Method of fabricating semiconductor device capable of providing MOSFET which is improved in a threshold voltage thereof
AssigneeNEC Corporation
InventorsHitoshi Abiko, Minoru Higuchi
Life of this patent
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Abstract
In a method of fabricating a semiconductor device by the use of a semiconductor substrate (1), boron ions (4) are implanted into the semiconductor substrate from a trench (3) which is formed to the semiconductor substrate. The trench is defined by a plurality of side surfaces and a bottom surface extending between the side surfaces. The boron ions are implanted through all of the side surfaces and the bottom surface. It is preferable that isolating material is filled into the trench to produce a trench isolation extending over a p-well (7) and a n-well (8).
Claims11
A method of reducing the inverse narrow channel effect in a semiconductor device having a p-well, an n-well, and a trench isolation extending over said p-well and said n-well to separate respective source/drain regions formed in the p-well and n-well, said method comprising the steps of:
- preparing a semiconductor substrate;
- forming a trench for the trench isolation in the semiconductor substrate, said trench being defined by a plurality of side surfaces and a bottom surface extending between the side surfaces;
- covering a region for said n-well with photoresist;
- reflowing said photoresist to produce reflowed photoresist;
- implanting boron ions into the semiconductor substrate through the side surfaces and bottom surface of the trench using an implantation direction that is diagonal to the semiconductor substrate;
- filling the trench with an isolating material to form the trench isolation;
- and
- implanting ions into the semiconductor substrate to form the respective p-well and n-well at opposite sides of the trench isolation.
A method of reducing the inverse narrow channel effect in a semiconductor device having a p-well, an n-well, and a trench isolation extending over said p-well and said n-well to separate respective source/drain regions formed in the p-well and n-well, said method comprising the steps of:
- preparing a semiconductor substrate;
- forming a trench for the trench isolation in the semiconductor substrate, said trench being defined by a plurality of side surfaces and a bottom surface extending between the side surfaces;
- applying photoresist to cover a region for said n-well while leaving exposed a region for said p-well;
- rounding shoulder portions of said photoresist by means of reflowing;
- and
- implanting boron ions into the semiconductor substrate through the side surfaces and bottom surface of the trench using said photoresist as a mask.
Dependencies are inferred from the claim text.