JP4798103B2 - Polishing pad - Google Patents

Description

The present invention relates to a polishing pad. More specifically, the present invention relates to a polishing pad having excellent polishing characteristics such as good slurry retention, high hardness, and a sufficiently flat polishing surface.
The present invention is widely used for polishing the surface of a semiconductor wafer or the like.

In recent years, CMP (Chemical Mechanical Polishing) has attracted attention as a polishing method capable of forming a polished surface having high flatness. In CMP, polishing is performed by causing a slurry, which is an aqueous dispersion in which abrasive grains are dispersed, to flow down from the upper side while sliding the polishing pad and the surface to be polished.
The polishing rate is a factor that greatly affects the productivity in this CMP. However, it is said that this polishing rate can be significantly improved by increasing the amount of slurry retained as compared with the prior art.

Conventionally, in CMP, 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 polishing pad.
However, it is difficult to freely control the foamed state in polyurethane foam, and it is extremely difficult to uniformly control the size of foam, the foaming density, and the like over the entire foam. As a result, the quality of the polishing pad made of polyurethane foam varies, which causes the polishing rate to vary.

A polishing pad in which a water-soluble substance is dispersed in various resins is known as a polishing pad that is easier to control pores than a polishing pad made of this foam (for example, Patent Document 1 and Patent Document 2). , See Patent Document 3). Among these, Patent Document 1 and Patent Document 2 describe the effectiveness of a polishing pad containing a water-soluble substance. Further, in Patent Document 3, the material of the matrix material is examined, and more stable polishing and improvement in polishing rate are recognized, but the slurry retention and polishing rate are not necessarily sufficient.
Furthermore, conventionally, slurries having different pHs in a wide pH range have been used, and a polishing pad that can cope with various slurries having different pHs is desired.

Japanese National Patent Publication No. 8-500622 JP 2000-34416 A JP 2000-33552 A

  The present invention has been made in view of the above circumstances, and even when using slurries having different pHs in a wide pH range, the polishing rate is high because of excellent slurry retention, and the hardness is high. It is an object of the present invention to provide a polishing pad that can be a polishing surface having sufficient flatness, and that can effectively prevent a decrease in retention and polishing rate during polishing and after dressing.

The inventors of the present invention have a mechanism in which the retention and polishing rate of the slurry gradually decrease during polishing, and the formation of pores in the dressing in which the pores on the surface of the polishing pad are formed (surfaced) or renewed (surface renewal) with a diamond grinding wheel or the like The mechanism was studied in detail. As a result, it was found that when shear stress was applied to the surface of the conventional polishing pad due to the above polishing and dressing, the matrix material as the main constituent material was stretched and then the pores were closed due to plastic deformation. . Furthermore, it was found that not only the surface to be polished but also the waste of the matrix material itself was generated, so that the pores were also blocked by this waste. That is, it has been found that it is difficult to maintain the polishing rate due to these causes. As a method for preventing these problems, it is effective to use a material having a crosslinked structure that exhibits elastic recovery in the matrix material. However, more stable polishing is desired, and the retention of the slurry and the polishing rate are improved. Further improvement is also necessary.
The present invention has been made based on such findings.

The present invention is as follows.
1. In a polishing pad containing a water-insoluble matrix material containing a cross-linked polymer and water-soluble particles dispersed in the water-insoluble matrix material, the water-soluble particles themselves into water in the entire pH range from pH 3 to pH 11. The solubility in water at 25 ° C. in the whole range from pH 3 to pH 11 is ± 10% by weight at 25 ° C. and the solubility in water at 25 ° C. in the case of pH 7 is ± The outer shell is formed on at least a part of the outermost part of the water-soluble particles by a coupling agent containing an amino group within 50%, and at least one of the water-insoluble matrix materials containing the crosslinked polymer. parts are, Ri crosslinked 1,2-polybutadiene der, the coupling agent is .gamma. (2-aminoethyl) - Ken, which is a aminopropyltrimethoxysilane Polishing pad.
2. The water-soluble particles themselves have a solubility in water at 25 ° C. in the entire range of pH 3 to pH 11 of 0.1 to 3% by mass, and the solubility in water at 25 ° C. in the case of pH 7 is pH 3 The water solubility at 25 ° C. in the entire range from 1 to pH 11 is within ± 50%. The polishing pad described in 1.
3 . The above 1. using the coupling agent in an amount of 0.001 to 10% by mass with respect to the water-soluble particles. Or 2 . The polishing pad described in 1.
4 . In a polishing pad containing a water-insoluble matrix material containing a crosslinked polymer, and water-soluble particles dispersed in the water-insoluble matrix material, the water-soluble particles are amino groups, epoxy groups, isocyanurate groups and A water-insoluble matrix material containing at least one hydroxyl group and having an outer shell formed on at least a part of the outermost part of the water-soluble particles by a coupling agent containing an amino group, and containing the crosslinked polymer polishing pad, which is a aminopropyltrimethoxysilane - at least a portion of the Ri crosslinked 1,2-polybutadiene der, the coupling agent is .gamma. (2-aminoethyl).
5 . The water solubility of the water-soluble particles per se in the entire pH 3 to pH 11 range is 0.1 to 10% by mass at 25 ° C., and the water solubility contained in the polishing pad when the polishing pad is immersed in water. 4. The elution degree in the entire pH range of pH 3 to pH 11 is 0.05 to 50% by mass at 25 ° C. The polishing pad described in 1.
6 . The water solubility of the water-soluble particles per se in the entire range from pH 3 to pH 11 is 0.1 to 10% by mass at 25 ° C., and the solubility in water at 25 ° C. in the case of pH 7 is from pH 3 the 4 solubility in water at 25 ° C. in the full range of pH11 is within 50% ±. Or 5 . The polishing pad described in 1.
7 . The water solubility of the water-soluble particles per se in the entire pH 3 to pH 11 range is 0.1 to 3% by mass at 25 ° C., and the solubility in water at 25 ° C. in the case of pH 7 is from pH 3 the 6 solubility in water at 25 ° C. in the full range of pH11 is within 50% ±. The polishing pad described in 1.
8 . 4. The coupling agent according to 4 above, wherein 0.001 to 10% by mass of the coupling agent is used relative to the water-soluble particles. To 7 . A polishing pad according to any one of the above.

In the polishing pad of the present invention, even when slurries having different pHs in a wide pH range are used, the pore formation state is good, the pores are not blocked by dressing, and the slurry retainability is good. Further, the water-soluble particles contained therein do not absorb moisture and swell and can be made into a polishing pad with high hardness, a high polishing rate, and good polishing characteristics such as flatness.
Furthermore, it is possible to solubility from pH3 water-soluble particles in water at 25 ° C. in the range pH11 specific range near Runode, a polishing pad having better polishing properties.
Further, since the water-insoluble matrix material contains a 1,2-polybutadiene cross-linked, the pad elastic recovery force is applied to, pores are not blocked, it can be an excellent polishing pad flatter, etc. .

  In the polishing pad of the present invention in which the water-soluble particles contain at least one amino group, epoxy group, isocyanurate group and hydroxyl group, the pore formation state is good, and the pore is not blocked by the dressing, and the slurry is retained. Good sex. In addition, the solubility of water-soluble particles in water can be easily adjusted within an appropriate range, the moisture absorption and swelling of the water-soluble particles inside the pad can be suppressed, and a particularly hard polishing pad can be obtained. High speed and good polishing properties such as flatness.

The present invention will be described in detail below.
The “water-insoluble matrix material” (hereinafter also simply referred to as “matrix material”) contains a crosslinked polymer.
The “crosslinked polymer” constitutes a matrix material, and imparts an elastic recovery force to the matrix material by having a crosslinked structure. By containing the cross-linked polymer, the displacement due to the shear stress applied to the polishing pad during polishing can be kept small, the matrix material is excessively stretched during polishing and dressing, and the pores are buried by plastic deformation. It is possible to effectively suppress the surface of the polishing pad from being fuzzed excessively. Therefore, pores are efficiently formed, the retention of the slurry during polishing is less likely to deteriorate, and there is little fuzzing and polishing flatness is not hindered.

Examples of such crosslinked polymers include uncrosslinked polymers such as thermoplastic resins, elastomers, rubbers and curable resins (thermosetting resins, photocurable resins, etc., resins that are cured by heat, light, etc.). Examples thereof include a crosslinked polymer obtained by crosslinking one of them, and a crosslinked polymer obtained by co-crosslinking two or more of these uncrosslinked polymers . In the present invention, crosslinked 1, 2-Polybutadiene is used at least . Further, a part of the polymer may be cross-linked, or the whole may be cross-linked. Furthermore, a mixture of a crosslinked polymer and a non-crosslinked polymer in which a part of the polymer is crosslinked may be used, or a mixture of a crosslinked polymer and a non-crosslinked polymer that are crosslinked as a whole. The crosslinking method may be either chemical crosslinking with a crosslinking agent or radiation crosslinking by irradiation with ultraviolet rays or electron beams.

  Examples of the thermoplastic resin include 1,2-polybutadiene resin, ethylene-vinyl acetate copolymer (EVA, usually containing 3% by mass or more of vinyl acetate units), polyolefin resins such as polyethylene, acrylonitrile-styrene- Butadiene copolymer (ABS resin, etc.), polystyrene resin, polyacrylic resin {(meth) acrylate resin, etc.], vinyl ester resin (excluding EVA), saturated polyester resin, polyamide resin, fluorine resin (Polyvinylidene fluoride, etc.), polycarbonate resins, polyacetal resins and the like.

  Elastomers include polyolefin elastomers (excluding EVA), styrene elastomers (styrene-butadiene-styrene copolymers, hydrogenated block copolymers (SEBS), etc.), thermoplastic polyurethane elastomers, thermoplastic polyesters. Examples include elastomers, polyamide-based elastomers, silicone resin-based elastomers, and fluororesin-based elastomers.

As rubber, butadiene rubber (high cis butadiene rubber, low cis butadiene rubber, etc.), isoprene rubber, conjugated diene rubber such as styrene-butadiene rubber, styrene-isoprene rubber, acrylonitrile-butadiene rubber, etc. Nitrile rubber, acrylic rubber, ethylene-propylene rubber, ethylene-α-olefin rubber such as ethylene-propylene-diene rubber, and other rubbers such as butyl rubber, silicone rubber, and fluorine rubber.
Examples of the curable resin include urethane resins, epoxy resins, (meth) acrylic resins, unsaturated polyester resins, polyurethane-urea resins, urea resins, silicon resins, phenol resins, and the like.

Among these crosslinked polymers, as described above, a crosslinked polymer obtained by crosslinking a 1,2-polybutadiene resin is used in the present invention . The crosslinked polymer has a large effect of improving moldability and wear resistance. Moreover, there is little softening by water absorption and it is stable with respect to the acid and alkali contained in a slurry.
As for a crosslinked polymer, only 1 type may contain and 2 or more types may contain .

  The matrix material may be modified with an acid anhydride group, a carboxyl group, a hydroxyl group, an epoxy group, an amino group, or the like. By this modification, the affinity between the matrix material and the water-soluble particles and slurry can be adjusted. In the case where the water-soluble particles contain at least one amino group, epoxy group, isocyanurate group and hydroxyl group, the matrix material containing the functional group and the water-soluble particles containing the functional group are in a required amount. It is preferable that the water-soluble particles do not react so much that they cannot be eluted.

  According to JIS K 6251, when a test piece made of a matrix material is ruptured at 80 ° C., the matrix material has an elongation remaining after rupture (hereinafter simply referred to as “breaking elongation at break”) of 100% or less. preferable. That is, it is preferable that the total distance between marked lines after breaking is not more than twice the distance between marked lines before breaking. This residual elongation at break is more preferably 30% or less (more preferably 10% or less, particularly preferably 5% or less, usually exceeding 0%). If the residual elongation at break exceeds 100%, the fine pieces scraped or stretched from the surface of the polishing pad at the time of polishing and surface renewal tend to easily block the pores, which is not preferable.

  In addition, the above-mentioned “breaking residual elongation” refers to a tensile test at a test piece shape dumbbell shape No. 3, tensile speed 500 mm / min, test temperature 80 ° C. according to JIS K 6251 “Tensile test method for vulcanized rubber”. When the test piece is broken, the elongation is obtained by subtracting the distance between the marked lines before the test from the total distance from each marked line to the broken part of the broken and divided test pieces. In actual polishing, since heat is generated by sliding, the test is performed at a temperature of 80 ° C.

  Further, the moisture content of the matrix material is preferably 3% or less, more preferably 2% or less, and particularly preferably 1% or less. When the water content is as low as 3% or less, swelling of water-soluble particles inside the polishing pad is sufficiently suppressed, and a polishing pad with high hardness can be obtained. Polishing such as in-plane uniformity and local planarity Improved characteristics. When the moisture content of the matrix material exceeds 3%, the water-soluble particles in the matrix material may be dissolved and / or swelled, and the polishing characteristics such as in-plane uniformity and local planarity may be reduced. Absent.

  The “water-soluble particles” are detached from the matrix material when the polishing pad comes into contact with water and / or a slurry that is an aqueous dispersion during polishing. In particular, water-soluble particles present in the vicinity of the outermost surface layer of the polishing pad are eluted, thereby forming pores. This pore has a function of holding slurry and temporarily retaining polishing waste. The water-soluble particles dispersed in the matrix material are not only dissolved and separated by contact with water, but also swell and contain water, etc., and can be released from the matrix material. is there. Further, the water-soluble particles dissolve or swell by contact with not only water but also an aqueous mixed medium containing an alcohol solvent such as methanol, and are released or released from the matrix material.

Examples of the water-soluble particles include organic water-soluble particles and inorganic water-soluble particles. Of these, organic water-soluble particles having generally low solubility in water are preferred. Organic water-soluble particles include saccharides (α, β or γ-cyclodextrin, polysaccharides such as dextrin and starch, lactose, mannitol, etc.), celluloses (hydroxypropylcellulose, methylcellulose, etc.), proteins, polyvinyl alcohol, Examples thereof include particles composed of polyvinylpyrrolidone, polyacrylic acid, polyacrylate, polyethylene oxide, water-soluble photosensitive resin, sulfonated polyisoprene, sulfonated polyisoprene copolymer, and the like. Of these, particles containing hydroxyl groups are particularly preferred. In addition, examples of the inorganic water-soluble particles that have low solubility in water and can be used in the present invention include particles made of calcium sulfate and the like. In addition, even if the particles are made of magnesium sulfate or the like having higher solubility, those having a solubility lowered to an appropriate range by containing an amino group or the like can be used.
Only 1 type may contain these water-soluble particles, and 2 or more types may contain them.

  Moreover, the average particle diameter of this water-soluble particle is 0.1-500 micrometers, More preferably, it is 0.5-100 micrometers. If the average particle size is less than 0.1 μm, the size of the pores to be formed is smaller than the abrasive grains used, so that it tends to be difficult to obtain a polishing pad that can sufficiently hold the slurry. On the other hand, if it exceeds 500 μm, the size of the pores formed becomes excessive, and the mechanical strength and polishing rate of the resulting polishing pad tend to decrease. Moreover, there is no restriction | limiting in particular about particle size distribution, A particle diameter may be equal or may be uneven. Furthermore, the shape of the water-soluble particles is not particularly limited, and may be any of plate shape, granular shape, amorphous shape, spherical shape, spindle shape, needle shape, and the like.

  The content of the water-soluble particles in the polishing pad is from 0.1 to 90% by volume, more preferably from 1 to 60% by volume when the total of the matrix material and the water-soluble particles is 100% by volume. %, Particularly preferably 2 to 40% by volume. When the content of the water-soluble particles is less than 0.1% by volume, pores are not sufficiently formed in the resulting polishing pad, and the polishing rate tends to decrease. On the other hand, when it contains water-soluble particles in excess of 90% by volume, it tends to be difficult to sufficiently prevent the water-soluble particles present inside the polishing pad from swelling or dissolving in the resulting polishing pad. It becomes difficult to maintain the hardness and mechanical strength of the resin at appropriate values.

In addition, epoxy resin, polyimide, polyamide, polysilicate, various coupling agents, etc. may be physically adsorbed or chemically bonded to the water-soluble particles, and further, both are in contact with each other. May be. This is preferable because moisture absorption of the water-soluble particles is suppressed. In the present invention, the outer shell is formed on at least a part of the outermost part of the water-soluble particles by the coupling agent containing an amino group .

  When the water-soluble particles contain at least one amino group, epoxy group, isocyanurate group and hydroxyl group, the water-soluble particles function as a compatibilizer and / or dispersion stabilizer between the matrix material and the water-soluble particles, The affinity between the matrix material and the water-soluble particles can be increased, and the dispersibility of the water-soluble particles in the matrix material can be improved. Thus, by improving the dispersibility of the water-soluble particles, a uniform polishing pad can be obtained, and polishing characteristics such as in-plane uniformity and local planarity are improved. As this functional group, a hydroxyl group is preferable as described above. When the matrix material is modified with an acid anhydride group, carboxyl group, hydroxyl group, epoxy group, amino group, etc., water-soluble particles containing a functional group and a matrix material containing a functional group, It is preferable not to react so that a required amount of water-soluble particles cannot be eluted.

As a coupling agent containing an amino group, γ- (2-aminoethyl) -aminopropyltrimethoxysilane is used.

  The treatment using an amino group-containing coupling agent can be carried out using 0.001 to 10% by mass, more preferably 0.01 to 5% by mass of the coupling agent with respect to the water-soluble particles. By this coupling agent treatment, the water-soluble particles contain amino groups on the surface. In addition, when the said outer shell is formed, even if this outer shell is formed only in a part of water-soluble particle | grains, the said effect can fully be acquired.

  The solubility of water-soluble particles per se in water (deionized water) is 0.1 to 10% by mass at 25 ° C., preferably 0.2 to 8% by mass, more preferably 0.5 to 5% by mass. . If the solubility is less than 0.1% by mass, elution of water-soluble particles at the time of polishing may be insufficient, and pores may not be sufficiently formed, and the polishing rate may be reduced. On the other hand, when the solubility exceeds 10% by mass, the solubility of water-soluble particles described later from the polishing pad may exceed the upper limit, which is not preferable. When the solubility is within this range, when the polishing pad of the present invention comes into contact with various slurries during polishing, water-soluble particles existing in the vicinity of the outermost layer of the polishing pad are dissolved or swelled to be released or released, Moderate pore formation is facilitated.

The water-soluble particles, since it contains an amino group, it is possible to lower the solubility in water, it can be more readily appropriate range the solubility of the water-soluble particles themselves. Furthermore, the solubility of water-soluble particles in water in the whole range from pH 3 to pH 11, preferably in the whole range from pH 1 to pH 13, is 0.1 to 3% by mass, particularly 0.5 to 2.5% by mass at 25 ° C. It is preferable. Thus, when the solubility in water is low, the elution degree described later can be easily adjusted to a preferred range, and the formation of pores to the inside of the polishing pad is prevented, and a polishing pad having sufficient hardness Polishing characteristics such as in-plane uniformity and local planarity can be improved.
Here, the solubility of water-soluble particles in water in the whole range from pH 3 to pH 11, preferably in the whole range from pH 1 to H13, is measured using water adjusted to pH by adding nitric acid or potassium hydroxide to deionized water. Solubility. The same applies to the following.

  Furthermore, the water solubility of the water-soluble particles themselves at 50 ° C. is preferably 0.5 to 15% by mass, more preferably 0.7 to 12% by mass, and particularly preferably 1 to 10% by mass. . If the solubility is less than 0.5% by mass, the pores may not be sufficiently formed as described above, and the polishing rate may decrease. On the other hand, if it exceeds 15% by mass, the degree of elution of water-soluble particles from the polishing pad may exceed the upper limit as described above, which is not preferable.

  Further, the water solubility of the above water-soluble particles per se in the whole range of pH 3 to pH 11, preferably in the whole range of pH 1 to pH 13, is 0.1 to 10% by mass at 25 ° C., and 25 ° C. in the case of pH 7 It is preferable that the solubility at 25 ° C. in the range of pH 3 to pH 11, preferably pH 1 to pH 13 is within ± 50%, preferably within 30%, more preferably within 20% with respect to water solubility in . In particular, the water solubility of the water-soluble particles themselves in the whole range from pH 3 to pH 11, preferably in the whole range from pH 1 to pH 13, is from 0.1 to 3% by weight, especially from 0.5 to 2.5% by weight at 25 ° C. And the solubility in water at 25 ° C. at pH 7 is within ± 50%, preferably 30%, at 25 ° C. in the whole range from pH 3 to pH 11, preferably in the whole range from pH 1 to pH 13. It is particularly preferable that it is within 20%, more preferably within 20%. Since the change in solubility due to pH is within this range, water-soluble particles existing in the vicinity of the outermost layer of the polishing pad dissolve or swell regardless of the pH during polishing and even if the pH changes during polishing. Accordingly, it is eliminated or liberated, and it becomes easy to form an appropriate pore.

  Furthermore, the elution degree of the water-soluble particles contained in the polishing pad when the polishing pad is immersed in water is preferably 0.05 to 50% by mass at 25 ° C., more preferably 0.1 to 25% by mass. %, Particularly preferably 0.2 to 10% by mass. Moreover, it is preferable that it is 0.05-50 mass% similarly at 50 degreeC, More preferably, it is 0.1-25 mass%, Most preferably, it is 0.2-10 mass%. When the degree of dissolution is less than 0.05% by mass, pores are not sufficiently formed, and a desired polishing rate may not be exhibited. Further, if it exceeds 50% by mass, pores may be formed to the inside of the polishing pad, the hardness of the polishing pad is lowered, and polishing characteristics such as in-plane uniformity and local planarity may be deteriorated. It is not preferable.

The degree of dissolution in water is preferably 0.05 to 50% by mass, more preferably 0.1 to 25% by mass, particularly at 25 ° C. in the range of pH 3 to pH 11, preferably in the range of pH 2 to pH 13. Preferably it is 0.2-10 mass%. When the elution degree is within a predetermined range at a pH within this range, regardless of the pH at the time of polishing, even if the pH changes during polishing, excessive elution of water-soluble particles can be suppressed, and the polishing pad Only water-soluble particles existing in the vicinity of the outermost layer are dissolved or swelled to be detached or liberated, and an appropriate pore can be easily formed. In addition, since the decrease in the hardness of the pad can be suppressed, excellent polishing characteristics such as in-plane uniformity and local planarity are maintained.
Here, the elution degree of water-soluble particles in water in the whole range of pH 3 to pH 11, preferably in the whole range of pH 1 to H13, is determined using water adjusted to pH by adding nitric acid or potassium hydroxide to deionized water. This is the measured elution degree.
In addition, the elution degree to the water of water-soluble particle | grains is the mass of the water-soluble particle | grains which were eluted in water when a polishing pad was immersed in water (deionized water) twice the mass ratio at 25 ° C. for 12 hours. It can be calculated as a value obtained by dividing by 100 the mass of the water-soluble particles contained in the polishing pad before immersion.

  The water-soluble particles have a function of increasing the indentation hardness of the polishing pad in addition to the function of forming pores (for example, Shore D hardness of 35 to 100). Due to the large indentation hardness, the pressure applied to the surface to be polished in the polishing pad can be increased. For this reason, not only the polishing rate is improved, but also high polishing flatness is obtained at the same time. Therefore, it is particularly preferable that the water-soluble particles are solid bodies that can ensure sufficient indentation hardness in the polishing pad.

  The pore size is preferably 0.1 to 500 μm (more preferably 0.5 to 100 μm). If the pore size is less than 0.1 μm, it may be smaller than the grain size of the abrasive grains, so that it tends to be difficult to hold the abrasive grains sufficiently. On the other hand, when the pore size exceeds 500 μm, it tends to be difficult to obtain sufficient strength and indentation hardness.

In the present invention, in the water-insoluble matrix and / or water-soluble particles, abrasive grains, oxidizing agents, alkali metal hydroxides, acids, salts that generate acids when used, pH, conventionally contained in the slurry 1 type (s) or 2 or more types, such as a regulator, surfactant, and an anti-scratch agent, can be contained. As a result, polishing can be performed by supplying only water during polishing.
Examples of the abrasive grains include particles made of silica, alumina, ceria, zirconia, titania and the like. These can use 1 type (s) or 2 or more types.

  Examples of the oxidizing agent include hydrogen peroxide, peracetic acid, perbenzoic acid, organic peroxides such as tert-butyl hydroperoxide, permanganic acid compounds such as potassium permanganate, and dichromic acids such as potassium dichromate. Examples thereof include compounds, halogen acid compounds such as potassium iodate, nitric acid compounds such as nitric acid and iron nitrate, perhalogen acid compounds such as perchloric acid, persulfates such as ammonium persulfate, and heteropolyacids. Of these oxidizing agents, persulfates such as ammonium persulfate are particularly preferred in addition to hydrogen peroxide and organic peroxide, which are harmless to decomposition products. These can use 1 type (s) or 2 or more types.

Examples of the alkali metal hydroxide include sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide. These can use 1 type (s) or 2 or more types.
Examples of the acid include organic acids and inorganic acids. Among these, as the organic acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, isoprenesulfonic acid, gluconic acid, lactic acid, citric acid, tartaric acid, malic acid, glycolic acid, malonic acid, formic acid, oxalic acid, succinic acid, fumaric acid , Maleic acid and phthalic acid. Moreover, as an inorganic acid, nitric acid, hydrochloric acid, sulfuric acid, etc. are mentioned. These acids can be used alone or in combination of two or more.
Examples of the salt include alkali metal salts such as ammonium salts, sodium salts and potassium salts of the above acids, and alkaline earth metal salts such as calcium salts and magnesium salts. These can use 1 type (s) or 2 or more types.

  Examples of the surfactant include cationic, anionic and nonionic. Among these, examples of the cationic surfactant include aliphatic amine salts and aliphatic ammonium salts. Examples of the anionic surfactant include fatty acid soaps, carboxylates such as alkyl ether carboxylates, sulfonates such as alkylbenzene sulfonates, alkylnaphthalene sulfonates, α-olefin sulfonates, and higher alcohol sulfates. Examples include ester salts, sulfate salts such as alkyl ether sulfates, polyoxyethylene alkylphenyl ether sulfates, and phosphate ester salts such as alkyl phosphate esters. Furthermore, examples of the nonionic surfactant include ether types such as polyoxyethylene alkyl ether, ether ester types such as glycerol ester polyoxyethylene ether, and ester types such as polyethylene glycol fatty acid ester, glycerol ester and sorbitan ester. It is done. These can use 1 type (s) or 2 or more types.

  As said anti-scratch agent, biphenol, bipyridyl, 2-vinylpyridine and 4-vinylpyridine, salicylaldoxime, o-phenylenediamine and m-phenylenediamine, catechol, o-aminophenol, thiourea, N-alkyl group contained (Meth) acrylamide, N-aminoalkyl group-containing (meth) acrylamide, 7-hydroxy-5-methyl-1,3,4-triazaindolizine, 5-methyl-1H-benzotriazole, phthalazine, melamine and 3- Examples include amino-5,6-dimethyl-1,2,4-triazine. These can use 1 type (s) or 2 or more types.

  In addition, the water-insoluble matrix material is a compatibilizer, a filler, a softener, an antioxidant, an ultraviolet absorber, an antistatic agent, a lubricant, a plasticizer, etc. in addition to the various materials conventionally contained in the slurry. These various additives can be added. Among these, as compatibilizers, homopolymers modified with acid anhydride groups, carboxyl groups, hydroxyl groups, epoxy groups, oxazoline groups, amino groups, block copolymers, random copolymers, and various nonions A system surfactant or the like can be used. In addition, as fillers, materials that improve rigidity such as calcium carbonate, magnesium carbonate, talc, clay, etc., and polishing effects such as silica, alumina, ceria, titania, zirconia, manganese dioxide, dimanganese trioxide, barium carbonate, etc. The material provided can be used. Furthermore, reactive additives such as sulfur and peroxide can be added to react and crosslink.

  The method for preparing the composition for forming the polishing pad is not particularly limited. When it has a kneading step, it can be kneaded by a known kneader or the like. Examples thereof include kneaders such as rolls, kneaders, Banbury mixers, and extruders (single screw and multi screw). The kneaded polishing pad composition can be processed into a desired shape such as a sheet, block, or film by performing press molding, extrusion molding, injection molding, or the like. Moreover, a polishing pad can be obtained by processing this into a desired size.

  Further, the water-soluble particles and the uncrosslinked polymer are kneaded by the above method, then processed into a desired shape, and the molded body is crosslinked by the above method to obtain a polishing pad. The heating temperature for cross-linking can be room temperature to 300 ° C, preferably 50 to 200 ° C. In addition, a composition containing water-soluble particles and an uncrosslinked polymer can be molded in a mold and crosslinked, and a molded product that has been previously molded into a desired shape can also be crosslinked.

  The method for dispersing the water-soluble particles in the matrix material is not particularly limited, but usually, the uncrosslinked polymer, the water-soluble particles, other additives, and the like can be kneaded and dispersed as described above. In this kneading, the uncrosslinked polymer is heated and kneaded so that it can be easily processed. At this temperature, the water-soluble particles are preferably solid. By being solid, it becomes easy to disperse water-soluble particles in a state exhibiting the above-mentioned preferable average particle diameter regardless of the compatibility with the uncrosslinked polymer. Therefore, it is preferable to select the type of water-soluble particles depending on the processing temperature of the uncrosslinked polymer used.

  As described above, the Shore D hardness of the polishing pad of the present invention is preferably 35 or more (usually 100 or less, more preferably 50 to 90, still more preferably 60 to 85). If the Shore D hardness is less than 35, the pressure that can be applied to the object to be polished during polishing tends to decrease, the polishing rate decreases, and polishing flatness may not be sufficient.

  Grooves and dot patterns can be formed in a predetermined shape on the surface (polishing surface) of the polishing pad of the present invention as necessary for the purpose of improving the discharge of slurry. Moreover, it can also be set as the polishing pad which exhibits a multilayered structure like the polishing pad which bonded the softer layer on the back surface (opposite side with respect to a polishing surface) of this polishing pad, for example. Further, the shape of the polishing pad is not particularly limited, and can be appropriately selected according to the polishing apparatus such as a disk shape, a belt shape, and a roller shape. Further, a through hole can be provided in the polishing pad of the present invention, and a window for detecting an end point having translucency can be attached.

The polishing pad of the present invention can be used in a polishing method for polishing the surface of various objects to be polished. According to this polishing method, chemical mechanical polishing with excellent flatness can be performed, and a high polishing rate can be obtained.
The object to be polished is not particularly limited, and various kinds of objects to be polished can be used. Examples of the object to be polished include an object to be polished with an embedding material and an object to be polished without an embedding material.
An object to be polished with an embedding material includes, for example, a substrate (usually at least a wafer and an insulating film formed on the surface of the wafer. The substrate is a semiconductor device having grooves on at least the surface thereof. A layered body or the like that is deposited (by CVD or the like) so that a desired material is embedded at least in the groove on the surface side. When polishing the object to be polished, it is possible to perform polishing for removing the excessively deposited embedding material by polishing using the polishing pad of the present invention and flattening the surface. When the object to be polished is provided with a stopper layer below the embedding material, the stopper layer can be polished simultaneously in the latter stage of polishing.

The embedding material is not particularly limited. For example, [1] SiO such as P-TEOS, PE-TEOS, O ₃ -TEOS, HDP-SiO and FSG (fluorine-added SiO ₂ insulating film) used in the STI process. ₂ type insulating material, [2] metal wiring material composed of at least one of Al and Cu used in damascene process, [3] at least one of Al, Cu and W used in via plug forming process via plug material consisting of seeds, [4] the interlayer insulating film formation step P-TEOS used _{in, PE-TEOS, O 3 -TEOS} , SiO 2 based insulating material such as HDP-SiO and FSG, the BPSG (SiO ₂ B And / or P-containing material), Low-k (organic low dielectric insulating material), SOG, and HSQ-SOG (hydrogen-containing porous SO) ) And the interlayer insulating film material such as. Examples of the stopper material constituting the stopper layer include nitride-based materials such as Si ₃ N ₄ , TaN, and TiN.
On the other hand, examples of the object to be polished without an embedded material include polysilicon and bare silicon.

  In polishing the object to be polished, a polishing agent can be usually used. Although it is preferable to select suitably the abrasive | polishing agent for each to-be-polished body suitably, For example, an aqueous dispersion is mentioned. The material constituting the aqueous dispersion is not particularly limited. For example, each of the above materials such as water, abrasive grains, oxidizing agent, alkali metal hydroxide, acid, pH adjusting agent, surfactant and anti-scratch agent may be used. Can be mentioned. These can use 1 type (s) or 2 or more types.

Hereinafter, the present invention will be described specifically by way of examples.
[1] Preparation of polishing pad composition and molding of polishing pad Example 1
80% by volume of 1,2-polybutadiene (trade name “JSR RB830”, manufactured by JSR Corporation) which is later crosslinked to form a matrix material, and 1% by mass of γ- (2-aminoethyl) -amino in advance as water-soluble particles Β-cyclodextrin treated with propyltrimethoxysilane having an average particle size of 16 μm (product name “Dexypearl β-100”, manufactured by Yokohama International Bio-Laboratory Co., Ltd., hereinafter referred to as “modified β-cyclodextrin” ) 20% by volume was kneaded with a router heated to 170 ° C. Thereafter, 0.3 part by mass of an organic peroxide (trade name “Perhexine 25B”, manufactured by NOF Corporation) was added and kneaded at 130 ° C., followed by a crosslinking reaction at 170 ° C. for 20 minutes in a mold. Molding was performed to obtain a polishing pad having a diameter of 60 cm and a thickness of 3 mm.

The mass of the obtained pad is about 1 kg and contains 280 g of modified β-cyclodextrin. This pad and double the amount of the mass, that is, 2 kg of deionized water were put into a stainless steel container, which was housed in a thermostatic chamber adjusted to 25 ° C. and stirred with a magnetic stirrer. After 12 hours, the pad was taken out, 1.5 g of the eluate was collected in an aluminum dish, and dried for 30 minutes with a dryer adjusted to 200 ° C. After drying, the mass of the solid content (modified β-cyclodextrin) remaining in the dish was 3.0 mg. From these numerical values, the elution degree of β-sylocdextrin eluted in deionized water [mass of modified β-cyclodextrin eluted by immersion / mass of modified β-cyclodextrin contained in the polishing pad] × 100, It was about 1.4 mass% when it computed as follows. Moreover, the elution degree when performing the same experiment except using the thermostat adjusted to 50 degreeC is about 1.5 mass%, and it turns out that the difference by temperature is very small.
Calculation method of elution degree: When the total elution amount is x (g) and the mass of the solid content remaining in the dish is y (3.0 mg), x / (2000 + x) = (y / 1000) /1.5, x is 4.008 g. Therefore, the elution degree is calculated as (1.408 / 280) × 100 = 1.428 and about 1.4%.

  The solubility of the modified β-cyclodextrin subjected to the coupling treatment in water was 2.3% by mass at 25 ° C. and 4.9% by mass at 50 ° C. The pH dependence of the solubility of this modified β-cyclodextrin at 25 ° C. is shown in FIG. According to FIG. 1, the solubility at pH 3, 5, 7, 9 and 11 is 2.4%, 2.5%, 2.5%, 2.7% and 2.6% by weight, respectively. Met. In addition, the pH at pH 3, 5, 9, and 11 is -4%, 0%, + 8%, and + 4%, respectively, with respect to the solubility at pH 7, and the solubility is in the range of pH 3 to pH 11. It can be seen that the change is very small. The pH was adjusted using nitric acid or potassium hydroxide.

Next, using an original groove processing machine manufactured by Kato Machine Co., Ltd. on the polishing surface side of this polishing pad, the average value of the groove width is 0.5 mm, the average value of the groove depth is 1 mm, and the average value of the pitch is 1.75 mm. A plurality of annular grooves were formed concentrically. Thereafter, the polishing performance of this polishing pad was evaluated as follows.
(1) Polishing speed and presence / absence of scratching A polishing pad was mounted on a surface plate of a polishing apparatus (manufactured by SFT, model “Lapmaster LM-15”), and the number of rotations of the surface plate was 50 rpm, which was diluted 3 times. Using a slurry for chemical mechanical polishing (product name “CMS 1101” manufactured by JSR Corporation) at a flow rate of 100 cc / min, the SiO ₂ film wafer was polished for 2 minutes, and the polishing rate and the presence or absence of scratches were evaluated. The polishing rate was calculated by measuring the film thickness before and after polishing with an optical film thickness meter, and dividing this film thickness difference by the polishing time. The scratch was confirmed by observing the polished surface of the polished SiO ₂ film wafer with an electron microscope. As a result, the polishing rate was 350 nm / min, and almost no scratch was observed.

(2) Evaluation of dishing After polishing a semiconductor wafer (manufactured by SKW, trade name “SKW-7”) under the following conditions, dishing is performed using a fine shape measuring apparatus (model “P-10”, manufactured by KLA-Tencor). Was measured. As a result, dishing was 70 nm and the polished surface was excellent in flatness.
Slurry; CMS1101 (JSR Corporation)
Chemical mechanical polishing equipment; EPO112 (manufactured by Ebara Corporation)
Slurry supply amount: 200 ml / min Polishing load: 400 g / cm ²
Plate rotation speed: 70 rpm
Head rotation speed: 70 rpm
Polishing rate: 400 nm / min Polishing time: 5.75 minutes (15% overpolish)

Reference Example 60 parts by volume of uncrosslinked 1,2-polybutadiene (trade name “JSR RB830” manufactured by JSR) and uncrosslinked ethylene-vinyl acetate copolymer (trade name “Ultrasen 630” manufactured by Tosoh Corporation) 20 Volume parts and 20 volume parts of β-cyclodextrin (manufactured by Yokohama Kokusai Bio Laboratory Co., Ltd., trade name “Dexy Pearl β-100”, average particle size 20 μm), which is water-soluble particles, were adjusted to 160 ° C. It knead | mixed using the biaxial extruder. Thereafter, 1.0 part by mass of an organic peroxide (manufactured by NOF Corporation, product name “Park Mill D40”) was added and further kneaded, and the kneaded product was extruded into a mold. Then, the crosslinking process hold | maintained at 170 degreeC for 18 minute (s) was performed, and the polishing pad of diameter 60cm and thickness 3mm was obtained. Next, on the polishing surface side of this polishing pad, using an original groove processing machine manufactured by Kato Machine Co., Ltd., the average value of the groove width is 0.5 mm, the average value of the groove depth is 0.5 mm, and the average value of the pitch is 4 mm. A plurality of annular grooves were formed concentrically. Furthermore, the polishing rate, the presence or absence of scratches, and dishing were evaluated in the same manner as in Example 1. As a result, the polishing rate was 300 nm / min, scratches were hardly observed, dishing was 60 nm, and the polished surface was excellent in flatness.

Comparative Example 1
A polishing pad having a diameter of 60 cm and a thickness of 3 mm was obtained according to Example 1 except that potassium sulfate (manufactured by Takasugi Pharmaceutical Co., Ltd.) having an average particle diameter of 20 μm was used as the water-soluble particles. Moreover, when the elution degree to the water of potassium sulfate was computed like Example 1, it was 80 mass%. When the same experiment was conducted in water at 50 ° C., the elution degree was 82% by mass. The solubility of potassium sulfate was 11% by mass at 25 ° C. and 12% by mass at 50 ° C. Furthermore, a plurality of annular grooves similar to those in Example 1 were concentrically formed on the polishing surface side of the polishing pad using an original groove processing machine manufactured by Kato Machine Co., Ltd. Further, the polishing rate, the presence or absence of scratches, and dishing were evaluated in the same manner as in Example 1. As a result, the polishing rate was 300 nm / min and there was no problem, but many scratches were observed, dishing was 180 nm, and the polished surface was inferior in flatness.

Comparative Example 2
Using an original groove processing machine manufactured by Kato Machine Co., Ltd. on the polishing surface side of a commercially available polyurethane foam polishing pad (Rodel Nitta, trade name “IC1000”), a plurality of annular grooves similar to those in Example 1 were formed. Concentric circles were formed. Further, the polishing rate, the presence or absence of scratches, and dishing were evaluated in the same manner as in Example 1. As a result, the polishing rate was 350 nm / min and there was no problem, but many scratches were observed, dishing was 150 nm, and the polished surface was inferior in flatness.

It is a graph which shows that the solubility in 25 degreeC in the water of (beta) -cyclodextrin couple | bonded with (gamma)-(2-aminoethyl) -aminopropyltrimethoxysilane with water hardly changes with pH.

Claims (8)

In a polishing pad containing a water-insoluble matrix material containing a cross-linked polymer and water-soluble particles dispersed in the water-insoluble matrix material, the water-soluble particles themselves into water in the entire pH range from pH 3 to pH 11. The solubility in water at 25 ° C. in the whole range from pH 3 to pH 11 is ± 10% by weight at 25 ° C. and the solubility in water at 25 ° C. in the case of pH 7 is ± Within 50%,
An outer shell is formed on at least a part of the outermost part of the water-soluble particles by the coupling agent containing an amino group,
At least a portion of the water-insoluble matrix material containing the cross-linked polymer, Ri crosslinked 1,2-polybutadiene der,
The polishing pad , wherein the coupling agent is γ- (2-aminoethyl) -aminopropyltrimethoxysilane . The water-soluble particles themselves have a solubility in water at 25 ° C. in the entire range of pH 3 to pH 11 of 0.1 to 3% by mass, and the solubility in water at 25 ° C. in the case of pH 7 is pH 3 2. The polishing pad according to claim 1, wherein the solubility in water at 25 ° C. in the entire range from 1 to pH 11 is within ± 50%. The polishing pad according to claim 1 or 2 , wherein 0.001 to 10% by mass of the coupling agent is used with respect to the water-soluble particles. In a polishing pad containing a water-insoluble matrix material containing a crosslinked polymer, and water-soluble particles dispersed in the water-insoluble matrix material, the water-soluble particles are amino groups, epoxy groups, isocyanurate groups and Containing at least one hydroxyl group,
An outer shell is formed on at least a part of the outermost part of the water-soluble particles by the coupling agent containing an amino group,
At least a portion of the water-insoluble matrix material containing the cross-linked polymer, Ri crosslinked 1,2-polybutadiene der,
The polishing pad , wherein the coupling agent is γ- (2-aminoethyl) -aminopropyltrimethoxysilane . The water solubility of the water-soluble particles per se in the entire pH 3 to pH 11 range is 0.1 to 10% by mass at 25 ° C., and the water solubility contained in the polishing pad when the polishing pad is immersed in water. 5. The polishing pad according to claim 4 , wherein the elution degree in the entire range of pH 3 to pH 11 is 0.05 to 50% by mass at 25 ° C. 5. The water solubility of the water-soluble particles per se in the entire range from pH 3 to pH 11 is 0.1 to 10% by mass at 25 ° C., and the solubility in water at 25 ° C. in the case of pH 7 is from pH 3 The polishing pad according to claim 4 or 5 , wherein the solubility in water at 25 ° C in the entire range of pH 11 is within ± 50%. The water solubility of the water-soluble particles per se in the entire pH 3 to pH 11 range is 0.1 to 3% by mass at 25 ° C., and the solubility in water at 25 ° C. in the case of pH 7 is from pH 3 The polishing pad according to claim 6 , wherein the solubility in water at 25 ° C in the entire range of pH 11 is within ± 50%. The polishing pad according to any one of claims 4 to 7 , wherein 0.001 to 10% by mass of the coupling agent is used with respect to the water-soluble particles.

Images