JP2008187086A - 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 polished surface, in which occurrence of scratch is suppressed sufficiently on the polished surface of an article to be polished. <P>SOLUTION: The chemical mechanical polishing pad has a polishing surface consisting of a plurality of regions having a plurality of linear grooves extending in parallel wherein at least one linear groove in each region reaches the end of the polishing surface and the directions of the linear grooves in two adjoining regions are different from each other. <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 occurrence 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
Having a polished surface consisting of a plurality of regions;
The plurality of regions each have a plurality of linear grooves extending in parallel,
At least one of the linear grooves in each region reaches the end of the polishing surface,
This is achieved by a chemical mechanical polishing pad in which the directions of the linear grooves of adjacent two regions are different.

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 regions. The boundary between adjacent regions can be linear, curved, or a combination thereof, but is preferably linear, rectangular, or triangular, and is rectangular or triangular with an angle between each straight line of 90 °. It is more preferable that it is wavy.
The number of regions of the polished surface is preferably 2 to 8, more preferably 2 to 5, and further preferably 3 or 4. The area ratio of each region is not limited. For example, the area ratio of each region when the number of regions is 3 can be about 2: 1: 1, and the area of each region when the number of regions is 4 is Can be approximately equal.

The region has a plurality of linear grooves each extending in parallel.
The groove width of each linear groove is preferably 0.25 to 4 mm, and more preferably 0.5 to 3 mm. The pitch of the grooves defined as the sum of the interval between the grooves and the groove width is preferably 2 to 30 mm, more preferably 4 to 10 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.
The surface roughness (Ra) inside the 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.

At least one linear groove in each region reaches the end of the polishing surface. With such a configuration, the polishing waste liquid is smoothly discharged during the chemical mechanical polishing process, and therefore, generation of scratches on the surface to be polished can be suppressed as much as possible. It will also contribute to the improvement of uniformity. The chemical mechanical polishing pad of the present invention is decisively different from, for example, a pad having a polygonal groove arranged concentrically or concentrically on the polishing surface.
The number of grooves reaching the end of the polished surface is preferably 2 or more, more preferably 4 to 40, for each region. Furthermore, it is preferable that it is 4-20.

The directions of the linear grooves existing in two adjacent regions on the polishing surface are different. As a result, an advantage that a high polishing rate and a high degree of in-plane uniformity can be achieved in the chemical mechanical polishing step is exhibited. The direction of the straight grooves existing in two adjacent regions is preferably 30 to 90 °, more preferably 60 to 90 °, and perpendicular to each other. It is preferable.
Both regions do not have to be clearly separated at the boundary between adjacent regions on the polishing surface. That is, in the vicinity of the boundary between adjacent regions, there may be a portion in which linear grooves belonging to both regions overlap or intersect each other. In this case, the range that may overlap is preferably 30 mm or less, and more preferably 10 mm or less.
Furthermore, at the boundary between adjacent regions, the linear grooves belonging to both regions may be in contact with each other without overlapping, or may be formed apart from each other.

  Each of the straight grooves existing in each region of the polishing surface of the chemical mechanical polishing pad of the present invention may be a broken straight line groove. Here, the “dashed straight groove” means a groove in which a plurality of linear concave portions are arranged in a vertical direction on a virtual straight line through non-recessed portions. To put it another way, a linear recess and a non-recess on an extension line of the linear recess, and a linear recess on the extension line are repeated by repeating a linear recess and a non-recess. The broken-line linear groove is formed.

1-4, the preferable example of the area | region which the polishing surface of the chemical mechanical polishing pad of this invention has, and arrangement | positioning of a linear groove | channel was shown.
The polishing surface of the chemical mechanical polishing pad of FIG. 1 has four regions defined by triangular wave-shaped boundaries, each of which is 90 degrees. The two regions located on the upper side and the lower side of FIG. 1 each have a plurality of linear grooves extending in parallel with the horizontal direction of the drawing. On the other hand, the two regions located on the right side and the left side of the figure each have a plurality of linear grooves extending in parallel with the vertical direction of the figure. The directions of the straight grooves existing in two adjacent regions of the polishing surface in FIG. 1 are orthogonal to each other. And several linear grooves which exist in the part close | similar to the outer periphery of a grinding | polishing surface among several linear grooves which each area | region each has have reached the edge part of the grinding | polishing surface. Although there is a portion where no groove is formed in the lower left portion of the polished surface in FIG. 1, this does not diminish the effect of the present invention. FIG. 2 is a diagram in which an instruction diagram for explaining the degree of overlapping of grooves belonging to each region at the boundary between adjacent regions is added to the same diagram as FIG. 1. Looking at the portion “a” surrounded by an ellipse, it can be seen that the groove belonging to the upper region of the figure and the groove belonging to the left side of the figure are in contact with each other but not intersecting. On the other hand, in the portion “b”, the grooves belonging to the upper region of the drawing and the grooves belonging to the right region of the drawing are formed to overlap (intersect) each other. Further, in the portion “c”, the groove belonging to the left region of the drawing does not contact the groove belonging to the lower region of the drawing.

  The polishing surface of the chemical mechanical polishing pad of FIG. 3 has three regions partitioned by a rectangular wave boundary, a large region penetrating the left and right of the drawing, and two small regions located above and below the region. In the polished surface of FIG. 3, the straight grooves in each region are broken straight lines. It will also be understood that the directions of the straight grooves existing in two adjacent regions of the polishing surface in FIG. 3 are orthogonal to each other. Further, each region has a linear groove reaching the end of the polishing surface. FIG. 4 is a diagram in which an instruction diagram for explanation is added to the same diagram as FIG. 3. In the portion “a ′” surrounded by an ellipse, the groove belonging to the upper region of the figure and the groove belonging to the center of the figure are in contact with each other but do not intersect. In the portion “b ′”, the groove belonging to the lower region of the figure and the groove belonging to the central region of the figure are formed so as to overlap (intersect) each other. In the portion “c ′”, the groove belonging to the lower region of the drawing does not contact the groove belonging to the central region of the drawing.

The chemical mechanical polishing pad of the present invention may be made of any material as long as the polishing surface has the configuration as described above as long as it can function as a chemical mechanical polishing pad. 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. A material having pores (for example, a foam or the like) can be used.
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. The figure which added the instruction | indication figure for description to FIG. An example of the structure of the groove group which the polishing surface of the chemical mechanical polishing pad of this invention has. The figure which added the instruction | indication figure for description to FIG.

Claims (4)

Having a polished surface consisting of a plurality of regions;
The plurality of regions each have a plurality of linear grooves extending in parallel,
At least one of the linear grooves in each region reaches the end of the polishing surface,
And the direction of the linear groove which two adjacent areas have are different,
A chemical mechanical polishing pad.   The chemical mechanical polishing pad according to claim 1, wherein the direction of the linear groove of two adjacent regions is orthogonal.   The chemical mechanical polishing pad according to claim 1, wherein the number of regions of the polishing surface is 2-5.   2. The chemical mechanical polishing pad according to claim 1, wherein each region has a plurality of parallel extending linear grooves having a width of 0.25 to 4 mm and a pitch of 4 to 30 mm.

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