| 摘要 |
PURPOSE:To enhance write efficiency and to execute an erasure operation surely by a method wherein a drain region is constituted by a semiconductor region of high impurity concentration and an end part on the side of a channel region in a source region is used as a semiconductor region of low impurity concentration. CONSTITUTION:A drain region is composed of an n<+> type semiconductor region 9 and an n<+> type semiconductor region 10, and is connected to an identical data line DL through an identical connection hole 14. A source region is composed of the n<+> type semiconductor region 9, the n<+> type semiconductor region 10 and an n<-> type semiconductor region 11. The drain region of a memory cell is constituted by a semiconductor region of high impurity concentration; an end part on the side of a channel region in the source region is used as a semiconductor region of low impurity concentration. Then, an electric field at the end part of the drain region becomes strong; the generation of hot electrons is increased; as a result, write efficiency is enhanced. In addition, because the avalanche breakdown voltage between the source region and a semiconductor substrate is increased, erasure efficiency by a tunnel can be enhanced. |
