Effects of H2O2 and pH on the Chemical Mechanical Planarization of Molybdenum

Abstract

The effects of H2O2 on the chemical etching and removal rate (RR) of molybdenum (Mo) were investigated. Static etch rate (SER) and chemical mechanical planarization (CMP) experiments were performed using H2O2-based slurries at different pH levels. X-ray photoelectron spectroscopy (XPS) and potentiodynamic polarization analysis showed the formation of Mo oxides by the reaction between Mo and H2O2. The Mo SER, which increased with H2O2 concentration, supported the dissolution of Mo oxides through the formation of peroxo Mo complexes with H2O2. The CMP removal mechanism was demonstrated by comparing the CMP RR with and without silica abrasives. In addition, the Mo oxidation rate by H2O2 on a millisecond time scale was characterized with chronoamperometry to explain different RRs at pH values ranging from 2 to 8. The CMP RR of Mo was high at pH 2 and pH 10; however, pH 2 showed a lower SER than pH 10, leading to lower surface roughness.