KR20030022388A - Abrasive Pad for CMP - Google Patents

Abstract

The polishing pad for CMP of the present invention has a substrate 12 and a polishing layer disposed on the substrate. The present invention has a substrate and a polishing layer disposed on the substrate, the polishing layer having a three-dimensional structure comprising a plurality of regularly arranged three-dimensional elements 11 having a predetermined shape. Provided are polishing pads for CMP comprising, as constituents, an abrasive composite containing a binder and advanced alumina abrasive grains produced by the CVD method.

Description

Abrasive Pad for CMP {Abrasive Pad for CMP}

The CMP process is known as a standard process for planarizing semiconductor wafers due to high integration and multi-layer wiring of devices. The basic structure of a CMP system includes two units, one for processing and one for cleaning. The processing unit generally includes, as a basic structure, a head portion for providing rotation and pressurization while holding a semiconductor wafer, a driving mechanism thereof, a platen attached to which a pad faces the semiconductor, and a driving mechanism thereof. In addition, the processing unit includes a mechanism for conditioning (dressing) the polishing pad, a mechanism for cleaning the wafer chuck surface, a mechanism for supplying a working liquid, and the like.

Since the structure or properties of the polishing pad have a great influence on the polishing properties generated by the processing, further improvement is desired as a key technology for supporting the CMP process. The structure of the polishing pad has microscopic and macroscopic aspects, all of which affect the polishing properties. Microscopic structures show types of abrasive grains and binders, foamed states, surface states, etc., while macroscopic structures exhibit surface shapes such as holes, grooves, and protrusions.

Japanese Patent Laid-Open No. 11-512874 discloses a polishing pad for a semiconductor wafer whose polishing layer has a regular three-dimensional structure. This polishing pad can be used for the CMP process. The use of an abrasive layer having a three-dimensional structure suppresses the problem of "loading", so that the polishing pad provides stable polishing and is excellent in durability.

However, the polishing pad having the three-dimensional structure of the polishing layer has a property that the performance of the polishing grain tends to affect the polishing properties. For this reason, there is a problem that it is difficult to sufficiently modify the finish of the polished surface by the use of general-purpose a-alumina abrasive grains. In particular, in the CMP process, the semiconductor wafer surface has a surface roughness of 1 to 2 nm Ry (maximum height, JIS B 0601) and ensures high flatness without OSF (oxidation induced lamination defects), microscratches and haze. It is required.

However, when the? -Alumina abrasive grains obtained by a conventional general manufacturing method are used in an abrasive material formed to have a three-dimensional structure, the friction force is high during polishing, and defects or scratches are likely to occur on the polished surface. On the other hand, the use of expensive abrasive grains such as diamonds increases the manufacturing cost of the polishing pad.

SUMMARY OF THE INVENTION The present invention solves the problems of the prior art, and its object is to provide a polishing pad for CMP having good friction characteristics, low cost and excellent durability without generating defects or scratches on the polished surface of the semiconductor wafer.

Summary of the Invention

The present invention has a substrate and a polishing layer disposed on the substrate, the polishing layer having a three-dimensional structure comprising a plurality of regularly arranged three-dimensional elements having a predetermined shape, wherein the polishing layer is a constituent component. The above object of the present invention is achieved by providing a polishing pad for CMP comprising an abrasive composite containing a binder and an advanced alumina abrasive grain produced by the CVD method.

The present invention relates to a polishing pad having a three-dimensional structure, in particular, a polishing pad having a three-dimensional structure in which the polishing layer is used to planarize a semiconductor wafer by a CMP (chemical and mechanical polishing) process.

1 is a cross-sectional view showing an example of the abrasive layer structure of the present invention.

2 is a cross-sectional view showing an example of the abrasive layer structure of the present invention.

3 is a cross-sectional view showing an example of the abrasive layer structure of the present invention.

4 is a plan view showing an example of the polishing layer of the present invention.

5 is an enlarged photograph of the polishing surface of the polishing pad for CMP as an example of the present invention.

6 is a plan view of the polishing surface of the polishing pad for CMP as an example of the present invention.

7 is a cross-sectional view of the polishing pad for CMP as an example of the present invention.

8 is a plan view of the polishing surface of the polishing pad for CMP as another example of the present invention.

9 is a plan view of the polishing surface of the polishing pad for CMP as another example of the present invention.

10 is a plan view of the polishing surface of the polishing pad for CMP as another example of the present invention.

It is a schematic diagram which shows the test method of the frictional force of a polishing pad.

12 is a plot graph showing how the frictional force generated in the polishing step changes over time.

Preferred Embodiments

Representative examples of the polishing layer are illustrated as FIGS. 1, 2, 3 and 4.

Preferred abrasive layers can be precisely shaped (as defined in the description) or irregularly shaped, with precisely shaped elements being preferred.

Individual three-dimensional element shapes may have any of a variety of geometric solid forms. Typically, the base of the shape in contact with the substrate has a larger surface area than the distal end of the composite. The shape of the element is cuboid, cylindrical, prismatic, truncated prismatic, striped, rectangular, pyramidal, truncated pyramidal, tetrahedral, truncated tetrahedral, conical, truncated conical, hemispherical, truncated hemispherical, cruciform or distal It can be chosen from many geometric solids, such as columnar cross sections.

The element pyramid may have four, five or six sides. In addition, the three-dimensional elements can have a mixture of different shapes. The three-dimensional elements can be arranged in a row, spiral, threaded or lattice form or can be arranged randomly.

The sides forming the three-dimensional element may be perpendicular to the substrate, inclined to the substrate, or tapered to decrease in width toward the distal end. If the sides are tapered, it is easy to remove the three-dimensional element from the cavity of the mold or manufacturing tool. The tapering angle may range from about 1 to 75 °, preferably from about 2 to 50 °, more preferably from about 3 to 35 °, most preferably from about 5 to 15 °.

Smaller angles are preferred because they produce a consistent nominal contact area as the composite wears. Thus, generally the tapered angle is a compromise between an angle large enough to facilitate removal of three-dimensional elements from the mold or manufacturing tool and small enough to produce a uniform cross-sectional area. In addition, three-dimensional elements having a larger cross section at the distal end than the base surface can be used, but a method more than a simple molding method may be required for manufacturing.

The height of each three-dimensional element is preferably the same, but it is possible to have elements of various heights in a single abrasive article. The height of the three-dimensional element relative to the substrate may generally range from less than about 2,000 μm, more particularly from about 25 to 200 μm.

The bases of three-dimensional elements may abut one another or the bases of adjacent three-dimensional elements may be separated from each other by some specific distance. In some embodiments, the physical contact between adjacent three-dimensional elements includes 33% or less of the vertical height dimension of each contact element. More preferably, the amount of physical contact between the elements in contact is in the range of 1 to 25% of the vertical height of each of the elements in contact.

This definition of "contacting" includes a bridge-like structure in which adjacent elements extend in contact between opposing sidewalls of an arrangement or elements in which common three-dimensional element lands share. Preferably, the land structures each have a height of 33% or less of the vertical height dimension of adjacent elements. The three-dimensional element land is formed from the same slurry used to form the three-dimensional element. The elements are adjacent in the sense that no intervening composite is placed on the direct virtual line drawn between the centers of the elements. Preferably, at least some of the three-dimensional elements are separated from each other to provide a concave area between the protrusions of the elements.

The line spacing of the three-dimensional elements can range from about one three-dimensional element per centimeter of line to about 100 three-dimensional elements per centimeter of line. The line spacing can be varied so that the concentration of the urea is higher at one location than at another. For example, the concentration may be greatest at the center of the abrasive article. The area density of the elements ranges from about 1 to 10, OO elements / cm ² .

It is also possible that the area of the substrate is exposed, ie the abrasive coating does not cover the entire surface area of the substrate. This type of arrangement is further described in US Pat. No. 5,014,468 (Ravipati et al.).

The three-dimensional element is preferably disposed on the substrate in a predetermined pattern or on the substrate in a predetermined position. For example, in an abrasive article made by providing a slurry between a substrate and a manufacturing tool having a cavity therein, the predetermined pattern of elements will correspond to the pattern of the cavity on the manufacturing tool. Thus, the pattern is reproducible from article to article.

In one embodiment of a given pattern, the three-dimensional elements are arrayed or arranged, meaning that the elements are present in a regular array such as aligned columns and rows or alternating offset columns and rows. If desired, one column of three-dimensional elements may be aligned directly before the second column of three-dimensional elements. Preferably, one row of polishing elements may be offset from the second row of three-dimensional elements.

In another embodiment, three-dimensional elements can be arranged in a "random" arrangement or pattern. This means that the elements are not a regular arrangement of the columns and rows described above. For example, the polishing elements may be as described in WO PCT 95/07797 published on March 23, 1995 (Hoopman et al.) And WO PCT 95/22436 published on August 24, 1995 (Hoopman et al.). Can be arranged in a manner. However, it is understood that this "random" arrangement is a predetermined pattern in that the position of the element on the abrasive article is predetermined and corresponds to the position of the cavity in the manufacturing tool used to manufacture the abrasive article.

In addition, the three-dimensional textured abrasive article may have a variable abrasive coating composition. For example, the center of the abrasive disc may contain an abrasive coating that is different (eg, softer, harder or more corrosive) than the external area of the abrasive disc.

In FIG. 1, the abrasive article 10 has a pyramidal three-dimensional element 11 secured or bonded to the substrate 12. There is a recess or valley 13 between adjacent three-dimensional elements. There is also a pyramidal three-dimensional element of the second column offset from the first column. The outermost point or distal end of the pyramidal abrasive element contacts the wafer surface during processing.

The abrasive article 20 of FIG. 2 has a pyramidal abrasive element of irregular shape. In this particular example, the three-dimensional element has a pyramidal shape. The boundary defining the pyramidal shape is irregular. Incomplete shape may be the result of slurry flow and twisting of the initial shape prior to significant curing or solidification of the binder precursor. Irregular shapes are characterized by not clean, unreproducible, inaccurate or incomplete plane or shape boundaries.

The abrasive article 30 of FIG. 3 has a truncated pyramidal abrasive element 31.

The abrasive article 40 of FIG. 4 has both three-dimensional elements of "cross" shape 41 and "x" shape 42. Three-dimensional elements are arranged in a pattern of columns. The three-dimensional elements of the various columns are offset from each other and are not directly aligned with the three-dimensional elements in adjacent columns. In addition, the rows of three-dimensional elements are separated by spaces or valleys. The bone or space may contain very small amounts (measured by height) of the abrasive composites or may not contain three-dimensional elements.

Another arrangement or arrangement of three-dimensional elements is similar to FIG. 3 except that each alternating column includes three-dimensional elements having a "cross" shape or three-dimensional elements having a "x" shape. In this arrangement, the polishing elements from odd rows are still offset from three-dimensional elements from even rows. In the above-described arrangement of cross-shaped or “x” shaped elements, the length of one line forming the cross or x shape is preferably about 750 μm and the width of the line forming the cross or x shape is about 50 μm.

5 is a perspective view of the polishing surface of the polishing pad for CMP as an example of the present invention. This shows the three-dimensional structure of the polishing layer. The three-dimensional structure of the abrasive layer is configured to include a plurality of three-dimensional elements. The shape of the three-dimensional element is cylindrical and a plurality of cylinders are regularly arranged.

6 is a plan view of the polishing surface of the polishing pad for CMP. This shows an example of the arrangement method of three-dimensional elements. A plurality of three-dimensional elements are laterally arranged at equal intervals to form columns A, B ..., and these columns are shifted so that the three-dimensional elements are arranged alternately and arranged longitudinally.

In Fig. 6, symbol d denotes the diameter of the cylinder which is a three-dimensional element. For example, d is 10 to 5000 µm, preferably 50 to 500 µm, more preferably 100 to 300 µm. The sign e represents the distance between adjacent three-dimensional elements in the same column. The symbol f represents the distance between adjacent three-dimensional elements in adjacent columns. The e and f values can be the same dimension or different dimensions and can be, for example, 10 to 10000 μm, preferably 50 to 1000 μm, more preferably 100 to 300 μm. In general, the e and f values are the same dimension.

It is sectional drawing which cut | disconnected the polishing pad for CMP shown in FIG. 6 along the XX 'surface. In FIG. 7, the polishing pad 1 has a substrate 2 and a polishing layer 3 disposed on the surface of the substrate 2. The polishing layer 3 has a three-dimensional structure.

The base material 2 is required to be uniform in thickness. If the thickness of the substrate 2 is not sufficiently uniform, a change in the polished surface of the semiconductor wafer and the wafer thickness may possibly occur. Any of a variety of substrates are suitable for the purposes of the present invention, including flexible substrates and relatively strong substrates.

Preferred materials for the substrate include polymer films, paper, fabrics, metal films, vulcanized fibers, nonwoven substrates, combinations thereof, and processed articles thereof. One preferred type of substrate is a polymer film. Examples of such films include polyesters, copolyester films, microgap polyester films, polyimide films, polyamide films, polyvinyl alcohol films, polypropylene films, polyethylene films, and the like. The thickness of the polymer film substrate is usually in the range of about 20 to 1000 μm, preferably 50 to 500 μm, more preferably 60 to 200 μm. For example, the substrate can be a polyethylene terephthalate (PET) film.

The adhesion between the polymeric film substrate and the abrasive coating should be good. In many cases, the adhesion is improved by coating the coating surface of the polymer film substrate. For example, the polymer film may be coated with a material such as polyethylene acrylic acid to promote bonding of the abrasive composite to the substrate.

The abrasive layer 3 consists of an abrasive composite containing a matrix of binder and abrasive grains 4 dispersed therein.

The abrasive composite is formed from a slurry containing a plurality of abrasive grains dispersed in a binder in an uncured or ungelled state. In curing or gelling, the abrasive composites are solidified, i.e., adhered to have the desired shape and the desired structure.

A type of abrasive grain suitable for the present invention is α-alumina particles. α-alumina particles are general-purpose oxide materials that are used in a wide range of applications, from refining aluminum materials to fine ceramic materials.

Up to now, industrial α-alumina particles have been produced by Bayer method, pyrolysis of fine aluminum hydroxide or alum, or electrofusion method. In these methods, the alumina material is baked or melted at high temperatures to form an alumina block, which is then ground, purified and sieved to adjust the particle size. For this reason, such α-particles are polycrystals having a non-uniform shape, contain a large amount of aggregated particles, and have a wide particle size distribution. In addition, there are problems such as low alumina purity depending on the intended use.

The α-alumina particles used in the present invention are preferably advanced abrasive grains. Advanced alumina particles refer to α-alumina particles produced by in situ chemical vapor deposition (hereinafter referred to as CVD method). Advanced alumina particles are superior in particle size distribution or uniformity of crystal system of the alumina particles as compared to those produced by baking and grinding.

Advanced Alumina Abrasive Grain is a homogeneous single crystal grain composed of grains of grown crystals, and has characteristics similar to spherical. In addition, since the growth size of the crystal can be controlled, the particle size distribution will be sharp. The features and uses of advanced alumina abrasive grains are described in "Development of Advanced Alumina", Functional Materials, Masahide Mohri, Shin-ichiro Tanaka, and Yoshio Uchida, published December 1996, Vol. 16, No. 12, pp. 18-27).

Particularly preferred advanced alumina abrasive grains for use in the present invention are described in Japanese Patent Laid-Open No. 06-191836. That is, it is homogeneous and does not have internal crystal species, has a polyhedral shape of more than 8 faces, D / H ratio (D is the maximum particle size parallel to the hexagonal lattice surface of α-alumina, the hexagonal closest lattice, and H is hexagonal Particle size perpendicular to the lattice surface) consisting of α-alumina single crystal particles having a particle size of at least O. 5 and at most 3.0, and a sodium content of less than O.O5% by weight in terms of Na ₂ O and alumina purity of at least 99.90% by weight. Α-alumina.

The dimensions of the polishing grains vary depending on the type of semiconductor wafer being polished and the required finish of the polishing surface. For example, the average particle size thereof is usually 0.1 to 50 µm, preferably 0.3 to 5 µm, more preferably 0.4 to 2 µm. Such advanced alumina abrasive grains are commercially available from Sumitomo Chemical Industry Co., Ltd. under the trade name “Sumicorundum”.

When advanced alumina particles are used as the polishing grain of the polishing pad for CMP having a three-dimensional structure, the polishing layer has a low frictional force during polishing in the CMP process to provide stable polishing, thereby making it difficult for defects and scratches to appear on the polished surface. do.

The binder is cured or gelled to form an abrasive layer. Preferred examples of the binder in the present invention are phenolic resin, resol-phenolic resin, aminoplast resin, urethane resin, epoxy resin, acrylic resin, polyester resin, vinyl resin, melamine resin, acrylated isocyanurate resin, urea -Formaldehyde resins, isocyanurate resins, acrylated urethane resins, acrylated epoxy resins and mixtures thereof. The binder may be a thermoplastic resin.

Particularly preferred binders are radiation curable binders. The radiation curable binder is a binder that is at least partially cured or at least partially polymerizable by irradiation energy. Depending on the binder to be used, energy sources such as heat, infrared radiation, electron beam, ultraviolet radiation or visible light irradiation are used.

Typically, such binders are polymerized by a free radical mechanism. Preferably, these binders are ethylenically unsaturated compounds such as ethylenically unsaturated monomers and oligomers, acrylated urethanes, acrylated epoxy, aminoplast derivatives having α, β-unsaturated carbonyl groups, isocyanurs having at least one ethylenically unsaturated group Rate derivatives, isocyanates having at least one ethylenically unsaturated group and mixtures thereof.

The ethylenically unsaturated compound may be monofunctional, difunctional, trifunctional, tetrafunctional or further multifunctional and may include both acrylic monomers and methacrylic monomers together. Ethylenically unsaturated compounds include both monomeric and polymeric compounds containing carbon atoms, hydrogen atoms, oxygen atoms and optionally nitrogen atoms and halogen atoms.

Oxygen atoms or nitrogen atoms or both are generally contained in ether groups, ester groups, urethane groups, amido groups and urea groups. Suitable ethylenically unsaturated compounds preferably have compounds having a molecular weight of less than about 4000, preferably having aliphatic monohydroxy groups or aliphatic polyhydroxy groups, and acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid or maleic acid. Esters prepared by reaction with unsaturated carboxylic acids.

Representative examples of ethylenically unsaturated monomers include ethyl methacrylate, styrenedivinylbenzene, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, Hydroxybutyl methacrylate, vinyltoluene, ethylene glycol diacrylate, polyethylene glycol diacrylate, ethylene glycol dimethacrylate, hexanediol diacrylate, triethylene glycol diacrylate, trimethylolpropane triacrylate, glycerol Triacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, pentaerythritol tetraacrylate and pentaerythritol tetramethacrylate.

Other ethylenically unsaturated substances include monoallyl, polyallyl and polymethallyl esters and carboxylic acid amides such as diallyl phthalate, diallyl adipate and N, N'- diallyl adipamide. In addition, other nitrogen-containing compounds include tris (2-acryl-oxyethyl) isocyanurate, 1,3,5-tri (2-methacryloxyethyl) -s-triazine, acrylamide, methacrylamide, N -Methyl-acrylamide, N, N'-dimethylacrylamide, N-vinyl-pyrrolidone and N-vinyl-piperidone.

Examples of suitable monofunctional acrylates and methacrylates that can be used in combination with difunctional or trifunctional acrylate and methacrylate monomers or with phenolic or epoxy resins are lauryl acrylate, octyl acrylate, 2 -(2-ethoxyethoxy) ethyl acrylate, tetrahydrofurfuryl methacrylate, cyclohexyl acrylate, stearyl acrylate, 2-phenoxyethyl acrylate, isooctyl acrylate, isobornyl acrylate, Isodecyl acrylate, polyethylene glycol monoacrylate and polypropylene glycol monoacrylate.

When the binder is cured by ultraviolet irradiation, a photoinitiator is required to initiate free radical polymerization. Examples of preferred photoinitiators for use in this purpose include organic peroxides, azo compounds, quinones, benzophenones, nitroso compounds, acryl halides, hydrazones, mercapto compounds, pyryllium compounds, triacrylimidazoles, bisimidazoles, Chloroalkyltriazines, benzoin ethers, benzyl ketals, thioxanthones and acetophenone derivatives. Preferred photoinitiators are 2,2-dimethoxy-1,2-diphenyl-1-ethanone.

If the binder is cured by visible light irradiation, the photoinitiator needs to initiate free radical polymerization. Examples of preferred photoinitiators for this purpose are described in US Pat. Nos. 4,735,632, column 3, line 25 to line 4, line 10, line 5 to lines 1 to 7, and line 6, which are incorporated herein by reference. To line 35.

The concentration of abrasive grains contained in the abrasive composites is usually 10 to 90% by weight, preferably 40 to 80% by weight, more preferably 60 to 75% by weight. This ratio varies depending on the size of the abrasive grains, the type of binder used, the required finish of the polished surface, and the like.

The abrasive composites may contain materials other than abrasive grains and binders. For example, the abrasive material may contain conventional additives such as coupling agents, lubricants, dyes, pigments, plasticizers, fillers, release agents, abrasive aids, and mixtures thereof.

The abrasive composites may contain a coupling agent. The addition of the coupling agent can significantly lower the coating viscosity of the slurry to be used to form the abrasive composites. Examples of preferred coupling agents for the present invention include organosilanes, zircoaluminates and titanates. The amount of coupling agent is usually less than 5% by weight, preferably less than 1% by weight of the binder.

The abrasive layer 3 has a three-dimensional structure comprising a plurality of regularly arranged three-dimensional elements 5 having a predetermined shape. These three-dimensional elements 5 are cylindrical. The height h of the cylinder is usually 10 to 500 µm, preferably 20 to 200 µm, more preferably 30 to 65 µm.

The abrasive grains 4 do not protrude beyond the surface of the shape of the three-dimensional element. In other words, the three-dimensional element 5 is composed of a smooth plane. For example, the surface roughness Ry of the surface constituting the three-dimensional element 5 is 2 µm or less, preferably 1 µm or less.

8 is a plan view of the polishing surface of the polishing pad for CMP as another example of the present invention. In this example, the three-dimensional element has a tetrahedron with ridges connected at normal points. In this case, the angle α formed between the two ridges is usually 30 to 150 degrees, preferably 45 to 140 degrees. The three-dimensional element may have a pyramidal shape. In this case, the angle formed between the two ridges is usually 30 to 150 degrees, preferably 45 to 140 degrees. The height h of the three-dimensional element is for example between 2 and 300 μm, preferably between 5 and 150 μm.

In FIG. 8, the symbol o represents the bottom side length of the three-dimensional element. The sign p represents the distance between the tops of adjacent three-dimensional elements. The length o is for example 5 to 1000 μm, preferably 10 to 500 μm. The distance p is for example 5 to 1000 μm, preferably 10 to 500 μm.

In the present application, the three-dimensional element may have a tetrahedron having a flat top surface by truncating the top to have a predetermined height. In this case, the height of the three-dimensional element is 5 to 95%, preferably 10 to 90% of the height of the normal truncated three-dimensional element.

9 is a plan view of the polishing surface of the polishing pad for CMP as another example of the present invention. In this example, the three-dimensional element has a pyramidal shape with a flat top surface truncated to have a predetermined height. The height of these three-dimensional elements is similar to that of the tetrahedron shown in FIG.

In FIG. 9, the symbol o represents the bottom side length of the three-dimensional element. The symbol u represents the distance between the bottom sides of adjacent three-dimensional elements. Reference sign y represents the length of one side of the upper surface. The length o is for example 5 to 2000 μm, preferably 10 to 100 μm. The distance u is for example 0 to 1000 μm, preferably 2 to 500 μm. The length y is for example 0.5 to 1800 μm, preferably 1 to 900 μm.

10 is a plan view of the polishing surface of the polishing pad for CMP as another example of the present invention. In this example, the three-dimensional element has a primitive consisting of laterally arranged triangular prisms, where the ends of the prismatic three-dimensional element are cut at an acute angle from the bottom thereof to form a house shape with four sloped surfaces. . The vertex angle of the triangle obtained by cutting a prismatic mold in a plane perpendicular to the longitudinal direction is usually 30 to 150 degrees, preferably 45 to 140 degrees. The height of the three-dimensional element is for example 2 to 600 μm, preferably 4 to 300 μm.

Here, the length of the prismatic three-dimensional element can extend substantially over the entire area of the polishing pad. In addition, the length of the three-dimensional element can be terminated to a suitable length as shown in FIG. The ends of the three-dimensional element can be aligned or unaligned. In addition, the top may be truncated to form a square mold having a flat top surface. In this case, the height of the three-dimensional element is 5 to 95%, preferably 10 to 90% of the height of the normal truncated three-dimensional element.

In Fig. 10, reference l denotes the length of the long bottom side of the three-dimensional element. The sign v represents the distance of the part of the three-dimensional element cut at an acute angle. The sign x represents the distance between the short bottom sides of adjacent three-dimensional elements. The symbol w represents the length (width of the three-dimensional element) of the short bottom side of the three-dimensional element. The sign p represents the distance between the tops of adjacent three-dimensional elements. The symbol u represents the distance between the long bottom sides of adjacent three-dimensional elements. The length l is, for example, from 5 to 100 000 micrometers, preferably from 10 to 50 micrometers. The distance v is for example 0 to 2000 μm, preferably 1 to 1000 μm. The distance x is for example 0 to 2000 μm, preferably 0 to 100 μm. The length w is for example between 2 and 2000 μm, preferably between 4 and 1000 μm. The distance p is for example between 2 and 4000 μm, preferably between 4 and 2000 μm. The distance u is for example 0 to 2000 μm, preferably 0 to 1000 μm.

The polishing pad for CMP of the present invention is preferably produced by the method described below.

First, an abrasive coating solution containing abrasive grains and a binder is prepared. The abrasive coating solution for use herein is a composition that contains an amount of binder, abrasive grains and optionally an additive such as a photoinitiator to constitute an abrasive composite, and may further contain a sufficient amount of volatile solvent to impart fluidity to the mixture. .

Subsequently, a mold sheet having a plurality of regularly arranged recesses is produced. The shape of the recess may be a shape inverting the three-dimensional element to be formed. The mold sheet may be made of a metal such as nickel or a plastic such as polypropylene. For example, a thermoplastic resin such as polypropylene is preferred because it can be embossed at its melting point on a metal tool to form recesses of a predetermined shape. to be. Moreover, when a binder is irradiation hardening type resin, it is preferable to use the material which permeate | transmits an ultraviolet-ray or visible light.

The mold sheet is filled with an abrasive coating solution. The filling step may be performed by applying the abrasive coating solution onto the mold sheet by a coating apparatus such as a roll coater.

The abrasive coating solution is adhered to the substrate by superimposing the substrate on the mold sheet. The bonding step is carried out by pressing with a roll, for example for lamination.

The binder is cured. As used herein, the term “curing” means that the binder is polymerized in the solid state. After curing, the specific shape of the polishing layer does not change.

The binder is cured by other irradiation energy, such as heat, infrared radiation or electron beam irradiation, ultraviolet radiation or visible light irradiation. The amount of irradiation energy applied may vary depending on the type of binder used and the source of irradiation energy. Usually, those skilled in the art can appropriately determine the amount of irradiation energy applied. The time required for curing may vary depending on the thickness, density, temperature of the binder, the properties of the composition, and the like.

For example, ultraviolet light (UV) can be irradiated from the transparent substrate to cure the binder.

The mold sheet is removed to prepare a polishing pad comprising a substrate and an abrasive layer having a three-dimensional structure. The binder can be cured after removing the mold sheet. The structure of the obtained polishing pad can be changed by conventional methods such as bonding onto a flat hard support.

The invention will be explained in more detail by the following examples. However, the present invention is not limited by these examples. Unless otherwise stated, "parts" in the examples refers to parts by weight.

Example

An abrasive coating solution was prepared by mixing the components shown in Table 1 below.

ingredient Mixing amount (part) Alumina abrasive grains produced by CVD (“Sumicorundum AA04” (manufactured by Sumitomo Chemical Industry Co., Ltd.), particle size: 0.4 μm) 100.0 Photopolymerizable acrylic monomer ("SR9003", commercially available from US Sartoner Co., Ltd.) 15.0 Photopolymerizable acrylic monomer ("SR339", commercially available from US Sartoner Co., Ltd.) 22.6 Dispersant (manufactured by "Disperbyk-L11", BYK-Chemie Co., Ltd.) 0.6 Photoinitiator ("Irgacure 819", manufactured by Ciba Specialty Chemicals Co., Ltd.) 0.4

A mold sheet made of polypropylene and having recesses in the shape of the inverted cylindrical three-dimensional elements shown in Figs. The distance between adjacent three-dimensional elements was adjusted such that the ratio of the total contact area to the semiconductor wafer was 18%. The dimensions are shown in Table 2 below.

sign Dimension (μm) d 200 e 218 f 218 h 45

The abrasive coating solution was applied onto a mold sheet made of polypropylene by a roll coater. A 100-micrometer-thick transparent PET film was overlaid on it, and it laminated | stacked by the pressure by the roll. Ultraviolet radiation was used to cure the binder.

The polishing pad was prepared by removing the mold sheet and cooling the product to room temperature. The polishing layer of the polishing pad had a three-dimensional structure shown in Fig. 5, and its dimensions were tape-shaped, 1.27 cm wide by 10 cm long. The polishing performance of the polishing pad was tested.

Friction

It is a schematic diagram which shows the test method of the frictional force of a polishing pad. As the object to be polished, a glass tube with a diameter of 10 mm was used. The glass tube 11, which is the object to be polished, was installed on the shaft of the motor (not shown). The polishing pad 12 was hung on the glass tube 11 with the polishing surface inward. One end was fixed to the torsion gauge 13, and 200 g of weight 14 was attached to the other end.

The motor was started to rotate the glass tube in the direction of the arrow. The rotation speed was set to 240 rpm. The friction force g displayed on the torsion gauge 13 was read and recorded over time. The results are shown in the graph of FIG.

The polishing pad of the present invention had a low frictional force and did not tend to increase in frictional force as the polishing time elapsed, thereby exhibiting excellent frictional characteristics.

Finish of polished surface

The finish of the polished surface of the glass tube polished for 4 minutes by the above-mentioned method was measured by an optical microscope (magnification 50x).

The polished surface polished with the polishing pad of the present invention was free of defects and scratches and had a high degree of flatness.

Comparative example

Example 1 except that alumina ("TIZOX B109", manufactured by Transelco Co., Ltd., manufactured by Transelco Co., Ltd., manufactured by Transelco Co., Ltd., manufactured by Transelco Co., Ltd.) was used in place of alumina abrasive grains prepared by CVD. Polishing pads were prepared in the same manner as and tested for their polishing performance. The results are shown in the graph of FIG.

The polishing pad of the comparative example had a high frictional force, and a tendency of the frictional force was increased as the polishing time elapsed, thereby showing poor frictional characteristics. In addition, the polished surface polished with the polishing pad of the comparative example had defects or scratches and had low flatness.

As described and described above, there is provided a polishing pad for CMP having good friction characteristics, low cost and excellent durability without causing defects or scratches on the polished surface of the semiconductor wafer.

Claims (5)

And a polishing layer disposed on the substrate, the polishing layer having a three-dimensional structure comprising a plurality of regularly arranged three-dimensional elements having a predetermined shape, the polishing layer having a binder and a CVD as a constituent component. A polishing pad for CMP comprising an abrasive composite containing advanced alumina abrasive grains produced by a method. The group according to claim 1, wherein the three-dimensional element has a cylindrical, conical, tetrahedral, pyramidal, tetrahedral shape with a flat top surface, or a pyramidal, pyramidal, square shape with a flat top surface and a stripe shape. Polishing pad for CMP selected from. The polishing pad for CMP according to claim 1, wherein an average particle size of the advanced alumina abrasive grain is in the range of 0.01 to 20 µm. The polishing pad for CMP according to claim 1, wherein the concentration of the abrasive grains contained in the abrasive composite is in the range of 10 to 90% by weight. The method of claim 1, wherein the binder is a phenolic resin, aminoplast resin, urethane resin, epoxy resin, acrylic resin, acrylated isocyanurate resin, urea-formaldehyde resin, isocyanurate resin, acrylated urethane resin, A polishing pad for CMP selected from the group consisting of acrylated epoxy resins, glues and mixtures thereof.