Selective Etching of Silicon for Selective Area Epitaxial Growth.

Process conditions are described for selectively etching silicon by wet and dry etching techniques. High etch rates are achieved and a selectivity etch rate of siliconetch rate of masking material as high as 600 is obtained when thermal oxide is used as a mask and SF6 as the gas in a reactive ion etcher at high pressure. Dry etch process parameters are optimized to produce undercut edge profiles and smooth silicon floors, both of which are necessary to accommodate the growth of epitaxial material in recesses. p4