| 摘要 |
PURPOSE: To improve the electrical characteristics and reliability of a non- volatile semiconductor device in which a silicon nitride layer is formed in the internal wall of an isolation trench. CONSTITUTION: The nonvolatile semiconductor memory device of this invention comprises a plurality of isolation trenches 3 formed under the main face of a semiconductor substrate, a silicon nitride layer 25 formed along the wall of the trench 3, a silicon oxide isolation film 21 formed in the trench 3, a thermal oxide film 4 extends on the silicon nitride layer 25 from the main face located in the circumference of the silicon nitride layer 25, in which the thickness of the thermal oxide film 4 located on the silicon nitride layer 25 is not less than that of located in the circumference of the silicon nitride layer 25, and further comprises a floating gate electrode 8, an insulation film 9, and a control gate electrode 35 formed on the insulation film 4.
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