Chemical Etching of Si1 − x Ge x in HF : H 2 O 2 : CH 3 COOH

The properties of a highly selective chemical etchant composed of hydrofluoric acid, hydrogen peroxide, and acetic acid is investigated in etching heterostructures. This solution has been found to etch much faster than Si over the entire range of Ge contents. The etch rate dependences are presented as functions of solution composition, Ge content, dopant type, diluent type, temperature, and stirring. Both n‐type and p‐type . layers with Ge contents of and , respectively, are investigated. It is found that the n‐type samples etch at a faster rate than p‐type for all Ge contents examined. When is used as the diluent instead of a significant enhancement in the etch rate results for all concentrations of Ge studied. Also, the amount of in the presence of has a significant effect on the magnitude of the etch rate as well as its behavior over time.