JP2001303027A - Composition for grinding and method for grinding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grinding composition which can strongly grind, gives ground surfaces having excellent smoothness and uniformity, and is especially useful for grinding semiconductor substrate materials and glass materials, and to provide a method for grinding. SOLUTION: This composition for grinding, characterized by comprising silica-containing abrasive grains, a fluorine-containing compound having a hydroxyl group and a fluorinated hydrocarbon group, and water, wherein the content of the silica-containing abrasive grains is 1 to 40 wt.% and the fluorine- containing compound is 0. 005 to 2.0 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing composition and a polishing method capable of obtaining a highly polished surface, and more particularly to a polishing composition having a high polishing rate and excellent smoothness and uniformity of a polished surface. In addition, the present invention relates to a polishing composition and a polishing method particularly useful for polishing a semiconductor substrate material.

[0002]

2. Description of the Related Art In recent years, a glass substrate for a display element or a memory disk, or an insulating film such as silica (SiO ₂ ) formed on a silicon wafer or a silicon wafer, and a metal film such as a copper film or a tantalum film have been developed. In polishing,
Aqueous slurry abrasives in which silica-based abrasive grains such as fumed silica and colloidal silica are suspended, and aqueous slurry abrasives in which alumina-based abrasive grains such as colloidal alumina and α-alumina are suspended are known. .

[0003] As these aqueous slurry abrasives, for example, alumina-based abrasives are disclosed in Japanese Patent Laid-Open No. 5-3295.
As disclosed in Japanese Patent Application Laid-Open No. 9-59351 and Japanese Patent Application Laid-Open No. Hei 5-59351, it is disclosed that a metal material such as an aluminum magnetic disk substrate plated with a nickel alloy can be polished to achieve polishing with good smoothness. However,
When these alumina-based abrasives are used for polishing a semiconductor substrate material for polishing an insulating film such as silica or a glass substrate having a hardness higher than that of the above-mentioned metal materials, the polishing rate is extremely low and is suitable for practical use. Absent.

On the other hand, silica-based abrasives are disclosed in, for example,
As can be seen in, for example, Japanese Patent No. 625002 and Japanese Patent No. 2894208, it is most widely used particularly for polishing a silicon wafer. This is because the silica-based abrasive has a high polishing rate and is the same component as the oxide formed on the surface of the silicon wafer, and is less likely to cause surface contamination than an abrasive made of other foreign elements, This is because silica fine particles are easily available and mass-produced.

However, with these conventional silica-based abrasives, when polishing a semiconductor material, a water-soluble surfactant such as a polyalkylsiloxane, a polyarylsiloxane, or a polyoxyalkylene ether is added to the polishing slurry (JP-A-8-197414). Publication) and water-soluble organic polymer compounds such as deoxyribonucleic acid, polyacryloamide, and polyvinylpyrrolidone (Japanese Patent Publication No. 6-23393). There is a problem. In order to cope with the recent demand for miniaturization of wiring, this problem has been demanded to be further improved since smooth polishing properties of a silicon wafer or the like serving as a substrate are increasingly required.

[0006]

Thus, the present invention provides:
Excellent in smoothness and uniformity of polishing, generation of scratches,
An object of the present invention is to provide a polishing composition and a polishing method that are useful for polishing a semiconductor substrate material such as a silicon wafer, which does not have a problem such as abrasive grains remaining on the surface of the object to be polished. is there.

[0007]

Means for Solving the Problems The present inventor has further studied silica-based abrasives in order to solve the above-mentioned problems, and has reached the present invention. That is, the present invention contains a silica-containing abrasive, a fluorine-containing compound having a hydrophilic group and a fluorinated hydrocarbon group, and water, and the content of the silica-containing abrasive is 0.1 to 40% by mass and In the polishing composition, the content of the fluorine-containing compound is from 0.005 to 2.0% by mass.

According to the study of the present inventor, when a silica-based abrasive is used, the smoothness of the polished surface of the polished material is sufficient even when various additives are added as described above. However, in some cases, scratches occur due to polishing and abrasive grains remain on the polished surface. However, when using a slurry-type abrasive composition containing a silica-containing abrasive grain and a fluorine-containing compound having a hydrophilic group and a fluorinated hydrocarbon group in a specific amount according to the present invention, the polishing target It has been found that the polished surface of the material has smoothness, and the occurrence of scratches and the residual abrasive particles are significantly reduced.

Although the mechanism why the above-mentioned improvement is brought about by the present invention is not necessarily clear, the presence of the above-mentioned fluorine-containing compound in the polishing composition of the present invention depends on the polished surface of the material to be polished. Polishing is performed while increasing the wettability of the silica-containing abrasive slurry, and the silica-containing abrasive particles constantly cover the polished surface, thereby improving the smoothness and uniformity of the polished surface. . Hereinafter, the polishing composition of the present invention will be described in more detail.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, silica-containing abrasive grains mean fine-grain silica. Fine-grained silica is industrially produced by a gas phase method or a liquid phase method. Fine-grained silica produced by the gas phase method is called fumed silica, and fine-grained silica produced by the liquid phase method is generally called colloidal silica. Fine-grain silica is generally amorphous, and in the present invention, amorphous silica is also preferably used.

In the present invention, the average particle size of silica means the average particle size of the particles in the isolated state without aggregation when the particles are present. When the particles exist in an aggregated state, it means the average particle diameter of the aggregated particles. In many cases, the fine-grained silica is present in an aggregated state, but in the present invention, it can be preferably used in such an aggregated state. The average particle size of silica can be preferably determined by particle size distribution using an image analysis method in transmission electron microscopy.

The average particle size of the silica-containing abrasive particles in the present invention is preferably from 5 to 300 nm. In the case of such an average particle diameter, for example, in polishing a semiconductor substrate material, a better effect can be obtained from the viewpoint of the surface roughness, that is, the grinding speed and the smoothness of the polished surface. That is, if the average particle size is smaller than this range, the polishing rate is decreased, while if the average particle size is larger than the above range, scratches are generated on the polished surface and the smoothness is poor, which is not preferable. Above all, the average particle size is 30-200n
m is appropriate.

The content of the silica-containing abrasive grains in the polishing composition of the present invention varies depending on the object to be polished, but is required to be 0.1 to 40% by mass in the composition. If the content of the silica-containing abrasive grains is less than 0.1% by mass, the polishing rate is undesirably low. If the content of the silica-containing abrasive grains exceeds 40% by mass, polishing is not uniform, and polishing flaws are liable to occur. The content of silica-containing abrasive grains is 2
25 mass% is preferred. The specific surface area of the silica-containing abrasive grains in the polishing composition of the present invention is 10 to 300 m ² / g are preferred.

The polishing composition of the present invention contains
Containing a hydrophilic group and a fluorinated hydrocarbon group.
Element compound (hereinafter, also simply referred to as fluorine-containing compound)
Preferably, it is represented by the structural formula, Rf- (X) nY.
Here, Rf is a perfluorohydrocarbon group, and X
May contain fluorine, oxygen and nitrogen atoms
It is a divalent organic group, and Y is a hydrophilic group. n is 0 or
Is an integer of 1. As such a hydrophilic group, a sulfonic acid group
(-SO₃M), oxysulfonic acid group (-OSO
₃M), carboxylic acid group (-COOM), phosphate group (PO
₃M), an amino group (—NR ₃Z), oxyalkylene group
Or it has an oxyalkylamine group. Where M is
Means hydrogen atom, alkali metal atom or ammonium group
R represents a lower alkyl group, and Z represents a halogen atom.
Show. Among the hydrophilic groups, among others, sulfonic acid groups,
Bonic acid group, oxyalkylene group and oxyalkylamine
At least one member selected from the group consisting of

Further, as the perfluorohydrocarbon group,
A chain or cyclic perfluorohydrocarbon group having preferably 5 to 13 carbon atoms is preferable. The fluorine-containing compound having a hydrophilic group and a fluorinated hydrocarbon group is preferably water-soluble, and preferably has a molecular weight of 300 to 2,000.

Preferred examples of the fluorine-containing compound having a hydrophilic group and a fluorinated hydrocarbon group include perfluoroalkylamine oxide, perfluoroalkylcarboxylate, perfluoroalkylphosphate, perfluoroalkyltrimethylammonium, and the like. And perfluoroalkyl betaines, perfluoroalkyl sulfonates, and perfluoroalkyl ethylene oxide adducts.

In the present invention, the above-mentioned fluorine-containing compound includes, among others, perfluoroalkylamine oxide,
At least one selected from perfluoroalkyl carboxylate, perfluoroalkyl sulfonate and perfluoroalkyl ethylene oxide adduct is preferred.

The content of the fluorine-containing compound in the polishing composition of the present invention is preferably 0.005 to 2.0% by mass. If the content is small, the effect of improving the polishing performance is small, which is not preferable. Even if the content is large, the effect of improving the polishing performance is not improved, and on the other hand, the cost is undesirably increased. The content is 0.03 to 1.0% by mass.
Is appropriate. Further, the fluorine-containing compound is preferably 0.1 to 100 parts by mass of the silica-containing abrasive grains.
40 parts by mass, particularly 0.5 to 10 parts by mass.

In the polishing composition of the present invention, a water-soluble organic polymer compound can be contained as a thickener or a dispersing agent, thereby improving the storage stability or polishing characteristics of the slurry. Can be. As such an organic polymer compound, a hydrocarbon compound is preferred from the viewpoint of cost. Preferred examples of such organic polymer compounds include ammonium polyacrylate, ammonium polymethacrylate, polyvinyl alcohol, ammonium polyoxyethylene lauryl ether sulfate, polyethylene glycol monostearate, alkyl cellulose, and polyacrylamide. These organic polymer compounds may be partial esters or partial hydrolysates as long as they are water-soluble. Above all, ammonium polyacrylate is effective in terms of effect and cost,
Particularly preferred. The molecular weight of these organic polymer compounds is
1000 to 20000 is preferred. The content of these organic polymer compounds in the polishing composition is preferably 0.1 to 5% by mass, and particularly preferably 0.5 to 3% by mass.

Further, the polishing composition of the present invention may further contain polishing abrasives other than silica, if necessary, to improve the polishing characteristics. In this case, the other abrasive grains are preferably alumina abrasive grains, ceria abrasive grains, zirconia abrasive grains, and the like. Examples of these abrasive grains include α-alumina having an average particle diameter of 0.1 to 2 μm, γ-alumina, or ceria.These abrasive grains are based on 100 parts by mass of silica-containing abrasive grains. 1 to 200 parts by mass, preferably 3 to 50 parts by mass can be mixed.

In the polishing composition of the present invention, silica-containing abrasive grains, a fluorine-containing compound, and a thickener, a dispersant, and other abrasive grains, which are added as needed, are dispersed in water. It is in a slurry state. Such a polishing composition is formed by dispersing the above-mentioned components in water. In the dispersion, if necessary, preferably, a homogenizer, an ultrasonic dispersing machine, or a stirring or dispersing machine such as a ball mill is used. be able to. The polishing composition of the present invention thus formed is excellent in dispersibility, has a low sedimentation speed, and can maintain a small rate of change in concentration over a long period of time.

The pH of the polishing composition of the present invention is preferably adjusted, if necessary. That is, the composition for polishing a semiconductor substrate material preferably has a pH of 8 to 13. When the pH is lower than 8, or when the pH is higher than 13, the polishing rate is undesirably reduced. A particularly preferred pH is 9-12.3. To adjust the pH, tetraalkylammonium hydroxide, potassium hydroxide, aqueous ammonia, ammonia gas or the like can be added as necessary.

The method for polishing a semiconductor substrate material or a glass substrate material using the polishing composition of the present invention is not particularly limited, and a general method is employed. In particular, a polishing apparatus including a holder for holding a substrate material to be polished and a polishing cloth is preferably used. Materials such as polyurethane, nonwoven fabric, and fluororesin can be used as the polishing cloth, and the polishing cloth can be subjected to groove processing or the like for holding a slurry of the polishing composition. The polishing conditions are not particularly limited, and the polishing cloth is rotated while continuously supplying the slurry of the polishing composition to the polishing cloth.
Polish while pressing with a pressure of cm ² . After the polishing is completed, the polished material is sufficiently washed with running water and dried.

As a material to be polished by the polishing composition of the present invention, a semiconductor substrate material, a glass substrate material, or the like, which is a material having a high polishing rate and a lack of a suitable abrasive, and a material having a high hardness, is conventionally suitable. ing. Examples of the semiconductor substrate material include at least one material of a semiconductor silicon wafer, a polysilicon film formed on the semiconductor substrate, an insulating film such as a silica insulating film, or a metal film. Examples of the glass substrate material include a glass substrate for a magnetic disk, a glass for a liquid crystal, and a glass for a PDP. Also,
The polishing composition of the present invention is not limited to a semiconductor substrate material or a glass substrate material, etc., a wiring board on which a silica insulating film is formed, a photomask, a lens, an optical glass such as a prism, an inorganic insulating film such as ITO, glass It can be advantageously used for polishing materials having high hardness such as inorganic conductive films such as silicon nitride and glass magnetic heads.

[0025]

Next, examples of the present invention will be described more specifically, but it goes without saying that the present invention is not limited to these examples.

Example 1 A fumed silica-containing slurry (manufactured by Cabot Corporation, containing 30% by mass of fumed silica in pure water, product number SC-1) was used as the silica-containing abrasive. On the other hand, "Surflon, S-141" (perfluoroalkylamine oxide, manufactured by Seimi Chemical Co., Ltd.) was used as the fluorine-containing compound. The silica-containing abrasive grains are mixed and stirred with ion-exchanged water containing the fluorine-containing compound such that the silica-containing abrasive grains in the abrasive are 10% by mass, and then the pH is adjusted to potassium hydroxide. Was adjusted to 10.8 to obtain a slurry-like polishing composition. The slurry was sampled and examined by a transmission electron microscope using an image processing method.
nm. The content of the fluorine-containing compound in the polishing composition was 0.07% by mass. Using the obtained composition, a silicon wafer was polished by the following method. Polishing machine SPAW manufactured by Speed Fam
Using a No. 36, a silicon wafer was polished for 10 minutes while supplying the obtained polishing composition at a rate of 1.2 liters per minute to a soft suede type polishing cloth. The polishing pressure was 100 g / cm ² , the relative speed between the wafer and the polishing cloth was 1.2 m / sec, and the temperature during polishing was 40 ° C. As a result of observing the presence or absence of irregularities on the polished surface of the wafer thus polished with a differential interference microscope, no irregularities were observed on the polished surface.

[Example 2] Instead of "Surflon S-141" as the fluorine-containing compound in Example 1,
"Surflon S-113" (perfluoroalkyl carboxylate, manufactured by Seimi Chemical Co., Ltd.) was used, and the content of the fluorine-containing compound in the polishing composition was 0.1% by mass.
Other than that described above, the content of silica-containing abrasive grains was 8 in the same manner as in Example 1.
A slurry-like polishing composition having a mass% of pH 10.3 was obtained. Using such a composition, in the same manner as in Example 1,
A polishing test of a silicon wafer was performed. As a result of observing the presence or absence of unevenness on the polished surface of the wafer obtained by polishing with a differential interference microscope, no unevenness was observed on the polished surface.

[Example 3] As the fluorine-containing compound in Example 1, instead of "Surflon S-141",
Except that C ₈ F ₁₇ SO ₃ K was used and the content of the fluorine-containing compound in the polishing composition was 0.1% by mass, the content of silica-containing abrasive grains was 8% by mass and the pH was 10 as in Example 1. .8
Was obtained as a slurry-like polishing composition. Using this composition, a polishing test of a silicon wafer was performed in the same manner as in Example 1. As a result of observing the presence or absence of unevenness on the polished surface of the wafer obtained by polishing with a differential interference microscope, no unevenness was observed on the polished surface.

Example 4 The polishing composition prepared in Example 1 further contained potassium polyacrylate (average molecular weight of about 10,000) in a content of 1.4% by mass in the polishing composition. A polishing composition having a silica-containing abrasive content of 10% by mass and a pH of 10.5 was obtained in the same manner as in Example 1 except that the above components were added. Using this composition, a polishing test of a silicon wafer was performed in the same manner as in Example 1. As a result of observing the presence or absence of unevenness on the polished surface of the wafer obtained by polishing with a differential interference microscope, no unevenness was observed on the polished surface.

Comparative Example 1 As the fluorine-containing compound in Example 1, "Surflon S-141" was used instead of
The same procedure as in Example 1 was repeated except that the polishing composition contained 1.5% by mass of a polyoxyethylene lauryl ether, which is a hydrocarbon compound, and the content of silica-containing abrasive particles was 10% by mass and the pH was 10.8. Was obtained. Using such a composition, a polishing test of a silicon wafer was performed in the same manner as in Example 1. The presence or absence of irregularities on the polished surface of the wafer obtained by polishing was observed with a differential interference microscope, and as a result, irregularities were observed on the polished surface.

According to the present invention, there is provided a polishing composition having a high polishing rate and excellent in smoothness and uniformity of a polished surface. Therefore, semiconductor substrate materials including insulating films such as a polysilicon film and a silica insulating film formed on a semiconductor silicon wafer or a semiconductor substrate and a glass substrate for a magnetic disk that require a highly polished surface are required. It is particularly useful for polishing glass materials for liquid crystal, glass for PDP, and the like.

Claims (7)

[Claims] A silica-containing abrasive, a fluorine-containing compound having a hydrophilic group and a perfluorohydrocarbon group, and water.
And the content of the silica-containing abrasive is 0.1 to 40% by mass.
And the content of the fluorine-containing compound is 0.005 to 2.0.
A polishing composition characterized by mass%. 2. The polishing composition according to claim 1, wherein the silica-containing abrasive has an average particle size of 5 to 300 nm. 3. The fluorine-containing compound according to claim 1, wherein the fluorine-containing compound has at least one selected from a sulfonic acid group, a carboxylic acid group, an oxyalkylene group and an oxyalkylamine group as a hydrophilic group. Polishing composition. 4. The method according to claim 1, wherein the fluorine-containing compound is at least one selected from perfluoroalkylamine oxides, perfluoroalkylcarboxylates, perfluoroalkylsulfonates and perfluoroalkylethylene oxide adducts. Or the polishing composition according to 3. 5. The polishing composition according to claim 1, wherein the pH is 8 to 13. 6. A method for polishing a semiconductor substrate material according to claim 1.
The polishing composition according to any one of Items 1 to 5, wherein 7. A polishing method for polishing a semiconductor substrate material by supporting the polishing composition according to claim 1 on a polishing cloth.