300mm Cold-Wall UHV/CVD Reactor for Low-Temperature Epitaxial (100) Silicon

Abstract

A 300mm cold-wall UHV/CVD reactor was used to grow epitaxial silicon layers on (100) SOI wafers at 500 to 800 °C using disilane, silane, and mixtures thereof. Spectroscopic ellipsometry was utilized to measure the deposition rates and wafer uniformities after growth, and high-resolution atomic force microscopy was employed to extract surface roughness and assess step flow growth. In the massflow controlled deposition region, both disilane and silane resulted in a linear dependence of growth rate on gas flow where disilane dominated over silane. In the reaction-limited regime, both precursors exhibited a perfect rate limitation with activation energies of ≈ 2 eV. Unlike in RPCVD, the deposition rate of disilane was found to approach twice that of silane at lowest temperatures. Step-flow growth was maintained even after 1μm of silicon was deposited under high-rate conditions. Additionally, continuous epitaxial films with thickness as low as 4 Aå were also obtained.