Semiconductor manufacturing method and semiconductor device

A method of manufacturing a semiconductor device comprising:

• forming a mask layer on a first-conductivity-type semiconductor substrate;
• etching the semiconductor substrate using the mask layer as a mask, thereby forming a projecting semiconductor layer;
• forming a first insulating layer on the semiconductor substrate to cover a portion of the projecting semiconductor layer, wherein the first insulating layer covers at least a portion of a side of the projecting semiconductor layer;
• forming a high-impurity-concentration layer in the portion of the projecting semiconductor layer by implanting a first-conductivity-type impurity into the portion of the projecting semiconductor layer via the first insulating layer which covers at least the portion of the side of the projecting semiconductor layer;
• forming gate insulating films on side surface portions of the projecting semiconductor layer which upwardly extend from an upper surface of the first insulating layer;
• and
• forming a gate electrode on the gate insulating films and on the first insulating layer,
• wherein the first-conductivity-type impurity is implanted into the first insulating layer perpendicularly to the semiconductor substrate so as not to contact any side surfaces of the projecting semiconductor layer, and wherein the impurity is moved to the portion of the projecting semiconductor layer by way of the impurity moving from the first insulating layer sideways into the portion of the projecting semiconductor layer by at least diffusion.