JP2008187117A - 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 with, in its polishing surface, a plurality of grooves in the shape of dashed-line extending from the central part toward the peripheral part. The grooves in the shape of dashed-line is linear and preferably consists of a group touching other group in the central part on the polishing surface and a group not touching other group in the central part on the polishing surface. <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 broken-line grooves extending 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 broken-line grooves extending in the direction from the center to the periphery. 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.
The broken-line groove is a line extending in the direction from the center to the periphery 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. The broken line-shaped groove only needs to extend in a direction from any one of the “center portions” toward the peripheral portion, and the shape thereof may be, for example, a linear shape, an arc shape, or a combination thereof. Preferably, it is linear.
The length of each linear concave portion of the broken-line groove is preferably 5 to 200 mm, and more preferably 20 to 100 mm. Moreover, the length of the non-recessed portion sandwiched between two adjacent linear recessed portions is preferably 5 to 100 mm, and more preferably 15 to 60 mm.

The number of the plurality of broken-line grooves is preferably 4 to 64, and more preferably 8 to 48.
The broken-line grooves may or may not be in contact with other broken-line grooves, but they do not intersect each other. Of the plurality of broken-line grooves, 2 to 32 are preferably in contact with other broken-line grooves in the central region, and more preferably 2 to 16 are in contact with other broken-line grooves. preferable. Of the plurality of broken-line grooves, 2 to 32 are preferably not in contact with other broken-line grooves in the central region, and 6 to 32 are other broken lines in the central region. More preferably, it is not in contact with the groove. The broken-line groove may be in contact with another broken-line groove at a place other than the center portion of the polishing surface.
Furthermore, between the adjacent two of the broken-line-shaped grooves that are in contact with the other broken-line-shaped grooves in the central area, there is a broken-line-shaped groove that starts from the central area and goes to the peripheral area. It is preferable that there are two or more grooves that are not in contact with other broken-line grooves in FIG.

In the case where a plurality of broken-line-shaped grooves are grooves that originate from the central part and extend to the peripheral part, the broken-line-shaped groove includes a groove that is not in contact with other broken-line grooves and a central part in the central region. In this region, it is preferable to comprise a groove in contact with another broken line groove. The broken line-shaped groove that is not in contact with the other broken line-shaped grooves 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 from there to the peripheral part. 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 a plurality of broken-line-shaped grooves are formed by a plurality of broken-line-shaped grooves that start from the central part and go to the peripheral part, and a plurality of broken-line shaped grooves that start from the middle of the central part and the peripheral part and go to the peripheral part The broken-line-shaped grooves that emanate from the middle between the center portion and the peripheral portion are points on an imaginary straight line that connects the center and the outer periphery of the pad, and correspond to a position of 20 to 80% from the center of the pad toward the outer periphery. It is preferable to start from a point, and it is more preferable to start from a point corresponding to a position of 40 to 60%. Even in this case, the plurality of broken-line grooves that start from the central part and go to the peripheral part are in contact with other broken-line grooves in the central area and other broken-line grooves in the central area. It is preferable to consist of a groove.
The grooves on the plurality of broken lines are preferably arranged as evenly as possible on the polishing surface of the chemical mechanical polishing pad of the present invention. The radial positions of the linear recesses and non-recesses constituting the broken-line grooves (that is, the distance from the center of the polishing surface of the linear recesses and non-recesses) may be coincident with each other by a plurality of broken-line grooves , May be different.

It is preferable that the width | variety of the linear recessed part which comprises each broken line-shaped groove | channel is 0.1 mm or more, More preferably, it is 0.1-5 mm, More preferably, it is 0.2-3 mm. The depth of the linear recess 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 linear concave portion, that is, the shape of the cut surface when the concave portion 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 using a broken-line groove formed by repeating linear recesses having such a size and shape, a chemical mechanical polishing pad excellent in both the polishing rate of the surface to be polished and the effect of reducing scratches can be obtained.
Moreover, it is preferable that the surface roughness (Ra) inside each linear recessed part is 20 micrometers or less, More preferably, it is 0.05-15 micrometers or less, More preferably, it is 0.05-10 micrometers or less. 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.

  In the vicinity of the boundary between each linear recess and the adjacent non-recess, the depth of the recess decreases gradually or in one step or stepwise in several steps. Become. When the depth of the concave portion is gradually or stepwise reduced, the distance from the depth of the deepest portion to the depth of 0 is preferably 3 to 50 mm, more preferably 10 to 30 mm. . Further, it is preferable that the depth of the concave portion gradually decreases and decreases in a so-called “tapered shape”. By creating a dashed groove composed of linear recesses that show such a taper-shaped decrease in the vicinity of the boundary between the linear recesses and the non-recesses, scratch generation is suppressed and a high polishing rate is expressed. In addition, the in-plane uniformity of the surface to be polished can be further improved.

Each of the broken-line grooves on the polishing surface of the chemical mechanical polishing pad of the present invention may be composed of a set of a plurality of broken-line grooves extending in parallel with each other. At this time, the distance between two adjacent broken-line grooves extending in parallel (the shortest distance between the two grooves) is preferably 2.5 to 50 mm, and more preferably 5 to 20 mm. The number of broken-line grooves constituting one set of broken-line grooves is preferably 2 to 5, more preferably 2 or 3.
When each of the broken-line-shaped grooves of the polishing surface of the chemical mechanical polishing pad of the present invention is composed of a plurality of broken-line-shaped grooves extending in parallel with each other, two of these groups are It is preferable that they are in contact with each other in the central region of the polishing surface, and all the remaining sets are not in contact with other broken-line groove sets.

1 and 2 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, 16 broken grooves are arranged at an angle of 22.5 °. Of these grooves, four grooves that form an angle of 90 ° with each other are in contact with each other at the center of the polishing surface, and the other twelve grooves all originate from a position slightly retracted from the center of the polishing surface. And is not in contact with other broken-line grooves. The radial positions of the linear recesses and the non-recesses constituting the broken-line grooves on the polishing surface in FIG. 1 are substantially the same in all the broken-line grooves.
In the chemical mechanical polishing pad of FIG. 2, 32 broken grooves are arranged at an angle of 11.25 °. Each of the broken-line grooves in FIG. 2 includes a pair of two broken-line grooves extending in parallel with each other. Of the 32 broken-line groove groups, two broken-line groove groups are in contact with each other at the center of the polishing surface, and none of the other groups are in contact with other groups. Of the grooves in the broken line shape of the polishing surface in FIG. 2, two sets in contact with each other originate from the center of the polishing surface, and four sets extending at an angle of 45 ° with these grooves are from a position slightly retracted from the center. The two pairs that originate and extend at an angle of 90 ° with the two pairs that are in contact with each other originate from a position that is further retracted from the center, and the two sets that are in contact with each other have an angle of 22.5 ° or 67.5 °. The eight pairs extending from the center originate from a position somewhat further from the center, and the remaining 16 pairs originate from a position farthest from the center. The radial positions of the linear recesses and the non-recesses constituting the dashed groove on the polishing surface in FIG. 2 are substantially the same between the dashed grooves belonging to the same group, but the dashed grooves belonging to the adjacent group. They are different.

The polishing surface of the chemical mechanical polishing pad of the present invention may have a plurality of circular grooves or spiral grooves arranged concentrically in addition to the plurality of dashed grooves 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 broken-line groove | channel which the polishing surface of the chemical mechanical polishing pad of this invention has. An example of the structure of the broken-line groove | channel which the polishing surface of the chemical mechanical polishing pad of this invention has.

Claims (6)

  A chemical mechanical polishing pad having a plurality of broken-line grooves extending in a direction from a central part to a peripheral part on a polishing surface.   2. The chemistry according to claim 1, wherein the plurality of broken-line grooves are composed of grooves that are in contact with other grooves at the center of the polishing surface and grooves that are not in contact with other grooves at the center of the polishing surface. Mechanical polishing pad.   2. The chemical mechanical polishing pad according to claim 1, wherein the broken-line groove is composed of a repetition of a linear recess having a length of 5 to 200 mm and a non-recess having a length of 5 to 100 mm.   2. The chemical mechanical polishing pad according to claim 1, wherein each of the broken-line grooves is composed of a plurality of grooves extending close to each other in parallel.   The chemical mechanical polishing pad according to any one of claims 1 to 4, wherein the broken-line groove is a broken-line 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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