Method of fabricating thin film transistor

1. A method of fabricating a thin film transistor, comprising the steps of:

(a) forming an amorphous silicon film containing hydrogen therein, on a substrate composed of resin; and

(b) irradiating laser beams to said amorphous silicon film at an intensity smaller than a threshold intensity at which said amorphous silicon film is crystallized such that said amorphous silicon film is not crystallized, said amorphous silicon film being included as a layer in said thin film transistor, wherein laser beams are irradiated to said amorphous silicon film at an intensity between about 70% to about 95% of said threshold intensity.

2. The method as set forth in claim 1 , wherein said step (a) includes the steps of: (a1) forming said amorphous silicon film on said resin substrate by sputtering; and (a2) doping hydrogen ions into said amorphous silicon film.

3. The method of claim 1 , wherein said amorphous silicon film is formed by plasma enhanced chemical vapor deposition.

4. The method of claim 3 , wherein said amorphous silicon film is formed at 200 degrees centigrade.

5. The method of claim 1 , wherein said amorphous silicon film is formed on a gate insulating film and a channel protection film is formed on said amorphous silicon film.

6. The method of claim 5 , wherein said gate insulating film, said channel protection film, and said amorphous silicon film are formed by plasma enhanced chemical vapor deposition.

7. The method of claim 5 , wherein said laser beams are irradiated to said amorphous silicon film through said channel protection film.

8. The method of claim 7 , further comprising: patterning said channel protection film into an island.

9. The method of claim 1 , wherein said amorphous silicon film is formed on a gate insulating film.

10. The method of claim 9 , further comprising:

introducing hydrogen into said amorphous silicon film.

11. A method of fabricating a thin film transistor, comprising the steps of:

(a) forming an amorphous silicon film containing hydrogen therein and acting as a channel region, on a substrate composed of resin; and

(b) applying an electric field to said amorphous silicon film, wherein said amorphous silicon film includes a first impurity region defining a drain of said thin film transistor and a second impurity region defining a source of said thin film transistor, said drain and said source disposed within said amorphous silicon film.

12. The method as set forth in claim 11 , wherein said step (a) includes the steps of:

(a1) forming said amorphous silicon film on said resin substrate by sputtering; and

(a2) doping hydrogen ions into said amorphous silicon film.

13. The method of claim 11 , wherein said amorphous silicon film is formed on a gate insulating film.

14. The method of claim 11 , further comprising:

introducing hydrogen into said amorphous silicon film.

15. The method of claim 14 , further comprising:

doping impurity into said amorphous silicon film in a selected region to form an impurity-doped region including said first impurity region and said second impurity region.

16. The method of claim 15 , further comprising:

patterning said amorphous silicon film into an island such that said island includes said impurity-doped region.

17. A method of fabricating a thin film transistor, comprising the steps of:

(a) forming an electrically insulating film on a substrate composed of resin;

(b) forming a gate electrode on said electrically insulating film;

(c) forming a gate insulating film on said electrically insulating film such that said gate electrode is entirely covered with said gate insulating film;

(d) forming a first amorphous silicon film on said gate insulating film;

(e) forming a channel-protection film on said first amorphous silicon film;

(f) irradiating laser beams to said first amorphous silicon film through said channel-protection film;

(g) pattering said channel-protection film into an island;

(h) forming a second amorphous silicon film on said first amorphous silicon film such that said channel-protection film is entirely covered with said second amorphous silicon film, said second amorphous silicon film containing impurity therein;

(i) patterning said second amorphous silicon film, said first amorphous silicon film and said gate insulating film into an island;

(j) forming a metal wiring layer around said second amorphous silicon film, said first amorphous silicon film and said gate insulating film such that the thus island-shaped second amorphous silicon film is partially exposed;

(k) partially removing said second amorphous silicon film with said metal wiring layer being used as a mask, to thereby expose said channel-protection film;

(l) forming an interlayer insulating film all over a product resulted from said step (k);

(m) forming said interlayer insulating film with a contact hole reaching said metal wiring layer; and

(n) forming a metal film on said interlayer insulating film such that said contact hole is filled with said metal film, said metal film defining a pixel electrode.

18. A method of fabricating a thin film transistor, comprising the steps of:

(a) forming an electrically insulating film on a substrate composed of resin;

(b) forming a gate electrode on said electrically insulating film;

(c) forming a gate insulating film on said electrically insulating film such that said gate electrode is entirely covered with said gate insulating film;

(d) forming a first amorphous silicon film on said gate insulating film;

(e) introducing hydrogen into said first amorphous silicon film;

(f) doping impurity into said first amorphous silicon film in a selected region to thereby form an impurity-doped region;

(g) irradiating laser beams to said first amorphous silicon film;

(h) pattering said first amorphous silicon film into an island such that said island includes said impurity-doped region;

(i) forming a metal wiring layer such that said metal wiring layer makes contact with said first amorphous silicon film;

(j) forming an interlayer insulating film all over a product resulted from said step (i);

(k) forming said interlayer insulating film with a contact hole reaching said metal wiring layer; and

(l) forming a metal film on said interlayer insulating film such that said contact hole is filled with said metal film, said metal film defining a pixel electrode.

19. A method of fabricating a thin film transistor, comprising the steps of:

(a) forming an electrically insulating film on a substrate composed of resin;

(b) forming a gate electrode on said electrically insulating film;

(c) forming a gate insulating film on said electrically insulating film such that said gate electrode is entirely covered with said gate insulating film;

(d) forming a first amorphous silicon film on said gate insulating film;

(e) introducing hydrogen into said first amorphous silicon film;

(f) doping impurity into said first amorphous silicon film in a selected region to thereby form an impurity-doped region;

(g) pattering said first amorphous silicon film into an island such that said island includes said impurity-doped region;

(h) forming a metal wiring layer such that said metal wiring layer makes contact with said first amorphous silicon film;

(i) forming an interlayer insulating film all over a product resulted from said step (h);

(j) forming said interlayer insulating film with a contact hole reaching said metal wiring layer;

(k) forming a metal film on said interlayer insulating film such that said contact hole is filled with said metal film, said metal film defining a pixel electrode; and

(l) applying an electric field across an impurity-doped region which will make a source of said thin film transistor and an impurity-doped region which will make a drain of said thin film transistor.

20. A method of fabricating a thin film transistor, comprising:

(a) forming an amorphous silicon film containing hydrogen therein, on a substrate composed of resin;

(b) irradiating laser beams to said amorphous silicon film at an intensity smaller than a threshold intensity at which said amorphous silicon film is crystallized such that said amorphous silicon film is not crystallized, said amorphous silicon film being included as a layer in said thin film transistor;

wherein said amorphous silicon film is formed on a gate insulating film and a channel protection film is formed on said amorphous silicon film;

wherein said laser beams are irradiated to said amorphous silicon film through said channel protection film;

(c) patterning said channel protection film into an island;

wherein said amorphous silicon film is a first amorphous silicon film; and

(d) forming a second amorphous silicon film on said first amorphous silicon film such that said channel protection film is entirely covered with said second amorphous silicon film.

21. The method of claim 20 , further comprising:

patterning said second amorphous silicon film, said first amorphous silicon film and said gate insulating film into an island.

22. The method of claim 21 , further comprising:

forming a metal wiring around said second amorphous silicon film, said first amorphous silicon film and said gate insulating film such that the thus island-shaped second amorphous silicon film is partially exposed.

23. The method of claim 22 , further comprising:

partially removing said second amorphous silicon film with said metal wiring layer used as a mask to expose said channel protection film.

24. The method of claim 23 , further comprising:

forming an interlayer insulating film all over a product resulted from said partially removing.

25. The method of claim 24 , further comprising:

forming said interlayer insulating film with a contact hole reaching said metal wiring layer.

26. The method of claim 25 , further comprising:

forming a metal film on said interlayer insulating film such that said contact hole is filled with said metal film, said metal film defining a pixel electrode.

27. A method of fabricating a thin film transistor, comprising:

(a) forming an amorphous silicon film containing hydrogen therein, on a substrate composed of resin;

(b) irradiating laser beams to said amorphous silicon film at an intensity smaller than a threshold intensity at which said amorphous silicon film is crystallized such that said amorphous silicon film is not crystallized, said amorphous silicon film being included as a layer in said thin film transistor, wherein said amorphous silicon film is formed on a gate insulating film;

(c) introducing hydrogen into said amorphous silicon film; and

(d) doping impurity into said amorphous silicon film in a selected region to form an impurity-doped region and wherein said irradiating is performed after said doping.

28. The method of claim 27 , further comprising:

pattering said amorphous silicon film into an island such that said island includes said impurity-doped region.

29. The method of claim 28 , further comprising:

forming a metal wiring layer such that said metal wiring layer makes contact with said amorphous silicon film.

30. The method of claim 29 , further comprising:

forming an interlayer insulating film all over a product resulted from said forming a metal wiring layer.

31. The method of claim 30 , further comprising:

forming said interlayer insulating film with a contact hole reaching said metal wiring layer.

32. The method of claim 31 , further comprising:

forming a metal film on said interlayer insulating film such that said contact hole is filled with said metal film, said metal film defining a pixel electrode.

33. A method of fabricating a thin film transistor, comprising:

forming an amorphous silicon film containing hydrogen therein, on a substrate composed of resin; and

applying an electric field to said amorphous silicon film including a first impurity region defining a drain of said thin film transistor and a second impurity region defining a source of said thin film transistor, said drain and said source disposed within said amorphous silicon film;

introducing hydrogen into said amorphous silicon film;

doping impurity into said amorphous silicon film in a selected region to form an impurity-doped region including said first impurity region and said second impurity region;

patterning said amorphous silicon film into an island such that said island includes at least one of said first impurity-doped region and said second impurity-doped region; and

forming a metal wiring layer such that said metal wiring layer makes contact with said amorphous silicon film.

34. The method of claim 33 , further comprising:

forming an interlayer insulating film all over a product resulted from said forming a metal wiring layer.

35. The method of claim 34 , further comprising:

forming said interlayer insulating film with a contact hole reaching said metal wiring layer.

36. The method of claim 35 , further comprising:

forming a metal film on said interlayer insulating film such that said contact hole is filled with said metal film, said metal film defining a pixel electrode.