Laser beam irradiation method and method of manufacturing a thin film transistor

• US 20040248347A1
• Filed: 07/06/2004
• Published: 12/09/2004
• Est. Priority Date: 12/28/2001
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Miyairi, Hidekazu, Shiga, Aiko, Shimomura, Akihisa, Tanaka, Koichiro, Kasahara, Kenji, Dairiki, Koji
• Granted Patent: US 7,176,042 B2
• Time in Patent Office: Days
• US Class Current: 438/166
• CPC Class Codes: H01L 21/02422 Non-crystalline insulating materials, e.g. glass, polymers
• CPC Class Codes: H01L 21/02488 Insulating materials
• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02683 Continuous wave laser beam
• CPC Class Codes: H01L 21/02686 Pulsed laser beam
• CPC Class Codes: H01L 27/1285 using control of the annealing or irradiation parameters, e.g. using different scanning direction or intensity for different transistors
• CPC Class Codes: H01L 27/1296 adapted to increase the uniformity of device parameters
• CPC Class Codes: H01L 29/6675 Amorphous silicon or polysilicon transistors
• CPC Class Codes: H01L 29/78672 Polycrystalline or microcrystalline silicon transistor
• CPC Class Codes: Y10S 438/949 Energy beam treating radiation resist on semiconductor

Abstract

A laser beam irradiation method that achieves uniform crystallization, even if a film thickness of an a-Si film or the like fluctuates, is provided. The present invention provides a laser beam irradiation method in which a non-single crystal semiconductor film is formed on a substrate having an insulating surface and a laser beam having a wavelength longer than 350 nm is irradiated to the non-single crystal semiconductor film, thus crystallizing the non-single crystal silicon film. The non-single crystal semiconductor film has a film thickness distribution within the surface of the substrate, and a differential coefficient of a laser beam absorptivity with respect to the film thickness of the non-single crystal semiconductor film is positive.

Claims

1. A laser beam irradiation method comprising:

obtaining data showing a dependence of a light absorptivity upon a film thickness of a semiconductor film at a certain wavelength of a laser beam;

forming a non-single crystal semiconductor film having a film thickness distribution over a substrate; and

irradiating the non-single crystal semiconductor film with a laser beam to crystallize the non-single crystal semiconductor film,

wherein a differential coefficient of an absorptivity of the laser beam with respect to a film thickness of the non-single crystal semiconductor film is positive.

2. A laser beam irradiation method according to claim 1, wherein the laser beam is a pulse oscillation laser beam.

3. A laser beam irradiation method according to claim 2, wherein the pulse oscillation laser beam comprises a high harmonic of a solid pulse laser.

4. A laser beam irradiation method according to claim 3, wherein the laser beam comprising the high harmonic of the solid pulse laser is one selected from the group consisting of an Nd:

YAG laser beam, an Nd;

YVO₄ laser beam, and an Nd;

YLF laser beam.

5. A laser beam irradiation method according to claim 1, wherein the laser beam is a continuous wave laser beam.

6. A laser beam irradiation method according to claim 5, wherein the continuous wave laser beam is an Ar laser beam.

7. A laser beam irradiation method according to claim 5, wherein the continuous wave laser beam comprises a high harmonic of a solid continuous wave laser.

8. A laser beam irradiation method according to claim 7, wherein the laser beam comprising the high harmonic of the solid continuous wave laser is one selected from the group consisting of an Nd:

YAG laser and an Nd;

YVO₄ laser.

33. A laser beam irradiation method according to claim 1, wherein the certain wavelength of the laser beam is 532 nm.

34. A laser beam irradiation method according to claim 1, wherein the data are obtained by a computer simulation.

9. A laser beam irradiation method comprising:

obtaining data showing a dependence of a light absorptivity upon a film thickness of a semiconductor film at a certain wavelength of a laser beam;

forming a non-single crystal semiconductor film having a film thickness distribution over a substrate; and

irradiating the non-single crystal semiconductor film with a laser beam to crystallize the non-single crystal semiconductor film,

wherein the film thickness of the non-single crystal semiconductor film is determined by a refractive index of the wavelength of the laser beam.

10. A laser beam irradiation method according to claim 9, wherein the laser beam is a pulse oscillation laser beam.

11. A laser beam irradiation method according to claim 10, wherein the pulse oscillation laser beam comprises a high harmonic of a solid pulse laser.

12. A laser beam irradiation method according to claim 11, wherein the laser beam comprising the high harmonic of the solid pulse laser is one selected from the group consisting of an Nd:

YAG laser beam, an Nd;

YVO₄ laser beam, and an Nd;

YLF laser beam.

13. A laser beam irradiation method according to claim 9, wherein the laser beam is a continuous wave laser beam.

14. A laser beam irradiation method according to claim 13, wherein the continuous wave laser beam is an Ar laser beam.

15. A laser beam irradiation method according to claim 13, wherein the continuous wave laser beam comprises a high harmonic of a solid continuous wave laser.

16. A laser beam irradiation method according to claim 15, wherein the laser beam comprising the high harmonic of the solid continuous wave laser is one selected from the group consisting of an Nd:

YAG laser and an Nd;

YVO₄ laser.

35. A laser irradiation method according to claim 9, wherein the certain wavelength of the laser beam is 532 nm.

36. A laser beam irradiation method according to claim 9, wherein the data are obtained by a computer simulation.

17. A method of manufacturing a thin film transistor comprising:

obtaining data showing a dependence of a light absorptivity upon a film thickness of a semiconductor film at a certain wavelength of a laser beam;

forming a non-single crystal semiconductor film having a film thickness distribution over a substrate; and

irradiating the non-single crystal semiconductor film with a laser beam to crystallize the non-single crystal semiconductor film,

wherein a differential coefficient of an absorptivity of the laser beam with respect to a film thickness of the non-single crystal semiconductor film is positive.

18. A method of manufacturing a thin film transistor according to claim 17, wherein the laser beam is a pulse oscillation laser beam.

19. A method of manufacturing a thin film transistor according to claim 18, wherein the pulse oscillation laser beam comprises a high harmonic of a solid pulse laser.

20. A method of manufacturing a thin film transistor according to claim 19, wherein the laser beam comprising the high harmonic of the solid pulse laser is one selected from the group consisting of an Nd:

YAG laser beam, an Nd;

YVO₄ laser beam, and an Nd;

YLF laser beam.

21. A method of manufacturing a thin film transistor according to claim 17, wherein the laser beam is a continuous wave laser beam.

22. A method of manufacturing a thin film transistor according to claim 21, wherein the continuous wave laser beam is an Ar laser beam.

23. A method of manufacturing a thin film transistor according to claim 21, wherein the continuous wave laser beam comprises a high harmonic of a solid continuous wave laser.

24. A method of manufacturing a thin film transistor according to claim 23, wherein the laser beam comprising the high harmonic of the solid continuous wave laser is one selected from the group consisting of an Nd:

YAG laser and an Nd;

YVO₄ laser.

37. A method of manufacturing a thin film transistor according to claim 17, wherein the certain wavelength of the laser beam is 532 nm.

38. A method of manufacturing a thin film transistor according to claim 17, wherein the data are obtained by a computer simulation.

25. A method of manufacturing a thin film transistor comprising:

obtaining data showing a dependence of a light absorptivity upon a film thickness of a semiconductor film at a certain wavelength of a laser beam;

forming a non-single crystal semiconductor film having a film thickness distribution over a substrate; and

irradiating the non-single crystal semiconductor film with a laser beam to crystallize the non-single crystal semiconductor film,

wherein the film thickness of the non-single crystal semiconductor film is determined by a refractive index of the wavelength of the laser beam.

26. A method of manufacturing a thin film transistor according to claim 25, wherein the laser beam is a pulse oscillation laser beam.

27. A method of manufacturing a thin film transistor according to claim 26, wherein the pulse oscillation laser beam comprises a high harmonic of a solid pulse laser.

28. A method of manufacturing a thin film transistor according to claim 27, wherein the laser beam comprising the high harmonic of the solid pulse laser is one selected from the group consisting of an Nd:

YAG laser beam, an Nd;

YVO₄ laser beam, and an Nd;

YLF laser beam.

29. A method of manufacturing a thin film transistor according to claim 25, wherein the laser beam is a continuous wave laser beam.

30. A method of manufacturing a thin film transistor according to claim 29, wherein the continuous wave laser beam is an Ar laser beam.

31. A method of manufacturing a thin film transistor according to claim 29, wherein the continuous wave laser beam comprises a high harmonic of a solid continuous wave laser.

32. A method of manufacturing a thin film transistor according to claim 31, wherein the laser beam comprising the high harmonic of the solid continuous wave laser is one selected from the group consisting of an Nd:

YAG laser and an Nd;

YVO₄ laser.

39. A method of manufacturing a thin film transistor according to claim 25, wherein the certain wavelength of the laser beam is 532 nm.

40. A method of manufacturing a thin film transistor according to claim 25, wherein the data are obtained by a computer simulation.