A QUANTITATIVE STUDY OF CHEMICAL ETCHING OF INP

Chemical etching of InP with HCl is used on a large scale, but limited information is available in the literature on the quantitative and mechanistic aspects of this reaction, A higher reaction rate is observed in alcoholic HCl than in aqueous HCl solutions. Also, a decrease of the reaction rate is observed with an increase in the degree of dissociation of HCl in aqueous solutions. We confirm that chemical etching depends on the concentration of nondissociated HCl molecules and that the reaction does not occur below a critical concentration. A first-order rate was obtained in aqueous and in alcoholic HCl solutions. The Arrhenius plot indicated an activation energy greater than 40 kJ . mol-1, indicating a kinetically controlled process. Scanning electron microscopy also showed profiles characteristic of a kinetically controlled process.