to 70 mm, further 15 to 60 mm, particularly 20 to 50 mm, which sufficiently suppresses the invasion of the slurry during CMP. It is preferable from the viewpoint of ensuring sufficient bendability as well as being able to do so.

The depth D1 of the first groove is 5 to 30% of the thickness T of the polishing layer, preferably 7 to 25%, more preferably 9 to 20%, and particularly preferably 11 to 15%. When the depth D1 of the first groove is less than 5% of the thickness T of the polishing layer, stress is less likely to be concentrated in the first groove when bent. Further, when the depth D1 of the first groove exceeds 30% of the thickness T of the polishing layer, the step due to the formation of the groove may affect the polishing characteristics.

The depth D1 of the first groove depends on the thickness T of the polishing layer, but is preferably 0.05 to 0.6 mm, more preferably 0.1 to 0.4 mm. If the depth D1 of the first groove is too shallow, stress tends to be difficult to concentrate in the first groove when bent. Further, if the first groove is too deep, the step due to the formation of the groove may affect the polishing characteristics.

The cross-sectional shape when the first groove is cut perpendicular to the longitudinal direction is not particularly limited, and examples thereof include a rectangle, a trapezoid, a triangle, a semicircle, a semi-oval, and a sinusoidal curve.

Further, the width W1 of the first groove is 0.3 to 4.0 mm, further 0.4 to 3.0 mm, particularly 0.5 to 2.5 mm, which is the first when bent. This is preferable because stress tends to be concentrated in the groove.

The flexural modulus of the polishing layer is preferably 1000 to 40,000 MPa, more preferably 14,000 to 30,000 MPa from the viewpoint that the effect of the present invention becomes remarkable because the polishing pad has high rigidity.

Further, the D hardness of the polishing layer is 50 to 90, further 60 to 88, particularly 65 to 85, which is a balance between the improvement of flattening property and the suppression of scratch generation on the surface to be polished. It is preferable because it is excellent in terms of shavings, and even a polishing pad having a high hardness can be easily bent at the time of disposal.

Further, the thickness T of the polishing layer should be in the range of 0.6 to 4.0 mm, further 0.7 to 3.0 mm, and particularly 0.8 to 2.0 mm in order to balance the polishing performance. It is preferable because of its excellent points.

Further, when the second groove and the first groove are projected onto a two-dimensional surface, having a portion where they overlap makes the thickness of the polishing layer thinner at the overlapping portion and makes it easier to bend. preferable. Further, satisfying D1 <T-D2 at the depth D1 of the first groove, the depth D2 of the second groove, and the thickness T of the polishing layer is satisfied with the first groove and the polishing surface of the anti-polishing surface. Since the second groove is separated from the second groove, the first groove is preferable because it does not easily affect the polishing characteristics of the polished surface.

In the polishing pad of the present embodiment, the cushion layer 2 is adhered to the anti-polishing surface R with the double-sided adhesive material 3 like the polishing pad 10, or another layer such as a support layer is laminated on the anti-polishing surface with the double-sided adhesive material. Even if it has a laminated structure of two or more layers, it is a single layer consisting only of a polishing layer such as a polishing pad in which a double-sided adhesive is attached to the anti-polishing surface and directly adheres to the rotary platen of the polishing device. It may be a structure. Among these, in particular, the cushion layer 2 is adhered to the anti-polishing surface R of the polishing layer 1 with the double-sided adhesive material 3 like the polishing pad 10, and the double-sided adhesive material is further adhered to the cushion layer 2 to form the polishing apparatus. A polishing pad having a laminated structure such as a polishing pad that adheres to a rotary platen is particularly preferable because the polishing uniformity in the surface to be polished can be more easily improved. When the polishing pad has a laminated structure, a cushion layer and a support layer are laminated on the anti-polishing surface of the polishing layer via a double-sided adhesive or an adhesive. In this case, it is preferable that the first groove is covered and closed by another layer laminated on the anti-polishing surface, so that the slurry does not easily penetrate into the first groove during polishing.

Next, other elements of the polishing pad of the present embodiment will be described in detail.

The polishing pad of this embodiment includes a polishing layer. As the material for forming the polishing layer, a synthetic or natural polymer material conventionally used for producing the polishing layer of the polishing pad is used without particular limitation. Specific examples of the polymer material forming the polishing layer include polyurethane, polyolefins such as polyethylene and polypropylene, polyester, polyamide, polyurea, polytetrafluoroethylene, melamine resin, neoprene (registered trademark), silicone rubber and fluororubber. Such as a polymer elastic body. These may be used alone or in combination of two or more.

Further, the polishing layer preferably has a non-foaming structure (non-porous). A polishing layer having a non-foamed structure is preferable because it can maintain high hardness and exhibits better flatness. Further, the polishing layer having a non-foamed structure is preferable because the pores are not exposed on the surface thereof and the abrasive grains in the slurry do not aggregate or adhere in the pores, so that scratches are less likely to occur. Further, the non-foamed structure polishing layer is preferable because the polishing layer has a lower wear rate than the foamed structure polishing layer and therefore has a longer life. The polishing pad of the present embodiment is preferable because even a non-foaming structure (non-porous) polishing pad can be easily bent at the time of disposal.

Among the polymer materials, the thermoplastic polyurethane having a non-foaming structure obtained by reacting a polyurethane raw material containing a polymer diol, an organic diisocyanate and a chain extender has a flattening performance having a high hardness and a high flexural modulus. It is particularly preferable because an excellent polishing layer can be easily obtained. Hereinafter, the thermoplastic polyurethane used as a material for forming the polishing layer will be described in detail as a representative example.

Examples of the polymer diol, the organic diisocyanate, and the chain extender, which are the raw materials for the polyurethane of the thermoplastic polyurethane, include the following compounds.

Specific examples of the high molecular weight diol include polyether diols such as polyethylene glycol and polytetramethylene glycol; poly (nonamethylene adipate) diol, poly (2-methyl-1,8-octamethylene adipate) diol, and poly (poly (2-methyl-1,8-octamethylene adipate) diol. Polyester diols such as 3-methyl-1,5-pentamethylene adipate) diols; polycarbonate diols such as poly (hexamethylene carbonate) diols and poly (3-methyl-1,5-pentamethylene carbonate) diols can be mentioned. These may be used alone or in combination of two or more.

Specific examples of the organic diisocyanate include aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and 1,4-bis (isocyanatomethyl) cyclohexane; 4 Aromatic diisocyanates such as, 4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and 1,5-naphthylene diisocyanate can be mentioned. These may be used alone or in combination of two or more. Among these, it is preferable from the viewpoint of excellent wear resistance of the polishing layer from which 4,4'-diphenylmethane diisocyanate can be obtained.

Examples of the chain extender include low molecular weight compounds having two or more active hydrogen atoms capable of reacting with isocyanate groups and having a molecular weight of 350 or less. Specific examples thereof include ethylene glycol, diethylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, and neopentyl. Diols such as glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,4-bis (β-hydroxyethoxy) benzene, 1,9-nonanediol, spiroglycol; ethylenediamine, tetra Examples thereof include diamines such as methylene diamine, hexamethylene diamine, nonamethylene diol, hydrazine, xylylenediol amine, isophorone diol, and piperazine. These may be used alone or in combination of two or more. Of these, 1,4-butanediol and / or 1,9-nonanediol are particularly preferred.

The blending ratio of each component of the polyurethane raw material is appropriately adjusted in consideration of the characteristics to be imparted to the polishing layer, and for example, organic diisocyanate is used with respect to 1 mol of active hydrogen atom contained in the polymer diol and the chain extender. It is preferable to mix each component at a ratio of 0.95 to 1.3 mol, more preferably 0.96 to 1.1 mol, and particularly 0.97 to 1.05 mol of the isocyanate group contained in. If the amount of isocyanate groups contained in the organic diisocyanate is too small, the mechanical strength and abrasion resistance of the obtained polyurethane tend to decrease. Further, when the amount of isocyanate groups contained in the organic diisocyanate is too large, the productivity of polyurethane and the storage stability of the polyurethane raw material tend to decrease.

The proportion of nitrogen atoms derived from the isocyanate group of the organic polyisocyanate in polyurethane is 4.5 to 7.6% by mass, further 5.0 to 7.4% by mass, and particularly 5.2 to 7.3. The mass% is preferable from the viewpoint that a polishing layer having particularly excellent flattening property and low scratch property can be obtained. If the proportion of nitrogen atoms derived from the isocyanate group is too low, the hardness of the obtained polishing layer tends to be low.

The thermoplasticity of the thermoplastic polyurethane means a property that can be melted and molded by a heating process such as extrusion molding, injection molding, calender molding, or 3D printer molding. Such a thermoplastic polyurethane is produced by using a polyurethane raw material containing a polymer diol, an organic diisocyanate and a chain extender, and using a known polyurethane production method such as a prepolymer method or a one-shot method. In particular, a method of melt-kneading and melt-polymerizing a polyurethane raw material in the absence of a solvent, and a method of continuous melt-polymerizing using a multi-screw screw type extruder are preferable from the viewpoint of excellent productivity. ..

The thermoplastic polyurethane obtained by continuous melt polymerization is pelletized and then made into a sheet-shaped molded product by various molding methods such as extrusion molding, injection molding, blow molding, and calendar molding. It is molded. In particular, extrusion molding using a T-die is preferable from the viewpoint that a sheet-shaped molded product having a uniform thickness can be obtained. The obtained sheet-shaped molded body is processed into a desired size by cutting, punching, cutting or the like, or processed into a desired thickness by grinding or the like to finish a sheet for a polishing layer.

Then, on the polished surface side of the polishing layer sheet, concentric, spiral, lattice-shaped, radial grooves, or grooves consisting of a plurality of holes for holding the slurry by grinding, cutting, or laser processing are performed. Alternatively, a second groove, which is a recess, is formed. Further, at least 1 is applied to the non-polished surface side of the polishing layer sheet to make it easier to bend when the polishing pad is discarded by grinding, cutting or laser processing, and to make it difficult to return to the original state due to elasticity after bending. Form the first groove of the book.

In this way, a polishing layer is produced in which a first groove is formed on the anti-polishing surface to facilitate bending when the polishing pad is discarded, and a second groove is formed on the polishing surface to hold the slurry. ..

The density of the polishing layer of the thermoplastic polyurethane is preferably 1.0 g / cm ³ or more, more preferably 1.1 g / cm ³ or more, and particularly ^{preferably 1.2 g / cm 3} or more. If the polishing layer of the thermoplastic polyurethane is too dense, the polishing pad tends to soften and reduce local flatness.

Further, in the polishing pad of the present embodiment, a cushion layer or a support layer may be laminated on the anti-polishing surface. The cushion layer is preferably a layer having a hardness lower than the hardness of the polishing pad. When the hardness of the cushion layer is lower than the hardness of the polishing pad, the hard polishing pad follows the local unevenness of the surface to be polished, and the cushion layer responds to the warp and swell of the entire substrate to be polished. In order to follow, polishing with an excellent balance between global flatness and local flatness becomes possible.

Specific examples of the material used as the cushion layer include a composite in which a non-woven fabric is impregnated with polyurethane (for example, "Suba400" (manufactured by Nitta Haas Co., Ltd.)); natural rubber, nitrile rubber, polybutadiene rubber, silicone rubber, etc. Rubber; Polyplastic elastomers such as polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, and fluorine-based thermoplastic elastomers; foamed plastics; polyurethane and the like. Among these, polyurethane having a foamed structure is particularly preferable because it is easy to obtain preferable flexibility as a cushion layer.

The thickness of the cushion layer is not particularly limited, but is preferably about 0.5 to 5 mm, for example. If the cushion layer is too thin, the effect of following the entire warp or waviness of the surface to be polished tends to decrease, and the global flatness tends to decrease. On the other hand, if the cushion layer is too thick, the entire polishing pad tends to be soft and stable polishing tends to be difficult. When the cushion layer is laminated on the polishing pad, the thickness of the polishing pad is preferably about 0.3 to 5 mm.

The polishing pad of the present embodiment described above is preferably used for CMP. Next, an example of CMP using the polishing pad 10 of the present embodiment will be described.

In CMP, for example, a CMP apparatus 100 including a circular rotary surface plate 101 as shown in FIG. 4, a slurry supply nozzle 102, a carrier 103, and a pad conditioner (not shown) is used.

The polishing pad 10 is attached to the surface of the rotary surface plate 101 with a double-sided adhesive (not shown). Further, the carrier 103 supports the object to be polished 50.

In the CMP apparatus 100, the rotary surface plate 101 is rotated by the motor shown in the figure, for example, in the direction indicated by the arrow. Further, the carrier 103 is rotated in the direction indicated by, for example, an arrow by a motor shown in the drawing while pressing the surface to be polished of the object to be polished 50 against the surface to be polished of the polishing pad 10. The pad conditioner (not shown) moves around the surface of the rotary surface plate 101 evenly, and sharpens the polished surface of the polishing pad to improve the holding power of the slurry. As the pad conditioner, for example, a pad conditioner in which diamond particles are fixed to the surface of a carrier by nickel electrodeposition or the like is used.

After sharpening the surface with a pad conditioner, polishing of the surface to be polished of the object to be polished 50 is started. In polishing, the slurry 60 is supplied from the slurry supply nozzle 102 to the surface of the rotating polishing pad 10. The slurry is, for example, a liquid medium such as water or oil; an abrasive such as silica, alumina, cerium oxide, zirconium oxide, silicon carbide; an oxidizing agent such as a base, an acid, a surfactant, a hydrogen peroxide, a reducing agent, or glycine. , A chelating agent such as EDTA, a pH adjuster such as a base and an acid, and a dispersant such as a water-soluble polymer. Further, when performing CMP, if necessary, a lubricating oil, a coolant, or the like may be used in combination with the slurry. Then, the object to be polished 50 fixed to the carrier 103 and rotating is pressed against the polishing pad in which the slurry is evenly distributed on the polishing surface. Then, the polishing process is continued until a predetermined flatness is obtained. Finished quality is affected by adjusting the pressing force applied during polishing and the speed of relative movement between the rotating surface plate and the carrier.

The polishing conditions are not particularly limited, but in order to perform efficient polishing, it is preferable that the rotation speeds of the rotary surface plate 101 and the object to be polished 50 are as low as 300 rpm or less, and the polishing pad 10 is pressed against the polishing pad 10. The pressure applied to the polished object 50 is preferably 150 kPa or less from the viewpoint of preventing scratches from occurring after polishing. Further, during polishing, it is preferable to continuously or discontinuously supply the slurry to the polishing pad 10 so that the slurry is evenly distributed on the polished surface.

Then, the polishing is completed by detecting the polishing end point polished to a predetermined flatness. Then, after the object to be polished after polishing is thoroughly washed with running water, water droplets adhering to the object to be polished are wiped off and dried using a spin dryer or the like. In this way, the surface to be polished becomes a smooth surface.

Such CMP of this embodiment is preferably used for polishing in a manufacturing process of various semiconductor devices, MEMS (Micro Electro Mechanical Systems) and the like. Examples of objects to be polished include semiconductor substrates such as silicon, silicon carbide, gallium nitride, gallium arsenide, zinc oxide, sapphire, germanium, and diamond; silicon oxide film formed on a wiring board having predetermined wiring, and silicon nitride. Insulator films such as films and low-k films, and wiring materials such as copper, aluminum, and tungsten; glass, crystals, optical substrates, hard disks, and the like can be mentioned. It is also possible to polish a metal film having a pattern such as a wiring pattern or a dummy pattern. The pitch between lines in the pattern varies depending on the product, but is usually about 50 nm to 100 μm. The polishing pad of the present embodiment is particularly preferably used for polishing an insulator film or a wiring material formed on a semiconductor substrate.

In the above-mentioned CMP, the polishing pad 10 reaches the end of its life such that the polishing surface is gradually worn, the polishing rate is lowered, the polishing becomes unstable, and scratches occur. When it is determined that the polishing pad 10 has reached the end of its life, the polishing pad 10 is peeled off from the rotary surface plate 101, then bent and discarded.

Specifically, as shown in FIG. 5, by bending the used polishing pad 10 along the first groove G1, the polishing pad 10 is folded along the diameter to be made compact. The double-sided adhesive material adhered to the rotary surface plate 101 is attached to the anti-polishing surface side of the polishing pad 10 after being peeled off from the rotary surface plate 101. Therefore, when the polishing pad 10 is mountain-folded with the polishing surface facing the upper surface and the polishing pad 10 is bent along the first groove, the double-sided adhesives adhering to the anti-polishing surface side face each other and adhere to each other. be able to. Therefore, by using the double-sided adhesive material for adhering to the rotary surface plate 101, the polishing pad 10 can be adhered and fixed in a folded state while being bent along the first groove. By folding the polishing pad in this way, the polishing pad can be made compact at the time of disposal.

Hereinafter, the present invention will be described in more detail with reference to Examples. The scope of the present invention is not limited to these examples.

[Manufacturing example]
Polytetramethylene glycol [abbreviation: PTMG], 1,4-butanediol [abbreviation: BD], and 4,4'-diphenylmethane diisocyanate [abbreviation: MDI] having a number average molecular weight of 850 in a mass ratio of PTMG: BD: MDI. Was blended in a ratio of 16.7: 20.7: 62.6, and was continuously supplied to a twin-screw extruder rotating coaxially by a metering pump to continuously melt-polymerize the thermoplastic polyurethane. Then, the melt of the polymerized thermoplastic polyurethane was continuously extruded into water in the form of strands, and then shredded with a pelletizer to obtain pellets. The pellets were dehumidified and dried at 70 ° C. for 20 hours, then fed to a single-screw extruder and extruded from a T-die to form a 2.0 mm thick sheet. Then, the surface of the obtained sheet was ground to obtain a uniform sheet having a thickness of 1.5 mm, and then cut out into a circular shape having a diameter of 810 mm to obtain a sheet for a polishing layer. According to JIS K 7311, the D hardness of the polishing layer sheet measured under the condition of the measurement temperature of 25 ° C. was 82. The flexural modulus of the polishing layer sheet was 25,400 MPa. The flexural modulus was measured using a "universal material testing machine 3365" manufactured by Instron in accordance with the measuring method of JIS K7203 1982.

[Example 1]
The anti-polished surface, which is one surface of a circular polishing layer sheet having a thickness of 1.5 mm and a diameter of 810 mm, obtained in Production Example 1 has a length of 750 mm, a width of 0.5 mm, and a depth of 0 so as to overlap the diameter. A linear first groove having a diameter of 3 mm and having both ends not reaching the outer circumference was formed by cutting. The distance to the outer circumference of the polishing layer sheet at each end of the first groove was 30 mm, and at this time, the first groove overlapped with 93% of the diameter of the circular outer peripheral string. The first groove was 20% of the thickness of the polishing layer. The cross-sectional shape of the deep groove is rectangular.

Then, a second concentric groove composed of a plurality of concentric circles having a width of 0.9 mm, a depth of 1.0 mm and a groove pitch of 6.5 mm was formed on the polished surface of the polishing layer by cutting. The cross-sectional shape of the second groove is also rectangular. In this way, the polishing layer is formed with a linear first groove on the anti-polishing surface for easy bending when the polishing pad is discarded, and a second groove for holding the slurry on the polishing surface. Manufactured.

Then, a cushion layer was attached to the anti-polishing surface of the polishing layer with a double-sided adhesive sheet to create a multi-layer type polishing pad. As the cushion layer, "Poron H48" manufactured by Inoac Corporation, which is a foamed polyurethane sheet having a thickness of 0.8 mm, was used. Then, the polishing characteristics of the obtained polishing pad were evaluated by the following evaluation method.

[Polishing speed and polishing uniformity]
The polishing pad was placed on the rotary surface plate of the Strasbaugh polishing device "nHance 6 EG". Then, using a diamond dresser (diamond count # 100) manufactured by Asahi Diamond Industry Co., Ltd., while flowing ultrapure water on the polishing surface of the polishing pad at a speed of 200 mL / min, the dresser rotation speed is 100 rpm and the polishing pad rotation speed is 50 rpm. The polished surface was conditioned for 60 minutes under the condition of a dresser load of 40 N.
Then, after conditioning the polishing pad, the slurry is supplied to the polishing surface of the polishing pad at a rate of 200 mL / min under the conditions of the polishing pad rotation speed of 95 rpm, the wafer rotation speed of 96 rpm, the polishing pressure of 210 hPa, and the retainer ring pressure of 280 hPa. A 12-inch-diameter silicon wafer having a film thickness of 1000 nm and a patternless SiO _{2 film on the surface was polished for 60 seconds.} As the slurry, Semi-Sperse 25 manufactured by Cabot Microelectronics and ultrapure water mixed at a ratio of 1: 1 were used.
Then, while flowing ultrapure water on the polished surface of the polishing pad at a speed of 200 mL / min, conditioning was performed for 30 seconds at a dresser rotation speed of 100 rpm, a polishing pad rotation speed of 50 rpm, and a dresser load of 40 N.
After that, the silicon wafer was replaced, and the above-mentioned polishing and conditioning were alternately repeated. In this way, a total of 10 silicon wafers were polished.

Then, for the 10th silicon wafer polished _{, the film thickness of the SiO 2} film before and after polishing was measured at 81 points on the wafer surface, and the polishing rate at each point was determined. The average value of the polishing speeds at 81 points was taken as the polishing speed.
Also, the polishing uniformity is
The evaluation was made based on the non-uniformity calculated by the formula [non-uniformity (%) = (σ / R) × 100]. The smaller the non-uniformity value, the more _{uniformly the SiO 2} film is polished in the silicon wafer surface, and the better the polishing uniformity is.

Then, the above-mentioned polishing was repeated a plurality of times, and the polishing pad having reached the end of its life was peeled off from the rotary surface plate. Then, by hand, the used polishing pad is bent along the first groove, and the polishing pad is bent along the first groove by using the double-sided adhesive material adhered to the rotary surface plate. It was fixed by adhering it in a folded state. The polishing pad that is discarded in this way has been made compact. The easiness of bending at this time was judged according to the following criteria. In addition, the adhesiveness of the cushion layer on the polishing pad at the time of disposal was judged according to the following criteria.

[Easy to fold]
A: An adult male with average physical strength was easily bent in a short time. In addition, when the adhesive layer on the cushion layer side was used for bonding, it was possible to maintain it.
B: An adult male with average physical strength was easily bent in a short time. Further, when the adhesive layer on the cushion layer side was used, the adhesive layer was attached for about 3 minutes, but after 5 minutes, it repelled and peeled off.
C: It was difficult for an adult male with average physical strength to easily bend and fit the cushion layer without taking time. Further, even if the adhesive layer on the cushion layer side was attached, it repelled and peeled off within 1 minute.

[Adhesion of cushion layer]
A: It was possible to re-bond.
B: Part of the adhesive strength was lost, and re-adhesion was difficult.

The results are shown in Table 1 below.

[Examples 2 to 5, Comparative Examples 2 to 5]
Both ends of the dimensions shown in Table 1 reach the outer circumference on the anti-polished surface, which is one surface of a circular polishing layer sheet having a thickness of 1.5 mm and a diameter of 810 mm, obtained in Production Example 1 so as to overlap the diameter. A polishing layer and a polishing pad were produced and evaluated in the same manner as in Example 1 except that the first linear groove was formed by cutting. The results are shown in Table 1.

[Comparative Example 1]
In Examples 1 and 2, a polishing layer and a polishing pad were manufactured and evaluated in the same manner as in Example 1 except that the first groove was not formed. Then, the above-mentioned polishing was repeated a plurality of times, and the polishing pad having reached the end of its life was peeled off from the rotary surface plate. Then, by hand, the used polishing pad is bent along the first groove, and the polishing pad is bent along the first groove by using the double-sided adhesive material adhered to the rotary surface plate. It was fixed by adhering it in a folded state. The polishing pad that is discarded in this way has been made compact. At this time, it was difficult to bend the polishing pad, it took a long time, and it was difficult to bend it. The results are shown in Table 1.

Referring to Table 1, the polishing pads obtained in Examples 1 to 5 were all excellent in polishing characteristics, bendability, and adhesiveness of the cushion layer. On the other hand, the polishing pad obtained in Comparative Example 1 in which the first groove was not formed was difficult to bend at the time of disposal. Further, the polishing pad obtained in Comparative Example 2 in which the depth of the first groove is less than 5% of the thickness of the polishing layer was also difficult to bend at the time of disposal. Further, the polishing pad obtained in Comparative Example 3 in which the depth of the first groove exceeds 30% of the thickness of the polishing layer had low polishing characteristics. Further, in the polishing pad obtained in Comparative Example 4 in which the distance to the outer circumference is 0 mm and the first groove where both ends reach the outer circumference is formed, the slurry penetrates into the first groove from the outer circumference to form a cushion layer. The adhesiveness was reduced. Further, the polishing pad obtained in Comparative Example 5 in which the distance to the outer circumference is 202.5 mm and the first groove is formed in which the overlap with the chord is 50% is also difficult to bend at the time of disposal. It was.

1,11,21 Polishing layer 2 Cushioning layer 3 Double-sided adhesive material 10,20,30 Polishing pad 50 Polished object 60 Slurry 100 CMP device 101 Rotating surface plate 102 Slurry supply nozzle 103 Carriers G1, G11, G12, G21, G22 1 groove G2 2nd groove P Polished surface R Anti-polished surface T1, T2, T11, T12, T13, T14, T21, T22, T23, T24 The end of the first groove

Claims (8)

At least a circular polishing layer having a polishing surface for polishing the object to be polished is provided.
The anti-polished surface of the polishing layer, which is opposite to the polishing surface, has at least one first groove.
The first groove is a polishing pad characterized in that both ends do not reach the outer circumference and the depth is 5 to 30% of the thickness of the polishing layer. The polishing pad according to claim 1, wherein the first groove overlaps 60 to 95% of the length of the chord with respect to the circular shape. The polishing pad according to claim 2, wherein the strings have a circular diameter. The polishing pad according to any one of claims 1 to 3, wherein the first groove is covered with a double-sided adhesive laminated on the anti-polishing surface and closed. The polishing pad according to claim 4, wherein a cushion layer is further laminated by the double-sided adhesive laminated on the anti-polishing surface. The polished surface further has a second groove for holding the slurry.
The polishing pad according to any one of claims 1 to 5, wherein the second groove and the first groove have a portion where they overlap when projected onto a two-dimensional surface. When the depth of the first groove is D1 (mm), the depth of the second groove is D2 (mm), and the thickness of the polishing layer is T (mm), D1 <T-D2. The polishing pad according to claim 6 or 7. The polishing pad according to any one of claims 1 to 7, wherein the polishing layer has a flexural modulus of 1000 to 40,000 MPa.

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