A semiconductor device according to a exemplary embodiment of the present invention includes a reverse spacer exposing a part of an epitaxial silicon layer on a silicon substrate, a gate oxide layer on at least the epitaxial silicon layer and a gate polysilicon layer on the gate oxide layer and at least part of the reverse spacer, and source/drain terminals including a first doped (shallow junction) region in the silicon substrate at a position exterior to the exposed epitaxial silicon layer and a second doped (deep junction) region neighboring the first doped region. The semiconductor device can thus have an epitaxial silicon channel of nanometer size, an ultra-shallow junction, and a deep junction.