JP2008221389A - Chemical mechanical polishing pad and chemical mechanical polishing method - Google Patents

Abstract

The present invention provides a chemical mechanical polishing pad and a chemical mechanical polishing method in which the occurrence of scratches on a surface to be polished of an object to be polished is sufficiently suppressed and the polishing rate and the uniformity within the surface to be polished are excellent.
A chemical mechanical polishing pad has at least a polishing surface and a non-polishing surface which is a back surface thereof, and the polishing surface is formed from a plurality of annular grooves 1 arranged concentrically and a central portion of the polishing surface. And a plurality of circular recesses 2 arranged on a plurality of virtual straight lines 3 extending in the direction toward the periphery. The chemical mechanical polishing method is a method for chemically mechanically polishing an object to be polished using a chemical mechanical polishing pad.
[Selection] Figure 1

Description

  The present invention relates to a chemical mechanical polishing pad and a chemical mechanical polishing method.

In the manufacture of semiconductor devices, chemical mechanical polishing (“CMP”) is employed as a polishing method capable of forming a surface having excellent flatness. In chemical mechanical polishing, a chemical mechanical polishing aqueous dispersion, for example, an aqueous dispersion in which abrasive grains are dispersed, flows down on the surface of the chemical mechanical polishing pad, and the polishing surface of the polishing pad and the polishing target surface of the object to be polished are slid. This is a technique for polishing while moving. 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 by providing a groove on the surface (polishing surface) of the chemical mechanical polishing pad, the polishing rate and the surface state of the polished surface after polishing are improved (see Patent Documents 1 to 3).
On the other hand, a polishing pad in which water-soluble particles are dispersed in a matrix resin has been proposed (see Patent Documents 4 to 6). In this technique, water-soluble particles dispersed in a matrix resin are dissolved and dropped by contacting with a chemical mechanical polishing aqueous dispersion or water during polishing to form pores. Also in this type of chemical mechanical polishing pad, various grooves are provided on the polishing surface.
In recent years, along with higher performance and smaller size of semiconductor devices, miniaturization and multi-layering of wiring have been advanced, and required performance for chemical mechanical polishing and chemical mechanical polishing pads has been increased. In Patent Document 1, the design of the chemical mechanical polishing pad is described in detail, but the polishing rate and the state of the polished surface after polishing are not yet satisfactory. In particular, a scratch-like surface defect called “scratch” may occur, or the thickness of the layer to be polished and removed may be different for each region of the surface to be polished, and improvement is desired. Further, from the viewpoint of shortening the process time required for chemical mechanical polishing, further improvement of the polishing rate is desired.
JP-A-11-70463 JP-A-8-216029 JP-A-8-39423 JP 2000-33552 A JP 2000-34416 A JP 2001-334455 A

  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. An object is to provide an excellent chemical mechanical polishing pad and chemical mechanical polishing method.

According to the present invention, the above object of the present invention is firstly
Having at least a polishing surface and a non-polishing surface that is the back surface thereof;
The polished surface is
A plurality of annular grooves arranged concentrically;
A plurality of circular recesses arranged on a plurality of virtual straight lines extending in the direction from the center of the polishing surface toward the periphery,
Achieved by chemical mechanical polishing pad.
Secondly, the object of the present invention is as follows.
This is achieved by a chemical mechanical polishing method in which a workpiece is chemically mechanically polished using the chemical mechanical polishing pad.

The chemical mechanical polishing pad of the present invention has a polishing surface and a non-polishing surface which is the back surface of the polishing surface. The chemical mechanical polishing pad of the present invention may further have a side surface that regulates a polishing surface and a non-polishing surface, and the thickness gradually decreases in the region of the outermost peripheral portion of the pad without having a clear side surface. Such a shape may be used.
The polishing surface of the chemical mechanical polishing pad of the present invention,
A plurality of annular grooves arranged concentrically;
A plurality of circular recesses arranged on a plurality of virtual straight lines extending in a direction from the center of the polishing surface toward the periphery.
Here, each of the plurality of annular grooves arranged concentrically is a closed curved groove formed in an annular shape (circular shape) with a certain width and depth, and is surrounded by this circle. The inner region is not recessed except when there are other grooves or recesses there, and forms the same plane as the polishing surface. On the other hand, each of the plurality of circular recesses has both a circumference and a region surrounded by the recess, and preferably exists as a cylindrical recess.

The centers of the plurality of concentric annular grooves are preferably coincident with the center of gravity of the polishing surface.
The size of each annular groove is not particularly limited, but the groove width is preferably 0.05 mm or more, more preferably 0.1 to 3.0 mm, and still more preferably 0.2 to 2.0 mm. The depth of the annular 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 groove interval defined as the shortest distance between two adjacent annular grooves (usually the width of the portion called “bank”) is preferably 0.5 mm or more, more preferably 1.0 to It is 10.0 mm, More preferably, it is 1.3-5.0 mm. The pitch of the plurality of annular grooves defined as the sum of the groove width and the groove interval is preferably 0.55 mm or more, more preferably 1.1 to 13.0 mm, and still more preferably 1. 5 to 7.0 mm. By arranging a plurality of annular grooves having a size in the above-mentioned range concentrically at the above-mentioned intervals or pitches, it is possible to provide a chemical mechanical polishing pad that has an excellent scratch reduction effect on the surface to be polished and has a long life. It becomes.
The cross-sectional shape of the annular groove, that is, the shape of the cut surface when each annular groove is cut in a plane parallel to the normal direction and perpendicular to the polishing surface is not particularly limited, but for example, a polygonal shape, a U-shape, etc. Can do. Examples of the polygon include a triangle, a quadrangle, and a pentagon.
The surface roughness (Ra) of the inner surface of the annular 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 plurality of circular recesses preferably has a diameter of 0.1 to 5.0 mm, more preferably 0.5 to 4.0 mm, and further 1.0 to 3.0 mm. preferable. The diameter of the circular recess is preferably more than 100% of the groove width of the annular groove and not more than 2,000%, and more preferably 300 to 1,000%. Further, the diameter of the circular recess is preferably 20% to 100%, more preferably 40 to 85% of the interval between the two adjacent annular grooves.
The depth of the circular recess is preferably 0.1 mm or more, more preferably 0.1 to 2.5 mm, and further preferably 0.2 to 2.0 mm. The depth of the circular recess may be the same as the depth of the annular groove described above, or may be deeper or shallower than the depth of the annular groove, but is the same as or deeper than the depth of the annular groove. It is preferable.
The cross-sectional shape of the circular recess, that is, the shape of the cut surface when the circular recess is cut by a plane that passes through the center of the circular recess and is perpendicular to the polishing surface, can be a triangle, a quadrangle, a pentagon, a U shape, or the like. When the cross-sectional shape of the circular recess is, for example, a quadrangle having a base, the base may be a straight shape, and may be a convex shape with a raised central part or a concave shape with a concave central part. The cross-sectional shape of the circular recess is a shape that does not have a base, or the depth of the circular recess when the base has a base but is convex or concave is the deepest part of the circular recess. And
By setting it as the circular recessed part of such a magnitude | size and a shape, the chemical mechanical polishing pad of this invention can balance a high polishing rate and the inhibitory effect of a scratch in a more balanced manner.

There are a plurality of circular recesses as described above on the polishing surface of the chemical mechanical polishing pad of the present invention, and these are arranged on a plurality of virtual straight lines extending in the direction from the center to the periphery of the polishing surface. . Here, the central portion refers to a region surrounded by a circle with a radius of 50 mm centered on the center of gravity of the polished surface. The virtual straight line extends in a direction from an arbitrary one of the “center portions” toward the peripheral portion. When there are a plurality of virtual straight lines on which the circular recesses are arranged on the polishing surface, each virtual straight line only needs to extend in a direction from one arbitrary point of the central part toward the peripheral part. The virtual straight lines do not intersect each other. All of these imaginary straight lines preferably extend in the direction from the center of the plurality of annular grooves toward the periphery. Moreover, it is preferable that all the virtual straight lines extend in the direction from the center of gravity of the polishing surface toward the peripheral portion.
A plurality of circular recesses are preferably arranged on at least one virtual straight line. In this case, each circular recess only needs to have a part of the circle on the virtual straight line, but it is preferable that the centers of all the circular recesses arranged on one virtual straight line are on the virtual straight line. In the chemical mechanical polishing pad of the present invention, it is preferable that a plurality of circular recesses are arranged on all virtual straight lines.
When a plurality of circular recesses are arranged on one virtual straight line, it is preferable that two adjacent circular recesses do not contact each other. Therefore, the distance between the centers of two adjacent circular recesses (hereinafter referred to as “center distance”) is preferably larger than the diameter of the circular recess. More preferably, the center-to-center distance is larger than the diameter of the circular recess and 3 to 20 mm.

The positional relationship between the circular recess and the annular groove is arbitrary, but it is preferable that the circular recess is disposed on the annular groove or between two adjacent annular grooves. This makes it possible to obtain a chemical mechanical polishing pad that is superior in balance between the polishing rate and the in-plane uniformity of the polishing amount of the surface to be polished.
As the positional relationship between the circular recess and the annular groove arranged on the virtual straight line, any one of the following three modes is preferable.

(1) A mode in which all the circular concave portions on the virtual straight line are arranged on the annular groove (hereinafter referred to as “mode (1)”).
(2) A mode in which all circular recesses on the imaginary straight line are disposed between two adjacent annular grooves (hereinafter referred to as “mode (2)”).
(3) A mode in which circular recesses arranged on annular grooves and circular recesses arranged between two adjacent annular grooves are alternately arranged on a virtual straight line (hereinafter referred to as “aspect (3)”) Called.)

In order to realize the arrangement of such circular recesses, for example, when the virtual straight line extends from the center of a plurality of annular grooves arranged concentrically toward the periphery of the polishing surface, the center-to-center distance is Following formula (2)

Center-to-center distance = annular groove pitch x 0.5 x n (2)

Where n is an integer.
It is preferable to set it as the value represented by these. In the above formula (2), n is more preferably an integer of 1 to 20, and even more preferably an even number of 2 to 10.
When three or more circular recesses are arranged on one imaginary straight line, the distances between the centers may be different or the same, but all the distances between the centers are equal. It is preferable.

It is preferable that 4 to 192 virtual straight lines on which circular recesses are arranged exist on the polished surface. This number is more preferably 4 to 128, still more preferably 4 to 96, and particularly preferably 4 to 64. The plurality of virtual straight lines are preferably arranged as evenly as possible on the polishing surface.
The circular recess is preferably not in contact with other circular recesses, and when there are a large number of virtual straight lines on which the circular recesses are arranged, the circular recesses are arranged at positions relatively close to the center of gravity of the polishing surface on the virtual straight line. The distance from the center of gravity of the polishing surface may be made different between two adjacent virtual straight lines.
When there are a plurality of virtual straight lines in which circular recesses are arranged on the polishing surface, these can be any combination of the above aspects (1) to (3), but all the virtual straight lines on the polishing surface are in a mode. The case (1) or the case where all virtual lines on the polishing surface are in the mode (2) is preferred, and the case where all virtual lines on the polishing surface are the mode (1) is more preferable.

The shape of the chemical mechanical polishing pad of the present invention can be, for example, a cylindrical shape, a polygonal column shape, etc., and is preferably a cylindrical shape. When the chemical mechanical polishing pad of the present invention is cylindrical, one of the bottom surfaces of the cylinder is the polishing surface, so that the shape is circular, and the center of gravity of the polishing surface is the center of the polishing surface.
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 number of concentric annular grooves existing on the polishing surface, the number of circular recesses arranged on one virtual line, and the total number of circular recesses arranged on the polishing surface depend on the shape and size of the polishing surface. Different.
For example, when the polishing surface is a circle having a diameter of 640 mm, the number of concentric annular grooves is preferably 70 to 160, and the number of circular recesses arranged on one imaginary straight line is 15 to 120. It is preferable that the total number of circular recesses arranged on the polishing surface is 240 to 7,680. When the polished surface is a circle having a diameter of 820 mm, the number of concentric annular grooves is preferably 100 to 200, and the number of circular recesses arranged on one virtual line is 20 to 140. It is preferable that the total number of circular recesses arranged on the polishing surface is 320 to 8,960.

  Hereinafter, preferred embodiments of the chemical mechanical polishing pad of the present invention will be specifically described with reference to the accompanying drawings. FIGS. 1 to 3 show examples of arrangement of the annular grooves and the circular recesses on the polishing surface of the preferred chemical mechanical polishing pad of the present invention. 1 to 3, nine annular grooves arranged concentrically on the polished surface and 36 to 136 circular recesses are drawn in the range, but these figures are schematic views, As the number of grooves and circular recesses, it should be understood that the number and the number calculated from the size of the polishing surface, the pitch, and the distance between the centers are preferable. Further, for convenience of explanation, in these drawings, the relative relationship between the width of the annular groove, the interval between the adjacent annular grooves, and the diameter of the circular recess is exaggerated. It should be noted that a virtual straight line that does not exist is drawn with a one-dot chain line, which is different from an actual chemical mechanical polishing pad.

The polishing surface of FIG. 1 is circular, and is arranged on nine annular grooves 1 arranged concentrically and 16 virtual straight lines (3 and 4) extending from the center of the polishing surface toward the outer periphery. And a plurality of circular recesses 2. Nine circular recesses 3 are arranged at equal intervals on the virtual straight line 3, and eight circular recesses 3 are arranged at equal intervals on the virtual straight line 4 adjacent to the virtual straight line 3. In addition, any of the circular recesses is disposed on the annular groove (that is, the intersection between the annular groove and the virtual straight line). In this case, the distance between the centers of the plurality of circular recesses 2 arranged on one imaginary straight line is equal to the pitch of the plurality of annular grooves arranged concentrically. The polishing surface of FIG. 1 avoids contact between the circular recesses at this position by not arranging the circular recess 2 on the innermost annular groove on the virtual straight line 4. The total number of circular recesses 2 on the polished surface in FIG.
The polishing surface of FIG. 2 is circular and is arranged on nine annular grooves 1 arranged concentrically and 16 virtual straight lines (3 and 4) extending from the center of the polishing surface toward the outer periphery. And a plurality of circular recesses 2. Five circular recesses 2 are arranged at equal intervals on the virtual straight line 3, and four circular recesses 2 are arranged at equal intervals on the virtual straight line 4 adjacent to the virtual straight line 3. Moreover, any circular recessed part is arrange | positioned on the annular groove. In this case, the distance between the centers of the plurality of circular recesses 2 arranged on one imaginary straight line is twice the pitch of the plurality of annular grooves arranged concentrically. In the polishing surface of FIG. 2, the circular recesses are in contact with each other in the region near the center of the polishing surface by making the distances from the center of the polishing surface of the circular recesses arranged on two adjacent virtual straight lines different. Avoid. The total number of circular recesses 2 on the polished surface in FIG.

The polishing surface in FIG. 3 is circular, and is arranged on nine annular grooves 1 arranged concentrically and 16 virtual straight lines (3 and 4) extending from the center of the polishing surface toward the outer periphery. And a plurality of circular recesses 2. Nine circular recesses 2 are arranged at equal intervals on the virtual straight line 3, and eight circular recesses 2 are arranged at equal intervals on the virtual straight line 4 adjacent to the virtual straight line 3. Moreover, any circular recessed part is arrange | positioned between the two adjacent annular grooves. In this case, the distance between the centers of the plurality of circular recesses 2 arranged on one virtual straight line is equal to the pitch of the plurality of annular grooves arranged concentrically. The polishing surface in FIG. 3 avoids contact between the circular recesses at this position by not disposing the circular recess 2 between the innermost annular groove on the virtual straight line 4 and the next annular groove. . The total number of circular recesses 2 on the polished surface in FIG.
The polishing surface in FIG. 4 is circular, and includes nine annular grooves 1 arranged concentrically and 16 imaginary straight lines (3, 4, 5 and 6) extending from the center of the polishing surface toward the outer periphery. And a plurality of circular recesses 2 arranged on the top. Two circular recesses 2 are arranged on the virtual straight line 3, and three circular recesses 2 are arranged on the virtual straight lines 4 to 6 at equal intervals. Any circular recess is arranged on the annular groove. In this case, the distance between the centers of the plurality of circular recesses 2 arranged on one virtual straight line is three times the pitch of the plurality of annular grooves arranged concentrically. In the polishing surface of FIG. 4, the circular recess 2 is not disposed on the innermost annular groove on the virtual straight line 3, and the distance from the center of the polishing surface of the circular recesses disposed on the virtual straight lines 4 to 6 is compared. By making them different, the circular recesses are prevented from contacting each other in a region near the center of the polishing surface. The total number of circular recesses 2 on the polished surface in FIG.

The polishing surface in FIG. 5 is circular, and includes nine annular grooves 1 arranged concentrically and 16 imaginary straight lines (3, 4, 5, and 6) extending from the center of the polishing surface toward the outer periphery. And a plurality of circular recesses 2 arranged on the top. Two circular recesses 2 are arranged on each of the virtual straight lines 3 to 5, and three circular recesses 2 are arranged on the virtual straight line 6 at equal intervals. Any circular recess is arranged on the annular groove. In this case, the center-to-center distances of the plurality of circular recesses 2 arranged on one virtual straight line are four times the pitch of the plurality of annular grooves arranged concentrically. The polishing surface in FIG. 5 avoids contact between the circular recesses in a region near the center of the polishing surface by making the distances from the center of the polishing surface of the circular recesses arranged on the imaginary straight line different from each other. The total number of circular recesses 2 on the polished surface in FIG.
The polishing surface of FIG. 6 is circular, and is arranged on nine annular grooves 1 arranged concentrically and 16 virtual straight lines (3 and 4) extending from the center of the polishing surface to the outer peripheral portion. And a plurality of circular recesses 2. Six circular recesses 2 are arranged at equal intervals on any virtual straight line. On the imaginary straight lines 3 and 4, circular concave portions arranged on the annular grooves and circular concave portions arranged between two adjacent annular grooves are alternately arranged. In this case, the distance between the centers of the plurality of circular recesses 2 arranged on one virtual straight line is 1.5 times the pitch of the plurality of annular grooves arranged concentrically. In the polishing surface of FIG. 6, the circular recesses are in contact with each other in the region near the center of the polishing surface by making the distances from the center of the polishing surface of the circular recesses arranged on two adjacent virtual straight lines different. Avoid. The total number of circular recesses 2 on the polished surface in FIG.

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.

A plurality of annular grooves arranged concentrically are, for example, a method of cutting after forming a rough shape of a chemical mechanical polishing pad, or a convex portion that engages with a desired circular groove when forming a rough shape of a chemical mechanical polishing pad. It can form by the method of using the metal mold | die which has. A plurality of circular recesses arranged on an imaginary straight line, for example, a method of forming a rough shape of a chemical mechanical polishing pad and then drilling with an end mill, and a desired circular recess when forming a rough shape of a chemical mechanical polishing pad. It can form by the method of using the metal mold | die which has a convex part to do.
Therefore, the chemical mechanical polishing pad of the present invention is a method of performing cutting and end mill drilling in any order after molding a rough shape of the chemical mechanical polishing pad made of the above material using a mold having no special protrusion. A method of performing end mill drilling or cutting after molding a rough shape of a chemical mechanical polishing pad made of the above material using a mold having a convex portion engaging with an annular groove or a convex portion engaging with a circular recess, and an annular groove It can be manufactured by a method of molding a chemical mechanical polishing pad made of the above-mentioned material using a mold having both a convex portion to be engaged and a convex portion to be engaged with a circular concave portion.

The chemical mechanical polishing method of the present invention is a method for chemically mechanically polishing an object to be polished using the above-described chemical mechanical polishing pad of the present invention. The chemical mechanical polishing method of the present invention can be carried out by a known method by mounting the chemical mechanical polishing pad of the present invention on a commercially available chemical polishing apparatus and using an appropriate aqueous dispersion for chemical mechanical polishing.
Examples of the material constituting the surface to be polished include a metal, a barrier metal, an insulator, and a combination thereof, which are wiring materials. Examples of the metal as the wiring material include tungsten, aluminum, copper, and alloys containing these. Examples of the barrier metal include tantalum, tantalum nitride, niobium, and niobium nitride. Examples of the insulator include SiO ₂ and boron phosphorus silicate containing a small amount of boron and phosphorus.
The chemical mechanical polishing pad of the present invention and the chemical mechanical polishing method of the present invention using the same realize extremely high in-surface uniformity while suppressing the generation of scratches on the surface to be polished and exhibiting a high polishing rate. can do. The reason why such an excellent effect is manifested is not clear, but the supplied chemical mechanical polishing aqueous dispersion is polished by the arrangement of special grooves and recesses on the polishing surface of the chemical mechanical polishing pad of the present invention. It is assumed that the efficiency of holding on the surface is improved and the removal of the polishing waste liquid is smooth.

Example 1
<Manufacture of chemical mechanical polishing pad>
1,2-polybutadiene (manufactured by JSR Corporation, trade name “JSR RB820” and “JSR RB810” volume ratio 25:75 mixture) 70 parts by volume and β-cyclodextrin (manufactured by Yokohama International Bio-Laboratory, 30 parts by volume of a trade name “Dexipal β-100” (average particle size 20 μm) was kneaded with a rudder adjusted to 160 ° C. Thereafter, Park Mill D40 (trade name, manufactured by NOF Corporation, containing 40% by weight of dicumyl peroxide) was added in an amount of 0.32 parts by weight (100% by weight of 1,2-polybutadiene). This corresponds to 0.128 parts by weight in terms of conversion.) After blending and further kneading at 120 ° C., pellets were obtained. This pellet was heated in a mold at 180 ° C. for 10 minutes and crosslinked to obtain a molded body having a diameter of 840 mm and a thickness of 3.0 mm. Thereafter, both sides of the molded body were ground 0.1 mm each with sandpaper to adjust the thickness to 2.8 mm, and a pad outline was obtained.
This pad outline is mounted on a table of a cutting machine manufactured by Kato Machine Co., Ltd., and concentric grooves having a width of 0.3 mm, a depth of 1.4 mm, and a rectangular cross-sectional shape are formed on one side (polished surface) of the molded body. Then, a region having a radius of 5.0 mm or more around the center of the polished surface was formed with a pitch of 3.0 mm. Next, a circular recess having a diameter of 3.0 mm and a depth of 1.4 mm was formed using an end mill “MG-EDS-3” manufactured by OSG Corporation. The circular concave portion is assumed to be 64 virtual straight lines from the center to the outer peripheral portion on the polished surface (the angles formed by the adjacent virtual straight lines are each 11.25 °), and each virtual straight line and the above are formed. Formed at the intersection with the annular groove. At this time, the center-to-center distance between adjacent circular recesses on the same imaginary straight line is equal to the pitch of the annular grooves, and the circular recesses are formed in the range of 5 to 254 mm from the center of the polishing surface. The virtual straight lines and the virtual straight lines in which the circular concave portions are formed in the range of 11 to 254 mm from the center of the polishing surface are arranged alternately. The arrangement of the annular grooves and the circular recesses on the polishing surface of the chemical mechanical polishing pad manufactured here is similar to the polishing surface shown in FIG.

<Evaluation of polishing performance>
About the polishing pad manufactured above, the outer periphery was cut with a diameter adjusting cutter to adjust the diameter to 20 inches, and then subjected to chemical mechanical polishing under the following conditions.

Chemical mechanical polishing apparatus: “Mirra / Mesa” manufactured by Applied Materials Co., Ltd. The chemical mechanical polishing pad was used by laminating a double-sided tape # 422 manufactured by 3M Co. on the back surface of the pad and mounted on the chemical mechanical polishing apparatus.
Object to be polished: 8 inch diameter wafer with Cu film (Advantec)
Plate rotation speed: 90rpm
Polishing head rotation speed: 85 rpm
Polishing pressure: 2 psi
Abrasive machine polishing aqueous dispersion: “CMS8401”, “CMS8452” manufactured by JSR Corporation and ion-exchanged water are mixed at a weight ratio of 1: 2: 3, and 30% by weight of hydrogen peroxide is added to the total amount of the aqueous dispersion. 0.1% by weight added to polishing machine polishing aqueous dispersion supply speed: 100 mL / min Polishing time: 1 minute

For the surface to be polished, 49 specific points are set evenly in the diameter direction except for the outer circumference of 3 mm, and the thickness of the Cu film before and after polishing is measured with a stylus type film thickness meter at these specific points. The polishing rate at each point was calculated from the difference and the polishing time.
When the average value of the polishing rates at these 49 points was evaluated as the polishing rate, it was 420 Å / min.
Next, the in-plane uniformity (%) of the polishing amount is calculated by the following formula using the difference in thickness of the Cu film before and after polishing at the 49 specific points (this value is referred to as “polishing amount”). did.

In-plane uniformity of polishing amount (%) = (standard deviation of polishing amount ÷ average value of polishing amount) × 100

The in-plane uniformity of the polishing amount was 3.8%.
Further, the polished surface after polishing was subjected to defect inspection by a wafer defect inspection apparatus “KLC351” manufactured by KLA-Tencor Corporation. First, the number of “KLC351” counted as “defects” was measured for the entire range of the wafer polished surface under the conditions of a pixel size of 0.39 μm and a threshold value of 20 (threshold). Next, these “defects” are sequentially displayed on the display of the apparatus, and the number of scratches on the entire wafer surface is measured by classifying whether or not each “defect” is a scratch. / Surface.

An example of the polishing surface of the chemical mechanical polishing pad of this invention. An example of the polishing surface of the chemical mechanical polishing pad of this invention. An example of the polishing surface of the chemical mechanical polishing pad of this invention. An example of the polishing surface of the chemical mechanical polishing pad of this invention. An example of the polishing surface of the chemical mechanical polishing pad of this invention. An example of the polishing surface of the chemical mechanical polishing pad of this invention.

Claims (6)

Having at least a polishing surface and a non-polishing surface that is the back surface thereof;
The polished surface is
A plurality of annular grooves arranged concentrically;
A plurality of circular recesses arranged on a plurality of virtual straight lines extending in the direction from the center of the polishing surface toward the periphery,
A chemical mechanical polishing pad.   The chemical mechanical polishing pad according to claim 1, wherein the circular recess has a diameter of 0.1 to 5.0 mm.   The chemical mechanical polishing pad according to claim 1, wherein a plurality of circular recesses are arranged on each virtual straight line.   The chemical mechanical polishing pad according to claim 3, wherein the distance between the centers of two adjacent circular recesses arranged on each virtual straight line is larger than the diameter of the circular recess and 3 to 20 mm.   The chemical mechanical polishing pad according to claim 1, wherein the number of imaginary straight lines on which circular concave portions are arranged is 4 to 192.   A chemical mechanical polishing method comprising polishing a workpiece to be chemical mechanically using the chemical mechanical polishing pad according to any one of claims 1 to 5.

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