A vapour etching technique for the photolithography of silicon dioxide

The vapour of hydrofluoric acid attacks silicon dioxide at room temperatures, at a rate comparable to that of the buffered solution of the acid normally used as the etchant for the photolithographic stage of planar silicon device technology. The reaction has been examined as a possible alternative to liquid etching in the processing of devices, and experiments have been performed to evaluate various proprietary photo-resists for use with vapour etching.