Semiconductor device including gate insulation films having different thicknesses
AssigneeNEC Electronics Corporation
InventorSadaaki Masuoka
Life of this patent
Estimating the term…
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 the steps of:
- forming an 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 the steps of:
- forming an isolation trench on a semiconductor substrate to separate an area of said semiconductor substrate into first through n-th circuit areas:
- filling said 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 semiconductor device comprising:
- a semiconductor substrate;
- an isolation trench receiving therein an in-trench silicon oxide film and separating an area of said semiconductor substrate into first through n-th circuit areas;
- and
- first through n-th thermal silicon oxide films formed in said first through n-th circuit areas, respectively, said first through n-th thermal silicon oxide films having first through n-th largest thicknesses, respectively,
- said in-trench silicon oxide film having a top surface higher than a top surface of said semiconductor substrate in said first circuit area, said in-trench silicon oxide film having a top surface substantially flush with said top surface of said semiconductor substrate in said second through n-th circuit areas.
A semiconductor device comprising:
- a semiconductor substrate;
- an isolation trench filled with a filling member and separating an area of said semiconductor substrate into first through n-th circuit areas;
- and
- first through n-th gate insulating films formed in said first through n-th circuit areas, respectively, said gate insulating films having first through n-th largest thicknesses, respectively,
- said filling member having a top surface higher than a top surface of said semiconductor substrate in said first circuit area, said filling member having a top surface substantially flush with said top surface of said semiconductor substrate in said second through n-th circuit areas.
Dependencies are inferred from the claim text.