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 method for chemical mechanical polishing of a substrate, comprising:
providing a substrate, wherein the substrate comprises dielectric materials of silicon oxide, and silicon nitride;
providing an acid 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 the 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;
providing a chemical mechanical polishing pad with a polishing surface;
creating dynamic contact at an interface between the polishing surface of the acid chemical mechanical polishing pad and the substrate with a down force of 0.69 to 34.5 kPa; and
dispensing the acid chemical mechanical polishing composition onto the chemical mechanical polishing pad at or near the interface between the chemical mechanical polishing pad and the substrate;
wherein the substrate is polished; and, wherein the silicon dioxide is removed from the substrate at enhanced removal rates over silicon nitride and polysilicon.
2. The method of claim 1 , wherein polishing is done at a platen speed of 93-113 revolutions per minute, a carrier speed of 87-111 revolutions per minute, an acid chemical mechanical polishing composition flow rate of 125-300 mL/min, a nominal down force of 21.4 kPa on a 200 mm polishing machine; and, wherein the chemical mechanical polishing pad comprises a polyurethane polishing layer containing polymeric hollow core microparticles and a polyurethane impregnated non-woven subpad.
3. The method of claim 1 , wherein the silica core of the abrasive particles further comprises an aminosilane compound.
4. The method of claim 1 , wherein the oxidizing agent is hydrogen peroxide.