Saddle type mos device

A MOS device comprising:

• a silicon substrate;
• a wall type silicon body protruding substantially perpendicular to the silicon substrate, the wall type silicon body having a height, a length, a width, a top surface and side surfaces, the wall type silicon body having a source region, a channel region and a drain region of the MOS device;
• a first insulating film formed on the top surface and the side surfaces of the wall type silicon body;
• a gate electrode formed on the channel region while having the first insulating film between the channel region and the gate electrode, an upper surface of the gate electrode being lower than the top surface of the wall type silicon body,
• wherein a top surface of the channel region, along with the first insulating film formed thereon, is depressed toward the silicon substrate to form a recess region to thereby define a recessed channel region near the recess region, and the gate electrode extends into the recess region and further extend, beyond the entire recess region, toward the silicon substrate along the side surfaces of the recessed channel region to form side-surface portions of the gate electrode, thereby forming a saddle-like form of gate electrode at the recessed channel region;
• a second insulation film formed on the first insulating film.