Patent ID: 8419970

Claim:
A polishing method comprising supplying a silicon nitride polishing liquid for chemical mechanical polishing of a body to be polished in a planarization process for manufacturing of a semiconductor integrated circuit, the body to be polished comprising at least a first layer containing silicon nitride and a second layer containing at least one silicon-including material selected from the group consisting of polysilicon, modified polysilicon, silicon oxide, silicon carbide and silicon oxycarbide, the silicon nitride polishing liquid having a pH of 2.5 to 5.0, and comprising (a) colloidal silica, (b) an organic acid that has at least one sulfonic acid group or phosphonic acid group in the molecular structure thereof and functions as a polishing accelerator for silicon nitride, (c) water and (d) a surfactant, to a polishing pad on a polishing platen, rotating the polishing platen, and thereby causing relative motion between the polishing pad and a surface to be polished of a body to be polished while the polishing pad and the surface to be polished are in contact with each other for carrying out polishing, wherein the (d) surfactant comprises a nonionic surfactant represented by Formula (III), an anionic surfactant represented by the Formula (VI), an anionic surfactant represented by the Formula (VII), or an anionic surfactant represented by the Formula (VIII), wherein the formulas are defined as follows: wherein R 1 and R 2 each independently represent a hydrogen atom, an alkyl group having 6 to 30 carbon atoms, an alkenyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkyl carbonyl group, or a polyoxyethylene chain, R 1 and R 2 may be linked to each other, and a represents an integer of 1 to 10; wherein R 2 represents an alkyl group having 6 to 30 carbon atoms, an alkenyl group, a cycloalkyl group, an aryl group, an aralkyl group, or a combination of two or more thereof, n represents an integer of 1 to 10, and X represents a hydrogen atom, sodium, potassium, ammonium, diethanolamine, or triethanolamine; wherein R 3 represents an alkyl group having 6 to 30 carbon atoms, an alkenyl group, a cycloalkyl group, an aryl group, an aralkyl group, or a combination of two or more thereof, and X represents a hydrogen atom, sodium, potassium, ammonium, diethanolamine, or triethanolamine; and wherein R 4 represents an alkylene group having 1 to 20 carbon atoms, an alkynylene group, a cycloalkylene group, an arylene group, an alkylene oxide group, or a combination of two or more thereof, R 5 to R 9 each independently represent a hydrogen atom, a hydroxy group, an alkyl group having 1 to 30 carbon atoms, an alkenyl group, a cycloalkyl group, an aryl group, an aralkyl group, a sulfo group, a carboxy group, or a hydrocarbon group containing any of these groups, and X represents a hydrogen atom, sodium, potassium, ammonium, diethanolamine, or triethanolamine.