Inductively coupled plasma deep etching of InP/InGaAsP in Cl2/CH4/H2 based chemistries with the electrode at 20 °C

Abstract

A Cl2/CH4/H2 inductively coupled plasma process without additional heating or wafer bonding is developed for the InP/InGaAsP material system. Vertical and smooth sidewalls can be observed in the scanning electron microscope images. The main factors of etch rate, selectivity, and sidewall roughness are analyzed relative to the gas concentration in a full factorial design of the experimental procedure. Under optimized conditions, an etch depth of more than 3 μm with smooth and vertical sidewalls can be obtained. A strong indication of a passivation effect of CH4 is obtained.