SiGe heterostucture field-effect transistor with ICP mesa treatments

Experimental realization of a Si/SiGe doped-channel field-effect transistors (DCFETs) using Ar+CF₄ mixed-gas inductively coupled plasma (ICP) dry-etching process is reported for the first time. Due to generating high-density plasma under low pressure, independently controlled plasma density as well as ion bombardment energy for ICP technology, a better anisotropic etching profile, together with a higher etching rate, compared to the reactive ion etching (RIE) process, can be obtained. As compared to device fabricat using wet etching mesa, the doped-channel FET using ICP mesa is shown having higher breakdown voltage with lower leakage current, higher transconductance, and larger current drivability due to the elimination of most of the parasitic current path between isolated devices. Moreover, the ICP etching rate as a function of plasma relative composition on Si and Si _0.7Ge_0.3 in Ar+CF₄ mixed-discharge has been investigated. A high and stable etching selectivity between Si and SiGe can be obtained by ICP technology.