JP2008187113A - Chemical mechanical polishing pad - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chemical mechanical polishing pad excellent in polishing speed and in-plane uniformity of the polished surface in which occurrence of scratch on the polished surface of an article to be polished is suppressed sufficiently. <P>SOLUTION: The chemical mechanical polishing pad is provided, in its polishing surface, with a plurality of groups each consisting of a plurality of grooves extending in parallel and in close proximity to each other from the central part toward the peripheral part. The plurality of groups preferably consists of a group touching other group in the central part on the polishing surface, and a group not touching other group. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a chemical mechanical polishing pad.

In the manufacture of semiconductor devices, chemical mechanical polishing (“CMP”) is employed as a polishing method capable of forming a surface having excellent flatness. Chemical mechanical polishing is a chemical mechanical polishing aqueous dispersion, for example, an aqueous dispersion in which abrasive grains are dispersed on the surface of the chemical mechanical polishing pad while sliding the polishing surface of the polishing pad and the polishing surface of the workpiece. This is a technique for polishing by flowing down. In this chemical mechanical polishing, it is known that the polishing result greatly depends on the properties and characteristics of the polishing pad.
Conventionally, in chemical mechanical polishing, a polyurethane foam containing fine bubbles is used as a polishing pad, and polishing is performed by holding a slurry in a hole (hereinafter referred to as “pore”) opened on the surface of the resin. At this time, it is known that the polishing rate and the polishing result are improved by providing grooves on the surface (polishing surface) of the chemical mechanical polishing pad (see Patent Documents 1 to 3).
However, in recent years, along with the high performance and miniaturization of semiconductor devices, the miniaturization and multi-layering of wiring have progressed, and the required performance for chemical mechanical polishing and chemical mechanical polishing pads has increased. Patent Document 1 describes the design of a chemical polishing pad in detail, but the polishing rate and the state of the polished surface after polishing are not yet satisfactory. In particular, scratch-like surface defects (hereinafter referred to as “scratch”) may occur, and improvements are desired.
JP-A-11-70463 JP-A-8-216029 JP-A-8-39423

  The present invention solves the above-mentioned conventional problems, and the object of the present invention is to sufficiently suppress the generation of scratches on the surface to be polished of the object to be polished, and to improve the polishing rate and uniformity within the surface to be polished. The object is to provide an excellent chemical mechanical polishing pad.

According to the present invention, the above object of the present invention is
This is achieved by a chemical mechanical polishing pad having a plurality of groove groups consisting of a plurality of grooves extending in parallel with each other in the direction from the center to the periphery on the polishing surface.

The chemical mechanical polishing pad of the present invention has a polishing surface, and preferably a non-polishing surface which is the back surface of the polishing surface, and side surfaces defining these surfaces.
The polishing surface of the chemical mechanical polishing pad of the present invention has a plurality of groove groups consisting of a plurality of grooves extending in close proximity to each other in the direction from the central portion toward the peripheral portion.
Each groove constituting each groove group is a line extending in a direction from the center portion to the peripheral portion of the polishing surface.
The “center portion” refers to a region surrounded by a circle with a radius of 50 mm centered on the center of gravity on the surface of the chemical mechanical polishing pad. Each groove only needs to extend in a direction from one arbitrary point of the “center portion” toward the peripheral portion, and the shape thereof may be, for example, a linear shape, an arc shape, or a combination thereof.
Each groove group is composed of a set of a plurality of grooves extending in parallel to each other. At this time, the plurality of grooves belonging to a certain group may originate from a position where the distance from the center of the polishing surface is equal, or may originate from a position where the distance from the center of the polishing surface is different.
The distance between two adjacent grooves extending in parallel (the shortest distance between the two grooves) is preferably 3 to 100 mm, and more preferably 10 to 50 mm. The number of grooves constituting one set of groove groups is preferably 2 to 5. The more preferable number varies depending on the structure of the groove group on the polishing surface. This will be described in the description of each configuration.

The number of groove groups on the polishing surface of the chemical mechanical polishing pad of the present invention is preferably 2 to 10 sets, and more preferably 2 to 4 sets.
Each groove group may or may not be in contact with other groove groups, but does not intersect each other. Two to four sets of the plurality of groove groups are preferably in contact with other groove groups in the central region, and more preferably two sets are in contact with each other. Of the plurality of groove groups, 2 to 70 sets are preferably not in contact with other groove groups in the central region, and 8 to 30 sets are more preferably not in contact with other groove groups. . The groove group may be in contact with another groove group at a place other than the central portion of the polishing surface.
When a plurality of groove groups are groove groups that are formed from grooves extending from the central portion and extending to the peripheral portion, the groove groups include a groove group that is not in contact with other groove groups in the central region, and a center It is preferable that it consists of a groove group in contact with another groove group in the region of the part. The groove belonging to the groove group that is not in contact with the other groove group in the central region is preferably a groove that starts from a position of 10 to 50 mm from the center of the pad and extends in the direction from the pad to the peripheral portion. It is more preferable that the groove starts from a position 20 to 50 mm from the center and extends in a direction from there to the periphery.
On the other hand, when the plurality of groove groups are composed of a plurality of groove groups that originate from the central part and go to the peripheral part and a plurality of groove groups that originate from the middle of the central part and the peripheral part and go to the peripheral part, Grooves belonging to the groove group originating from the middle of the peripheral portion are points on an imaginary straight line connecting the center and outer periphery of the pad, and are generated from a point corresponding to a position of 20 to 80% from the center of the pad toward the outer periphery. It is preferable that the point is emitted from a point corresponding to a position of 40 to 60%. Even in this case, a plurality of groove groups that start from the central portion and go to the peripheral portion are grooves that are not in contact with other groove groups in the central region, and grooves that are in contact with other groove groups in the central region. It preferably consists of a group.

The plurality of groove groups are preferably arranged as evenly as possible on the polishing surface of the chemical mechanical polishing pad of the present invention.
The position on the radius of each point of each groove constituting one groove group (that is, the distance from the center of the polishing surface of the point where each groove originates) may be the same or different. Good.
When the groove group is composed of a groove group that is in contact with other groove groups in the central region of the polishing surface and a groove group that is not in contact with other groove groups in the central region, each groove group is configured. The number of grooves is preferably 2 or 3. On the other hand, when the groove group consists only of groove groups that are not in contact with other groove groups in the central region of the polishing surface, the number of grooves constituting each groove group is preferably 3 to 5, More preferably, the number is 3 or 4.

The width of each groove constituting each groove group is preferably 0.1 mm or more, more preferably 0.1 to 5 mm, and still more preferably 0.2 to 3 mm. The depth of the groove is preferably 0.1 mm or more, more preferably 0.1 to 2.5 mm, and still more preferably 0.2 to 2.0 mm. The cross-sectional shape of the groove, that is, the shape of the cut surface when the groove is cut in the direction perpendicular to the length direction is not particularly limited, and may be, for example, a polygonal shape or a U-shape. Examples of the polygon include a triangle, a quadrangle, and a pentagon. Of these, a rectangular shape is preferable. By having a groove group composed of a plurality of grooves having such a size and shape, a chemical mechanical polishing pad excellent in both the polishing speed of the surface to be polished and the scratch reduction effect can be obtained.
The surface roughness (Ra) inside each groove is preferably 20 μm or less, more preferably 0.05 to 15 μm, and still more preferably 0.05 to 10 μm. By setting the surface roughness to 20 μm or less, scratches generated on the surface to be polished during the chemical mechanical polishing step can be more effectively prevented.
The surface roughness (Ra) is defined by the following formula (1).
Ra = Σ | Z−Zav | / N (1)
In the above formula, N is the number of measurement points, Z is the height of the roughness surface, and Zav is the average height of the roughness surface.

Each of the grooves constituting the groove group included in the polishing surface of the chemical mechanical polishing pad of the present invention may be a broken line-shaped groove extending in a direction from the central portion toward the peripheral portion. Here, the “broken-line groove” means a groove in which a plurality of linear recesses are arranged in a vertical direction on a virtual line via non-recesses. To put it another way, a linear recess and a non-recess on the extension line of the linear recess, and a linear recess on the extension line are repeated by repeating the linear recess and the non-recess. A broken-line groove is formed.
When the grooves constituting the groove group are broken lines, the number of grooves constituting each groove group is preferably two or three.

1, 2 and 3 show preferred examples of the arrangement of a plurality of broken-line grooves on the polishing surface of the chemical mechanical polishing pad of the present invention.
In the chemical mechanical polishing pad of FIG. 1, 32 sets of groove groups are arranged at an angle of 11.25 ° on the polishing surface. The groove group in FIG. 1 is composed of a pair of two linear grooves extending in parallel with each other. Of the 32 sets of groove groups each consisting of a linear groove, the two sets of groove groups are in contact with each other at the center of the polishing surface. None of the other groove groups are in contact with other groups. Of the groove groups of the polishing surface in FIG. 1, two groove groups extending at an angle of 90 ° with the two sets of groove groups in contact with each other originate from a position slightly retracted from the center. Four sets extending at an angle of ° originate from a position that is further retracted from the center, and eight sets extending at an angle of 22.5 ° or 67.5 ° with these grooves are positions that are further retracted from the center. The remaining 16 pairs originate from the position farthest from the center.
In the chemical mechanical polishing pad of FIG. 2, 32 sets of grooves are arranged on the polishing surface at an angle of 11.25 °. The groove group in FIG. 2 includes a pair of two broken-line grooves extending in parallel with each other. Of the 32 groove groups each consisting of a dashed-line groove, the two groove groups are in contact with each other at the center of the polishing surface, and the other groove groups are not in contact with the other groups. In the groove group of the polishing surface in FIG. 2, two sets in contact with each other start from the center of the polishing surface, and four sets extending at an angle of 45 ° with these grooves start from a position slightly retracted from the center, Two pairs extending at an angle of 90 ° with two pairs in contact with each other originate from a position slightly further retracted from the center, and at an angle of 22.5 ° or 67.5 ° with two sets in contact with each other. The 8 pairs that extend are from a position that is further retracted from the center, and the remaining 16 sets start from a position farthest from the center.
In the chemical mechanical polishing pad of FIG. 3, 32 sets of groove groups are arranged at an angle of 11.25 ° on the polishing surface. The groove group in FIG. 3 is composed of a set of three linear grooves extending in parallel with each other. Of the 32 sets of groove groups each consisting of a linear groove, the two sets of groove groups are in contact with each other at the center of the polishing surface. None of the other groove groups are in contact with other groups. Of the groove groups of the polishing surface in FIG. 1, the two groove groups that are in contact with each other at the center of the polishing surface and the two sets of groove groups that extend at an angle of 90 ° are from a position slightly retreated from the center. The four sets that diverge from these grooves and extend at an angle of 45 ° originate from a position that is further retracted from the center, and the eight sets that extend at an angle of 22.5 ° or 67.5 ° from these grooves from the center. Furthermore, it starts from a position somewhat retracted, and the remaining 16 sets start from a position farthest from the center.

The polishing surface of the chemical mechanical polishing pad of the present invention may have a plurality of circular grooves and spiral grooves arranged concentrically in addition to the plurality of groove groups as described above.
The number of circular grooves and the number of turns of the spiral grooves arranged concentrically can be, for example, 20 to 400. The preferable width, depth, cross-sectional shape, and surface roughness inside the groove of the circular groove and the spiral groove are the same as those described above for the broken-line groove.

Examples of the material constituting the chemical mechanical polishing pad of the present invention include a water-insoluble portion and a material containing water-soluble particles dispersed in the water-insoluble portion, or a water-insoluble portion and an empty space dispersed in the water-insoluble portion. It can be set as the raw material (for example, foam etc.) which has a hole.
In the former material, an organic material is preferably used as the material constituting the water-insoluble portion. As the organic material, for example, a thermoplastic resin, an elastomer, a rubber, a cured resin (a resin obtained by curing a thermosetting resin, a photocurable resin, or the like by heat, light, or the like) can be used alone or in combination. Such an organic material is preferably composed of only a crosslinked polymer or a mixture of a crosslinked polymer and a non-crosslinked polymer. As the crosslinked polymer, among the above organic materials, a crosslinked rubber, a cured resin, a crosslinked thermoplastic resin, a crosslinked elastomer, and the like can be used. Among these, a crosslinked thermoplastic resin or a crosslinked elastomer is preferable, and a crosslinked 1,2-polybutadiene is more preferable.
Examples of the water-soluble particles in the former material include organic water-soluble particles and inorganic water-soluble particles. Examples of the organic water-soluble particles include saccharides, celluloses, proteins, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, polyethylene oxide, water-soluble photosensitive resins, sulfonated polyisoprene, and sulfonated isoprene copolymers. Can be mentioned. Examples of the material for the inorganic water-soluble particles include potassium acetate, potassium nitrate, potassium carbonate, potassium hydrogen carbonate, potassium chloride, potassium bromide, potassium phosphate, and magnesium nitrate.
Of these, saccharides are preferable, and cyclodextrin is particularly preferable.
On the other hand, as the water-insoluble member constituting the chemical mechanical polishing pad comprising the latter water-insoluble part and a material having pores dispersed in the water-insoluble part, for example, polyurethane, melamine resin, polyester, polysulfone, polyvinyl acetate Etc.
The size of the water-soluble particles or dispersed pores contained in the water-insoluble part is an average value, preferably 0.1 to 500 μm, more preferably 0.5 to 100 μm.

The shape of the chemical mechanical polishing pad capable of forming a groove on the polishing surface by applying the method of the present invention can be, for example, a columnar shape, a polygonal columnar shape, etc., preferably a columnar shape.
As the size of the polishing pad, for example, in the case of a cylindrical polishing pad, the diameter of the bottom surface (polishing surface) can be, for example, 150 to 1,200 mm, and particularly 500 to 820 mm. The thickness of the polishing pad can be, for example, 0.5 to 5.0 mm, particularly 1.0 to 3.0 mm, and particularly 1.5 to 3.0 mm.
The chemical mechanical polishing pad of the present invention can realize extremely high uniformity in the polished surface while suppressing the generation of scratches on the polished surface and expressing a high polishing rate. The reason why such an excellent effect appears is not clear, but the flow of the chemical mechanical polishing aqueous dispersion to be supplied becomes smooth due to the special groove configuration of the polishing surface of the chemical mechanical polishing pad of the present invention. As a result, it is assumed that the supply, retention, and discharge of the aqueous dispersion are controlled to the optimum state.
The chemical mechanical polishing pad of the present invention can be attached to a commercially available chemical polishing apparatus and used for chemical mechanical polishing by a known method.

An example of the structure of the groove group which the polishing surface of the chemical mechanical polishing pad of this invention has. An example of the structure of the groove group which the polishing surface of the chemical mechanical polishing pad of this invention has. An example of the structure of the groove group which the polishing surface of the chemical mechanical polishing pad of this invention has. An example of the structure of the groove group which the polishing surface of the chemical mechanical polishing pad of this invention has. An example of the structure of the groove group which the polishing surface of the chemical mechanical polishing pad of this invention has.

Claims (6)

  A chemical mechanical polishing pad comprising a plurality of groove groups each having a plurality of grooves extending in parallel with each other on a polishing surface in a direction from a central portion toward a peripheral portion.   The chemical mechanical polishing pad according to claim 1, wherein the number of grooves constituting each groove group is 3 to 5.   2. The chemical mechanical polishing pad according to claim 1, wherein the plurality of groove groups include a groove group in contact with another groove group at a central portion of the polishing surface and a groove group not in contact with the other groove group.   The chemical mechanical polishing pad according to claim 1, wherein each of the grooves constituting each groove group is a broken-line groove.   The chemical mechanical polishing pad according to any one of claims 1 to 4, wherein each of the grooves constituting each groove group is a linear groove.   The chemical mechanical polishing pad according to any one of claims 1 to 5, further comprising a plurality of concentric circular grooves formed on the polishing surface.

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