Semiconductor device improved in resistance to breaking due to cosmic rays

摘要

The specific resistance p of a wafer constituting a single pn junction of a pnpn junction of a GTO thyristor ranges from one-seventeenth the rated voltage to one-twelfth the rated voltage. The thickness (W3) of the wafer is set substantially equal to the width of a depletion layer formed at the pn junction such that punch-through occurs close to the rated voltage. Consequently, the resistance to breaking due to cosmic rays can be improved, the probability of occurrence of defects can be reduced to such an extent as to cause no problems, and the thickness of an n--type base layer can be made smaller than that of a prior art one.