Patterning of Sc0.3Al0.7N Film for Piezoelectric MEMS Devices

Piezoelectric coefficient in Sc
x
Al
1-x
N was reported to increase as scandium-doping x increases up to 43%. However, the patterning of Sc
0.3
Al
0.7
N film for the fabrication of piezoelectric micro-electromechanical systems (MEMS) devices poses challenges such as low etch rate, uncontrollable sidewall profile, micro-trenching, and significant bottom molybdenum (Mo) electrode loss. In this work, engineering of the sidewall profile by etch byproduct redeposition through plasma etch parameters and development of Sc
x
Al
1-x
N etch with a soft landing on the bottom Mo electrode was investigated. Post-etch analysis on the exposed Sc
0.3
Al
0.7
N sidewall was also performed to validate any presence of conducting residues and surface oxidation.