Synethetic quartz glass subtrate polishing slurry and manufacture of synethetic quartz glass substrate using the same

Abstract

A polishing slurry comprising a collagen derivative and a colloidal solution is effective for polishing of synthetic quartz glass substrates. It prevents formation of defects having a size that can be detected by a high-sensitivity flaw detector.

1 . A method for manufacturing a synthetic quartz glass substrate through rough polishing and final polishing steps, comprising
 preparing a polishing slurry comprising a collagen derivative and a colloidal solution, said collagen derivative being a polymer resulting from polymerization of a monomer in the form of tripeptide represented by the sequence [Gly-Xaa-Yaa] n  wherein Xaa and Yaa are amino acids and n is a degree of polymerization and having a weight average molecular weight of 1,000 to 10,000,000,   keeping the polishing slurry at a temperature lower than the denaturing temperature of the collagen derivative in the rough polishing step, and   feeding the polishing slurry to the final polishing step in which polishing is carried out at a higher temperature than the temperature at which the collagen derivative is denatured by the heat generated during polishing.   
     
     
         2 . The method of  claim 1 , wherein the collagen derivative is gelatin or collagen peptide. 
     
     
         3 . The method of  claim 1 , wherein the colloidal solution is a colloidal silica dispersion having a colloidal silica concentration of 20 to 50% by weight. 
     
     
         4 . The method of  claim 1 , further comprising a carboxylic acid or a salt thereof. 
     
     
         5 . The method of  claim 1 , having pH 8 to 11. 
     
     
         6 . The method of  claim 5 , wherein the pH is adjusted using at least one member selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides, basic salts, amines, and ammonia.