A semiconductor device has an n.sup.--semiconductor layer and
p.sup.+-diffusion regions each having a depth of 14 to 20 .mu.m (design
value) selectively formed in the n.sup.- semiconductor layer. With the
entire surface of the chip irradiated with light ions, such as He ions, a
lifetime killer is introduced from a position d2 shallower than a
position d1 of a p-n junction surface, formed from the
n.sup.--semiconductor layer and the p.sup.+-diffusion regions, to a
position d3 deeper than the position d1 to form a short-lifetime region
over the entire chip. The irradiation is carried out so that the light
ion irradiation half width is not more than the depth of the
p.sup.+-diffusion regions and a position of a peak of the light ions
becomes deeper than the light ion irradiation half width and within the
range between 80% and 120% of the depth of the p.sup.+-diffusion regions.
Thus, in a semiconductor device such as a converter diode, a capability
for a high decay rate of a reverse recovery current di/dt can be brought
sufficiently high to such an extent that the device can withstand a
lightening surge with a low forward voltage VF being kept low.