| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a highly reliable semiconductor memory device such as an NROM having a memory capacity of two or more bits for one device, by ensuring a large reading window as a difference in current between a written state and a deletion state. <P>SOLUTION: In a p-type semiconductor layer 101, a heavily doped region 109 in which the concentration of p-type impurities different from right and left n-type diffusion regions 106, 107 becomes extremely large is formed by oblique ion implantation in the center of a channel region 108. The memory device has a first insulating film 102, a charge storing insulating film 103, and a second insulating film 104 on the semiconductor layer 101; and further has a gate electrode 105 made of polysilicon on an upper surface thereof. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
