| 摘要 |
A method for forming a U-shaped vertically long groove in a region where a channel portion of a transistor is formed to make a channel length longer than an apparent channel length additionally requires a photolithography process for forming a groove; therefore, it has a problem in terms of costs and yield. By forming a three-dimensional channel region with the use of a gate electrode or a structure having an insulating surface, a channel length is made three times or more, preferably five times or more, further preferably ten times or more as long as a channel length when seen from the above. |
