Polishing composition, polishing method, and method of producing semiconductor substrate

Abstract

A polishing composition according to the present invention contains abrasive grains, a basic inorganic compound, an anionic water-soluble polymer, and a dispersing medium, in which a zeta potential of the abrasive grains is negative, an aspect ratio of the abrasive grains is 1.1 or less, in a particle size distribution of the abrasive grains obtained by a laser diffraction/scattering method, a ratio D90/D50 of a particle diameter D90 when an integrated particle mass reaches 90% of a total particle mass from a fine particle side to a particle diameter D50 when the integrated particle mass reaches 50% of the total particle mass from the fine particle side is more than 1.3, and the basic inorganic compound is an alkali metal salt.

What is claimed is: 
     
         1 . A polishing composition comprising:
 abrasive grains; a basic inorganic compound; an anionic water-soluble polymer; and a dispersing medium,   wherein a zeta potential of the abrasive grains is negative,   an aspect ratio of the abrasive grains is 1.1 or less,   in a particle size distribution of the abrasive grains obtained by a laser diffraction/scattering method, a ratio D90/D50 of a particle diameter D90 when an integrated particle mass reaches 90% of a total particle mass from a fine particle side to a particle diameter D50 when the integrated particle mass reaches 50% of the total particle mass from the fine particle side is more than 1.3, and   the basic inorganic compound is an alkali metal salt.   
     
     
         2 . The polishing composition according to  claim 1 , wherein the anionic water-soluble polymer is at least one selected from the group consisting of a polyacrylic acid-based polymer and a polymethacrylic acid-based polymer. 
     
     
         3 . The polishing composition according to  claim 1 , wherein a molecular weight of the anionic water-soluble polymer is 5,000 or more and 6,000,000 or less. 
     
     
         4 . The polishing composition according to  claim 1 , wherein a pH is 9.5 or higher. 
     
     
         5 . The polishing composition according to  claim 1 , wherein the abrasive grains contain alumina. 
     
     
         6 . The polishing composition according to  claim 5 , wherein the alumina contains a γ phase as a crystal phase. 
     
     
         7 . The polishing composition according to  claim 5 , wherein a pregelatinization rate of the alumina is less than 50%. 
     
     
         8 . The polishing composition according to  claim 5 , wherein a fracture strength of the alumina is 0.5 GPa or more. 
     
     
         9 . A polishing method comprising:
 polishing an object to be polished using the polishing composition according to  claim 1 .   
     
     
         10 . A method for producing a semiconductor substrate, comprising:
 the polishing method according to  claim 9 .