Method of surface treatment of semiconductor substrates

Abstract

A sidewall passivation layer is deposited on an etched feature in a semiconductor substrate with a hydrocarbon deposition gas by introducing H,, determining certain mixture percentages for the hydrocarbon gas/H,mix at which the etch rate for the substrate peaks, the etch rate begins to rise from a generally steady state, and/or the etch rate falls to zero, and then maintaining the mixture percentage within a selected range. Where the hydrocarbon gas/H,mix is maintained at a percentage between the steady-state etch rate percentage and the peak etch rate percentage, then relatively high ion energies are used. Where the hydrocarbon gas/H,mix is maintained at a percentage between the peak etch rate percentage and the percentage where the etch rate falls to zero, then relatively low ion energies are used. High aspect-ratio features in a semiconductor substrate can be produced by performing alternating etching and depositing a passivation layer on the substrate, where the deposition is performed according to the above-described deposition process.