Method for making semiconductor transistor device by implanting punch

Abstract

Insulating films formed on side walls of a gate electrode are removed for a self-alignment to selectively implant impurities only into end portions of a source region and a drain region. Therefore, p.sup.+ -type semiconductor regions are selectively formed only on sides near a channel region of the source and the drain regions. A punch through of the source or drain region is prevented by the p.sup.+ -type semiconductor regions controlling an inversion threshold voltage. Therefore, the impurity concentration of the p-type substrate can be settled low, and the semiconductor transistor device can be miniaturized without increasing a parasitic junction capacitance. Moreover, since the impurity concentration in the channel region is ununiform, a drivability of the transistor can be increased. As a result, a semiconductor transistor device with a high withstand voltage and a high drivability in which the inversion threshold voltage can be easily controlled, and a method for producing the same are provided.