| abstract |
A highly reliable and miniaturized nonvolatile semiconductor memory device is provided. A silicon nitride dot for accumulating electric charges located between source / drain diffusion layers in a p-type well formed in a silicon substrate and silicon oxide films. To form a memory cell having a control gate 212 and auxiliary gates 204a and 204a ', and accumulate electrons in the silicon nitride dots (part A) on the drain (206') side or the silicon nitride dots on the source (206) side. In this way, writing is performed. Since the silicon nitride, which is the charge storage portion, is formed in a dot shape, charge transfer in the channel direction is suppressed, the charges at the source end and the drain end can be prevented from being mixed, and the charge retention characteristics are improved. Further, even if the gate length is shortened, the charge retention characteristics can be secured. [Selection] Fig. 39 |