Semiconductor thin film forming method

• US 6,582,996 B1
• Filed: 08/30/2000
• Issued: 06/24/2003
• Est. Priority Date: 07/13/1998
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Fujitsu Limited
• Inventors: Hara, Akito, Sasaki, Nobuo
• Primary Examiner(s): Whitmore; Stacy
• Application Number:
  US09/650,641
• Time in Patent Office: 1,028 Days
• Field of Search: 438/166,304,487
• US Class Current: 438/166
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/02422 Non-crystalline insulating materials, e.g. glass, polymers
• CPC Class Codes: H01L 21/0245 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02488 Insulating materials
• CPC Class Codes: H01L 21/02496 Layer structure
• CPC Class Codes: H01L 21/02505 consisting of more than two layers
• CPC Class Codes: H01L 21/02513 Microstructure
• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 21/02672 using crystallisation enhancing elements
• CPC Class Codes: H01L 21/02683 Continuous wave laser beam
• CPC Class Codes: H01L 21/02686 Pulsed laser beam
• CPC Class Codes: H01L 21/02691 Scanning of a beam
• CPC Class Codes: H01L 27/1281 by using structural features to control crystal growth, e.g. placement of grain filters
• CPC Class Codes: H01L 29/04 characterised by their crystalline structure, e.g. polycrystalline, cubic or particular orientation of crystalline planes characterised by physical imperfections H01L29/30
• CPC Class Codes: H01L 29/66757 Lateral single gate single channel transistors with non-inverted structure, i.e. the channel layer is formed before the gate
• CPC Class Codes: H01L 29/66772 Monocristalline silicon transistors on insulating substrates, e.g. quartz substrates H01L29/66666 takes precedence; thin film FinFETs H01L29/66795
• CPC Class Codes: H01L 29/78654 Monocrystalline silicon transistors
• CPC Class Codes: H01L 29/78675 with normal-type structure, e.g. with top gate
• CPC Class Codes: H01L 29/78696 characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel H01L29/78612 takes precedence; transistors having a drain offset region or a lightly doped drain [LDD] H01L29/78621

Abstract

A polycrystal thin film forming method comprising the step of forming a semiconductor thin film on a substrate 14, and the step of flowing a heated gas to the semiconductor thin film while an energy beam 38 is being applied to the semiconductor thin film at a region to which the gas is being applied to thereby melt the semiconductor film, and crystallizing the semiconductor thin film in its solidification. The energy beam is applied while the high-temperature gas is being flowed, whereby the melted semiconductor thin film can have low solidification rate, whereby the polycrystal thin film can have large crystal grain diameters and can have good quality of little defects in crystal grains and little twins.

Claims

1. A polycrystal silicon thin film forming method comprising the steps of:

forming a silicon layer on a substrate;

forming a heat reservoir layer on an upper surface of the silicon layer and side surfaces of the silicon layer;

applying short pulsed laser beams to the silicon layer to crystallize the silicon layer; and

removing the heat reservoir layer.

2. A polycrystal silicon thin film forming method according to claim 1, wherein the silicon layer has a small-width region.

3. A polycrystal silicon thin film forming method according to claim 2, wherein the small-width region is monocrystallized in the step of crystallizing the silicon layer.

4. A polycrystal silicon thin film forming method according to claim 1, wherein

the substrate is short pulsed laser beam permeable; and

the short pulsed laser beams are applied to the substrate on the side of the surface without the heat reservoir film formed on in the step of crystalizing the silicon layer.

5. A polycrystal silicon thin film forming method according to claim 1, wherein the short pulsed laser beams are applied to the silicon layer with the substrate heated up to a prescribed temperature in the step of crystalizing the silicon layer.

6. A polycrystal silicon thin film forming method according to claim 1, wherein the heat reservoir film with an opening formed in down to the upper surface of the silicon layer is formed in the step of forming the heat reservoir film.

7. A polycrystal silicon thin film forming method according to claim 1, further comprising:

the step of forming on the silicon layer an isolation film having etching characteristics different from those of the heat reservoir film, after the step of forming the silicon layer and before the step of forming the heat reservoir layer.

8. A polycrystal silicon thin film forming method according to claim 1, wherein the silicon layer comprises an amorphous silicon film, a polycrystal silicon film or a micro-crystal silicon film.

9. A polycrystal silicon thin film forming method according to claim 1, wherein the heat reservoir film comprises an amorphous silicon layer, a polycrystal silicon layer, a metal layer, a metal-content silicon layer or an impurity-content silicon layer.

10. A thin film transistor fabrication method comprising the steps of:

forming a silicon layer on a substrate;

forming a heat reservoir layer on an upper surface of the silicon layer and side surfaces of the silicon layer;

applying short pulsed laser beams to the silicon layer to crystallize the silicon layer so as to form a channel layer; and

removing the heat reservoir layer.

11. A liquid crystal display device fabrication method comprising the steps of:

forming a silicon layer on a substrate;

forming a heat reservoir layer on an upper surface of the silicon layer and side surfaces of the silicon layer;

applying short pulsed laser beams to the silicon layer to crystallize the silicon layer so as to form a channel layer of a transistor; and

removing the heat reservoir layer.

12. A method for fabricating a semiconductor device including an active semiconductor film formed on an insulating substrate, comprising the steps of:

forming a semiconductor film in the shape of an island on one surface of the insulating substrate;

covering the semiconductor film with an isolation film;

covering a side surface of the semiconductor film with a heat retaining film, the isolation film being formed between the semiconductor film and the heat retaining film;

crystallizing the semiconductor film by applying energy beams to the semiconductor film from said one surface of the insulating substrate to form the active semiconductor film; and

removing the heat retaining film.

13. A method for fabricating a semiconductor device according to claim 12, wherein a heat absorbing body is provided below the semiconductor film to perform the application of the energy beams.

14. A method for fabricating a semiconductor device according to claim 12, wherein the heat retaining film is formed thicker than the semiconductor film.

16. A method for fabricating a semiconductor device according to claim 12, wherein the semiconductor film before the application of the energy beams is formed of amorphous silicon or polycrystal silicon.

18. A method for fabricating a semiconductor device according to claim 12, wherein the heat retaining film is formed of a semiconductor material, a metal material, an insulating material, a mixture of these materials or a compound of these materials.

20. A method for fabricating a semiconductor device according to claim 12, wherein an excimer laser is used for a light source for applying the energy beams.

22. A method for fabricating a semiconductor device according to claim 12, wherein

a channel region of the active semiconductor film is formed to be narrower than the rest part of the active semiconductor film.

24. A method for fabricating a semiconductor device according to claim 12, wherein

a width-reduced part is formed in a channel region.

15. A method for fabricating a semiconductor device including an active semiconductor film formed on an insulating substrate, comprising the steps of:

forming a semiconductor film in the shape of an island on one surface of the insulating substrate;

covering the semiconductor film with an isolation film;

covering the entire surface of the semiconductor film with the heat retaining film, the isolation film being formed between the semiconductor film and the heat retaining film;

crystallizing the semiconductor film by applying energy beams to the semiconductor film from the other surface of the insulating substrate to form the active semiconductor film; and

removing the heat retaining film.

17. A method for fabricating a semiconductor device according to claim 15, wherein the semiconductor film before the application of the energy beams is formed of amorphous silicon or polycrystal silicon.

19. A method for fabricating a semiconductor device according to claim 15, wherein the heat retaining film is formed of a semiconductor material, a metal material, an insulating material, a mixture of these materials or a compound of these materials.

21. A method for fabricating a semiconductor device according to claim 15, wherein an excimer laser is used for a light source for applying the energy beams.

23. A method for fabricating a semiconductor device according to claim 15, wherein

a channel region of the active semiconductor film is formed to be narrower than the rest part of the active semiconductor film.

25. A method for fabricating a semiconductor device according to claim 15, wherein

a width-reduced part is formed in a channel region.

26. A method for forming a semiconductor thin film comprising the steps of:

forming a semiconductor film in the shape of an island on one surface of an insulating substrate;

covering the semiconductor film with an isolation film;

covering a side of the semiconductor film with a heat retaining film, the isolation film being formed between the semiconductor film and the heat retaining film;

crystallizing the semiconductor film by applying energy beams to the semiconductor film from said one surface of the insulating substrate to form an active semiconductor film; and

removing the heat retaining film.

27. A method for forming a semiconductor thin film, comprising the steps of:

forming a semiconductor film in.the shape of an island on one surface of an insulating substrate;

covering the semiconductor film with an isolation film;

covering the entire surface of the semiconductor film with a heat retaining film, the isolation film being formed between the semiconductor film and the heat retaining film;

crystallizing the semiconductor film by applying energy beams to the semiconductor film from the other surface of the insulating substrate to form an active semiconductor film, and

removing the heat retaining film.

28. A method for forming a silicon thin film, comprising the steps of:

forming a silicon layer on one surface of an insulating substrate;

forming a heat retaining film on at least a side of the silicon layer;

applying continuous-wave energy beams to the silicon layer to crystallize the silicon layer, and

removing the heat retaining film.

29. A method for forming a silicon thin film according to claim 28, wherein

the insulating substrate is pervious to the energy beams; and

in the step of crystallizing the silicon layer, the energy beams of an above 400 nm-wavelength are applied.

30. A method for forming a silicon thin film according to claim 29, wherein

in the step of forming the heat retaining layer, the heat retaining layer is formed also on the upper surface of the silicon layer;

and

in the step of crystallizing the silicon layer, the energy beams are applied from said one surface of the insulating substrate.

31. A method for forming a silicon thin film according to claim 28, wherein

in the step of forming the heat retaining layer, the heat retaining layer is formed selectively near a partial region of the silicon layer.

32. A method for forming a silicon thin film according to claim 28, wherein in the step of forming the silicon layer, the silicon layer is formed to have a width changed in a partial region of the silicon layer.

33. A method for forming a silicon thin film according to claim 28, wherein in the step of forming the silicon layer, a cut is formed in a part of the silicon layer.

34. A method for forming a silicon thin film according to claim 32, wherein in the step of crystallizing the silicon layer, the energy beams are scanned from the width-reduced part of the silicon layer toward a width-increased part of the silicon layer.

35. A method for forming a silicon thin film according to claim 33, wherein in the step of crystallizing the silicon layer, the energy beams are scanned from the width-reduced part of the silicon layer toward a width-increased part of the silicon layer.

36. A polycrystal silicon thin film forming method comprising the steps of:

forming a silicon layer in the shape of an island having a small-width region on a substrate;

forming a heat reservoir layer on an upper surface of the silicon layer and side surfaces of the silicon layer; and

applying short pulsed laser beams to the silicon layer to monocrystallize the small-width region of the silicon layer.

37. A thin film transistor fabrication method comprising the steps of:

forming a silicon layer in the shape of an island having a small-width region on a substrate;

forming a heat reservoir layer on an upper surface of the silicon layer and side surfaces of the silicon layer; and

applying short pulsed laser beams to the silicon layer to monocrystallize the small-width region of the silicon layer so as to form a channel layer.

38. A liquid crystal display device fabrication method comprising the steps of:

forming a silicon layer in the shape of an island having a small-width region on a substrate;

forming a heat reservoir layer on an upper surface of the silicon layer and side surfaces of the silicon layer; and

applying short pulsed laser beam to the silicon layer to monocrystallize the small-width region of the silicon layer so as to form a channel layer of a transistor.

39. A method of fabricating a semiconductor device including an active semiconductor film formed on an insulating substrate, comprising the steps of:

forming a semiconductor film in the shape of an island having a small-width region on one surface of the insulating substrate;

covering the semiconductor film with an isolation film;

covering a side surface of the semiconductor film with a heat retaining film, the isolation film being formed between the semiconductor film and the heat retaining film; and

crystallizing the semiconductor film by applying energy beams to the semiconductor film from one surface of the insulating substrate to form the active semiconductor film,

wherein the small-width region is a channel region of the active semiconductor film.

40. A method of fabricating a semiconductor device including an active semiconductor film formed on an insulating substrate, comprising the steps of:

forming a semiconductor film in the shape of an island having a small-width region on one surface of the insulating substrate;

covering the semiconductor film with an isolation film;

covering the entire surface of the semiconductor film with a heat retaining film, the isolation film being formed between the semiconductor film and the heat retaining film; and

crystallizing the semiconductor film by applying energy beams to the semiconductor film from the other surface of the insulating substrate to form the active semiconductor film,

wherein the small-width region is a channel region of the active semiconductor film.

41. A method of forming a semiconductor thin film comprising the steps of:

forming a semiconductor film in the shape of an island having a small-width region on one surface of an insulating substrate;

covering the semiconductor film with an isolation film;

covering a side of the semiconductor film with the heat retaining film, the isolation film being formed between the semiconductor film and the heat retaining film; and

crystallizing the semiconductor film by applying energy beams to the semiconductor film from said one surface of the insulating substrate to form an active semiconductor film.

42. A method of forming a semiconductor thin film comprising the steps of:

forming a semiconductor film in the shape of an island having a small-width region on one surface of an insulating substrate;

covering the semiconductor film with an isolation film;

covering the entire surface of the semiconductor film with the heat retaining film, the isolation film being formed between the semiconductor film and the heat retaining film; and

crystallizing the semiconductor film by applying energy beams to the semiconductor film from the other surface of the insulating substrate to form an active semiconductor film.

43. A method of forming a silicon thin film, comprising the steps of:

forming a silicon layer in the shape of an island having a small-width region on one surface of an insulating substrate;

forming a heat retaining film on at least a side of the silicon layer; and

applying continuous-wave energy beams to the silicon layer to crystallize the silicon layer.