Patent ID: 7928496

Claim:
A semiconductor memory device including an array of cell transistors, each cell transistor comprising: a first insulator formed on a semiconductor substrate; a first electrode disposed on the first insulator; a second insulator disposed on the first electrode and continuously disposed in one direction across a plurality of the cell transistors; a second electrode disposed on the second insulator and continuously disposed in the one direction; and diffusion layers disposed in the semiconductor substrate, the first and second electrodes disposed between adjacent ones of the diffusion layers, wherein the second insulator includes: a first silicon oxide film; a silicon-rich silicon nitride film formed on the first silicon oxide film and substantially uniformly containing more silicon than that in a silicon nitride film with a stoichiometric composition over an entire film thickness; and a second silicon oxide film formed on the silicon-rich silicon nitride film, and wherein the silicon-rich silicon nitride film has a ratio of a silicon concentration and a nitrogen concentration set to 1:0.9 to 1:1.2 (SiN x , where 0.9≦x≦1.2).