Patent ID: 8167684

Claim:
A chemical mechanical polishing slurry for polishing a copper layer without excessively or destructively polishing a barrier layer beneath the copper layer, comprising: an acid, wherein said acid is selected from the group consisting of hexanedioic acid, itaconic acid, formic acid, and 1,2,3,4-butane tetracarboxylic acid; a surfactant, wherein said surfactant is selected from the group consisting of an anionic surfactant and a nonionic surfactant; a silica sol having silica polishing particles that are surface modified with a surface charge modifier and that have potassium ions attached thereto, wherein said potassium ions are in an amount greater than 100 ppm based on a total weight of said silica polishing particles; wherein said slurry has a pH value ranging from 3 to 4.