Semiconductor device including gate insulation films having different thicknesses
AssigneeNEC Electronics Corporation
InventorSadaaki Masuoka
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Abstract
A method for forming three gate oxide films having different thicknesses in first through third circuit areas, respectively. The method includes the consecutive steps of forming a first gate oxide film having a largest thickness in all the areas, removing the first gate oxide film and forming a second gate oxide film having a second largest thickness in the second circuit area, and removing the first gate oxide and forming a third gate oxide film having a smallest thickness in the third circuit area. The resultant gate oxide films have accurate thicknesses.
Claims12
A method for fabricating a semiconductor device having thermal silicon oxide films having n different thicknesses, given n being an integer not smaller than three, said method comprising:
- forming at least one isolation trench receiving therein an in-trench oxide film on a semiconductor substrate to separate an area of said semiconductor substrate into first through n-th circuit areas;
- forming a first thermal oxide film having a largest thickness among said n different thicknesses in said first through n-th circuit areas;
- and
- iterating, consecutively for i=2 to i=n, removing said first thermal oxide film in said i-th circuit area and forming an i-th thermal oxide film having an i-th largest thickness among said n different thickness in said i-th circuit area.
A method for fabricating a semiconductor device including gate oxide films having n different thicknesses, given n being an integer not smaller than three, said method comprising:
- forming at least one isolation trench on a semiconductor substrate to separate an area of said semiconductor substrate into first through n-th circuit areas;
- filling said at least one isolation trench with a filling member so that said filling member has a top surface higher than a top surface of said semiconductor substrate;
- forming a first gate oxide film having a largest thickness among said n different thicknesses in said first through n-th circuit areas;
- and
- iterating, consecutively for i=2 to i=n, removing said first gate oxide film in said i-th circuit area and forming an i-th gate oxide film having an i-th largest thickness among said n different thicknesses in said i-th circuit area.
A method for fabricating a semiconductor device having thermal silicon oxide films with n different thicknesses, n being an integer not smaller than 2, said method comprising:
- forming one or more isolation trenches on a semiconductor substrate to separate areas of said semiconductor substrate into first through n-th circuit areas;
- filling said isolation trenches with a filling member so that said filling member has a top surface higher than a top surface of said semiconductor substrate;
- forming a first gate oxide film having essentially a thickness corresponding to a largest thickness among said n different thicknesses in said first through n-th circuit areas;
- forming a protective mask over said first through n-th circuit areas except for an i-th one of said n circuit areas, said i-th circuit area being a circuit area other than said first circuit area;
- and
- removing said first thermal oxide film in said i-th circuit area until said top surface of said filling member becomes essentially flush with said top surface of said semiconductor substrate.
Dependencies are inferred from the claim text.