surface of the semiconductor substrate 100 is formed on the first well 101 similarly a second channel region 125 which includes a plurality of second channel layers 125 a and 125 b arranged perpendicular to the main surface of the semiconductor substrate 100 is formed on the second well 105 a plurality of first tunnels 111 a u2032 and 111 b u2032 are formed between the first channel layers 121 a and 121 b and a tunnel shaped first groove 111 c u2032 is formed on the uppermost first channel layer 121 b likewise a plurality of second tunnels 115 a u2032 and 115 b u2032 are formed between the second channel layers 125 a and 125 b and a tunnel shaped second groove 115 c u2032 is formed on the uppermost second channel layer 125 b first source drain regions 161 of n type conductivity are formed respectively at both sides of the first channel region 121 such that they are connected to the first channel layers 121 a and 121 b similarly second source drain regions 165 of p type conductivity are formed respectively at both sides of the second channel region 125 such that they are connected to the second channel layers 125 a and 125 b the superscript u201c u201d represents that a region is heavily doped with dopants and the superscript u201c u2212 u201d represents that a region is lightly doped with dopants the number of the tunnels and the channel layers included in each of the first and second regions 121 and 125 should be considered in descriptive sense only and not for purposes of limitation that is the first and second channel regions 121 and 125 may include more than two tunnels and more than two channel layers a first gate insulating.