In a metal-oxide semiconductor (MOS) transistor with an elevated
source/drain structure and in a method of fabricating the MOS transistor
with the elevated source/drain structure using a selective epitaxy growth
(SEG) process, a source/drain extension junction is formed after an
epi-layer is formed, thereby preventing degradation of the source/drain
junction region. In addition, the source/drain extension junction is
partially overlapped by a lower portion of the gate layer, since two gate
spacers are formed and two elevated source/drain layers are formed in
accordance with the SEG process. This mitigates the short channel effect
and reduces sheet resistance in the source/drain layers and the gate
layer.