Semiconductor memory device and method for manufacturing the same

A method for manufacturing a semiconductor memory device, comprising:

• forming a plurality of word lines at predetermined intervals on a semiconductor substrate, each having a gate insulating film, a charge storage layer, a first insulating film, and a controlling gate electrode which are stacked in order, and including a metal oxide layer above the level of the gate insulating film;
• forming a second insulating film having a film thickness of 15 nm or less so as to cover a side of the word line and a surface of the semiconductor substrate between the word lines;
• and
• forming a third insulating film so as to cover the word lines and a place between the word lines using a CVD technique.

A method for manufacturing a semiconductor memory device, comprising:

• forming a first insulating film on a semiconductor substrate;
• forming a first electrode layer on the first insulating film;
• forming a trench formed at predetermined intervals along a first direction by etching the first electrode layer, the first insulating film, and the semiconductor substrate;
• forming an element isolating insulating film so as to fill in the trench;
• forming a second insulating film including a metal oxide layer on the first electrode layer and the element isolating insulating film;
• forming a second electrode layer on the second insulating film;
• forming a third insulating film on the second electrode layer;
• forming word lines formed at predetermined intervals along a second direction perpendicular to the first direction by removing the third insulating film, the second electrode layer, the second insulating film, the first electrode layer, the first insulating film, and the element isolating insulating film so as to expose a surface of the semiconductor substrate;
• forming a fourth insulating layer having a film thickness of 15 nm or less on a side of the word line and the surface of the semiconductor substrate between the word lines;
• and
• forming a fifth insulating film using a CVD technique so as to cover the word line and a place between the word lines.