A junction field effect transistor (JFET) is provided that is capable of a
high voltage resistance, high current switching operation, that operates
with a low loss, and that has little variation. This JFET is provided with
a gate region (2) of a second conductivity type provided on a surface of a
semiconductor substrate, a source region (1) of a first conductivity type,
a channel region (10) of the first conductivity type that adjoins the
source region, a confining region (5) of the second conductivity type that
adjoins the gate region and confines the channel region, a drain region
(3) of the first conductivity type provided on a reverse face, and a drift
region (4) of the first conductivity type that continuously lies in a
direction of thickness of the substrate from a channel to a drain. A
concentration of an impurity of the first conductivity type in the drift
region and the channel region is lower than a concentration of an impurity
of the first conductivity type in the source region and the drain region
and a concentration of an impurity of the second conductivity type in the
confining region.
