A method of processing a semiconductor substrate having a first conductivity type includes, in part, forming a first implant region of a second conductivity type in the semiconductor substrate where the first implant region is characterized by a first depth, forming a second implant region of the first conductivity type in the semiconductor substrate where the second implant region is characterized by a second depth smaller than the first depth, forming a porous layer within the semiconductor substrate where the porous layer is adjacent the first implant region, and growing an epitaxial layer on the semiconductor substrate thereby causing the porous layer to collapse and form a cavity.