A INTRODUCTION

Wet chemical etching processes have three general applications: (1) defect or damage revealing, (2) polishing and (3) pattern formation or device shaping. Certain chemical etchants provide the effect of producing surface features on the semiconductor which can be related to the defects in the crystal. This is essentially true of dislocations, which often form etch pits at their points of intersection with a surface, thus providing a simple way of estimating dislocation densities. Chemical etching is also used for removing the damage layer of material close to the surface, for producing a high-quality shiny flat surface, and for shaping semiconductor devices, as well as for characterising structural and compositional features (staining and p-n junction delineation). Many etching characteristics of InP have been studied by a number of groups. A useful description of the theoretical and practical aspects of etching is given by Sangwal [1] and Notten et al [2].

B WET CHEMICAL ETCHING