JPH1133896A - Abrasive grains, abrasive and polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide polishing abrasive particles remaining on a surface of a substrate to be polished by satisfactorily polishing the surface of the substrate to be polished, and then by simple cleaning using an aqueous cleaning liquid mainly containing pure water or the like. Can be sufficiently removed. SOLUTION: Abrasive grains having a hydrophilic surface and having an absolute value of surface potential (zeta potential) of 50 mV or less at pH 7, preferably terminated with a hydrophilic group, more preferably a hydroxyl group, Therefore, the surface of the silicon semiconductor substrate is polished with an abrasive containing abrasive grains of a metal oxide having a hydrophilic surface, and then washed with an aqueous cleaning solution. As the metal oxide of the abrasive grains, cerium oxide, zirconium oxide, manganese oxide and the like are preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing abrasive, an abrasive and a polishing method used for polishing the surface of a substrate to be polished, and more particularly to a semiconductor substrate called a bare wafer as a substrate to be polished, and more particularly to an oxide film or a metal. The present invention relates to a polishing abrasive, a polishing agent, and a polishing method suitably applied to a semiconductor substrate provided with a thin film such as a film or a wiring.

[0002]

2. Description of the Related Art Conventionally, when performing precision polishing typified by polishing of a semiconductor substrate, first, an abrasive is dispersed on a surface plate on which a polishing cloth is stuck, and a supporting substrate is placed on a rotating or vibrating surface plate. The held substrate to be polished is pressed with an appropriate pressure, and the surface of the substrate to be polished is polished and flattened. Thereafter, the surface of the substrate to be polished is washed to remove particles adhering to the surface, particularly abrasive grains of the abrasive.

[0003]

When a substrate to be polished is washed, metal contamination on the surface due to metal impurities from a polishing apparatus, a polishing cloth, a polishing agent, or the like at the end of polishing is performed. At least four steps are required as shown. 1) mechanical cleaning for removing fine particles adhering by polishing with a brush; 2) cleaning with an alkaline chemical solution for further removing fine particles; 3) cleaning with an acidic chemical solution for removing metal contamination, or using a chelating agent. Cleaning, and 4) pre-cleaning for subsequent manufacturing processes.

In the above-mentioned conventional polishing method, at least four steps 1) to 4) must be performed in order to remove metal contamination. Further, depending on conditions, it may be necessary to perform each washing step a plurality of times, and it is necessary to go through an extremely large number of steps. Further, in some cases, cleaning with an extremely dilute acidic chemical solution may be performed. For example, when the substrate to be polished is a semiconductor substrate and wirings made of aluminum (alloy) are already formed on the surface, Since a defect occurs in which the wiring is corroded at a certain rate, a reduction in yield is inevitable.

On the other hand, in order to avoid corrosion of the wiring,
If the cleaning step using a cleaning solution having a corrosive action on aluminum is not performed, there is a problem that metal contamination mainly due to the remaining surface of the abrasive grains cannot be sufficiently removed.

US Pat. No. 4,968,381 discloses that at the final stage of the polishing step, at least one type of polar compound containing a hydrophilic group / hydrophobic group selected from the group consisting of alcohol, ketone, ether, ester and amide, For example, a polishing method using an abrasive to which ether or polyether such as diethylene glycol diethyl ether or diethylene glycol dimethyl ether is added as an additive is disclosed.

[0007] Japanese Patent Application Laid-Open No. 2-275629 discloses that a semiconductor substrate is rinsed and polished with a solution obtained by diluting an oxidizing agent such as sodium peroxide, sodium chlorate, hydrogen peroxide and ozone immediately before polishing is completed. A polishing method for making a semiconductor substrate surface hydrophilic is disclosed.

Japanese Patent Application Laid-Open No. 7-235519 discloses a polishing method for making a semiconductor substrate surface after final polishing hydrophilic by using a mixed solution of hydrobromic acid, glycerin and water as an abrasive. I have.

JP-A-8-22970 discloses an organic compound having a molecular weight of 100 or more and having at least one hydrophilic group such as a carboxyl group or a sulfo group, for example, a high molecular weight ammonium polycarboxylate or a high molecular weight ammonium salt of polysulfonic acid. There has been disclosed a polishing method for preventing dishing by using an abrasive containing.

Also, Fuso Siltec (Corporation) has a high-purity amorphous-silica fine powder (Quartron colloid (PL series), trade name) manufactured by a sol-gel method using alkoxysilane as a raw material, and has a strong alkyl-modified property. Synthetic silica fine powder exhibiting lipophilicity (Quartron / water-repellent fine powder (WR series), trade name) is on sale. PL
The series includes uses as a polishing agent for semiconductor substrates, fillers for various coatings, and materials for synthetic glass.

Accordingly, an object of the present invention is to provide a polishing apparatus which is capable of polishing a surface of a substrate to be polished after the surface of the substrate to be polished is satisfactorily polished and then easily cleaned mainly with an aqueous cleaning solution containing pure water. An object of the present invention is to provide a polishing abrasive, a polishing agent, and a polishing method capable of sufficiently removing particles.

[0012]

[Means for Solving the Problems]

(Polishing Abrasive) The polishing abrasive of the present invention is characterized in that its surface is hydrophilic. The absolute value of the surface potential (zeta potential) as a measure of hydrophilicity is 0 to 50 m at pH7.
V.

The method for imparting hydrophilicity to the surface of the abrasive grains is not particularly limited, but is preferably at least a part, preferably 80% or more, and more preferably a completely hydrophilic functional end of the abrasive grains. Terminating with a group.

The abrasive grains are preferably at least one metal oxide selected from the group consisting of light metals, transition metals and rare earth metals, and have at least a part of the terminal, preferably 80% of the terminal. As described above, more preferably, the terminal is completely substituted with a hydrophilic functional group. In this specification, the light metal refers to a metal having a low specific gravity, such as an alkali metal, an alkaline earth metal, aluminum, beryllium, and magnesium. The metal oxide is preferably an oxide of aluminum, zirconium, manganese, titanium, cerium, calcium, barium or copper.

The hydrophilic functional group means a group containing atoms such as oxygen, nitrogen, sulfur and the like, and includes, for example, groups such as a hydroxyl group, a carboxyl group, an amino group, a carbonyl group and a sulfo group, preferably a hydroxyl group. It is.

Abrasive grains whose ends are terminated with a hydrophilic functional group, for example, a hydroxyl group, can be prepared by a plasma irradiation method or a sol-gel method (metal) known to those skilled in the art using a metal alkoxide containing the metal as a starting material. A method of preparing a hydrous sol by hydrolyzing an alkoxide). Among these, the sol-gel method is preferred.

The metal alkoxide used in the sol-gel method is not particularly limited as long as it is an alcohol ester of a metal selected from the above-mentioned metal group, but the number of carbon atoms of the alkoxy group is 1 to 3 from the viewpoint of easy hydrolysis. 4 is preferred. The method for producing the metal alkoxide is also not particularly limited, and examples thereof include methods known to those skilled in the art, such as a reaction between a simple metal, an oxide, a hydroxide, or a halide and an alcohol. The method for terminating the terminal with a functional group such as a carboxyl group, an amino group, a carbonyl group, and a sulfo group is not particularly limited, and a method known to those skilled in the art can be used.

The metal alkoxide has a content of a metal element other than the metal of 10 p in order to prevent contamination by the metal.
It is preferably a high-purity metal alkoxide of pm or less, preferably 1 ppm or less, more preferably 0.1 ppm or less.

As the size of the abrasive grains increases, the polishing rate increases. However, if the abrasive grains are larger than necessary, the substrate to be polished may be damaged.
0 nm, preferably 10 to 100 nm, more preferably 20 to 50 nm.

(Abrasive) The abrasive of the present invention contains the above-mentioned abrasive grains and a solvent. The solvent may contain, in addition to deionized water, if necessary, a dispersing aid such as a known surfactant, electrolytic ionized water, and the like. The content of a dispersing aid such as a surfactant is 10% by weight or less, preferably 3% by weight or less, more preferably 1 to 3% by weight of the total solvent. The pH of the abrasive is not particularly limited, and may be appropriately set according to the intended polishing application. For example, when polishing an oxide film of a silicon semiconductor substrate, the pH is 8 to 13, preferably 8 to 12, and more preferably 10 to 12. pH is determined by amines such as monoethylamine and isopropylamine, KOH,
It may be adjusted by adding ammonia or the like. When the metal film is polished, the pH is 2 to 6, preferably 2 to 5, and more preferably 3 to 4. The pH may be adjusted by adding iron nitrate, copper sulfate, or the like.

The abrasive grains are preferably uniformly dispersed in the abrasive. For example, the abrasive grains can be uniformly dispersed in a colloidal state or by adding a dispersing aid such as the above-mentioned surfactant.

If the viscosity of the abrasive is low, it is difficult to uniformly disperse the abrasive grains. If the viscosity is high, it is difficult to polish the silicon semiconductor substrate while maintaining the uniformity of the thickness of the oxide film and the metal film. Since it becomes difficult, when the abrasive grains are dispersed in a solvent at 1% by weight and measured at 25 ° C. using a rotational viscometer according to the method specified in JIS Z 8803, usually 1 to 10 mPa · s, preferably 1-5mPa
S, more preferably 1-2 mPa · s.

(Polishing Method) In the polishing method of the present invention, a first step of polishing a substrate to be polished by using the above-mentioned polishing agent, and after the first step, polishing the surface of the polished substrate to be polished is performed. Cleaning using an aqueous cleaning liquid to remove the abrasive grains remaining on the surface.

The polishing temperature is usually 10 to 70 ° C., preferably 20 to 50 ° C., and more preferably 20 to 40 ° C. In the case of using a polishing apparatus that performs polishing by pressing a substrate to be polished against a polishing cloth on a rotating platen, the number of rotations of the platen is 1
0 to 200 r / min, preferably 20 to 80 r / min, more preferably 20 to 50 r / min.
15 psi (6895 to 103421 Pa), preferably 3 to 10 psi (20684 to 68948 Pa), and more preferably 3 to 7 psi (20684 to 48263).
Pa). Further, the amount of the supplied abrasive is 0.1-1.
01 / min, preferably 0.1 to 0.5 (1 / min), more preferably 0.2 to 0.3 (1 / min).

In the case of an oxide film, the polishing rate is set at a polishing temperature of 25.
° C, the rotation speed of the platen 30 r / min, the pressing pressure 7 psi (48
263 Pa) as standard polishing conditions, 100 to 300.
nm / min, preferably 150-250 nm / min.

In the case of a metal film, the polishing rate is set at a polishing temperature of 25.
° C, the number of rotations of the platen 50 r / min, the pressing pressure 4 psi (27
579 Pa) under the polishing conditions of 150 to 400 nm /
Min, preferably 250-400 nm / min.

The cleaning liquid is not particularly limited as long as it is an aqueous cleaning liquid. For example, an aqueous cleaning liquid containing ammonia, hydrogen peroxide, pure water or the like is used. The percentage of use is usually
The weight ratio is 1-2: 1-5: 4-40. A chemical solution containing a chelating agent such as citric acid may be added to the cleaning solution.
-30% by weight, preferably 2-10% by weight, more preferably 5-10% by weight. The washing temperature is not particularly limited, and is, for example, 70 to 90 ° C.

The abrasive grains, abrasives and polishing method of the present invention are suitably used for polishing a semiconductor substrate, especially a silicon semiconductor substrate.

[0029]

In the abrasive of the present invention, the contained abrasive grains have a hydrophilic surface, and preferably have their terminals terminated with hydrophilic functional groups. Therefore, the polishing agent is very well compatible with an aqueous cleaning solution such as a chemical solution or pure water used in a cleaning process after polishing, and by using such a polishing agent, the polishing agent can be used to clean the substrate to be polished during cleaning. The abrasive which is effectively dispersed in the cleaning liquid from the surface and remains after polishing is easily and reliably removed.

For example, when the substrate to be polished is the most frequently used silicon semiconductor substrate, and the conventional polishing abrasive grains are cerium oxide whose end is not subjected to a hydrophilization treatment, both are made of different materials. Thus, no electrochemical repulsion occurred, and the polished substrate could not be sufficiently cleaned. However, when the cerium oxide of which the terminal is hydrophilized according to the present invention is used, since the abrasive grains have excellent hydrophilicity as described above, the abrasive grains are well adapted to an aqueous cleaning solution and easily removed. This is not only cerium oxide,
As long as it has a hydrophilic surface, it can be sufficiently applied to oxides of metals such as light metals, transition metals, and rare earth metals. Therefore, according to a preferred embodiment of the present invention, an abrasive which contains desired metal oxide particles from the above-mentioned metal group and is extremely excellent in abrasiveness and detergency is realized.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. The present invention is not limited by these embodiments. (First embodiment)

First, a first embodiment of the present invention will be described. Here, an example is described in which the substrate to be polished is a silicon semiconductor substrate and the metal oxide particles of the polishing grains are cerium oxide. FIG. 1 is a structural formula showing a process of forming abrasive grains of an abrasive according to the first embodiment.

In order to form the abrasive grains, first, tetraethoxycerium is used as a starting material, and a hydrocondensation polymerization reaction is caused in the presence of a predetermined catalyst to convert cerium (Ce) via oxygen. Form a network,
Granulation is performed while taking a structure equivalent to the normal crystal structure of cerium oxide to form abrasive grains of cerium oxide. In this state, since the abrasive grains contain a large amount of ethoxy groups and react with unreacted and remaining raw materials to form a gel, the particle size cannot be controlled. Therefore, a process of terminating the ends with hydroxyl groups is performed by distilling the abrasive grains at a temperature of about 100 ° C. while adding water. Thereby, final polishing abrasive grains are obtained. Usually, by this treatment, the terminal is always terminated with a hydroxyl group, which is a typical hydrophilic group, and thus has a hydrophilic surface. Dehydration from two adjacent hydroxyl groups may form an -O- bond, but when the amount is such that the hydrophilicity of the surface is not affected,
It is included in the scope of the present invention. This is the same in the second embodiment and the third embodiment. The abrasive containing the abrasive grains serves as an abrasive for a substrate to be polished such as a silicon semiconductor substrate.

According to this method for forming abrasive grains,
By controlling the hydrolysis polymerization reaction time, it is possible to change the degree of polymerization (the size of the abrasive grains), and specifically, it is possible to control the particle diameter of the abrasive grains to about 10 to 10000 nm. .

Subsequently, the surface of the silicon semiconductor substrate is subjected to chemical mechanical polishing (CM) using the polishing agent formed as described above.
The method of flattening by P) will be described with reference to FIG.

First, as shown in FIG. 2A, a silicon semiconductor substrate 1 is moved from a wafer carrier 2 and is held by a support base 3 during the fabrication of a semiconductor device. Then, as shown in FIG. 2B, the above-mentioned abrasive is supplied to the polishing pad 5 from the abrasive supply mechanism 4. While supplying the abrasive in this manner, the silicon semiconductor substrate 1 is pressed against the polishing pad 5 on the rotating platen 6, and the surface of the silicon semiconductor substrate 1 is polished for about 2 to 5 minutes while applying pressure, and flattened. Become

Thereafter, as shown in FIG. 2 (c), the wafer carrier 2 containing the polished silicon semiconductor substrate 1 is immersed (dipped) in a cleaning tank 7 filled with a cleaning liquid. The surface of the semiconductor substrate 1 is cleaned.

Here, in the polishing agent used in the above-mentioned polishing step, the ends of the cerium oxide polishing abrasive grains contained therein are terminated with hydrophilic functional groups as described above. Therefore, this polishing agent is extremely well compatible with an aqueous cleaning solution such as a chemical solution or pure water used in a cleaning process after polishing, and the polishing solution causes the polishing agent remaining on the surface of the substrate to be polished after polishing. It is easily and reliably removed. A conventional polishing agent using cerium oxide whose terminal is not subjected to a hydrophilic treatment as a polishing abrasive as a metal oxide cannot be sufficiently removed in the cleaning step because the metal oxide is a material different from that of the silicon semiconductor substrate. On the other hand, since this abrasive has excellent hydrophilicity, it is possible to obtain sufficiently good detergency even when cerium oxide is used as the metal oxide.

Therefore, if the surface of the silicon semiconductor substrate 1 is polished by using the polishing agent of the first embodiment, after the surface of the silicon semiconductor substrate 1 is satisfactorily polished, a conventional complicated cleaning step is performed. Without removing the polishing abrasive grains remaining on the surface of the silicon semiconductor substrate 1 by a simple cleaning mainly using an aqueous cleaning liquid mainly containing pure water or the like, metal contamination on the surface of the silicon semiconductor substrate 1 is reduced. It can be easily and sufficiently removed.

(Second Embodiment) Next, a second embodiment of the present invention will be described. Here, similarly to the first embodiment, a polishing agent including polishing abrasive grains whose ends are terminated with a hydrophilic functional group will be described as an example, but they differ in that the metal oxide is different.

FIG. 3 is a structural formula showing a process of forming abrasive grains of an abrasive according to the second embodiment. Here, as in the case of the first embodiment, a zirconium (Zr) network is formed by causing a hydrocondensation polymerization reaction in the presence of a predetermined catalyst. Then, granulation is performed while taking a structure similar to the normal crystal structure of zirconium oxide, and the same processing as in the first embodiment is performed, thereby finally obtaining abrasive grains made of zirconium oxide. The ends of the abrasive grains are always terminated with a hydroxyl group, which is a typical hydrophilic group, and thus have a hydrophilic surface. The abrasive containing the abrasive grains serves as an abrasive for a substrate to be polished such as a silicon semiconductor substrate.

In the abrasive of the second embodiment, the ends of the abrasive grains contained therein are terminated with hydrophilic functional groups as described above. Therefore, this polishing agent is extremely well compatible with an aqueous cleaning solution such as a chemical solution or pure water used in a cleaning process after polishing, and the polishing solution causes the polishing agent remaining on the surface of the substrate to be polished after polishing. It is easily and reliably removed. Conventional abrasives using zirconium oxide as abrasive grains as metal oxides could not be sufficiently removed in the cleaning step because the metal oxides are of a different material from the silicon semiconductor substrate. On the other hand, since this abrasive has excellent hydrophilicity, it is possible to obtain sufficiently good detergency even when zirconium oxide is used as the metal oxide.

Therefore, if the surface of the substrate to be polished typified by the silicon semiconductor substrate is polished by using the polishing agent of the second embodiment, the surface of the substrate to be polished is polished satisfactorily. Without performing a complicated washing process, by simple washing using an aqueous washing solution mainly containing pure water, etc.,
The polishing abrasive grains remaining on the surface of the substrate to be polished are sufficiently removed, so that metal contamination on the surface of the substrate to be polished can be easily and sufficiently removed.

(Third Embodiment) Next, a third embodiment of the present invention will be described. Here, as in the first embodiment, an example of a polishing agent containing abrasive grains whose surface is terminated with a hydrophilic functional group will be described, but the difference is that the metal oxide is different.

FIG. 4 is a structural formula showing a process of forming abrasive grains of an abrasive according to the third embodiment. Here, as in the case of the first embodiment, manganese (M) is produced by inducing a hydrocondensation polymerization reaction in the presence of a predetermined catalyst.
The network of n) is formed. Then, granulation is performed while taking a structure equivalent to the normal crystal structure of manganese oxide, and the same processing as in the first embodiment is performed, thereby finally obtaining abrasive grains made of manganese oxide. The ends of the abrasive grains are always terminated with a hydroxyl group, which is a typical hydrophilic group, and thus have a hydrophilic surface. The abrasive containing the abrasive grains serves as an abrasive for a substrate to be polished such as a silicon semiconductor substrate.

In the abrasive of the third embodiment, the ends of the abrasive grains contained therein are terminated with hydrophilic functional groups as described above. Therefore, this polishing agent is extremely well compatible with an aqueous cleaning solution such as a chemical solution or pure water used in a cleaning process after polishing, and the polishing solution causes the polishing agent remaining on the surface of the substrate to be polished after polishing. It is easily and reliably removed. Conventional polishing agents using manganese oxide as abrasive grains as metal oxides could not be sufficiently removed in the cleaning step because the metal oxide is a material different from that of the silicon semiconductor substrate. On the other hand, since this abrasive has excellent hydrophilicity, it is possible to obtain sufficiently good detergency even when manganese oxide is used as the metal oxide.

Therefore, if the surface of the substrate to be polished typified by the silicon semiconductor substrate is polished using the polishing agent of the third embodiment, the surface of the substrate to be polished is polished well, Without performing a complicated washing process, by simple washing using an aqueous washing solution mainly containing pure water, etc.,
The polishing abrasive grains remaining on the surface of the substrate to be polished are sufficiently removed, so that metal contamination on the surface of the substrate to be polished can be easily and sufficiently removed.

In the first to third embodiments, cerium oxide, zirconium oxide and manganese oxide are exemplified as metal oxides whose surfaces are terminated with hydrophilic functional groups, but the present invention is not limited to these. It will not be done. As the above-described metal oxide, for example, an oxide of another transition metal or a rare earth metal, or an oxide of a light metal such as aluminum oxide is also suitable.

[0049]

Here, the surface of a silicon semiconductor substrate is polished using an abrasive containing abrasive grains having a hydrophilic surface according to the present invention, and then the dip type cleaning apparatus shown in the first embodiment is used. A description will be given of an experimental result obtained by examining the degree of cleaning when cleaning is performed by using a polishing agent based on comparison with a case using a conventional abrasive. The surface potential (zeta potential) of the abrasive grains of the present invention used in this example is also shown below,
By measuring the surface potential (zeta potential), it is possible to know whether or not the abrasive grains present in the solution easily adhere to the substrate.

Silicon oxide terminated at the terminal with a hydroxyl group and having an average particle size of about 500 nm (surface potential (zeta potential) at pH 7-23 mV) and cerium oxide (pH
7, surface potential (zeta potential) -35 mV), zirconium oxide (surface potential (zeta potential) at pH 7)
-42 mV), manganese oxide (surface potential (zeta potential) -28 mV at pH 7), surfactant and water were mixed, KOH was added to adjust the pH to 10, and the abrasive (N
o. 1 to No. 4) was prepared. The surface potential (zeta potential) of the abrasive grains was measured by Coulter (USA)
Was measured using a Coulter Dersa 440 potentiometer according to the manufacturer's manual. The content of the metal oxide in the abrasive was 1% by weight, and the viscosity measured at 25 ° C. using a rotational viscometer by a method specified in JIS Z 8803 was about 1 mPa · s. Also, for comparison, the conventional abrasive (No.
5-No. 8) was used.

A silicon semiconductor substrate (8 inches in diameter; 200 mm) was polished using the above-mentioned polishing agent. The polishing conditions were a polishing temperature of 25 ° C., a rotation speed of the platen of 30 r / min, and a pressing pressure of 4 psi (27579 Pa). The polishing rate of the oxide film was about 150 nm / min for polishing agents 1 and 5 containing silicon oxide, and polishing agents 2 and 6 containing cerium oxide.
Of about 300 nm / min, about 250 nm / min for abrasives 3 and 7 containing zirconium oxide, and about 300 nm / min for abrasives 4 and 8 containing manganese oxide. Did not.

Subsequently, after cleaning the silicon semiconductor substrate at a temperature of 70 ° C. using the dip-type cleaning apparatus shown in FIG. 2C, the number of particles having a diameter of 0.2 μm or more remaining on the surface is reduced. Was counted. Note that a solution obtained by mixing ammonia, hydrogen peroxide and pure water at a weight ratio of 1: 2: 20 was used as the cleaning liquid.

The experimental results are shown in Table 1 below. Thus, when the conventional abrasive is used, when the metal oxide is silicon oxide, the number of particles having a particle size of 0.2 μm or more is 10 μm or more.
0 (No. 5), and the order of cerium oxide, zirconium oxide and manganese oxide was 1000 (No. 6, No. 7, No. 8). On the other hand, in the case where the abrasive of the present embodiment was used, even when cerium oxide, zirconium oxide and manganese oxide were used as metal oxides (No. 2, No. 3, and No. 4).
The number of residual particles could be reduced to several tens of orders comparable to silicon oxide (No. 1).

[0054]

[Table 1]

As described above, it has been proved that the use of the polishing agent of this embodiment makes it possible to greatly reduce the number of residual particles to a level of several tens by simply performing simple cleaning.

Therefore, silicon oxide whose absolute value of the surface potential (zeta potential) at pH 7 is 25 mV or less, 40 mV
The following cerium oxide, 45 mV or less zirconium oxide, and 30 mV or less manganese oxide are preferably used.

In this experiment, the case where the substrate was cleaned by the dipping method was exemplified. However, in order to further perform the cleaning, mechanical cleaning for removing fine particles adhered by polishing with a brush may be performed. . Specifically, as shown in FIGS. 5A and 5B, first, the silicon semiconductor substrate 1 is moved from the wafer carrier 2 and held by the support base 3 as in the case of FIG. Is polished and flattened. Subsequently, as shown in FIG. 5C, the surface of the silicon semiconductor substrate 1 is cleaned by nipping the pair of brushes 11. By this operation, the number of residual particles can be reduced to about ten. in this case,
Since the abrasive grains have hydrophilicity, rinsing constantly removes residual particles from the brush. Therefore, contamination of the subsequent silicon semiconductor substrate by the residual particles is prevented.

[0058]

According to the present invention, after the surface of a substrate to be polished is polished well, a simple cleaning process using an aqueous cleaning liquid mainly containing pure water or the like can be performed without performing a complicated cleaning process as in the prior art. By such cleaning, the polishing abrasive grains remaining on the surface of the substrate to be polished can be sufficiently removed, and metal contamination on the surface of the substrate to be polished can be easily and sufficiently removed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a structural formula in a process of forming abrasive grains according to a first embodiment of the present invention.

FIG. 2 is a schematic view for explaining a polishing step and a cleaning step of a silicon semiconductor substrate in the embodiment of the present invention.

FIG. 3 is a schematic view showing a structural formula in a process of forming abrasive grains according to a second embodiment of the present invention.

FIG. 4 is a schematic view showing a structural formula in a process of forming abrasive grains according to a third embodiment of the present invention.

FIG. 5 is a schematic diagram for explaining a polishing step and another cleaning step of the silicon semiconductor substrate in the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silicon semiconductor substrate 2 Wafer carrier 3 Support base 4 Abrasive supply mechanism 5 Polishing cloth 6 Surface plate 7 Cleaning tank

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masatoshi Sakai 9-19 Nihonbashi Tomizawa-cho, Chuo-ku, Tokyo Inside Fuso Siltec Co., Ltd. (72) Inventor Michihiro Yoshinaga 1-10-8 Nihonbashi-Horidomecho, Chuo-ku, Tokyo No. ITOCHU Techno-Chemical Co., Ltd.

Claims (16)

[Claims] An abrasive having a hydrophilic surface and an absolute value of a surface potential (zeta potential) of 50 mV or less at pH7. 2. An abrasive having a hydrophilic surface and comprising abrasive grains having an absolute value of a surface potential (zeta potential) of 50 mV or less at pH7. 3. The abrasive grains are silicon oxide having an absolute value of surface potential (zeta potential) of 25 mV or less at pH 7, cerium oxide of 40 mV or less, zirconium oxide of 45 mV or less, or manganese oxide of 30 mV or less. 3. The abrasive according to claim 2, wherein: 4. A polishing agent characterized by containing abrasive grains in which at least a part of the terminal is substituted by a hydrophilic functional group. 5. The polishing agent according to claim 4, wherein the hydrophilic functional group is a hydroxyl group, a carboxyl group, an amino group or a sulfo group. 6. The polishing grain according to claim 4, wherein the abrasive is an oxide of at least one metal selected from the group consisting of light metals, transition metals and rare earth metals.
The abrasive according to the above. 7. The polishing agent according to claim 6, wherein the metal group comprises aluminum, zirconium, manganese, titanium, cerium, barium, and copper. 8. The method according to claim 1, wherein the polishing abrasive is a metal alkoxide of at least one metal selected from the group consisting of light metals, transition metals and rare earth metals.
The abrasive according to claim 4, wherein the abrasive is prepared by a gel method. 9. A polishing method for polishing a surface of a substrate to be polished using an abrasive, wherein the surface of the substrate to be polished has a hydrophilic surface, and the absolute value of the surface potential (zeta potential) is 50 mV at pH 7
A method for polishing a substrate to be polished, comprising a first step of polishing using the following polishing abrasive grains. 10. The method according to claim 1, further comprising, after the first step, a second step of cleaning the polished surface of the substrate to be polished with an aqueous cleaning liquid to remove the polishing abrasive grains remaining on the surface. The polishing method according to claim 9, wherein: 11. The polishing method according to claim 9, wherein at least a part of the terminal of the polishing abrasive grain is substituted with a hydrophilic functional group. 12. The polishing method according to claim 11, wherein the hydrophilic functional group is a hydroxyl group, a carboxyl group, an amino group or a sulfo group. 13. The polishing method according to claim 9, wherein the polishing abrasive is an oxide of at least one metal selected from the group consisting of a light metal, a transition metal and a rare earth metal. Method. 14. The polishing method according to claim 13, wherein the group of metals comprises aluminum, zirconium, manganese, titanium, cerium, barium, and copper. 15. The abrasive grain is prepared by a sol-gel method using a metal alkoxide of at least one metal selected from a metal group consisting of light metals, transition metals and rare earth metals as a starting material. The polishing method according to claim 9, wherein: 16. The abrasive grains are silicon oxide having an absolute value of surface potential (zeta potential) of 25 mV or less at pH 7, cerium oxide of 40 mV or less, zirconium oxide of 45 mV or less, or manganese oxide of 30 mV or less. The polishing method according to claim 9, wherein: