Chemical mechanical polishing composition containing composite silica particles, method of making the silica composite particles and method of polishing a substrate
View Patent ↗A chemical mechanical polishing composition includes water, colloidal silica abrasive particles with a silica core containing a nitrogen species, a cerium compound coating including cerium oxide, cerium hydroxide or mixtures thereof, and a positive zeta potential, optionally an oxidizing agent, optionally a pH adjusting agent, optionally a biocide and optionally a surfactant. The chemical mechanical polishing composition has a pH of less than 7. Also described is a method of polishing a substrate containing silicon dioxide and a method of making the composite colloidal silica particles with the coating of cerium oxide, cerium hydroxide or mixtures thereof. The chemical mechanical polishing composition can be used to enhance the removal of silicon dioxide from a substrate in an acid environment.
1. A chemical mechanical polishing composition comprising:
water;
colloidal silica abrasive particles comprising a silica core comprising a nitrogen species, 0.005 wt % to 0.01 wt % cerium oxide, wherein cerium oxide coats the silica core, and a positive zeta potential;
an oxidizing agent;
optionally a pH adjusting agent;
optionally a biocide;
optionally a surfactant; and
a pH less than 7.
2. The chemical mechanical polishing composition of claim 1 , wherein the silica core of the abrasive particles further comprises an aminosilane compound.
3. The chemical mechanical polishing composition of claim 1 , wherein the oxidizing agent is hydrogen peroxide.