JP5385653B2 - Polishing pad and polishing method - Google Patents

Description

  The present invention relates to a polishing pad and a polishing method suitable for polishing functional materials such as Si wafers, SiC wafers, and plastic lenses used for semiconductor wafers.

  Functional materials such as Si wafers, SiC wafers, and plastic lenses used for semiconductor wafers need to obtain high quality and high smooth surfaces in order to exhibit their performance. Although it is difficult to form a high-quality, high-smooth surface, processing in as short a time as possible is desired. Examples of functional materials include CMP of silicon semiconductors and their application devices, high-speed operation, compound semiconductors that require light emitting and receiving performance, SiC and GaN for power devices, hard disk substrates that are becoming larger in capacity, difficult due to high refractive index There is a plastic lens that has become a processed material.

  Among functional material processing steps, the polishing step is an important step because it is responsible for forming the shape and surface accuracy. Today, chemical mechanical polishing is applied as well as silicon polishing. In addition, high-quality and low-cost polishing is required in all cases. Therefore, research and development on abrasives and polishing tools, which are important factors affecting the polishing characteristics in this chemical mechanical polishing, are underway.

  For example, Patent Document 1 proposes a method of mainly polishing tantalum using a soluble silane compound. In Patent Document 2, ultra-precise grinding is performed in which the rotational shake of the grinding wheel head and the turntable of the turntable carrying the workpiece are 0.1 μm or less, and then the grinding wheel is removed and the polishing tool (pad, An ultra-precise processing method is disclosed in which mirror polishing is performed in the same manner as ultra-precision grinding by exchanging with a film). Further, in Patent Document 2, two sets of the same grinding wheel head are arranged in parallel in the same ultraprecision grinding apparatus, a grinding wheel is mounted on one side, and a polishing tool (pad, film) is mounted on the other side. An ultra-precise machining method is disclosed in which polishing is performed by moving a workpiece. These processing methods described in Patent Document 2 can perform grinding and polishing with the same apparatus, and are intended to improve efficiency and reduce costs. Patent Document 3 discloses a method for improving the polishing efficiency by using a hydrazine compound as a polishing accelerator for a silicon substrate.

Japanese translation of PCT publication No. 2004-502824 Japanese Patent Laid-Open No. 5-285807 JP 7-228863 A

  Here, the technique of Patent Document 1 has a problem that the adsorptive force is weak and the abrasive is difficult to be held by the workpiece or the polishing tool. In the technique of Patent Document 2, it is necessary to introduce a new apparatus, and it is necessary to perform grinding to such an extent that mirror finishing can be applied, which makes it difficult to manage a grinding wheel for grinding. Moreover, although the technique of Patent Document 3 recognizes the polishing acceleration effect by the hydrazine compound, the hydrazine compound has a problem that the environmental load is high. Furthermore, in the technique of Patent Document 3, an improvement in polishing performance is expected by combining improvements of the abrasive itself.

  In addition, with the recent increase in accuracy and functionality in functional material applied products, in addition to further improvement in accuracy in the polishing process, there has been a demand for reduction of environmental impact.

  The present invention has been completed in view of the above problems, and it is possible to polish the functional materials in general with high efficiency, and to ensure good polishing characteristics in terms of surface roughness, flatness, shape stability, etc. An object to be solved is to provide a polishing pad and a polishing method that can be used.

The polishing pad of the present invention according to claim 1 which solves the above-mentioned problem is characterized in that it is a hydrophobic powder which is a fine powder processed by contacting an organosilazane compound having a partial structure represented by the following formula (A) in the molecule. Abrasive grains containing abrasive grains, and
And a base material that forms a porous body in which the abrasive grains are contained.

(In the formula (A), the portion represented by * is bonded to another portion. The other portion may be a structure connecting between a plurality of *. X is a hydrogen or hydrocarbon group. Selected.)
The polishing pad of the present invention according to claim 2 that solves the above problem is characterized in that, in claim 1, the fine powder is formed of silica and / or silica treated with a surface silane coupling agent. is there.

  A feature of the polishing pad of the present invention according to claim 3 that solves the above-mentioned problem is that, in claim 1 or 2, the polishing abrasive has a volume average particle diameter of 0.01 μm or more and 5 μm or less. .

  The feature of the polishing pad of the present invention according to claim 4 that solves the above problem is that, in any one of claims 1 to 3, the content of the polishing abrasive grains is 5 to 90 on the basis of the total mass. It is in mass%.

  A feature of the polishing pad of the present invention according to claim 5 that solves the above problem is that, in any one of claims 1 to 4, the surface of the substrate has a groove.

The feature of the polishing pad of the present invention according to claim 6 that solves the above problem is that, in any one of claims 1 to 5, the base material is formed from a resin composition,
The molten resin composition or the resin composition dissolved in a solvent is mixed with the abrasive grains, and then the resin composition is solidified.

The feature of the polishing method according to claim 7 that solves the above problem is the use of the polishing pad according to any one of claims 1 to 6,
Polishing is performed using a polishing liquid that does not contain solid matter.

  In the invention which concerns on Claim 1, the abrasive grain containing the hydrophobized abrasive grain which is the fine powder processed in contact with the organosilazane compound which has the partial structure shown by said Formula (A) in a molecule | numerator is included. By having it, the adsorption | suction power to the base material of the abrasive grain for polishing improves and it becomes possible to aim at the effective utilization of the abrasive grain for grinding | polishing. Here, since the base material is porous, the abrasive grains for polishing can be held in the holes. The holes may be continuous or discontinuous. In the case of discontinuity, the abrasive grains held inside the hole are exposed to the outside along with the wear of the base material and exhibit a polishing action. In particular, by adopting a fine powder made of silica as in claim 2 or adopting abrasive grains having a particle size distribution as in claim 3, a higher polishing ability can be exhibited. .

  In the invention which concerns on Claim 4, it became possible to exhibit high polishing efficiency by prescribing | regulating content of the abrasive grain for polishing.

  In the invention which concerns on Claim 5, it becomes possible to remove the to-be-polished object produced | generated by grinding | polishing effectively from a grinding | polishing surface by providing a groove part in the surface of a base material, and can always maintain a high grinding | polishing capability. .

  In the invention according to claim 6, the base material is formed from the resin composition, and the abrasive grains are mixed and dispersed in the melted or solutionized resin composition, thereby uniformly polishing the base material in the base material. The grains can be dispersed. Further, the abrasive grains to be dispersed have high affinity for the resin composition and excellent durability as described above.

  In the invention which concerns on Claim 7, since it grind | polishes without using a solid substance using the polishing pad of this invention, the load to the environment originating in a solid substance can be decreased. In normal polishing, a polishing liquid containing polishing grains as a solid material is interposed between a polishing pad and an object to be polished.

It is a schematic sectional drawing which shows the relationship between the abrasive grain for polishing in this embodiment, and the hole of a base material.

  The polishing pad and the polishing method of the present invention will be described in detail below based on the embodiments.

(Polishing pad)
The polishing pad of the present embodiment has polishing abrasive grains and a substrate. The polishing pad of this embodiment can be in the form of a film or plate. In that case, it is desirable to affix to some fixing member. By affixing on the fixing member and abutting on the surface of the object to be polished, the abrasive grains contained in the polishing pad exposed to the outside polish the object to be polished. The polishing pad can be fixed on the fixing member via an adhesive layer, a cushion layer, or the like. The adhesive layer exhibits an effect of adhering the polishing pad onto the fixing member, and the cushion layer exhibits an effect of allowing the polishing pad to adhere to an object to be polished by bending itself.

  Polishing abrasive grains contain hydrophobized abrasive grains. The content of the hydrophobized abrasive grains is not limited, but is preferably 0.01% by mass or more, more preferably 0.1% or more based on the total mass of the abrasive grains for polishing. The polishing abrasive particles preferably have a volume average particle size of 0.01 μm or more and 5 μm or less, and more preferably 0.02 or 0.1. When the smoothness required for the polished surface after polishing is large, it is desirable to reduce the average particle size of the abrasive grains, but from the viewpoint of improving the polishing rate, it is desirable that the average particle size is large. Further, it is desirable not to contain abrasive grains having a certain particle size (for example, 3 μm, 5 μm) or more (or the content is limited) according to the required smoothness.

  A hydrophobized abrasive grain is a silazane compound having a partial structure represented by the above formula (A) with respect to a fine powder to be elementary (hereinafter referred to as “silazane compound” unless otherwise indicated) It is a silazane compound having a structure.) Produced by bringing it into contact. Here, in the formula (A), the structure of the other portion connected to the portion represented by * is not limited, but in addition to (a) a hydrocarbon group, (b) a carbon atom in the hydrocarbon group. And / or a part of carbon atom and hydrogen atom may be substituted with oxygen or nitrogen, or (c) a part or all of hydrogen atom may be substituted with halogen. The hydrocarbon group may have a structure in which a plurality of * are connected, in which case the present compound becomes a cyclic compound.

The silazane compound is preferably a silazane compound represented by the following general formula (1), a cyclopolysilazane compound represented by the following general formula (2), or a cyclic organosilicon compound represented by the following general formula (3). .
(1): R ₃ Si—NH—SiR ₃ ,

  After the silazane compound is brought into contact with the fine powder, it can be heated or left as it is. Examples of the method for bringing the silazane compound into contact with the fine powder include a method in which the silazane compound is directly mixed with the fine powder, and a method in which the silazane compound is dissolved or dispersed in an appropriate solvent and mixed with the fine powder. Mixing can be facilitated by stirring or the like.

  R in the general formula (1) is a monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 4 carbon atoms, particularly preferably 1 to 2 carbon atoms, and examples of the monovalent hydrocarbon group include a methyl group, Alkyl groups such as ethyl group, propyl group, isopropyl group and butyl group, etc., preferably methyl group, ethyl group and propyl group, particularly preferably methyl group and ethyl group can be selected independently. The monovalent hydrocarbon group replaces one or more hydrogen atoms with a halogen group, hydroxyl group, ester group, ether group, amide group, ureido group, urea group, cyano group, nitro group, sulfone group, or the like. It may contain a substituted alkyl group. The six Rs may all be the same, may be different groups, or may be partly the same. Preferred examples of the silazane compound include hexamethyldisilazane and hexaethyldisilazane, and more preferred is hexamethyldisilazane.

  R in the general formula (2) is the same as that in the formula (1), and n is represented by an integer of 3 to 10. Preferred cyclopolysilazane compounds include 1,1,3,3,5,5-hexamethylcyclotrisilazane and 1,1,3,3,5,5-hexaethylcyclotrisilazane. X is hydrogen or a hydrocarbon group. The hydrocarbon group for X preferably has about 1 or 2 carbon atoms.

  R, X, and n in the general formula (3) are the same as those in the formula (1). m is represented by an integer from 1 to n. Preferred cyclic organosilicon compounds include compounds having the following structure (n is 3, m is 1).

The amount of the silazane compound is not particularly limited, but the number of moles of tri-monovalent hydrocarbon silyl groups per unit surface area of the fine powder is 0.1 to 15 μmol / m ² , preferably 0.5 to 8 μmol / m ² . Although it does not specifically limit as a fine powder which it is desirable to process so that it may be an inorganic substance and a silica, a silicon carbide, an alumina, boron nitride etc. (including these mixtures) are desirable. By bringing the silazane compound into contact with the fine powder, the surface of the fine powder is hydrophobized. Examples of the fine powder include a spherical product, a crushed product, a mixture of a sphere and a crushed product.

  The fine powder can be subjected to other treatments in addition to the treatment with the silazane compound. Other treatments can be performed before or after the treatment with the silazane compound or simultaneously with the treatment with the silazane compound. As other treatments, treatments that can be hydrophobized are preferred. For example, silane coupling agents, titanates, zirconium coupling agents, anionic surfactants, nonionic surfactants, silicones, etc. are brought into contact with the surface of the fine powder to cause a chemical reaction to modify the surface. Or can be physically adsorbed to modify the surface.

  The abrasive grains to be contained other than the hydrophobized abrasive grains are not particularly limited, and general abrasive grains (silica, silicon carbide, alumina, boron nitride, etc.) can be employed.

  The substrate is a porous body. For example, a foamed resin such as a nonwoven fabric or foamed urethane. The pores forming the porosity may be continuous or discontinuous. The polishing composition is held in the holes. In addition, that a hole continues means that it continues from the outside (namely, it communicates with the exterior). Discontinuous means not continuous (not communicated) to the outside. There may be a mixture of continuous holes and discontinuous holes. Further, the size of the formed holes is almost the same as the size of the abrasive grains for polishing, and there are cases where they are in close contact with the substrate. In some cases, the abrasive grains are held between the substrate and the base material through a gap. FIG. 1 shows the types of the hole shape and the state of dispersion of the abrasive grains for polishing.

  FIG. 1 (a) shows a form in which discontinuous holes are formed in the substrate 2, and the size of the formed holes and the size of the abrasive grains 1 dispersed are the same. That is, the polishing abrasive grain 1 and the substrate 2 are in close contact with each other without a gap. FIG. 1B shows a form in which discontinuous holes are formed in the substrate 2a, and the size of the formed holes is larger than the size of the abrasive grains 1 for dispersion. That is, the hole does not communicate with the outside, and there is a gap between the hole and the abrasive grains for polishing. In FIG. 1 (c), holes continuous with the outside are formed in the substrate 2b, and abrasive grains 1 are dispersed in the holes. The hole is tubular. In FIG. 1 (d), holes continuous with the outside are formed in the substrate 2c, and the abrasive grains 1 for polishing are dispersed in the holes. The base material 2c is a nonwoven fabric in which fibers are gathered. Moreover, the abrasive grains dispersed in the nonwoven fabric may be fixed to the nonwoven fabric with a binder.

As for the hole diameter of the hole which a base material has, it is desirable that it is about 1 micrometer-100 micrometers. Although the addition amount of polishing composition is not specifically limited, When making it contain uniformly in a base material, about 5-90 mass% can be contained on the basis of the whole mass. Moreover, it can also be a grade which hold | maintains the abrasive grain of about 20g per 1 m < ² > on the basis of the surface area of a base material.

(Polishing method)
The polishing method of this embodiment is a method of polishing an object to be polished in the presence of a polishing liquid using the polishing pad of this embodiment. The polishing liquid does not have solids such as abrasive grains for polishing. Although not included in the polishing method of the present embodiment, the polishing pad of the present embodiment can be applied to a polishing method in which a polishing liquid containing solids such as polishing abrasive grains is interposed.

  The polishing liquid may be aqueous or non-aqueous. The polishing liquid may also contain one or more additives selected from alkaline substances, oxidizing agents, oxide solubilizers, abrasive dispersants, chelating agents, and sugars. The workpiece is polished while dripping this polishing liquid. The abrasive dispersing agent is added in order to uniformly disperse the abrasive grains dropped from the polishing pad in the polishing liquid. Depending on the type of workpiece (such as copper), the chelating agent can reduce the surface hardness of the workpiece and promote polishing. Saccharides can appropriately control the wettability of abrasive grains.

(Test 1)
-Preparation of polishing pad Contacted and reacted 50 nm colloidal silica (polishing abrasive grains of Comparative Example 1) and colloidal silica (fine powder) of Comparative Example 1 with a silazane compound (R is all methyl group compound). (Hydrophobized abrasive grains: polishing abrasive grains of Example 1) was prepared. It was confirmed by IR spectrum whether or not it was hydrophobized. As a result, absorption was recognized at about 2900 to 3000 cm ^−1, and the presence (introduction) of trimethylsilyl group was confirmed on the surface of colloidal silica.

  A polishing member (polishing tool) was prepared by impregnating the non-woven fabric (Nitta Hearth SUBA400) with the abrasive grains of Example 1 and Comparative Example 1, and the polishing rate when the Si wafer was polished was measured. The impregnation of the abrasive grains for polishing was performed as follows. First, each polishing abrasive is dispersed in a dispersion medium (Example 1: isopropanol, Comparative Example 1: water) at a concentration of 40% by mass on a nonwoven fabric having a size of φ380 mm so that the above solution becomes 5 g. Were impregnated into a nonwoven fabric (the polishing pad of Example 1 and the polishing pad of Comparative Example 1).

Further, water-based urethane resin (Takelac WS5100: manufactured by Takeda Pharmaceutical Co., Ltd., solid content concentration of 30% by mass) is applied to the polishing abrasive grains of Example 1 so that the mass ratio of the polishing abrasive grains to the urethane resin is 4: 1. 5 g of the mixture was applied to the surface of the same nonwoven fabric as in Example 1 and dried at 110 ° C. (Polishing pad of Example 2)
The polishing of the Si wafer uses MATLAB 15 and drops an aqueous solution prepared by dissolving piperazine as an additive to 0.6% by mass on each polishing member under polishing conditions of a pressure of about 27 kPa (4 psi) and a rotation speed of 60 rpm. I went there. As a control test, a similar test was performed on a non-woven fabric not impregnated with abrasive grains. As a result, while the polishing rate of the polishing pad of Example 1 was 1.4 μm / min and the polishing rate of the polishing pad of Example 2 was 1.3 μm / min, the polishing pad of Comparative Example 1 and In the control test, the polishing rate was about 0 μm / min. The reason why the polishing did not proceed substantially in the polishing member of Comparative Example 1 was presumed to be because the impregnated polishing abrasive particles were drained by the dropped additive aqueous solution. Therefore, it has been clarified that the polishing pads of Examples 1 and 2 have a high durability with little loss of polishing abrasive grains.

(Test 2)
100 parts by weight of abrasive grains of Example 1 were added to 100 parts by weight of Coronate C-6912 (manufactured by Nippon Polyurethane Industry) heated to 80 ° C., mixed, heated to 110 ° C., and further 3,3′-dichloro. 20 parts by mass of -4,4'-diaminodiphenylmethane (MOCA) was added. The obtained dispersion was poured into a mold to prepare a disc-shaped polishing pad having a thickness of 1.2 mm and φ380 mm. The content of polishing abrasive grains in the pad was 45% by mass. Double-sided tape was affixed to the back side of the pad and fixed on the fixing member. As a result of measuring the polishing rate under the same conditions as in Example 1, the polishing condition was 1.3 μm / min.

Claims (8)

Abrasive grains containing hydrophobized abrasive grains, which are fine powders processed in contact with an organosilazane compound having a partial structure represented by the following formula (A) in the molecule;
A polishing pad comprising a porous body containing the polishing abrasive grains (however, the outer diameter is 2 to 500 nm, the aspect ratio is 5 to 15000, and the hollow structure is formed in the center) Except for those containing multi-layered carbon fibers having

(In the formula (A), the portion represented by * is bonded to another portion. The other portion may be a structure connecting between a plurality of *. X is a hydrogen or hydrocarbon group. Selected.) Polishing abrasive grains comprising hydrophobized abrasive grains, which are fine powders processed in contact with the cyclopolysilazane compound represented by the general formula (2) or the cyclic organosilicon compound represented by the general formula (3) When,
A polishing pad comprising a base material that forms a porous body in which the polishing abrasive grains are contained.

(In General Formula (2) and General Formula (3), R is an independent monovalent hydrocarbon group having 1 to 10 carbon atoms, and the monovalent hydrocarbon group is a halogen group, a hydroxyl group, or an ester group. , An ether group, an amide group, a ureido group, a urea group, a cyano group, a nitro group, and a sulfone group may include a substituted alkyl group that substitutes one or more hydrogen atoms, and X is selected from hydrogen and a hydrocarbon group N is represented by an integer from 3 to 10. m is represented by an integer from 1 to n. The polishing pad according to claim 1 or 2 micro-powder is formed from silica, and / or surface silane coupling agent-treated silica. The abrasive grains have a volume-average diameter in the 0.01μm or more, the polishing pad according to any one of claims 1 to 3 is 5μm or less. The polishing pad according to any one of claims 1 to 4 , wherein a content of the polishing abrasive is 5 to 90% by mass based on the total mass. Polishing pad according to any one of claims 1 to 5 the surface of the substrate having the groove. The substrate is formed of a resin composition;
The resin composition was melt, or with the resin composition dissolved in a solvent, after mixing the abrasive grains, claim 1-6 which is formed by solidifying the resin composition 2. The polishing pad according to item 1. Using the polishing pad according to any one of claims 1 to 7 ,
A polishing method comprising polishing using a polishing liquid containing no solid matter.

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