Patent ID: 7754168

Claim:
A method of preparing a concentrate of fine ceria particles that is ready for use for chemical mechanical polishing of a substrate, the method comprising the steps: a) reacting a reactant mixture comprising: i) water, ii) an aqueous solution of water-soluble cerium salt compound, and iii) ammonia or an ammonium salt at a reaction temperature of 250-700° C. under a reaction pressure of 180-550 bar for 0.01 sec to 10 min in a continuous reactor to produce a solution containing the fine ceria particles, the cerium salt compound being present in an amount of 0.01 to 20 wt % in the reactant mixture; and b) concentrating the solution containing the fine ceria particles in a concentrator having a filter with a pore size of 0.01 to 10 μm, wherein the cerium salt is selected from the group consisting of cerium nitrate, ammonium cerium nitrate, and a mixture thereof, and the ammonia or ammonium salt is present in the reactant mixture at a molar ratio of 0.5-3 relative to nitric acid to achieve conversion stoichiometrically from the cerium salt compound, whereby the concentrate of fine ceria particles is ready for use in chemical mechanical polishing without further processing.