Anisotropic Etching of InP and InGaAs by Using an Inductively Coupled Plasma in Cl2/N2 and Cl2/Ar Mixtures at Low Bias Power

In order to obtain low-damage and vertical-etch profiles during etching of InP and In0.53Ga0.47As, we used inductively-coupled-plasma (ICP) etching with Cl-2/N-2 and Cl-2/Ar gas chemistries at bias powers below 25 W. Vertical etch features were obtained at a gas mixture of Cl-2 : N-2 = 2 : 13 and a bias power of 25 W for both materials. In the etch process for InP using Cl-2/N-2 gas chemistry, PNx was formed on the sample surface. The vapor pressure of PNx was significantly lower than that of PClx as revealed by X-ray photoelectron spectroscopy (XPS) results. Therefore, through the sidewall passivation by PNx, the sidewall of InP was blocked from the etching species, and that resulted in a highly vertical profile at low bias power. On the other hand, in the etch process for InGaAs using Cl-2/N-2 gas chemistry, As-N bonds formed on the surface during the etching, and the sidewall passivation by As-N appeared to cause vertical etch profiles at low bias power.