Vertical and Smooth, etching of InP by Cl_2/CH_4/Ar Inductively Coupled Plasma at Room Temperaure

摘要

We study the room-temperature dry, etching of InP by inductively coupled plasma (ICP) using Cl_2/CH_4/Ar mixtures. Etches were characterized in terms of anisotropy and surface roughness by scanning electron microscopy and atomic force microscopy, respectively. It is found that the flow ratio between Cl_2 and CH_4, ICP power, rf chuck power, and table temperature can greatly influence the, etching result. By adjusting, etching parameters, vertical sidewall and smooth surface can be obtained simultaneously, together with a moderate, etch rate and a good select ratio. The root-mean-square surface roughness is measured to be as low as 0.27 nm. To the best of our knowledge, this is the best results for InP to date. The, etch rate is 855 nm/min, and the selectivity ratio over SiO_2 is estimated to the higher than 15:1. The stoichiometry of the, etched surface has also been investigated by Auger electron spectroscopy. The, etched surface is found to manifest a slight P deficiency, and the ratio between P and In reaches the stoichiometric value within about 0.75 nm depth into the surface.