PURPOSE: To enhance the transistor characteristics by a method wherein the second conductivity type impurities are to be implanted in the substrate surface between element formation parts.

CONSTITUTION: The impurities in the different conductivity type from that of the impurities implanted in a drain region 22 and a source region 24 are implanted in the substrate 10 surface existing between element formation parts. Accordingly, when an oblique ion implanting step is performed, the impurities are partly reflected on the sidewalls of protrusions 20 wherein the impurities are ion-implanted so that a parasitic MOS transistor may not be formed on the substrate 10 surface existing between the protrusions 20 even if the partly reflected impurities are implanted in the substrate 10 surface existing between the protrusions 20. Through these procedures, the excellent transistor characteristics can be displayed when the miniaturized semiconductor device is to be manufactured.