A Novel SiGe Fin-on-insulator FinFET Device with a SiN Spacer Protection Scheme

A novel SiGe fin on insulator (FOI) structure and its FinFET device on a bulk-Si substrate are extensively investigated in this paper. A high-quality SiGe layer epitaxial grown on a Si substrate is realized and a similar notched SiGe/Si fin profile is attained by using the three-step etching process of previous Si FOI structure. However, direct isolation oxidation cannot be applied to get an isolation structure due to lower SiGe thermal stability. Therefore, a SiN film protection post SiGe fin reveal strategy (scheme A) and SiN spacer protection post step-I etching strategy (scheme B) are developed to realize the SiGe FOI structure. Although scheme A can attain a fully oxidation of notched Si fin and no oxidation of SiGe fin, the SiGe fin is distorted due to the large stress induced by the high temperature spike anneal treatment. Compared with the scheme A, a fully isolation of the SiGe fin structure can be achieved and the SiGe fin can maintain well without any oxidation or distorted profile impact. Meanwhile, SiGe FOI FinFET device is also successfully prepared by using the scheme B, which further verifies that it is a practical and effective solution for the fabrication of SiGe FOI structure.