Fabrication of Ge-MOS capacitors with high quality interface by ultra-thin SiO 2/GeO 2 bi-layer passivation combined with the subsequent SiO 2-depositions using magnetron sputtering

Abstract

Ge-MOS capacitors were fabricated by a novel method of ultra-thin SiO 2/GeO 2 bi-layer passivation (BLP) for Ge surface combined with the subsequent SiO 2-depositions using magnetron sputtering. For the Ge-MOS capacitors fabricated by BLP with O 2, to decrease oxygen content in the subsequent SiO 2 deposition is helpful for improving interface quality. By optimizing process parameters of the Ge surface thermal cleaning, the BLP, and the subsequent SiO 2 deposition, interface states density of 4 × 10 11 cm −2 eV −1 at around mid-gap was achieved, which is approximately three times smaller than that of non-passavited Ge-MOS capacitors. On the contrary, for the Ge-MOS capacitors fabricated by BLP without O 2, interface quality could be improved by an increase in oxygen contents during the subsequent SiO 2 deposition, but the interface quality was worse compared with BLP with O 2.