Some Fundamental Aspects of Profile Etching at InP Surfaces

Abstract

Etching profiles at mask edges on (100) InP are obtained in acidic FeCl3 containing solutions under uniform illumination and in iodic acid solutions in darkness. For-both etching systems, the results of microscopic etching near mask edges are compared to the macroscopic etching behavior of individual crystallographic faces. In the case of photoetching by FeCl3, a difference in profile shape is observed between p- and n-type samples, associated with the fact that the photoetching occurs by an electrochemical mechanism At p-type samples; the slowest etching face [i.e., the (111) face] is revealed whereas at n-type, profiles with very rough bottoms are observed. A tentative interpretation for this phenomenon is proposed. Mo difference in profile shape is found between p- and n-type in the iodic acid solution, which operates through a chemical mechanism. An anisotropic microscopic etching behavior is however observed. A model, in which the presence of a thin oxide layer on the InP plays a crucial role, can explain this etching behavior.