Dopant-selective etch stops in 6H and 3C SiC

A novel photoelectrochemical etching process for 6H- and 3C-SiC is described. This method enables n-type material to be etched rapidly (up to 25 μm/min), while a buried p-type layer acts as an etch stop. Dissolution of SiC takes place through hole-catalyzed surface dissolution. The holes are supplied either from the bulk (e.g., p-SiC) or by UV photogeneration (in n- or p-SiC). The differing flatband potentials of n- and p-type SiC in HF solutions allow the selection of a potential range for which hole current injection occurs only in n-type materials, facilitating dopant-selective etching. This process can be utilized in controlled etching of deep features, as well as in precise patterning of multilayer films.