SEMICONDUCTOR MEMORY DEVICE AND MANUFACTURING METHOD THEREOF

摘要

a n type first area which has a side connected to a channel (22) with a p type source/drain region on the p type semiconductor substrate (21) and the source/drain region of a memory cell transistor connected to the surface of the semiconductor substrate (21); a n type second area which has density lower than the first area, being connected to the semiconductor substrate (21) and to the part of the above side and expanding to the channel (22); a n type third area which is connected to the rest of the above side, surrounding the second area and expanding to the channel (22) and having density lower than the second area.