Chemical Etching of Silicon

Abstract

The kinetics of the etching of silicon in the system , , and was studied as a function of the composition of the etchant at 25°C. A triaxial plot of the etch rate vs. composition of the etchant shows two extreme modes of behavior. In the region of high nitric acid compositions, etch rates are functions only of the hydrofluoric acid concentration. In the region of high hydrofluoric acid compositions, nitric acid concentration determines the etch rates. The kinetic behavior in the latter region is complicated by autocatalysis in which the reduction products of nitric acid are involved.