Semiconductor memory device and method for producing same

A semiconductor memory device comprising:

• a semiconductor substrate;
• a semiconductor region of a first conductive type formed in said semiconductor substrate;
• a diffusion region of a second conductive type different from said first conductive type, said diffusion region being formed on a surface of said semiconductor region;
• a trench formed in said semiconductor substrate so as to be adjacent to said diffusion region;
• a capacitor insulator film formed on a portion of a side surface of said trench, which extends from a position at a predetermined depth of said trench to a bottom portion of said trench, and on a bottom surface of said trench;
• a storage node formed so that a surface of said storage node buried in said trench is at the same depth as the position of said predetermined depth of said trench;
• a first insulator film formed in a portion of said side surface of said trench above the position of said predetermined depth of said trench, said first insulator film having a window in a region contacting said diffusion region;
• and
• a storage node electrode formed on said storage node so as to bury said trench, the uppermost surface of a region of said storage node electrode contacting said diffusion region via said window and being formed of a mono-crystalline silicon region,
• wherein an MIS transistor is formed in said semiconductor region, and said diffusion region is one of a source region and a drain region of said MIS transistor, and said MIS transistor has a gate insulator film which extends to a portion on said storage node electrode, and said gate insulator film is a CVD oxide film or a silicon oxynitride film.