Wet chemical etching is commonly used for uniform stripping or patterning through a mask of dielectric and metallization layers. In contrast to RIE all processes are more or less isotropic and mask underetching is present. Selectivities toward mask and substrate materials are usually much better than with RIE processes. Another special wet etching process used in bulk micromaching technology is the anisotropic, crystal-oriented, KOH or TMAH etch.
Standard RCA process (SC1, SC2, HF-dip) is used for wafer cleaning. Special Solvent bathes are available for resist stripping. All standard etch bathes are SPC controlled (etch rate monitoring).