Reverse Dry Etching Using a High-Selectivity Carbon Mask Formed by Electron Beam Deposition

A reverse dry etching technique using showered electron beam (EB) assisted etching is reported whereby a surface layer of carbon formed on GaAs substrates resulting from EB irradiation of oil vapor in the vacuum system is used as a mask for EB assisted etching. As a result of GaAs reverse pattern transfer, high selectivity is obtained between the mask material and the GaAs substrate. Auger electron spectroscopy (AES) measurements show this mask to be an ultrathin carbon layer. A 0.6 µm linewidth reverse pattern is transferred onto the substrate using this technique.