Potassium Permanganate as Oxidizer in Alkaline Slurry for Chemical Mechanical Planarization of Nitrogen-doped Polycrystalline Ge2Sb2Te5 Film

For phase-change memory beyond the 30 nm design rule, chemical mechanical planarization (CMP) performing at a high polishing rate, reasonable selectivity, and no corrosion-induced pits is essential for planarizing nitrogen-doped polycrystalline Ge2Sb2Te5 (GST) deposited on the confined memory cell structure. We develop a new alkaline slurry added with KMnO4 used as an oxidizer. The alkaline slurry added with 0.3 wt % KMnO4 has a polycrystalline GST film polishing rate of 5200 angstrom/min, a polishing rate selectivity between polycrystalline GST and SiO2 film of 100:1, and no corrosion-induced pit. In addition, polycrystalline GST film CMP using the alkaline slurry added with KMnO4 is observed to follow a cyclic reaction polishing mechanism. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3486886] All rights reserved.This investigation was financially supported by Collaborative Industry Project between Hanyang University and Hynix Semiconductor Inc., Acceleration Research Program of the Ministry of Education, Science and Technology and the Brain Korea 21 Project in 2010. We also thank Sumco Corp. for helping us with the experiments