High Resolution Etching of Semiconductors by the Feedback Mode of the Scanning Electrochemical Microscope

High resolution (~µm) etching of semiconductors has been achieved by applying the scanning electrochemical microscope (SECM) in the feedback mode. Strong oxidants, such as bromine, were electrogenerated in situ at an ultramicro-electrode (UME) and used as etchants. The current flowing at the UME was also used to monitor the distance between the UME and the surface. The variables that affect the size and shape of the etched pattern, the required properties of the redox couple, and the mechanism of the etching process are discussed. This approach was successfully applied to several III-V and II-VI semiconductors: gallium arsenide, gallium phosphide, cadmium telluride, and mercury cadmium telluride.