Patent ID: 7859013
Filing Date: 2010-12-28
Classification: H01L

Abstract:
1. A field effect transistor comprising: a first semiconductor layer having a first surface and a second surface opposite said first surface, said first semiconductor layer comprising a first conductivity type dopant; a substrate adjacent to said first surface; a gate adjacent to said second surface; a gate sidewall spacer on said second surface positioned laterally immediately adjacent to said gate; a recess in said first semiconductor layer, said recess undercutting said gate sidewall spacer such that a sidewall of said recess is positioned below said gate sidewall spacer and such that a bottom surface of said recess is positioned a predetermined distance from said second surface and further above said first surface; a second semiconductor layer filling said recess; a channel region in said first semiconductor layer at said second surface below said gate; a source/drain extension in said second semiconductor layer within said recess such that said source/drain extension is positioned laterally relative to said channel region, said source/drain extension comprising a second conductivity type dopant having a different conductivity type than said first conductivity type dopant; a halo comprising an implant region within said first semiconductor layer bordering said recess along said bottom surface and said sidewall such that said halo is positioned at said predetermined distance below said second surface immediately adjacent to said source/drain extension and further positioned between and immediately adjacent to both said source/drain extension and said channel region at said second surface, said implant region comprising said first conductivity type dopant at a first concentration greater than a second concentration of said first conductivity type dopant in said first semiconductor layer outside said implant region and further having edges exhibiting essentially zero outdiffusion of said first conductivity type dopant such that said halo does not extend vertically to said first surface.