Effects of H <sub>2</sub> O <sub>2</sub> and pH on the Chemical Mechanical Planarization of Molybdenum
Heon-Yul Ryu, Lieve Teugels, K. Devriendt, Herbert Struyf, Tae‐Gon Kim, Jin-Goo Park
Abstract
The effects of H 2 O 2 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 H 2 O 2 -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 H 2 O 2 . The Mo SER, which increased with H 2 O 2 concentration, supported the dissolution of Mo oxides through the formation of peroxo Mo complexes with H 2 O 2 . The CMP removal mechanism was demonstrated by comparing the CMP RR with and without silica abrasives. In addition, the Mo oxidation rate by H 2 O 2 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.