Semiconductor integrated circuit device and process for producing the same

Abstract

A semiconductor integrated circuit device with third gates comprising second conduction type source/drain diffusion layer regionsformed first conduction type well, floating gatesformed on semiconductor substratethrough an insulator film, control gatesformed on floating gatesthrough nitrogen-introduced silicon oxide filmand third gatesdifferent from the floating gates and the control gates, formed through the semiconductor substrates, the floating gates, the control gates and the insulator film, where the third gates are formed as filled in gaps between the floating gates existing in a vertical direction to word lines and channels and the height of third gatesthus formed is made lower than that of floating gates, has improved reduction of memory cell size and operating speed and improved reliability after programming/erasing cycles.