Abstract: A semiconductor memory device is provided with a memory region including SAMOS type memory transistors and a non-memory or peripheral region including MOS transistors which are interconnected to form logic circuits such as decoders for controlling the operation of each of said memory transistors. Each of the transistors includes a pair of first and second doped polysilicon layers and an interlayer insulating film provided as sandwiched between the pair of first and second doped polysilicon layers. In the memory region, the first and second doped polysilicon layers define floating and control gate electrodes, respectively; whereas, in the non-memory region, the first and second doped polysilicon layers are electrically interconnected by a through-the-layer electrode formed through the interlayer insulating film.