As for chemical mechanical polishing (CMP) of polycrystalline Ge2Sb2Te5 (pc-GST), the corrosion-inhibition efficiency and polishing rate of 1-vinyl-2-pyrrolidinone (VP) and polyvinyl pyrrolidone (PVP) with molecular weights of 3.5 k, 25 k, and 1300 k g/mol were estimated. The estimation results show that there is an optimal molecule weight of the corrosion inhibitor (i.e., 3.5 k g/mol) to achieve free of corrosion pits and the lowest surface roughness after polishing test. These results demonstrate that the formation of a uniform polymeric passivation layer arising from a corrosion inhibitor can prevent a direct penetration of the oxidizer H2O2 at the optimum molecule weight of the corrosion inhibitor during the pc-GST CMP. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.032204jes] All rights reserved.