Effects of High Dielectric Constant Abrasives on ECMP

Abstract

ECMP (Electro-Chemical Mechanical Polishing) presents high removal rate, low polishing pressure and good polished surface because the action of electrochemistry accelerates copper dissolution. It is considered to be a most promising novel Cu planarization process to replace traditional CMP (Chemical Mechanical Polishing). However, the micro asperity heights of coarse surface are often too small compared to the distance between anode and cathode, so the asperities are difficult to be selectively removed. In this paper, high dielectric constant abrasives were used in ECMP to solve this problem. High dielectric constant abrasives can improve the distribution of electric field, amplify the gradient of electric field and enhance the ability of selective removal. Based on the results of experiments, rutile TiO2, as one of high dielectric constant abrasives, is better than SiO2 and anatase TiO2 in ECMP process. The material removal rate of electrolyte containing rutile TiO2 is 0.078mg/min, and the surface roughness is Ra18.2nm.