Polishing composition comprising polishing particles having high water affinity

Abstract

A polishing composition having silica-based abrasive grains and a polishing method. A polishing composition having silica particles, wherein on the basis of a colloidal silica dispersion of the silica particles, the dispersion has an Rsp of 0.15 to 0.7 as measured using pulse NMR, and the colloidal silica particles have a shape coefficient SF1 of 1.20 to 1.80, wherein Rsp is calculated based on equation (1): Rsp =( Rav−Rb )/( Rb )  (1) (wherein Rsp is an index that indicates water affinity; Rav is an inverse of a relaxation time of the colloidal silica dispersion; and Rb is an inverse of a relaxation time of a blank aqueous solution obtained by removing the silica particles from the colloidal silica dispersion), and the shape coefficient SF1 is calculated based on equation (2): SF 1=(area of a circle whose diameter is a maximum diameter of the particle)/(projected area)  (2).

1 . A polishing composition comprising silica particles, wherein on the basis of a colloidal silica dispersion of the silica particles, the dispersion has an Rsp of 0.15 to 0.7 as measured using pulse NMR, and the colloidal silica particles have a shape coefficient SF1 of 1.20 to 1.80, wherein Rsp is calculated based on equation (1):
     Rsp =( Rav−Rb )/( Rb )  (1)
   (wherein Rsp is an index that indicates water affinity; Ray is an inverse of a relaxation time of the colloidal silica dispersion; and Rb is an inverse of a relaxation time of a blank aqueous solution obtained by removing the silica particles from the colloidal silica dispersion), and   the shape coefficient SF1 is calculated based on equation (2):
     SF 1=(area of a circle whose diameter is a maximum diameter of the particle)/(projected area)  (2).
 
   
     
     
         2 . The polishing composition according to  claim 1 , wherein the colloidal silica dispersion has an average particle diameter of 40 to 200 nm as measured by a dynamic light scattering method, and the silica particles in the dispersion have an average primary particle diameter of 10 to 80 nm as measured by a nitrogen gas adsorption method. 
     
     
         3 . The polishing composition according to  claim 1 , wherein the colloidal silica dispersion is obtained by being subjected to a thermal history at a temperature of 110° C. or higher and lower than 150° C., in particle growth of activated silica under alkaline conditions in the presence of potassium ions. 
     
     
         4 . The polishing composition according to  claim 1 , further comprising at least one additive selected from the group consisting of an acid component, an alkali component, a water-soluble compound, a chelating agent, an oxidizing agent, and a metal corrosion inhibitor. 
     
     
         5 . The polishing composition according to  claim 4 , wherein the alkali component is potassium hydroxide or potassium hydrogen carbonate, or a mixture of potassium hydroxide or potassium hydrogen carbonate with sodium hydroxide, ammonia, primary ammonium hydroxide, secondary ammonium hydroxide, tertiary ammonium hydroxide, quaternary ammonium hydroxide, primary ammonium carbonate, secondary ammonium carbonate, tertiary ammonium carbonate, quaternary ammonium carbonate, primary ammonium hydrogen carbonate, secondary ammonium hydrogen carbonate, tertiary ammonium hydrogen carbonate, quaternary ammonium hydrogen carbonate, lithium carbonate, sodium carbonate, potassium carbonate, lithium hydrogen carbonate, or sodium hydrogen carbonate. 
     
     
         6 . The polishing composition according to  claim 4 , wherein the chelating agent is an aminocarboxylic acid-based chelating agent or a phosphonic acid-based chelating agent. 
     
     
         7 . The polishing composition according to  claim 1 , wherein the polishing composition has a pH of 1 to 12. 
     
     
         8 . The polishing composition according to  claim 1 , wherein the polishing composition is used to polish a silicon wafer or a device wafer.