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US 7,125,769 B2Granted
Method of fabricating flash memory device
AssigneeHynix Semiconductor Inc.
InventorCha Deok Dong
Life of this patent
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Abstract
A method of fabricating a flash memory devices disclosed wherein, upon formation of sidewall oxide films, a regrown thickness of a screen oxide film is controlled. The width of an element isolation film is reduced by means of an etch process for removing the re-growth oxide film. This allows a floating gate space to be easily secured, and a thickness of the sidewall oxide films is reduced by means of a liner nitride film pre-treatment cleaning process. It is thus possible to secure the trench space, which facilitates gap-filling.
Claims22
A method of fabricating a flash memory device, comprising the steps of:
- forming a screen oxide film and a pad nitride film on a semiconductor substrate;
- etching the pad nitride film, the screen oxide film and the semiconductor substrate to form trenches;
- forming sidewall oxide films on the surface of the semiconductor substrate in which the trenches are formed, and regrowing the screen oxide film in such a way to have a predetermined thickness;
- reducing a thickness of the sidewall oxide films;
- forming a liner nitride film on the entire surface including the trenches;
- forming element isolation films within the trenches;
- removing the liner nitride film and the pad nitride film to expose the element isolation films that are projected upwardly from the semiconductor substrate;
- etching the entire surface so that the screen oxide film is removed, thereby reducing the width of the element isolation films, which are exposed due to the removal of the pad nitride film;
- and
- forming floating gates with tunnel dielectric films being interspersed between neighboring element isolation films.
7 more elements
Dependencies are inferred from the claim text.