Evaluation of surface damage on GaAs etched with an electron cyclotron resonance source

Surface damage induced by dry etching on GaAs with an electron cyclotron resonance source has been studied using both electrical measurements and surface analysis techniques. It is found that the unalloyed contact resistance extracted from the transmission lines is very sensitive to the etch‐induced damage, and it increases significantly with ion energy and ion flux but decreases with etch temperature. Conducting wires that are 40 to 1000 nm wide have been etched down to 1.3 μm deep with vertical profile and smooth surface morphology. The extracted sidewall damage depth of these wires ranges from 2.7 to 20.4 nm and it increases with ion energy and ion flux but decreases with etch temperature. At 200 W rf power, the sidewall damage depth decreases from 13.1 to 4.0 nm after removing 10 nm of the etched surface using low‐energy reactive chlorine species. Results from cross‐sectional transmission electron microscopy show a higher defect density and a shallower defect depth for samples etched with higher rf power. A lower defect density and a deeper defect depth are found at higher etch temperature. Auger electron spectroscopy shows that after etching with the Cl₂/Ar plasma, the stoichiometry is not changed even at high microwave power or high etch temperature.