Fabrication of semiconductor device including chemical mechanical polishing

1. A method of fabricating a semiconductor device comprising:

forming a first insulation film over a semiconductor substrate, said semiconductor substrate including an outer region and an inner region located at an inner side of said outer region;

forming a first wiring over said first insulation film in said inner region;

forming a second insulation film over said first wiring and over said first insulation film;

decreasing a film thickness of said second insulation film in said inner region with regard to a film thickness of said second insulation film in said outer region; and

planarizing said second insulation film after said decreasing said film thickness of said second insulation film.

2. The method as claimed in claim 1 , wherein there is formed another wiring in said first insulation film by a damascene process in electrical connection with said first wiring.

3. The method as claimed in claim 1 , wherein said decreasing said film thickness of said second insulation film includes:

forming a mask over said second insulation film in said outer region;

removing a part of said second insulation film in said inner region while using said mask as an etching mask; and

removing said mask after said removing said part of said second insulation film.

4. The method as claimed in claim 3 , wherein

said semiconductor substrate includes an outermost peripheral region at an outer side of said outer region to reach an edge of said semiconductor substrate, and wherein

forming said mask includes:

forming a resist film over said second insulation film; and

removing said resist film from said inner region and from said outermost peripheral region.

5. The method as claimed in claim 1 , wherein said decreasing said film thickness is conducted such that said first wiring is not exposed from said second insulation film.

6. The method as claimed in claim 5 , wherein said second insulation film is formed with a film thickness exceeding 1.5 times a height of said first wiring, and said step of decreasing said film thickness decreases said film thickness of said second insulation film at least by 10%.

7. The method as claimed in claim 1 , wherein a film thickness of said first insulation film in said outer region is thinner than a film thickness of said first insulation film in said inner region.

8. The method as claimed in claim 7 , further including, before forming said first wiring:

forming an opening exposing a lower wiring in said first insulation film;

forming a conductive material of said lower wiring in said opening that exposes said lower wiring; and

polishing said first insulation film and said conductive material of said lower wiring to form said lower wiring.

9. The method as claimed in claim 1 , further including:

forming a conductive plug that is connected to said first wiring in said second insulation film after planarizing said second insulation film; and

forming an optical reflection layer over said second insulation film and said conductive plug.

10. The method as claimed in claim 9 , further comprising forming a liquid crystal layer over said optical reflection layer,

wherein a liquid crystal display device includes said semiconductor substrate, said first insulation film, said first wiring, said second insulation film, said conductive plug, said optical reflection layer and said liquid crystal layer.

11. A method of fabricating a semiconductor device comprising:

forming a first insulation film over a semiconductor substrate that includes an outer region and an inner region located at an inner side of said outer region;

forming a first wiring over said first insulation film in said outer region and in said inner region;

forming a second insulation film over said first wiring and over said first insulation film; and

polishing said second insulation film.

12. A semiconductor device, comprising:

a semiconductor substrate that includes an outer region and an inner region located at an inner side of said outer region;

a first insulation film formed over said semiconductor substrate;

a lower wiring formed in said first insulation film in said inner region;

a first wiring formed over said first insulation film in said outer region and in said inner region;

a second insulation film formed over said first wiring;

a conductive plug formed in said second insulation film in electrical connection with said first wiring; and

an optical reflection layer formed over said second insulation film and said conductive plug.

13. The semiconductor device as claimed in claim 12 , wherein a film thickness of said first insulation film in said outer region is thinner than a film thickness of said first insulation film in said inner region.