US 8,900,335 B2  22  21  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):  INDUSTRIAL APPLICABILITY  (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  (III) 2,2’-azobis[N-(2-carboxyethyl)-2-methyl propiona› mide ]amphoteric azo compound and  (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,  (I) at least one peroxide selected from the group consisting  of anmionium persulfate, potassium persulfate, and  sodium persulfate,  the polymerization initiator is at least one selected from the  group consisting of (I) to (IV):  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 polymer (D) has a weight-average molecular weight of  200 to 100,000,  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,  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,  mixing the ingredients (A),  (C), (D) and (E), to prepare the  CMP polishing slurry,  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  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,  2.  A method of producing a CMP polishing slurry, com› prising preparing ingredient (A) cerium oxide particles,  ingredient  (C) water,  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 ). 