WET CHEMICAL DIGITAL ETCHING OF GAAS AT ROOM-TEMPERATURE

A new room temperature wet chemical digital etching technique for GaAs is presented which uses hydrogen peroxide and an acid in a two-step e tching process to remove GaAs in approximately 15 Angstrom increments. In the first step, GaAs is oxidized by 30% hydrogen peroxide to form an oxide layer that is diffusion limited to a thickness of 14 to 17 An gstrom for time periods from 15 to 120 s. The second step removes this oxide layer with an acid that does not attack unoxidized GaAs. These steps are repeated in succession until the desired etch depth is obtai ned. Experimental results are presented for this digital etching techn ique demonstrating the etch rate and process invariability with respec t to hydrogen peroxide and acid exposure times.