JP2003234315A - Polishing liquid for cmp process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide polishing liquid capable of stably showing superior polishing characteristics. <P>SOLUTION: The polishing liquid for CMP process containing polishing materials and an aqueous solvent has a characteristic presented by a relation between polishing speed (R), which is measured by a polishing-speed measuring method explained below, and the pressure of a polishing head (P) in equation (1) which is represented by a line (T). (1) R=aP+A, where A is no less than -900 and not more than 500 and a is not less than 50 and not more than 500. 'The method of measuring polishing speed' is constituted such that: a silicon wafer formed by a specified manner, having a silicon oxide film on the surface, is fixed on the polishing head; and this wafer is pressed on a polishing pad fixed on a polishing disk at a polishing head pressure of 5-20 kPa and polished for one minute by rotating the disk and the head at a respective rotational speed by supplying the polishing liquid to the pad. Film thicknesses at 49 locations are measured to obtain average values before and after the polishing and the difference between these average values provides the polishing rate (Å/min) at respective polishing head pressure. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polishing liquid for a CMP process. More specifically, it relates to a polishing liquid for a CMP process when manufacturing a semiconductor element, and is particularly used in a step of flattening an interlayer insulating film, a step of separating shallow trench elements, a step of forming a buried layer in a groove such as a capacitor or a metal wiring. The present invention relates to a polishing liquid for CMP process.

[0002]

2. Description of the Related Art Conventionally, in the CMP process, a technique has been known in which a polymer type anionic surfactant is used in combination with a polishing liquid for the purpose of improving the flatness after polishing (Japanese Patent Laid-Open No. 20-200200).
01-57353). CMP is a polishing method for removing the level difference of a pattern formed on the surface of a device wafer and planarizing it, and is a mechanochemical polishing (Chemical Chemical) that combines chemical polishing and mechanical polishing.
al Mechanical Planarizatio
n) is meant.

[0003]

However, this method has a problem in that aggregating occurs when the polymer type anionic surfactant and the polishing liquid are mixed with each other and the device wafer is scratched, resulting in defects in polishing characteristics. There is. further,
Even after the cleaning, there is a problem that the polymer type anionic surfactant and the abrasive are likely to remain on the surface of the work piece, and the yield rate of the device wafer cannot be increased. In addition, it is necessary to mix the two liquids of the polymer type anionic surfactant and the abrasive just before polishing, which causes a problem of low workability. That is, an object of the present invention is to provide a polishing liquid for a CMP process that can stably exhibit excellent polishing characteristics (flatness, low residual abrasive, low scratch, etc.).

[0004]

As a result of intensive studies to achieve the above object, the present inventor has solved the above problems by using a polishing liquid having a specific correlation between the polishing rate and the polishing head pressure. As a result, they have reached the present invention.
That is, the present invention comprises an abrasive and an aqueous solvent,
Polishing rate (R) measured by the following polishing rate measuring method <
A straight line (T) obtained by approximating Å / min> and polishing head pressure (P) <kPa> by a linear approximation method is represented by the following general formula (1), and is a polishing liquid for a CMP process. General formula R = aP + A (1) However, A is -900 or more and 500 or less, and a is 50.
The above is 500 or less.

<Polishing Rate Measuring Method> A silicon wafer having a diameter of 8 inches and having a silicon oxide film (thickness: 15,000Å) formed by tetraethoxysilane (TEOS) -plasma CVD method on the surface thereof is held on a polishing head. A silicon wafer is pressed against a polishing pad held on a polishing platen at a polishing head pressure of 5, 10, 15 or 20 kPa, and a polishing liquid at 25 ° C. is supplied to the polishing pad at 200 ml / min, while rotating the polishing platen. Polish at 58 rpm for 1 minute while rotating the polishing head at a rotation speed of 60 rpm.
Silicon wafers before polishing and after polishing at each polishing head pressure are located in the center and concentric circles, respectively 4
The film thickness at 9 locations is measured by an optical interference film thickness measuring device to obtain an arithmetic mean value, and the difference in the average film thickness before and after polishing is defined as the polishing rate (Å / min) at each polishing head pressure.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventor has found that in the above general formula (1), the value of A is a polishing characteristic, that is, when a device wafer having a step on the surface is polished, the recess of the step is not polished, It has been found that there is a large correlation with the property that only the convex portions can be selectively polished (step relief property). That is, in the general formula (1), A is 500 or less, preferably 400 or less, more preferably 300 or less, and particularly preferably 200 or less. A is -900 or more, preferably -800 or more, more preferably -500 or more, and particularly preferably -200 or more. A
When the value is less than -900 or more than 500, the step relaxation performance when polishing a device wafer having a step on the surface becomes poor, that is, the polishing characteristics (flatness characteristics) become poor. A
The value of can be generally controlled by the particle size of the abrasive and the addition amount of the additive such as the surfactant, and the particle size of the abrasive is decreased or the amount of the additive such as the surfactant is increased. It tends to be smaller. Conversely, A tends to increase as the particle size of the abrasive increases.

A is 500 or less, preferably 45
It is 0 or less, more preferably 400 or less, and particularly preferably 350 or less. Further, a is 50 or more, preferably 60 or more, more preferably 70 or more, and particularly preferably 100 or more. If a is less than 50, the polishing rate becomes slow. If it exceeds 500, the polishing rate becomes fast, so that process control becomes difficult and the productivity tends to decrease. In general, the value of a tends to increase as the particle size of the abrasive increases, and tends to decrease as the particle size decreases. A CMP in which the relationship obtained by approximating the polishing rate (R) and the polishing head pressure (P) measured by the above polishing rate measurement method by the linear approximation method is represented by the general formula (1).
When used as a process polishing liquid, excellent polishing characteristics (flatness, etc.) are likely to be stably exhibited.

Next, the polishing rate measuring method will be described.
The silicon wafer used in this polishing rate measurement method is tetraethoxysilane (TEOS) -plasma CVD according to a conventional method.
It is a silicon wafer having a silicon oxide film with a thickness of 15,000Å formed on the surface thereof and having a diameter of 8 inches. The thickness is 0.75 mm. Such a silicon wafer can be obtained, for example, from SEMATECH.

As the polishing pad, a circular polishing pad having a diameter of 24 inches is used, which is obtained by laminating two layers of a soft support layer made of a non-woven fabric as a base material and a closed foam layer having grooves. As such a polishing pad, for example, Rodel (Rod)
EL company IC1000 (050) K-Groove /
S400 can be used.

The polishing apparatus has a polishing platen (having a diameter of 24 inches or more) and a polishing head. The rotation number of the polishing platen can be set to 58 rpm, the rotation number of the polishing head can be set to 60 rpm, and the polishing head pressure is 5. , 10, 15 or 20 kPa. Furthermore, the polishing liquid is supplied at 25 ° C.
Can be added dropwise at 200 ml / min. As the polishing device, for example, a single-side polishing machine (MAT-ARW681
M: manufactured by MUTI Co., Ltd.) can be used.

The average film thickness difference is determined for each silicon wafer before polishing and after polishing at each polishing head pressure, and this is taken as the polishing rate (Å / min) at the polishing head pressure. As the film thickness measurement points, 49 points are located in the central part of the silicon wafer and concentrically, that is, the central part of the silicon wafer, 8 concentric circles having a diameter of 6 cm with the central part as the center of the circle, and the same 12 cm in diameter. Concentric 1
There are 6 places and 24 concentric circles with the same diameter of 18 cm (black circles in FIG. 1). The film thickness is measured by an optical interference film thickness measuring device. As an optical interference film thickness measuring device,
For example, Nanospec / AFT M6100 (manufactured by Nanometrics) can be used.

As the polishing liquid satisfying the formula (1), it is possible to use one in which an abrasive is dispersed in an aqueous solvent. The aqueous solvent means a solvent containing water as an essential component. The aqueous solvent is preferably an aqueous solvent in which the hardness of the polishing pad measured using the aqueous solvent is equal to or less than the hardness of the polishing pad measured using 2% by weight ammonia water. By satisfying it, the polishing characteristics (flatness characteristics) are dramatically improved. That is, it is preferable that the aqueous solvent satisfies the following general formula (2). General formula (ks) ≧ (ka) (2) [(ks) is the hardness of the polishing pad measured using an aqueous solvent, and (ka) is the hardness of the polishing pad measured using 2 wt% ammonia water. The hardness of the polishing pad is measured by the following measuring method. ] Method for measuring hardness of polishing pad; polishing pad 5 cm x 1.5
The sample is cut into cm, immersed in 200 ml of an aqueous solvent or 200 ml of 2% by mass ammonia water, allowed to stand at 70 ° C. for 20 hours in a closed state, and then measured according to JIS 7215 (1986) Durometer hardness type D test method for plastics. The polishing pad has a thickness of 1.17 to 1.37 mm,
The hardness measured according to JIS D 7215 (1986) plastic durometer hardness type D test method is 52 to 62, and the hardness measured according to JIS 7222 (1985) density measurement method of hard foamed plastic is 0.6 to
0.85 g / cm3 of polyurethane foam is used. Further, as the polishing pad, a polishing pad having a compression rate (described in detail semiconductor CMP technology [Japan Industrial Research Institute] P112) of 0.5 to 4.0% using an automatic compression rate measuring device designated by Rodel is used. It is preferable that it is easier to determine the hardness change in the hardness measurement test. A specific example of this is IC1000 manufactured by Rodel Company.

As the aqueous solvent satisfying the above conditions, an aqueous solvent containing a basic substance is preferable. The basic substance is not particularly limited as long as it dissolves in water and exhibits basicity, and for example, ammonia, amines, alkali metal hydroxides and alkali metal salts of weak acids can be used.

Examples of amines include alkylamines, polyamines, and amino alcohols. Examples of the alkylamine include monoalkylamines having 1 to 8 carbon atoms (isopropylamine, isobutylamine, etc.), dialkylamines having 2 to 12 carbon atoms (dipropylamine, diisopropylamine, dibutylamine, diisobutylamine, dipropylammonium hydroxide). , Diisopropylammonium hydroxide, etc.), trialkylamine having 3 to 16 carbon atoms (tripropylamine, triisopropylamine, triisobutylamine, etc.), tetraalkylammonium hydroxide having 4 to 20 carbon atoms (tetramethylammonium hydroxide, And tetraethylammonium hydroxide).

Examples of the polyamine include the following. (1) Aliphatic polyamine (C2-18): For example, C2-C6 alkylenediamine [ethylenediamine,
Propylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, etc.], polyalkylene (C2-6) polyamine [diethylenetriamine, iminobispropylamine, bis (hexamethylene) triamine, triethylenetetramine, tetraethylenepentamine , Pentaethylenehexamine, etc.], N-alkyl (C1 to C4) or N-hydroxyalkyl (C2 to C4) substitution products thereof (dialkyl (C1 to C3) aminopropylamine, trimethylhexamethylenediamine) , Aminoethylethanolamine, methyliminobispropylamine, etc.]; Aliphatic or heterocyclic aliphatic polyamines having 1 to 16 carbon atoms, for example, 3,9-bis (3-aminopropyl) -2,4,8,10 -Tetraoxaspiro [5 5] undecane; carbon atoms 8 to 16
Aromatic ring-containing aliphatic amines such as xylylenediamine, tetrachloro-p-xylylenediamine, and the like; (2) Alicyclic polyamines (having 4 to 16 carbon atoms), such as 1,3-diaminocyclohexane, isophoronediamine, and menthanediamine. , 4,4'-methylenedicyclohexanediamine (hydrogenated methylenedianiline) and the like; (3) Heterocyclic polyamine (having 4 to 16 carbon atoms), for example, piperazine, N-aminoethylpiperazine, 1,4-diaminoethylpiperazine and the like. ;

(4) Aromatic polyamines (having 6 to 2 carbon atoms)
0): unsubstituted aromatic polyamine, for example 1,2-, 1,
3- and 1,4-phenylenediamine, 2,4'- and 4,4'-diphenylmethanediamine, crude diphenylmethanediamine [polyphenylpolymethylenepolyamine], diaminodiphenylsulfone, benzidine, thiodianiline, bis (3,4-diamino) Phenyl) sulfone, 2,6-diaminopyridine, m-aminobenzylamine, triphenylmethane-4,4 ', 4 "-triamine, naphthylenediamine; nuclear-substituted alkyl groups (e.g. methyl, ether, n- and i-). Aromatic polyamines having an alkyl group having 1 to 4 carbon atoms such as propyl and butyl, such as 2,4- and 2,6-tolylenediamine,
Crude tolylenediamine, diethyl tolylenediamine, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 4,4'-bis (o-toluidine), dianisidine, diaminoditolyl sulfone, 1,3-dimethyl- 2,4-diaminobenzene, 1,3-diethyl-2,
4-diaminobenzene, 1,3-dimethyl-2,6-diaminobenzene, 1,4-diethyl-2,5-diaminobenzene, 1,4-diisopropyl-2,5-diaminobenzene, 1,4-dibutyl- 2,5-diaminobenzene, 2,4-diaminomesitylene, 1,3,5-triethyl-2,4-diaminobenzene, 1,3,5-triisopropyl-2,4-diaminobenzene, 1-methyl-
3,5-diethyl-2,4-diaminobenzene, 1-methyl-3,5-diethyl-2,6-diaminobenzene,
2,3-dimethyl-1,4-diaminonaphthalene, 2,
6-dimethyl-1,5-diaminonaphthalene, 2,6-
Diisopropyl-1,5-diaminonaphthalene, 2,6
-Dibutyl-1,5-diaminonaphthalene, 3,3 ',
5,5'-tetramethylbenzidine, 3,3 ', 5,5
′ -Tetraisopropylbenzidine, 3,3 ′, 5,5
′ -Tetramethyl-4,4′-diaminodiphenylmethane, 3,3 ′, 5,5′-tetraethyl-4,4′-diaminodiphenylmethane, 3,3 ′, 5,5′-tetraisopropyl-4,4 ′ -Diaminodiphenylmethane,
3,3 ', 5,5'-Tetrabutyl-4,4'-diaminodiphenylmethane, 3,5-diethyl-3'-methyl-2', 4-diaminodiphenylmethane, 3,5-diisopropyl-3'-methyl- 2 ', 4-diaminodiphenylmethane, 3,3'-diethyl-2,2'-diaminodiphenylmethane, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 3,3', 5,5'-tetraethyl- 4,4'-diaminobenzophenone, 3,3
′, 5,5′-Tetraisopropyl-4,4′-diaminobenzophenone, 3,3 ′, 5,5′-tetraethyl-4,4′-diaminodiphenyl ether, 3,3 ′,
5,5'-Tetraisopropyl-4,4'-diaminodiphenyl sulfone, mixtures of these isomers in various proportions;

Nuclear substitution electron withdrawing groups (eg Cl, Br,
Aromatic polyamines having halogens such as I and F; alkoxy groups such as methoxy and ethoxy; nitro groups, etc., such as methylenebis-o-chloroaniline, 4-chloro-o-
Phenylenediamine, 2-chloro-1,4-phenylenediamine, 3-amino-4-chloroaniline, 4-bromo-1,3-phenylenediamine, 2,5-dichloro-
1,4-phenylenediamine, 5-nitro-1,3-phenylenediamine, 3-dimethoxy-4-aminoaniline; 4,4'-diamino-3,3'-dimethyl-5,5
′ -Dibromo-diphenylmethane, 3,3′-dichlorobenzidine, 3,3′-dimethoxybenzidine, bis (4-amino-3-chlorophenyl) oxide, bis (4-amino-2-chlorophenyl) propane, bis (4-) Amino-2-chlorophenyl) sulfone, bis (4-amino-3-methoxyphenyl) decane, bis (4-aminophenyl) sulfide, bis (4-aminophenyl) telluride, bis (4-aminophenyl) selenide, bis ( 4-amino-3-methoxyphenyl) disulfide, 4,4'-methylenebis (2-iodoaniline), 4,4'-methylenebis (2-bromoaniline), 4,4'-methylenebis (2-fluoroaniline), 4-Aminophenyl-2-chloroaniline; aromatic polyamines having secondary amino groups [above Part or all of -NH2 of an aromatic polyamine is replaced by -NH-R '(R' is an alkyl group such as a lower alkyl group such as methyl or ether)] eg 4,4'-di (methylamino ) Diphenylmethane, 1-methyl-2-methylamino-4-aminobenzene;

(5) Polyamide polyamine [eg low molecular weight obtained by condensation of dicarboxylic acid (such as dimer acid) and excess polyamines (more than 2 mol per 1 mol of acid) (the above alkylenediamine, polyalkylenepolyamine etc.) Polyamide polyamine]; (6) Polyether polyamine [Hydrogenated cyanoethylated product of polyether polyol (polyalkylene glycol etc.)]; (7) Cyanoethylated polyamine [eg acrylonitrile and polyamines (the above alkylenediamine, polyalkylenepolyamine etc.)] Cyanoethylated polyamine obtained by addition reaction with, for example, biscyanoethyldiethylenetriamine, etc.] (8) Hydrazines (hydrazine, monoalkylhydrazine, etc.), dihydrazides (succinic acid dihydrazide) Adipic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, etc.), guanidines (butylguanidine, 1-cyanoguanidine, etc.), and dicyandiamide (9) chain amidines, cyclic amidines (imidazoles, imidazolines, pyrimidines) Etc.); and mixtures of two or more thereof.

(10) Quaternary Ammonium Salt of Amidines The following quaternary ammonium cations include the following. Examples of counter anions include, but are not limited to, halogen ions, carboxylate anions, sulfonate anions, phosphate anions, and the like. (I) Imidazolinium having 3 to 30 or more carbon atoms; 1,2,3-trimethylimidazolinium, 1,2,
3,4-Tetramethylimidazolinium, 1,3,4-trimethyl-2-ethylimidazolinium, 1,3-dimethyl-2,4-diethylimidazolinium, 1,2-dimethyl-3,4- Diethylimidazolinium, 1,2-dimethyl-3-ethylimidazolinium, 1-ethyl-3-
Methylimidazolinium, 1-methyl-3-ethylimidazolinium, 1,2,3,4-tetraethylimidazolinium, 1,2,3-triethylimidazolinium, 4-
Cyano-1,2,3-trimethylimidazolinium, 2-
Cyanomethyl-1,3-dimethylimidazolinium, 4
-Acetyl-1,2,3-trimethylimidazolinium,
3-acetylmethyl-1,2-dimethylimidazolinium, 4-methylcarboxymethyl-1,2,3-trimethylimidazolinium, 3-methoxy-1,2-dimethylimidazolinium, 4-formyl-1, 2,3-trimethylimidazolinium, 4-formyl-1,2-dimethylimidazolinium, 3-hydroxyethyl-1,2,
3-trimethylimidazolinium, 3-hydroxyethyl-1,2-dimethylimidazolinium, etc .;

(Ii) Imidazolium having 3 to 30 or more carbon atoms; 1,3-dimethylimidazolium, 1-ethyl-3-methylimidazolium, 1-methyl-3-ethylimidazolium, 1,2,2. 3-trimethylimidazolium, 1,2,3,4-tetramethylimidazolium,
1,3-dimethyl-2-ethylimidazolium, 1,2-
Dimethyl-3-ethylimidazolium, 1-ethyl-3
-Methyl imidazolium, 1-methyl-3-ethyl imidazolium, 1,2,3-triethyl imidazolium,
1,2,3,4-tetraethylimidazolium, 1,3-
Dimethyl-2-phenylimidazolium, 1,3-dimethyl-2-benzylimidazolium, 1-benzyl-
2,3-dimethylimidazolium, 4-cyano-1,
2,3-Trimethylimidazolium, 3-cyanomethyl-1,2-dimethylimidazolium, 4-acetyl-
1,2,3-trimethylimidazolium, 3-acetylmethyl-1,2-dimethylimidazolium, 4-carboxymethyl-1,2,3-trimethylimidazolium,
4-methoxy-1,2,3-trimethylimidazolium, 4-formyl-1,2,3-trimethylimidazolium, 3-formylmethyl-1,2-dimethylimidazolium, 3-hydroxyethyl-1,2- Dimethyl imidazolium, 2-hydroxyethyl-1,3-dimethyl imidazolium, N, N'-dimethylbenzimidazolim, N, N'-diethylbenzimidazolim, N-
Methyl-N'-ethylbenzimidazolium and the like;

(Iii) Tetrahydropyrimidinium having 4 to 30 or more carbon atoms; 1,3-dimethyltetrahydropyridinium, 1,2,3-trimethyltetrahydropyridinium, 1,2,3,4-tetramethyltetrahydropyridinium , 8-methyl-1,8-diazabicyclo [5,4,0] -7-undecenium, 5-methyl-
1,5-diazabicyclo [4,3,0] -5-nonenium, 4-cyano-1,2,3-trimethyltetrahydropyrimidinium, 3-cyanomethyl-1,2-dimethyltetrahydropyrimidinium, 4-acetyl -1, 2,
3-trimethyltetrahydropyrimidinium, 3-acetylmethyl-1,2-dimethyltetrahydropyrimidinium, 4-methylcarboxymethyl-1,2,3-trimethyl-tetrahydropyrimidinium, 4-methoxy-
1,2,3-trimethyltetrahydropyrimidinium,
3-methoxymethyl-1,2-dimethyltetrahydropyrimidinium, 4-hydroxymethyl-1,2,3-trimethyltetrahydropyrimidinium, 4-hydroxymethyl-1,3-dimethyltetrahydropyrimidinium and the like;

(Iv) dihydropyrimidinium having 4 to 30 or more carbon atoms; 1,3-dimethyl-2,4- or -2,6-dihydropyrimidinium [these are
It is written as 3-dimethyl-2,4, (6) -dihydropyrimidinium, and the same expression is used below. ], 1, 2, 3
-Trimethyl-2,4, (6) -dihydropyrimidinium, 1,2,3,4-tetramethyl-2,4, (6)-
Dihydropyrimidinium, 1,2,3,5-tetramethyl-2,4, (6) -dihydropymidinium, 8-methyl-1,8-diazacyclo [5,4,0] -7,9 ( 1
0) -undecanedienium, 5-methyl-1,5-diazacyclo [4,3,0] -5,7 (8) -nonadienium, 2-cyanomethyl-1,3-dimethyl-2,4.
(6) -Dihydropyrimidinium, 3-acetylmethyl-1,2-dimethyl-2,4, (6) -dihydropyrimidinium, 4-methylcarboxymethyl-1,2,3-
Trimethyl-2,4, (6) -dihydropyrimidinium, 4-methoxy-1,2,3-trimethyl-2,4
(6) -dihydropyrimidinium, 4-formyl-1,
2,3-trimethyl-2,4, (6) -dihydropyrimidinium, 3-hydroxyethyl-1,2-dimethyl-
2,4, (6) -dihydropyrimidinium, 2-hydroxyethyl-1,3-dimethyl-2,4, (6) -dihydropyrimidinium and the like;

(V) Guanidium having an imidazolinium skeleton having 3 to 30 or more carbon atoms; 2-dimethylamino-1,3,4-trimethylimidazolinium, 2-
Diethylamino-1,3,4-trimethylimidazolinium, 2-diethylamino-1,3-dimethyl-4-ethylimidazolinium, 2-dimethylamino-1-methyl-3,4-diethylimidazolinium, 2- Diethylamino-1,3,4-triethylimidazolinium, 2
-Dimethylamino-1,3-dimethylimidazolinium, 2-diethylamino-1,3-dimethylimidazolinium, 2-diethylamino-1,3-diethylimidazolinium, 1,5,6,7-tetrahydro-1 , 2-
Dimethyl-2H-imide [1,2a] imidazolinium, 1,5,6,7-tetrahydro-1,2-dimethyl-
2H-pyrimido [1,2a] imidazolinium, 1,5
-Dihydro-1,2-dimethyl-2H-pyrimido [1,2a] imidazolinium, 2-dimethyl-3-cyanomethyl-1-methylimidazolinium 2-dimethylamino-3-methylcarboxymethyl-1-methyl Imidazolinium, 2-dimethylamino-3-methoxymethyl-1-methylimidazolinium, 2-dimethylamino-4-formyl-1,3-dimethylimidazolinium,
2-dimethylamino-3-hydroxyethyl-1-methylimidazolinium, 2-dimethylamino-4-hydroxymethyl-1,3-dimethylimidazolinium and the like;

(Vi) Guanidium having an imidazolium skeleton having 3 to 30 or more carbon atoms; 2-dimethylamino-1,3,4-trimethylimidazolium, 2-diethylamino-1,3,4-trimethylimidazolium , 2-diethylamino-1,3-dimethyl-4-ethylimidazolium, 2-diethylamino-1-methyl-
3,4-diethylimidazolium, 2-diethylamino-1,3,4-triethylimidazolium, 2-dimethylamino-1,3-dimethylimidazolium, 2-dimethylamino-1-ethyl-3-methylimidazolium,
2-Diethylamino-1,3-diethylimidazolium, 1,5,6,7-tetrahydro-1,2-dimethyl-2H-imide [1,2a] imidazolium, 1,5
6,7-Tetrahydro-1,2-dimethyl-2H-pyrimido [1,2a] imidazolium, 1,5-dihydro-
1,2-Dimethyl-2H-pyrimido- [1,2a] imidazolium, 2-dimethylamino-3-cyanomethyl-
1-methylimidazolium, 2-dimethylamino-acetyl-1,3-dimethylimidazolium, 2-dimethylamino-4-methylcarboxymethyl-1,3-dimethylimidazolium, 2-dimethylamino-4-methoxy-1 , 3-dimethylimidazolium, 2-dimethylamino-3-methoxymethyl-1-methylimidazolium,
2-dimethylamino-3-formylmethyl-1-methylimidazolium, 2-dimethylamino-4-hydroxymethyl-1,3-dimethylimidazolium and the like;

(Vii) Guanidium having a tetrahydropyrimidinium skeleton having 4 to 30 or more carbon atoms; 2
-Dimethylamino-1,3,4-trimethyltetrahydropyrimidinium, 2-diethylamino-1,3,4-
Trimethyltetrahydropyrimidinium, 2-diethylamino-1,3-dimethyl-4-ethyltetrahydropyrimidinium, 2-diethylamino-1-methyl-3,
4-diethyltetrahydropyrimidinium, 2-dimethylamino-1,3-dimethyltetrahydropyrimidinium, 2-diethylamino-1,3-dimethyltetrahydropyrimidinium, 2-diethylamino-1,3-diethyltetrahydropyrimidinium , 1, 3, 4, 6,
7,8-Hexahydro-1,2-dimethyl-2H-imide [1,2a] pyrimidinium, 1,3,4,6,7,
8-Hexahydro-1,2-dimethyl-2H-pyrimido [1,2a] pyrimidinium, 2,3,4,6-tetrahydro-1,2-dimethyl-2H-pyrimido [1,2]
a] Pyrimidinium, 2-dimethylamino-3-cyanomethyl-1-methyltetrahydropyrimidinium, 2-
Dimethylamino-4-acetyl-1,3-dimethyltetrahydropyrimidinium 2-dimethylamino-4-methylcarboxymethyl-1,3-dimethyltetrahydropyrimidinium, 2-dimethylamino-3-methylcarboxymethyl-1- Methyltetrahydropyrimidinium,
2-Dimethylamino-3-methoxymethyl-1-methyltetrahydropyrimidinium, 2-dimethylamino-4
-Formyl-1,3-dimethyltetrahydropyrimidinium, 2-dimethylamino-3-hydroxyethyl-1
-Methyltetrahydropyrimidinium, 2-dimethylamino-4-hydroxymethyl-1,3-dimethyltetrahydropyrimidinium and the like;

(Viii) Guanidium having a dihydropyrimidinium skeleton having 4 to 30 or more carbon atoms; 2-
Dimethylamino-1,3,4-trimethyl-2,4
(6) -Dihydropyrimidinium, 2-diethylamino-1,3,4-trimethyl-2,4 (6) -dihydropyrimidinium, 2-dimethylamino-1-methyl-3,
4-diethyl-2,4 (6) -dihydropyrimidinium, 2-diethylamino-1-methyl-3,4-diethyl-2,4 (6) -dihydropyrimidinium, 2-diethylamino-1,3,3 4-triethyl-2,4 (6)-
Dihydropyrimidinium, 2-diethylamino-1,3
-Dimethyl-2,4 (6) -dihydropyrimidinium,
2-Diethylamino-1,3-dimethyl-2,4 (6)
-Dihydropyrimidinium, 2-dimethylamino-1-
Ethyl-3-methyl-2,4 (6) -dihydropyrimidinium, 1,6,7,8-tetrahydro-1,2-dimethyl-2H-imido [1,2a] pyrimidinium, 1,
6-dihydro-1,2-dimethyl-2H-imide [1,
2a] pyrimidinium, 1,6-dihydro-1,2-dimethyl-2H-pyrimido [1,2a] pyrimidinium,
2-dimethylamino-4-cyano-1,3-dimethyl-
2,4 (6) -dihydropyrimidinium, 2-dimethylamino-4-acetyl-1,3-dimethyl-2,4
(6) -Dihydropyrimidinium, 2-dimethylamino-3-acetylmethyl-1-methyl-2,4 (6) -dihydropyrimidinium, 2-dimethylamino-3-methylcarboxymethyl-1-methyl- 2,4 (6) -dihydropyrimidinium, 2-dimethylamino-4-methoxy-1,3-dimethyl-2,4 (6) -dihydropyrimidinium, 2-dimethylamino-4-formyl-1, Three
-Dimethyl-2,4 (6) -dihydropyrimidinium,
2-Dimethylamino-3-formylmethyl-1-methyl-2,4 (6) -dihydropyrimidinium, 2-dimethylamino-4-hydroxymethyl-1,3-dimethyl-
2,4 (6) -dihydropyrimidinium and the like;

The amino alcohols include alkanol amines such as mono-, di- and tri-alkanolamines (monoethanolamine, monoisopropanolamine, monobutanolamine, triethanolamine, tripropanolamine, etc.); Alkyl (C1-C4) substituted product [N, N-dialkylmonoalkanolamine (N, N-dimethylethanolamine, N, N-diethylethanolamine, etc.), N-alkyldialkanolamine (N-methyldiethanolamine, N-butyldiethanolamine, etc.)]; and a quaternary nitrogen atom formed by a quaternizing agent such as dimethylsulfate or benzyl chloride.

As the alkali metal hydroxide, for example,
Examples thereof include sodium hydroxide and potassium hydroxide. Examples of the weak acid alkali metal salt include alkali metal carbonates such as sodium carbonate and potassium carbonate, alkali metal acetates such as sodium acetate and potassium acetate, and alkali metal phosphates such as sodium phosphate and potassium phosphate and sodium polyphosphate. Salt etc. are mentioned.

Of these, preferred is ammonia,
Amines and alkali metal hydroxides. More preferred are ammonia and alkali metal hydroxides.

The content of the basic substance is determined by the above general formula (2).
There is no problem as long as it satisfies the formula, and it is 5% by weight or less, more preferably 3% by weight or less, particularly preferably 2% by weight or less, based on the weight of the polishing liquid. For example, 2% by weight or less is preferable when using ammonia and amine, and 0.05% by weight or less is preferable when using an alkali metal hydroxide.

The content of the aqueous solvent is preferably 50% by weight or more, more preferably 52% by weight or more, particularly preferably 55% by weight, based on the weight of the polishing liquid.
That is all. Further, it is preferably 99% by weight or less,
It is more preferably 95% by weight or less, and particularly preferably 90% by weight or less. Within this range, A in the general formula (1) easily falls within the above range, and as a result, more excellent polishing characteristics (flatness characteristics) are easily obtained.

As the abrasive, both inorganic powder and organic powder can be used. As the organic powder, epoxy resin powder, urethane resin powder, vinyl resin powder,
Polyester, benzoguanamine resin powder, silicone resin powder, novolac resin powder, phenol resin powder and the like are used. As the inorganic powder, metal oxide, metal nitride or the like is used. Examples of the metal oxide include metal oxides of lanthanoids of 4A group, 3B group, 4B group and 3A group of the long periodic table of elements, such as zirconium oxide, aluminum oxide, silicon dioxide and cerium oxide. Can be mentioned. Examples of the metal nitride include metal oxides of 4A, 3B and 4B of the periodic table of elements and lanthanoids, such as zirconium nitride, aluminum nitride, silicon nitride and cerium nitride.

Zirconium oxide includes monoclinic, tetragonal and amorphous zirconium oxides in terms of crystal system. Further, there is also one called fumed zirconia from the manufacturing method. Either can be used. Further, aluminum oxide includes α-alumina, δ-alumina, θ-alumina, κ-
There are alumina, and other morphologically different ones, and there is also one called fumed alumina from the manufacturing method, and any of them can be used. In addition, as silicon dioxide, there are various types of colloidal silica, fumed silica, and other manufacturing methods and manufacturing methods, but any of them can be used. In addition, cerium oxide includes trivalent and tetravalent cerium oxides, and hexagonal, equiaxed, and face-centered cubic crystals, depending on the crystal system. . Further, silicon nitride includes α-silicon nitride, β-silicon nitride,
Both amorphous silicon nitride and other morphologically different ones can be used.

Of these abrasives, inorganic powders are preferable, metal oxides are more preferable, silicon dioxide is particularly preferable, and colloidal silica is most preferable.

As described above, the volume average particle diameter of the abrasive is preferably small, specifically 150 nm or less, more preferably 100 nm or less, particularly preferably 70 nm or less, and 5 nm or more. Preferably, it is more preferably 10 nm or more, and particularly preferably 3 nm.
It is 0 nm or more. Within this range, A in the general formula (1) is likely to be in the above range, and as a result, more excellent polishing characteristics (flatness characteristics) are likely to be obtained. In addition,
The volume average particle diameter is measured according to the method of measuring particle diameter distribution of JIS R1629-1997 fine ceramic raw material by laser diffraction / scattering method.

In the polishing liquid of the present invention, the above-mentioned polishing materials can be optionally used in combination as required. The combination of abrasives used, the particle size, and the proportion used are not particularly limited. The content of the abrasive is preferably 1% by weight or more, more preferably 5% by weight or more, and particularly preferably 10% by weight, based on the weight of the polishing liquid.
That is all. Further, it is preferably 50% by weight or less,
It is more preferably 45% by weight or less, and particularly preferably 40% by weight or less. Within this range, A in the general formula (1) easily falls within the above range, and as a result, more excellent polishing characteristics (flatness characteristics) are easily obtained.

If desired, a surface active agent may be added to the polishing liquid of the present invention. Further, known additives such as a chelating agent, a rust preventive and / or an organic solvent can be added.

As the surface active agent, nonionic surface active agents, anionic surface active agents, cationic surface active agents and amphoteric surface active agents can be used. As the nonionic surfactant, those usually used for abrasives for CMP process can be used. For example, an aliphatic alcohol (having 8 to 2 carbon atoms) can be used.
4) Alkylene oxide (Alkylene has 2 to 8 carbon atoms)
Addition product (degree of polymerization = 1 to 100), polyoxyalkylene (alkylene having 2 to 8 carbon atoms, degree of polymerization = 1 to 100) higher fatty acid (carbon number 8 to 24) ester [polyethylene glycol monostearate (degree of polymerization = 20) and polyethylene glycol distearate (degree of polymerization = 30)
Etc.], polyhydric (divalent to 10 valent or higher) alcohol (carbon number 2 to 10) fatty acid (carbon number 8 to 24) ester [glyceryl monostearate, ethylene glycol monostearate, sorbitan monolaurate and dioleic acid Sorbitan, etc.], polyoxyalkylene (alkylene carbon number 2-8, degree of polymerization = 1-100) polyvalent (divalent to 10 valent or higher) alcohol (carbon number 2 to 10)
Higher fatty acid (C8-24) esters [polyoxyethylene monolaurate (degree of polymerization = 10) sorbitan and polyoxyethylene (degree of polymerization = 50) methyl glucoside dioleate, etc.], polyoxyalkylene (alkylene having 2 to 2 carbon atoms) 8, degree of polymerization = 1 to 100) alkyl (having 1 to 22 carbon atoms) phenyl ether, polyoxyalkylene (having 2 to 8 carbon atoms of alkylene, degree of polymerization = 1 to 100) alkyl (having 8 to 24 carbon atoms) amino ether, 1: 1 coconut oil fatty acid diethanolamide and alkyl (8 carbon atoms
-24) Dialkyl (C1-6) amine oxide [lauryl dimethyl amine oxide etc.] etc. are mentioned.

As the anionic surfactant, CM is usually used.
What is used for the abrasive for P process can be used, for example, carboxylic acid having 8 to 24 carbon atoms or a salt thereof, [polyoxyethylene (degree of polymerization = 1 to 100) sodium lauryl ether acetate, polyoxyethylene (polymerized Degree = 1 to 1
00) disodium lauryl sulfosuccinate, etc.], sulfuric acid salt having 8 to 24 carbon atoms [sodium lauryl sulfate, polyoxyethylene (degree of polymerization = 1 to 100) sodium lauryl sulfate, polyoxyethylene (degree of polymerization = 1 to 100)
100) lauryl sulfate triethanolamine, polyoxyethylene (degree of polymerization = 1 to 100) coconut oil fatty acid monoethanolamide sodium sulfate,], sulfonate having 8 to 24 carbon atoms [sodium dodecylbenzene sulfonate, etc.] and carbon number 8 to 24 phosphoric acid ester salts [sodium lauryl phosphate, etc.], other [sulfosuccinic acid polyoxyethylene (polymerization degree = 1 to 100) lauroyl ethanolamide disodium, coconut oil fatty acid methyl taurine sodium, coconut oil fatty acid sarcosine sodium, Coconut oil fatty acid sarcosine triethanolamine, N-coconut oil fatty acid acyl-L-glutamic acid triethanolamine, N-coconut oil fatty acid acyl-L-glutamate sodium, lauroylmethyl-β-alanine sodium, etc.]
Etc.

As the cationic surfactant, CM is usually used.
What is used for P process abrasives can be used, for example, quaternary ammonium salt type [stearyl trimethyl ammonium chloride, behenyl trimethyl ammonium chloride, distearyl dimethyl ammonium chloride, lanolin fatty acid aminopropyl ethyl dimethyl ammonium ether sulfate] , Amine salt type [stearic acid diethylaminoethylamide lactate, dilaurylamine hydrochloride, oleylamine lactate, etc.] and the like.

As the amphoteric surfactant, those usually used for abrasives for CMP process can be used. For example, betaine type amphoteric surfactants [coconut oil fatty acid amide propiyldimethylaminoacetic acid betaine, lauryldimethylaminoacetic acid betaine can be used. , 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, lauryl hydroxysulfobetaine, lauroylamidoethyl hydroxyethyl carboxymethyl betaine hydroxypropyl, etc.], amino acid type amphoteric surfactant [β-laurylaminopropionic acid Sodium and the like]. These surfactants can be used alone or as a mixture of two or more kinds. When a surfactant is used, its content is 0.000 based on the weight of the polishing liquid.
It is preferably 1% by weight or more, more preferably 0.001.
It is preferably not less than 0.01% by weight, more preferably not more than 0.01% by weight, further preferably not more than 7% by weight, particularly preferably not more than 5% by weight.

As the chelating agent, those which are usually used for abrasives for CMP process can be used. Examples thereof include sodium polyacrylate, sodium ethylenediaminetetraacetate, sodium succinate, 1-hydroxyethane-1,
1-diphosphonate sodium etc. are mentioned. When a chelating agent is used, its content is preferably 0.0001% by weight or more, more preferably 0.001% by weight or more, and particularly preferably 0.01% by weight, based on the weight of the polishing liquid. It is above, preferably 10% by weight or less, more preferably 7% by weight or less, and particularly preferably 5% by weight or less.

As the rust preventive, those usually used for abrasives for CMP process can be used, for example, salts of aliphatic carboxylic acids (oleic acid, stearic acid, etc.) with alkali metals or alkaline earth metals; Sulfonic acid (petroleum sulfonate, etc.); Phosphate ester (lauryl phosphate, etc.), silicates such as sodium silicate, calcium silicate, nitrite such as sodium nitrite, 1,2,3-benzotriazole, carboxybenzotriazole Benzotriazole and the like. In addition, these may use 2 or more types together.

Examples of the organic solvent include alcohols having 1 to 3 carbon atoms (methanol, ethanol, isopropanol, etc.), ethers having 2 to 4 carbon atoms (dimethyl ether, diethyl ether, etc.), and ketones having 3 to 6 carbon atoms (acetone and methyl). Isobutyl ketone etc.) and mixtures thereof are used. Of these, alcohols having 1 to 3 carbon atoms are preferable, and methanol, ethanol and isopropanol are more preferable. The content of the organic solvent is preferably 10% by weight or less, more preferably 3% by weight or less, and particularly preferably 1% by weight or less, based on the weight of the aqueous solvent.

The polishing liquid of the present invention can be manufactured by the same method as that for the ordinary polishing material for CMP process. The polishing liquid is supplied from the polishing liquid storage tank to the vicinity of the polishing head on the polishing surface plate of the polishing apparatus by using a metering pump. After polishing, polishing liquid, polishing debris, etc. remaining on the silicon wafer are removed by washing. The cleaning device is a normal batch type,
Any of the single-wafer type can be used. The polishing liquid of the present invention is
It is ideal for surface flattening of device wafers and liquid crystal display substrates in the semiconductor industry.

[0046]

The present invention will be further described below with reference to examples, but the present invention is not limited thereto.

Example 1 Colloidal silica (volume average particle diameter 50 nm) was dispersed in a 1.0 wt% ammonia aqueous solution using a stirrer to prepare a polishing liquid 1 having an abrasive concentration of 30 wt% and a pH of 10.8. .

Example 2 Colloidal silica (volume average particle size 70 nm) was dispersed in a 0.01 wt% potassium hydroxide aqueous solution using a stirrer to prepare a polishing liquid 2 having an abrasive concentration of 30 wt% and a pH of 9.8.
Was prepared.

Example 3 Colloidal silica (volume average particle diameter 50 nm) was dispersed in a 0.01 wt% potassium hydroxide aqueous solution using a stirrer to prepare a polishing liquid 3 having an abrasive concentration of 30 wt% and a pH of 9.8.
Was prepared.

Example 4 Colloidal silica (volume average particle size 70 nm) was dispersed in a 2 wt% potassium hydroxide aqueous solution using a stirrer to prepare a polishing liquid 4 having an abrasive concentration of 30 wt% and a pH of 11.5. .

Comparative Example 1 Colloidal silica (volume average particle diameter 200 nm) was dispersed in a 0.01 wt% potassium hydroxide aqueous solution using a stirrer to prepare a polishing liquid 5 having an abrasive concentration of 30 wt% and a pH of 9.8. did.

Comparative Example 2 Fumed silica (average volume particle diameter 150 nm) was dispersed in a 0.5 wt% potassium hydroxide aqueous solution using a stirrer, and a polishing liquid 6 having an abrasive concentration of 13 wt% and a pH of 10.8 was prepared. Was prepared.

Comparative Example 3 Cerium oxide (average volume particle diameter 250 nm) was dispersed in water using a stirrer. Then, 2% by weight of an aqueous solution of ammonium polyacrylic acid salt was added to this dispersion to prepare a polishing solution 7 having an abrasive concentration of 1% by weight and a pH of 8.3.

<Correlation of Polishing Speed with Polishing Head Pressure Measured by Using Aqueous Solvent Used in Examples> Polishing tests of blanket wafers with the polishing solutions 1 to 7 of Examples 1 to 4 and Comparative Examples 1 to 3 went. As the work piece,
An 8-inch diameter silicon wafer on which a silicon oxide film having a thickness of 15,000 Å was formed by tetraethoxysilane (TEOS) -plasma CVD method was used. For polishing, a single-sided polishing machine (MAT-ARW681M: manufactured by MU) was used, and the polishing pad was IC1000 (050).
K-Groove / Suba400 (made by Rodel)
Was used.

Polishing conditions are as follows: polishing head pressure at polishing is 5,
For four conditions of 10, 15 and 20 kPa, the polishing head rotation speed was 58 rpm, and the polishing platen rotation speed was 60 rp.
m, polishing liquid flow rate 200 ml / min, polishing liquid temperature 25 ° C.,
Polishing was carried out for a polishing time of 1 minute. Before and after polishing under the above four conditions, an optical interference type film thickness measuring device (Nanospec / AFTM
6100: manufactured by Nanometrics Co., Ltd.) was used to determine the arithmetic mean value of the film thickness at 49 concentric circles on the silicon wafer. The polishing rate was calculated from these values, and the correlation of the polishing rate with respect to the polishing head pressure was determined by the linear approximation method. The obtained (a) and (A) are shown in Table 1.

<Hardness of Polishing Pad Measured Using Aqueous Solvent Used in Examples> Examples 1 to 4 and Comparative Examples 1 to
The hardness (ks) of the polishing pad was measured using the aqueous solvent used in the polishing liquids 1 to 7 of No. 3. And the hardness (ka) of the polishing pad was measured using a 2 wt% aqueous ammonia solution 8.
The test was carried out by polishing a 5 cm * 1.5 cm polishing pad (product name: IC1000 [Rodale], thickness: 1.27 mm,
A compressibility of 1.0% and a density of 0.73 g / cm3) are dipped in 200 ml of an aqueous solvent contained in a glass bottle, and left in a circulating air dryer at 70 ° C for 20 hours. After lightly wiping the surface of the taken-out polishing pad, the hardness of the polishing pad is measured based on the test method of JIS D 715 (1986) plastic durometer hardness type D. The hardness (ks and ka) of the obtained polishing pad is shown in Table 1.

<Evaluation 1: Flatness> Next, a polishing test was carried out on these patterned wafers having surface irregularities with these polishing liquids. A SKW7-2 (manufactured by SKW) pattern wafer was used as a workpiece. Polishing is one side polishing machine M
AT-ARW681M (manufactured by MUT) is used, and the polishing pad is IC1000 (050) K-Groove.
/ Suba400 (made by Rodel) was used. The polishing conditions are as follows: polishing head pressure at polishing is 40 kPa, polishing head rotation speed is 58 rpm, and polishing platen rotation speed is 60 rp.
m, the flow rate of the polishing liquid was 200 ml / min, and the polishing time was 1 minute.

The patterned wafer after polishing was thoroughly washed in running water, water droplets adhering to the semiconductor substrate were wiped off by using a spin dryer or the like, and then dried to obtain an optical interference type film thickness measuring instrument (Nanospec / AFT 6100A). (Made by Nanometrics Co., Ltd.) at the center of the wafer, at half of the radius at 6 o'clock, at half of the radius at 9 o'clock, at half of the radius at 12 o'clock and at the edge of 3 o'clock The ratio of the line widths of the convex portion and the concave portion in the existing 5 dies is 10:90, 3
0:70, 40:60, 50:50, 60:40, 7
7 points of 0:30 and 90:10 were measured, the average value of the difference in the film thickness between the convex portion and the concave portion at each point was calculated as the residual step of the wafer, and the results determined by the following criteria are shown in Table 1. It was

[0059] ◎: Less than 2000Å ○: 2000 Å or more and less than 3000 Å △: 3000 Å or more and less than 5000 Å ×: 5000 Å or more

<Evaluation 2: Number of remaining abrasives and number of scratches>
Surf Scan A for patterned wafer polished in Evaluation 2
IT1 (manufactured by KLA-Tencor Co., Ltd.) was used to observe the number of residual abrasives and the number of scratches on the wafer due to polishing. The number of residual abrasive agglomerates and scratches of 0.2 μm or more existing on the wafer was judged according to the following criteria and is shown in Table 1. ◎: Less than 20 ○: 20 or more and less than 30 △: 30 or more and less than 50 ×: 50 or more

[0061]

[Table 1]

From the results shown in Table 1, when polishing is performed using the polishing liquid for CMP process of the present invention, polishing performance (flatness performance) is obtained.
It is found that the surface finish of the wafer is excellent, with less residual abrasive and less scratches.

[0063]

INDUSTRIAL APPLICABILITY The polishing liquid for CMP process of the present invention is superior in polishing performance (flatness performance, residual polishing material performance) to the polishing liquid for CMP process which has been conventionally used, and is industrially used. It has a great utility value.

[0064]

[Brief description of drawings]

FIG. 1 is a schematic diagram showing measurement points of a film thickness of a silicon wafer.

Claims (6)

[Claims] 1. A polishing rate (R) <Å containing an abrasive and an aqueous solvent and measured by the following polishing rate measuring method.
/ Min> and the polishing head pressure (P) <kPa> by a linear approximation method is represented by the following general formula (1): CMP process polishing liquid. General formula R = aP + A (1) However, A is -900 or more and 500 or less, and a is 50 or more and 500 or less. <Polishing speed measurement method> Tetraethoxysilane (TEOS)
A silicon oxide film (thickness 15,
A silicon wafer having a diameter of 000Å) on the surface is held on a polishing head, and the polishing head pressure is set to 5, 1 on the polishing pad held on the polishing platen.
While pressing at 0, 15 or 20 kPa and supplying the polishing liquid at 25 ° C. onto the polishing pad at 200 ml / min, the polishing platen was rotated at a rotation speed of 58 rpm and the polishing head was rotated at a rotation speed of 6
Polish for 1 minute while rotating at 0 rpm. For silicon wafers before polishing and after polishing with each polishing head pressure, the film thickness at 49 locations located in the center and concentric circles is measured by an optical interference film thickness measurement device to obtain an arithmetic mean value, and before and after these polishing. The difference in the average film thickness of the above is defined as the polishing rate (Å / min) at each polishing head pressure. 2. The polishing liquid according to claim 1, wherein the aqueous solvent satisfies the following general formula (2). General formula (ks) ≧ (ka) (2) [(ks) is the hardness of the polishing pad measured using an aqueous solvent, and (ka) is the hardness of the polishing pad measured using 2 wt% ammonia water. The hardness of the polishing pad is measured by the following measuring method. ] Method for measuring hardness of polishing pad; polishing pad 5 cm x 1.5
The sample is cut into cm, immersed in 200 ml of an aqueous solvent or 200 ml of 2% by mass ammonia water, allowed to stand at 70 ° C. for 20 hours in a closed state, and then measured according to JIS 7215 (1986) Durometer hardness type D test method for plastics. The polishing pad has a thickness of 1.17 to 1.37 mm,
JIS 7215 (1986) Durometer hardness of plastic type D has a hardness of 52 to 62, and JIS
7222 (1985) has a density of 0.6 to 0.85 g / cm3 measured by the method for measuring the density of rigid foamed plastic.
Polyurethane foam is used. 3. The polishing liquid according to claim 1, wherein the abrasive is at least one kind of inorganic particles selected from the group consisting of silicon dioxide, aluminum oxide, cerium oxide, silicon nitride and zirconium oxide. 4. The volume average particle diameter of the abrasive is 1 nm or more and 1
The polishing liquid according to claim 1, which has a thickness of 20 nm or less. 5. The polishing liquid according to claim 1, wherein the polishing material is colloidal silica. 6. A method for producing a device wafer, which includes a polishing step using the polishing liquid according to claim 1.