Inductively coupled plasma-reactive ion etching of InSb using CH4/H2/Ar plasma

InSb is an important material for optoelectronic devices. Most InSb devices are currently wet etched, and the etching geometries are limited due to the isotropic nature of wet etching. Inductively coupled plasma (ICP)-reactive ion etching (RIE) is a more desirable alternative because it offers a means of producing small anisotropic structures especially needed in large format infrared focal plane arrays. This work describes the novel use of ICP-RIE for fabricating InSb mesas with CH4/H-2/Ar plasma and presents the influences of the process parameters on the etch rate and surface morphology. The parameters investigated include bias radio frequency power (50-250 W), % CH4 in H-2 (10-50), argon (Ar) partial pressure (0-0.3 Pa with total pressure of 1.0 Pa), and total pressure (0.35-4 Pa). With the process parameters optimized in this investigated ranges, good etching results have been achieved with etch rates up to 80 nm/min, and etch features with sidewall angles of about 80 degrees, the etched surface is as smooth as before the RIE process.