A semiconductor device has a fin-type transistor formed in a projecting semiconductor
region. The projecting semiconductor region is formed on a major surface of a semiconductor
substrate of a first conductivity type. A gate electrode of the fin-type transistor
is formed on at least opposed side surfaces of the projecting semiconductor region,
with a gate insulating film interposed. Source and drain regions are formed in
the projecting semiconductor region such that the source and drain regions sandwich
the gate electrode. A channel region of the first conductivity type is formed in
the projecting semiconductor region between the source and drain regions. The following
relationship is established:
TFIN(/4qNCH)1/2
where TFIN is a width of the projecting semiconductor region, NCH
is an impurity concentration in the channel region, is a dielectric
constant of a semiconductor material of the projecting semiconductor region, and
q is an elementary charge.
