US Patent 7709277 PAA-based etchant, methods of using same, and resultant structures

A wet-etch composition may include: peracetic acid (PAA); and a fluorinated acid; a relative amount of the PAA in the composition being sufficient to ensure an etch rate of (P-doped-SiGe):(P-doped-Si) that is substantially the same as an etch rate of (N-doped-SiGe):(N-doped-Si). Such a wet-etch composition is hereafter referred to as a PAA-based etchant and can be used to make, e.g., a CMOS MBCFET, an electrode of a capacitor, etc.