Etching of InP by H3PO4, H2O2 Solutions

This paper deals with the chemical etching of (100) InP using a phosphoric acid and hydrogen peroxide mixture. It is shown that the etching rate is strongly dependent on the relative concentration of the two species; it is maximal for an equivolumic solution, and depending on the dilution it ranges from 70 to 20 A/min. The activation energy of a non-diluted solution is approximately 14 kcal/mol. The post-etch surface state of the sample analysed by SEM and XPS, shows a very smooth surface for all concentrations, and the formation of a InPO4·xH2O layer. This solution can be used as a very precise etchant in devices processes.