Source/drain elevation process using implantation enhanced selective etching

A technique for formation of elevated source/drain structure has been demonstrated. 100 nm thick epitaxial silicon/polysilicon layer was formed on patterned Si/SiO/sub 2/ structure by chemical vapor deposition (CVD) at 700/spl deg/C. Structural damage was selectively introduced in polysilicon layer by a low dose Argon implantation at 140 keV. Crystal damage in epitaxial silicon layer was kept minimum by aligning the implantation in vertical <100> channeling direction. A short duration post-anneal at 420/spl deg/C was used for structural recovery of the silicon layer. Polysilicon layer was then selectively removed by wet etching. With careful selection of implantation dose and energy, we were able to avoid the commonly observed faceting effect of elevated silicon layer near pattern edges.