high-density area (convex region: 70%) and in the low-den› sity area ( convex region: 10%) was 57 to 64 run, while the difference in concave-region residual SiO$_{2 }$ film thickness between them was 165 to 186 run, indicating that influence by the difference in pattern density occurred and irregular pol- ishing was performed. 

The experimental results above show that the wafer was polished uniformly with little influence by the difference in pattern density in Examples 1 to 6. In particular, in Examples 1 to 4, the wafer was polished enough uniformly ata favorable 10 polishing speed with less influence due to the pattern density difference. 

The present invention provides a polishing slurry for use in CMP methods of smoothening the surface of an interlayer dielecrtric film, a BPSG film, a shallow-trench-isolation insu› lation film, and the like, that is resistant to the fluctuation in film thickness due to difference in pattern density, allows polishing of a silicon oxide film and others in high-speed processing and easier process management, and a polishing method by using the polishing slurry. 

The invention claimed is: 

1. A method of producing a CMP polishing slurry, com› prising preparing ingredient (A) cerium oxide particles, ingredient (B) a dispersant, ingredient (C) water, 

obtaining a solution containing ingredient (D) selected from the group consisting of at least one of a polymer of at least one of a methacrylic acid and the salt thereof, a polymer of at least one of a methacrylic acid and the salt thereof and a monomer having an unsaturated double bond, and mixtures thereof, synthesized with use of a polymerization initiator, and 

mixing the ingredients (A), (B), (C) and (D) to prepare the CMP polishing slurry, 

wherein the polymerization initiator is a compound soluble completely at 25° C. when it is added at a ratio of 0.5 mass part in 99.5 mass parts of water or a compound soluble at 25° C. when it is added at a ratio of0.5 mass part in 99 .5 mass parts of water and at least one of an organic acid and an inorganic acid is added thereto in an amount of 2 moles with respect to 1 mole of the poly- merization initiator, 

wherein the content of the methacrylic acid and the salt thereof for the polymer (D) is 10 to 100 tool % with respect to the total amount of the monomer components, 

the amount of dispersant added is 0.01 mass parts or more and 10 mass parts or less with respect to 100 mass parts of the cerium oxide particles, 

the amount of cerium oxide particles added is 0.1 to 5 mass parts with respect to 100 mass parts of the CMP polish› ing slurry, the polymer (D) has a weight-average molecular weight of 200 to 100,000, 

the amount of the polymer (D) is 0.01 to 5 mass parts with respect to 100 mass parts of the CMP polishing slurry, and 

(IV): 

(I) at least one peroxide selected from the group consisting of anm10nium persulfate, potassium persulfate, and sodium persulfate, 

(II) at least one redox initiator initiators in combination of a sulfite salt, and selected from the combinations of (i) at least one selected from the group consisting of ammo- nium sulfite, ammonium hydrogen sulfite, potassium sulfite, potassium hydrogen sulfite, sodium sulfite, and 

## INDUSTRIAL APPLICABILITY 

sodium hydrogen sulfite and (ii) at least one selected from the group consisting of oxygen, air, and peroxide, 

(III) 2,2’-azobis[N-(2-carboxyethyl)-2-methyl propiona› mide ]amphoteric azo compound and 

(IV) at least one cationic azo compound selected from the group consisting of l-[(1-cyano-1-methylethyl)azo]for› mamide, 2,2’-azobis {2-methyl-N-[l,1-bis(hydroxym› ethyl)-2-hydroxyethyl]propionamide }, 2,2’-azobis{ 2- methyl-N-[2-(l-hydroxybutyl)]-propionamide }, 2,2’› azo bis[2-methyl-N-(1-hydroxyethy I) ]-propionamide, 2,2’-azo bis[2-( 5-methy 1-2-imidazolin-2-yl )propane] hydrochloride salt, 2,2’-azobis[2-(2-imidazolin-2-yl) propane], 2,2’-azobis[2-(2-imidazolin-2-yl)propane] hydrochloride salt, 2,2’-azobis[2-(2-imidazolin-2-yl) propane]sulfate hydrate salt, 2,2’-azobis[2-(3,4,5,6- tetrahydropyrimidin-2-yl)propane]hydrochloride salt, 2,2’-azobis { 2-[ 1-(2-hydroxyethyl)-2-imidazolin-2-yl] propane }hydrochloride salt, 2,2’-azobis[N-(2-carboxy› ethyl)-2-methylpropionamidine], and 2,2’-azobis(2-me› thyl propionamidoxime ). 

2. A method of producing a CMP polishing slurry, com› prising preparing ingredient (A) cerium oxide particles, ingredient (C) water, 

obtaining a solution containing ingredient (D) selected from the group consisting of at least one of a polymer of at least one of a methacrylic acid and the salt thereof, a polymer of at least one of a methacrylic acid and the salt thereof and a monomer having an unsaturated double bond, and mixtures thereof, synthesized with use of a polymerization initiator, 

synthesizing ingredient (E) at least one of a polymer of at least one of an acrylic acid and the salt thereof, and a polymer of at least one of an acrylic acid and the salt thereof and a monomer having an unsaturated double bond and 

mixing the ingredients (A), (C), (D) and (E), to prepare the CMP polishing slurry, 

wherein the polymerization initiator is a compound soluble completely at 25° C. when it is added at a ratio of 0.5 mass part in 99.5 mass parts of water or a compound soluble at 25° C. when it is added at a ratio of0.5 mass part in 99 .5 mass parts of water and at least one of an organic acid and inorganic acid is added thereto in an amount of 2 moles with respect to 1 mole of the poly› merization initiator, 

the content of the methacrylic acid and the salt thereof for the polymer (D) is 10 to 100 mo!% with respect to the total amount of the monomer components, 

the polymer (D) has a weight-average molecular weight of 200 to 100,000, 

the amount of the polymer (D) is 0.01 to 5 mass parts with respect to 100 mass parts of the CMP polishing slurry, and 

the polymerization initiator is at least one selected from the group consisting of (I) to (IV): 

(I) at least one peroxide selected from the group consisting of anmionium persulfate, potassium persulfate, and sodium persulfate, 

(II) at least one redox initiator initiators in combination of a sulfite salt, and selected from the combinations of (i) at least one selected from the group consisting of ammo› nium sulfite, ammonium hydrogen sulfite, potassium sulfite, potassium hydrogen sulfite, sodium sulfite, and sodium hydrogen sulfite and (ii) at least one selected from the group consisting of oxygen, air, and peroxide, 

(III) 2,2’-azobis[N-(2-carboxyethyl)-2-methyl propiona› mide ]amphoteric azo compound and 

