Epitaxial growth of si and sige using high-order silanes without a carrier gas at low temperatures via uhvcvd and lpcvd

Abstract

Conventional Si or SiGe epitaxy via chemical vapor deposition is performed at high temperatures with a large amount of hydrogen gas using silane (SiH4) or dichlorosilane (SiCl2 H2) precursors. These conventional precursors show low growth rates at low temperatures, particularly below 500◦ C although a low thermal budget becomes more important for modern fabrication techniques. High-order silane precursors, such as disilane, trisilane, and tetrasilane, are candidates for low-temperature epitaxy due to the lower strength of the Si-Si bonds compared to that of the Si-H bonds. In addition, the consumption of vast amounts of hydrogen gas is an additional burden of the low-temperature process due to its low throughput. In this study, we explored Si and SiGe epitaxial growth behaviors using several high-order silanes under ultra-high vacuum chemical vapor deposition (UHVCVD) and low-pressure chemical vapor deposition (LPCVD) conditions without a carrier gas. Disilane showed high-quality epi-growth under both pressure conditions, whereas trisilane and tetrasilane showed enhanced growth rates and lower quality.