Inductively coupled plasma etching of Si_1-xGe_x in CF₄/Ar and Cl₂/Ar discharges

In this article, we report the experimental realization of SiGeSi materials using C F4 Ar and Cl2 Ar mixed-gas inductively coupled plasma (ICP) etching process. The effects of process parameters such as gas combination and gas species on etch rates and selectivities were investigated. It was found that samples in C F4 gas result in a faster etching rate than those obtained in Cl2 gas, which are responsible for a lower boiling point for Si-based fluoride. The lower boiling point provides more chemically active Si and SiGe materials. Moreover, the selectivity of 1.5 between Si0.3 Ge0.7 Si by ICP technology was found and higher than that obtained previously by reactive ion etching reported in the literature. Based on these etch characteristics, the application of the ICP process to the device fabrication of SiGe doped-channel field-effect transistors was conducted. The devices using ICP mesa have excellent pinch-off characteristics with relatively low leakage current, small output conduction in the saturated region, and low knee voltage.