Polishing Composition and Polishing Method

Abstract

A first polishing composition includes abrasive grains and an iodine compound and has a pH of 6 or more. The first polishing composition can suitably polish the Si [0001] plane of a single crystal silicon carbide substrate. A second polishing composition includes an iodine compound and has a pH of 8 or less. The second polishing composition can suitably polish the C [000-1] plane of a single crystal silicon carbide substrate. A third polishing composition includes abrasive grains and an iodine compound and has a pH of 6 to 8, inclusive. The third polishing composition can suitably polish each of the Si [0001] and C [000-1] planes of a single crystal silicon carbide substrate.

1 . A method for polishing an object formed of single crystal silicon carbide, comprising:
 preparing a polishing composition containing abrasive grains; an iodine compound selected from the group consisting of an iodic acid, a periodic acid, and a salt thereof; and water, and having a pH of 6 or more; and   polishing the object using the polishing composition.   
   
   
       2 . The method according to  claim 1 , wherein the object to be polished is a substrate having a side composed of a Si[0001] plane, and wherein the polishing of the object includes polishing the side of the substrate using the polishing composition. 
   
   
       3 . The method according to  claim 1 , further comprising, prior to the polishing of the object using the polishing composition, preliminarily polishing the object using a slurry containing abrasive grains of diamond. 
   
   
       4 . The method according to  claim 1 , wherein the abrasive grains are colloidal silica. 
   
   
       5 . The method according to  claim 4 , wherein the colloidal silica has an average primary particle size of from 25 to 85 nm. 
   
   
       6 . The method according to  claim 1 , wherein the iodine compound is orthoperiodic acid, H 5 IO 6 , or sodium metaperiodate, NaIO 4 . 
   
   
       7 . The method according to  claim 1 , wherein the polishing composition further contains lithium hydroxide, an inorganic lithium salt, or ammonia. 
   
   
       8 . The method according to  claim 1 , wherein the polishing composition has a pH of from 7 to 12. 
   
   
       9 . A method for polishing an object formed of single crystal silicon carbide, comprising:
 preparing a polishing composition containing an iodine compound selected from the group consisting of an iodic acid, a periodic acid, and a salt thereof; and water, and having a pH of 8 or less; and   polishing the object using the polishing composition.   
   
   
       10 . The method according to  claim 9 , wherein the object to be polished is a substrate having a side composed of a C[000-1] plane, and wherein the polishing of the object includes polishing the side of the substrate using the polishing composition. 
   
   
       11 . The method according to  claim 9 , further comprising, prior to the polishing of the object using the polishing composition, preliminarily polishing the object using a slurry containing abrasive grains of diamond. 
   
   
       12 . The method according to  claim 9 , wherein the polishing composition further contains abrasive grains. 
   
   
       13 . The method according to  claim 12 , wherein the abrasive grains are colloidal silica. 
   
   
       14 . The method according to  claim 13 , wherein the colloidal silica has an average primary particle size of from 25 to 85 nm. 
   
   
       15 . The method according to  claim 9 , wherein the iodine compound is orthoperiodic acid, H 5 IO 6 , or sodium metaperiodate, NaIO 4 . 
   
   
       16 . The method according to  claim 9 , wherein the polishing composition has a pH of from 1 to 7. 
   
   
       17 . A method for polishing an object formed of single crystal silicon carbide, comprising:
 preparing a polishing composition containing abrasive grains; an iodine compound selected from the group consisting of an iodic acid, a periodic acid, and a salt thereof; and water, and having a pH of 6 to 8; and   polishing the object using the polishing composition.   
   
   
       18 . The method according to  claim 17 , wherein the object to be polished is a substrate having a first side composed of a Si[0001] plane and a second side composed of a C[000-1] plane, and wherein the polishing of the object includes polishing, using the polishing composition, the first surface and the second surface of the substrate simultaneously or one by one. 
   
   
       19 . The method according to  claim 17 , further comprising, prior to the polishing of the object using the polishing composition, preliminarily polishing the object using a slurry containing abrasive grains of diamond. 
   
   
       20 . The method according to  claim 17 , wherein the abrasive grains are colloidal silica. 
   
   
       21 . The method according to  claim 20 , wherein the colloidal silica has an average primary particle size of from 25 to 85 nm. 
   
   
       22 . The method according to  claim 17 , wherein the iodine compound is orthoperiodic acid, H 5 IO 6 , or sodium metaperiodate, NaIO 4 .