Etching Characteristics of HBr-Based Chemistry on InP Using the ICP Technique

A systematic study of the etching of InP material by hydrogen bromide (HBr)-based chemistry is conducted using the inductively coupled plasma (ICP) technique. Sidewall profiles, material selectivity, surface morphologies, and the residual species due to the chemistry are observed as functions of varying process parameters like ICP power, reactive ion etching (RIE) power and pressure. The highest selectivity of InP:PR of 4.2 is achieved at an ICP power of 100 W for a constant set of RIE power, pressure, HBr flow rate, and temperature parameters. Sidewall striations on etched faces have been eliminated by optimizing baking parameters on the photoresist pattern prior to etching. A characteristic kink effect phenomenon is observed with the introduction of argon in HBr chemistry to which is attributed the fluctuation of the chamber pressure. X-ray photoelectron spectroscopy results indicate the strong presence of InBr x , which is believed to affect the formation of anisotropic sidewalls at room temperature.