Non-volatile semiconductor memory device and method of manufacturing the same
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorShu Shimizu
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Abstract
A non-volatile semiconductor memory device includes a plurality of trenches for element-isolation formed on the main surface of a semiconductor substrate, a nitrided silicon layer formed along the wall surface of the trench, a silicon oxide film for element-isolation formed in the trench, a thermal oxide film extending from the aforementioned main surface located at the periphery of the nitrided silicon layer onto the nitrided silicon layer, the thickness of a portion located on the nitrided silicon layer of which is not less than the thickness of a portion located at the periphery of nitrided silicon layer, a floating gate electrode formed on the thermal oxide film, an insulating film, and a control gate electrode.
Claims13
A non-volatile semiconductor memory device, comprising:
- a semiconductor substrate having a main surface;
- a plurality of trenches for element-isolation formed in said semiconductor substrate;
- a nitrided silicon layer formed along a wall surface of said trench;
- a first insulating film for element-isolation formed in said trench;
- a second insulating film extending from on said main surface located at a periphery of said nitrided silicon layer onto said nitrided silicon layer, a thickness of a portion located on said nitrided silicon layer being at least a thickness of a portion located at the periphery of said nitrided silicon layer;
- a floating gate electrode formed on said second insulating film;
- and
- a control gate electrode formed above said floating gate electrode with a third insulating film interposed.
A method of manufacturing a non-volatile semiconductor memory device, comprising the steps of:
- forming a mask film including a first conductive film on a main surface of a semiconductor substrate with a first insulating film interposed;
- forming a plurality of trenches for element-isolation by etching said semiconductor substrate using said mask film;
- oxidizing a wall surface of said trench;
- forming a nitrided silicon layer extending along the wall surface of said trench by nitriding the wall surface of said trench after said oxidizing;
- forming a second insulating film for element-isolation in said trench;
- exposing said first conductive film by reducing thickness of said mask film;
- forming a second conductive film above said first conductive film with a third insulating film interposed;
- forming a floating gate electrode and a control gate electrode by patterning said second conductive film, said third insulating film and said first conductive film.
Dependencies are inferred from the claim text.