Semiconductor device and manufacturing method of semiconductor device

A semiconductor device, comprising:

• a semiconductor substrate;
• a first metal insulator semiconductor field effect transistor formed over the semiconductor substrate;
• a second metal insulator semiconductor field effect transistor formed over the semiconductor substrate and having a second gate electrode formed with an insulating film inserted between the second gate electrode and a first gate electrode of the first metal insulator semiconductor field effect transistor;
• a first diffusion layer electrode;
• a first channel region, corresponding to the first gate electrode, of the first metal insulator semiconductor field effect transistor;
• a second channel region, corresponding to the second gate electrode, of the second metal insulator semiconductor field effect transistor;
• and
• a second diffusion layer electrode opposite to the first diffusion layer electrode with the first channel region and second channel region sandwiched therebetween,
• the first diffusion layer electrode, the first channel region, the second channel region, and the second diffusion layer being in a direction crossing with the respective gate electrodes of the first and second metal insulator semiconductor field effect transistors, wherein:
• a gate insulating film of the second metal insulator semiconductor field effect transistor has a charge retaining function;
• a current flowing between the first diffusion layer electrode and the second diffusion layer electrode is controlled by a change in voltage characteristics caused by the second gate electrode;
• the device has a convex shaped semiconductor region in a direction crossing with a channel direction connecting the first diffusion layer electrode and the second diffusion layer electrode;
• and
• the first channel region of the first metal insulator semiconductor field effect transistor is formed over a side wall of the convex shaped semiconductor region.