Patent ID: 9558959
Date: 2017-01-31
CPC Classifications: C09G,H01L

Claim:
1. A polishing method, comprising: applying a polishing composition to a substrate having silicon nitride and silicon oxide on its surface; bringing a pad into contact with the substrate and composition and moving the pad in relation to the substrate; removing at least a portion of the silicon nitride from the substrate at a first rate; and removing at least a portion of the silicon oxide from the substrate at a second rate, wherein a ratio of said first rate to said second rate is 7 or higher, and wherein the composition comprises: a) an anionic abrasive; b) a nitride removal rate enhancer comprising a carboxylic acid or a carboxyl/carboxylate group for increasing silicon nitride rates; c) water; and (d) optionally, an anionic polymer; wherein the polishing composition has a pH of about 2 to about 6.5.