Beam homogenizer, laser irradiation apparatus, and method for manufacturing semiconductor device

• US 20050079645A1
• Filed: 09/29/2004
• Published: 04/14/2005
• Est. Priority Date: 09/30/2003
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Moriwaka, Tomoaki
• Granted Patent: US 7,169,630 B2
• Time in Patent Office: Days
• US Class Current: 438/29
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 27/0994 Fibers, light pipes optical fibers per se G02B6/02
• CPC Class Codes: H01L 21/02595 polycrystalline
• CPC Class Codes: H01L 21/02678 Beam shaping, e.g. using a mask
• CPC Class Codes: H01S 3/005 Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping shaping laser beam for working metal or other materials B23K26/06; optical elements, systems or apparatus in general G02B

Abstract

The energy distribution of the beam spot on the irradiated surface changes due to the change in the oscillation condition of the laser or before and after the maintenance. The present invention provides an optical system for forming a rectangular beam spot on an irradiated surface including a beam homogenizer for homogenizing the energy distribution of the rectangular beam spot on the irradiated surface in a direction of its long or short side. The beam homogenizer includes an optical element having a pair of reflection planes provided oppositely for reflecting the laser beam in the direction where the energy distribution is homogenized and having a curved shape in its entrance surface. The entrance surface of the optical element means a surface of the optical element where the laser beam is incident first.

Claims

1. A beam homogenizer for shaping a beam spot on an irradiated surface into rectangular comprising:

an optical element for homogenizing energy distribution of the rectangular beam spot in a direction of its long or short side,

wherein the optical element has a pair of reflection planes provided oppositely for reflecting a laser beam in the direction where the energy distribution is homogenized, and

wherein the optical element has a curved shape in its entrance surface where the laser beam is incident.

3. A beam homogenizer according to claim 1 or claim 2,

wherein the optical element is a light pipe.

4. A beam homogenizer according to claim 1 or claim 2,

wherein the optical element is an optical waveguide.

5. A beam homogenizer according to claim 1 or claim 2,

wherein the curved shape is cylindrical.

6. A beam homogenizer according to claim 1 or claim 2,

wherein the curved shape has curvature in a direction where the optical element acts.

7. A beam homogenizer according to claim 1 or claim 2,

wherein the rectangular beam spot has an aspect ratio of 10 or more.

8. A beam homogenizer according to claim 1 or claim 2,

wherein the rectangular beam spot has an aspect ratio of 100 or more.

2. A beam homogenizer for shaping a beam spot on an irradiated surface into rectangular comprising:

an optical element for homogenizing energy distribution of the rectangular beam spot in a direction of its long or short side, and

one or a plurality of cylindrical lenses for projecting a plane having homogeneous energy distribution formed by the optical element to the irradiated surface,

wherein the optical element has a pair of reflection planes provided oppositely for reflecting a laser beam in the direction where the energy distribution is homogenized, and

wherein the optical element has a curved shape in its entrance surface where the laser beam is incident

9. A laser irradiation apparatus for shaping a beam spot on an irradiated surface into rectangular comprising:

a laser oscillator and

an optical element for homogenizing energy distribution in a direction of its long or short side of the rectangular beam spot,

wherein the optical element has a pair of reflection planes provided oppositely for reflecting a laser beam in a direction where the energy distribution is homogenized, and

wherein the optical element has a curved shape in its entrance surface where the laser beam is incident.

10. A laser irradiation apparatus for shaping a beam spot on an irradiated surface into rectangular comprising:

a laser oscillator,

an optical element for homogenizing energy distribution in a direction of its long or short side of the rectangular beam spot, and

one or a plurality of cylindrical lenses for projecting a plane having homogeneous energy distribution formed by the optical element to the irradiated surface,

wherein the optical element has a pair of reflection planes provided oppositely for reflecting a laser beam in a direction where the energy distribution is homogenized, and

wherein the optical element has a curved shape in its entrance surface where the laser beam is incident.

11. A laser irradiation apparatus according to claim 9 or claim 10,

wherein the optical element is a light pipe.

12. A laser irradiation apparatus according to claim 9 or claim 10,

wherein the optical element is an optical waveguide.

13. A laser irradiation apparatus according to claim 9 or claim 10,

wherein the curved shape is cylindrical.

14. A laser irradiation apparatus according to claim 9 or claim 10,

wherein the curved optical surface has curvature in a direction where the optical element acts.

15. A laser irradiation apparatus according to claim 9 or claim 10,

wherein the rectangular beam spot has an aspect ratio of 10 or more.

16. A laser irradiation apparatus according to claim 9 or claim 10,

wherein the rectangular beam spot has an aspect ratio of 100 or more.

17. A laser irradiation apparatus according to claim 9 or claim 10,

wherein the laser oscillator is one selected from the group consisting of an excimer laser, a YAG laser, a glass laser, a YvO₄ laser, a YLF laser, an Ar laser, and a GdVO₄ laser.

18. A laser irradiation apparatus according to claim 9 or claim 10, further comprising:

a scanning stage for moving an irradiated object having an irradiated surface relative to a beam spot.

19. A laser irradiation apparatus according to claim 9 or claim 10, further comprising:

an automatic transferring apparatus for transferring the irradiated object having the irradiated surface to the scanning stage.

20. A method for manufacturing a semiconductor device comprising:

forming a non-single crystal semiconductor film over a substrate, and

performing laser annealing in such a way that a laser beam which is emitted from a laser oscillator and which is shaped into a rectangular beam spot on the non-single crystal semiconductor film through an optical system including an optical element for homogenizing energy distribution of the laser beam in a direction of its long or short side is irradiated to the non-single crystal semiconductor film while moving a position of the beam spot,

wherein the optical element has a pair of reflection planes provided oppositely for reflecting the laser beam in the direction where the energy distribution is homogenized, and

wherein the optical element has a curved shape in its entrance surface where the laser beam is incident.

22. A method for manufacturing a semiconductor device according to claim 20 or claim 21,

wherein the optical element is a light pipe.

23. A method for manufacturing a semiconductor device according to claim 20 or 21,

wherein the optical element is an optical waveguide.

24. A method for manufacturing a semiconductor device according to claim 20 or claim 21,

wherein the curved shape is cylindrical.

25. A method for manufacturing a semiconductor device according to claim 20 or claim 21,

wherein the curved shape has curvature in a direction where the optical element acts.

26. A method for manufacturing a semiconductor device according to claim 20 or claim 21,

wherein the rectangular beam spot has an aspect ratio of 10 or more.

27. A method for manufacturing a semiconductor device according to claim 20 or claim 21,

wherein the rectangular beam spot has an aspect ratio of 100 or more.

28. A method for manufacturing a semiconductor device according to claim 20 or claim 21,

wherein the laser oscillator is one selected from the group consisting of an excimer laser, a YAG laser, a glass laser, a YVO₄ laser, a YLF laser, an Ar laser, and a GdVO₄ laser.

21. A method for manufacturing a semiconductor device comprising:

forming a non-single crystal semiconductor film over a substrate, and

performing laser annealing in such a way that a laser beam which is emitted from a laser oscillator and which is shaped into a rectangular beam spot on the non-single crystal semiconductor film through an optical system including an optical element for homogenizing energy distribution of the laser beam in a direction of its long or short side and one or a plurality of cylindrical lenses for projecting a plane having homogeneous energy distribution formed by the optical element to the non-single crystal semiconductor film is irradiated to the non-single crystal semiconductor film while moving a position of the beam spot,

wherein the optical element has a pair of reflection planes provided oppositely for reflecting the laser beam in a direction where the energy distribution is homogenized, and

wherein the optical element has a curved shape in its entrance surface where the laser beam is incident.