Surrounding gate transistor semiconductor device

A semiconductor device comprising:

• a first-conductive type semiconductor substrate
• a second-conductive type impurity region formed in a part of the first-conductive type semiconductor substrate;
• a first silicon pillar of an arbitrary cross-sectional shape formed on the second-conductive type impurity region;
• a first insulating body surrounding a part of a surface of the first silicon pillar;
• a gate surrounding the first insulating body;
• a second silicon pillar which is formed on the first silicon pillar and which includes a second-conductive type impurity region and a diameter of the second silicon pillar being wider than a diameter of the first silicon pillar,
• a second insulating body surrounding a remaining surface of the first silicon pillar which is not surrounded by the first insulating body, the second insulating body surrounding the gate and the second silicon pillar,
• wherein the first silicon pillar includes a second-conductive type high-concentration impurity region adjacent the second-conductive type impurity region formed in the part of the semiconductor substrate, and a second-conductive type high-concentration impurity region adjacent the second silicon pillar;
• wherein:
• the gate is disposed to be separated from the semiconductor substrate by the second insulating body and is disposed to be separated from the second silicon pillar by the second insulating body;
• and
• the capacitance between the gate and the semiconductor substrate is less than a gate capacitance, or the capacitance between the gate and the second silicon pillar is less than the gate capacitance.