SILICON SURFACE CLEANING USING PHOTOEXCITED FLUORINE-GAS DILUTED WITH HYDROGEN

We demonstrated surface cleaning using photoexcited fluorine gas diluted with hydrogen (UV/F2/H-2). We found that LTV/F2/H-2 cleaning selectively removed native Si oxide from thermal oxide without etching the bulk Si. The dangling bonds on the Si surface-after UV/F2/H-2 cleaning were almost exclusively terminated with hydrogen atoms, with few bonds to fluorine. UV/F2/H-2 cleaning effectively flattened the Si surface. We applied UV/F2/H-2 Cleaning to Si epitaxy. This cleaning allowed us to obtain single-crystal Si film with preannealing temperatures as low as 600-degrees-C. This temperature is lower than that of conventional methods by ca. 150-degrees-C. UV/F2/H-2 cleaning is a good dry precleaning method for various processes which include Si epitaxy.