PURPOSE: To improve the reproducibility and uniformity of characteristics by forming by self-aligning source, drain regions and a gate electrode.

CONSTITUTION: A reverse mesa projection 11 is formed by etching on a single crystal substrate by using a mask 83 used for both ion implanting and etching. Then, impurity ions are selectively implanted on a single crystal substrate 1 from above the projection 11, and a high impurity density region to become a source and drain region 2 is formed. Then, a single crystal substrate 1 is again etched, and the etching is advanced until the top of the projection 11 is removed. Thereafter, relatively low density impurity ions are implanted from above, and an operating region 3 is formed. The substrate 1 formed in this manner has a middle high locus 12 self-aligned to the relative position to the region 2. The relation of this relative position can be decided by the ion implanting angle at the time of forming the shape of the projection 11 and the region 2.