An IGFET (40 or 42) has a channel zone (64 or 84) situated in body material
(50). Short-channel threshold voltage roll-off and punchthrough are
alleviated by arranging for the net dopant concentration in the channel
zone to longitudinally reach a local surface minimum at a location between
the IGFET's source/drain zones (60 and 62 or 80 and 82) and by arranging
for the net dopant concentration in the body material to reach a local
subsurface maximum more than 0.1 .mu.m deep into the body material but not
more than 0.1 .mu.m deep into the body material. The source/drain zones
(140 and 142 or 160 and 162) of a p-channel IGFET (120 or 122) are
provided with graded-junction characteristics to reduce junction
capacitance, thereby increasing switching speed.
