Study of AlScN thin film deposition on large size silicon wafer

Abstract

This work prepared Al0.8Sc0.2N thin films (AlScN) with a thickness of 1 μm on Φ = 200 mm (100) bare silicon wafers and studied the effects of sputtering power, substrate bias power and gas flow on the quality of films. The microstructure, crystal orientation and piezoelectric response of the AlScN thin films were comprehensively investigated. The prepared films exhibit highly c-axis texture and smooth surface on large size wafers, which meet with the requirement of massive production of micro-electro-mechanical system devices. The best full width half maximum of 1.34° was obtained in the films deposited with the sputtering power of 4 kW. Substrate bias power can enable the film to achieve stress close to 0 without obviously deteriorating other properties. N2 flow ratio has the greatest impact on the c-axis texture and surface morphology of AlScN films. Lower N2 flow ratio will promote the generation of surface abnormal oriented grains, resulting in the degradation of (002) orientation of AlScN and surface roughness, thereby deteriorating the piezoelectric performance of the film. N2 ratio greater than 60 % and compressive stress are preferred for the deposition of AlScN piezoelectric films.