Effective passivation of defects in Ge-rich SiGe-on-insulator substrates by Al 2O 3 deposition and subsequent post-annealing

Abstract

A method of Al 2O 3 deposition and subsequent post-deposition annealing (Al 2O 3-PDA) was proposed to passivate electrically active defects in Ge-rich SiGe-on-insulator (SGOI) substrates, which were fabricated using Ge condensation by dry oxidation. The effect of Al 2O 3-PDA on defect passivation was clarified by surface analysis and electrical evaluation. It was found that Al 2O 3-PDA could not only suppress the surface reaction during Al-PDA in our previous work [Yang H, Wang D, Nakashima H, Hirayama K, Kojima S, Ikeura S. Defect control by Al-deposition and the subsequent post-annealing for SiGe-on-insulator substrates with different Ge fractions. Thin Solid Films 2010; 518: 2342–5.], but could also effectively passivate p-type defects generated during Ge condensation. The concentration in the range of 10 16–10 18 cm −3 for defect-induced acceptors and holes in Ge-rich SGOI drastically decreased after Al 2O 3-PDA. As a result of defect passivation, the electrical characteristics of both back-gate p-channel and n-channel metal–oxide-semiconductor field-effect transistors fabricated on Ge-rich SGOI were greatly improved after Al 2O 3-PDA.