Application of Cl2 for low temperature etch and epitaxy

In this work, two most typical applications of Cl2 etch relevant for sub-10 nm CMOS device production, namely sacrificial etch and selective deposition are presented. It is shown that Si0.7Ge0.3 sacrificial etch with Cl2 is possible in the temperature range of 350 °C–400 °C when He is used as a carrier gas. This temperature range can be further lowered when He is substituted with N2. Use of N2 also allows Si etch at very low temperatures (∼400 °C) which are not accessible for etching with HCl and potentially can be used for sacrificial etch of Si and Si-based epitaxial selective growth processes. Furthermore, a combination of Cl2 with high order Si and Ge precursors allowed development of cyclic selective epitaxial processes at temperatures as low as 400 °C with active dopant concentrations of ∼1 × 1020 cm−3 for Si0.7Ge0.3:B and ∼3 × 1019 cm−3 for Si0.7Ge0.3:P.