Etching Characteristics and Mechanism of InP in Inductively Coupled HBr/Ar Plasma

Investigations of InP etch characteristics and mechanisms in HBr/Ar inductively coupled plasma were carried out. The etch rates of InP and the photoresist were measured as functions of HBr/Ar mixing ratio at fixed gas pressure (5 mTorr), input power (800 W). and bias power (200 W). Langmuir probe diagnostics and zero-dimensional (global) plasma modeling provided the information on plasma parameters, plasma composition, and fluxes of active species. It was found that, with variations in gas mixing ratio. the InP etch rate follows the changes in Br atom density and flux, but shows opposite behavior of the changes in H atoms and positive ions. These findings allow one to conclude that, under a given set of input process parameters. the InP etch process is not limited by the ion-surface interaction kinetics and that Br atoms are the main chemically active species.