Semiconductor integrated circuit device having improved punch-through resistance and production method thereof, semiconductor integrated circuit device including a low-voltage transistor and a high-voltage transistor

1. A fabrication method of a semiconductor integrated circuit device comprising:

forming a first well in a semiconductor substrate, which includes a first device region, a second device region and a third device region, of said first device region by performing an ion implantation;

forming a first gate insulation film on said semiconductor substrate of said first device region;

forming a floating gate on said first gate insulation film;

forming a dielectric film on said floating gate;

forming, after forming said dielectric film, a second well in said semiconductor substrate of said second device region and a third well in said semiconductor substrate of said third device region;

forming a second gate insulation film on said semiconductor substrate of said second well and said third well;

removing said second gate insulation film of said third device region;

forming a third gate insulation film of a thickness different from a thickness of said second gate insulation film on said semiconductor substrate of said third device region after removing said second gate insulation film of said third device region;

forming a control gate, first gate electrode and second gate electrode on said dielectric film, said second gate insulation film and third gate insulation film respectively.

2. The fabrication method of the semiconductor integrated circuit device as claimed in claim 1 , wherein

forming said dielectric film includes forming said dielectric film on said semiconductor substrate of said second device region and said third device region; and

forming said second well and said third well includes introducing an impurity element into said semiconductor substrate via said dielectric film and

the fabrication method of the semiconductor integrated circuit device as claimed in claim 1 , further comprising

removing said dielectric film of said second device region and said third device region after forming said second well and said third well, and before forming said second gate insulation film.

3. The fabrication method of the semiconductor integrated circuit device as claimed in claim 1 , wherein said second well and said third well are formed simultaneously.

4. The fabrication method of the semiconductor integrated circuit device as claimed in claim 3 , wherein

said semiconductor substrate includes a fourth device region and a fifth device region, and

the fabrication method of the semiconductor integrated circuit device as claimed in claim 3 , further comprising

forming a fourth well and a fifth well in said semiconductor substrate of said fourth device region and fifth device region respectively before forming said dielectric film.

5. The fabrication method of the semiconductor integrated circuit device as claimed in claim 4 , wherein said second well and said third well are formed simultaneously, and said fourth well and said fifth well are formed simultaneously.

6. The fabrication method of the semiconductor integrated circuit device as claimed in claim 1 , wherein

forming said floating gate includes forming a first conductor film on said first gate insulation film, and patterning said first conductor film to form said floating gate.

7. The fabrication method of the semiconductor integrated circuit device as claimed in claim 1 , wherein

forming said control gate, said first gate electrode and said second gate electrode includes forming a second conductor film on said dielectric film, said second gate insulation film and said third gate insulation film, and patterning said second conductor film to form said control gate, said first gate electrode and said second electrode.

8. A fabrication method of a semiconductor integrated circuit device comprising:

forming a first well in a semiconductor substrate, which includes a first device region and a second device region, of said first device region by performing an ion implantation;

forming a first gate insulation film on said semiconductor substrate of said first device region;

forming a floating gate on said first gate insulation film;

forming a dielectric film on said floating gate;

forming a second well in said semiconductor substrate of said second device region after forming said dielectric film;

forming a second gate insulation film on said semiconductor substrate of said second well;

forming a control gate, first gate electrode on said dielectric film and said second gate insulation film respectively.

9. The fabrication method of the semiconductor integrated circuit device as claimed in claim 8 , wherein

forming said dielectric film includes forming said dielectric film on said semiconductor substrate of said second device region; and

forming said second well includes introducing an impurity element into said semiconductor substrate of said second device region via said dielectric film, and

the fabrication method of the semiconductor integrated circuit device as claimed in claim 1 , further comprising

removing said dielectric film of said second device region after forming said second well, and before forming said second gate insulation film.

10. The fabrication method of the semiconductor integrated circuit device as claimed in claim 8 , wherein

forming said floating gate includes forming a first conductor film on said first gate insulation film, and patterning said first conductor film to form said floating gate.

11. The fabrication method of the semiconductor integrated circuit device as claimed in claim 1 , wherein

forming said control gate, said first gate electrode includes forming a second conductor film on said dielectric film and said second gate insulation film, and patterning said second conductor film to form said control gate and said first gate electrode.