Method of laser irradiation, laser irradiation apparatus, and method of manufacturing a semiconductor device

• US 8,722,521 B2
• Filed: 08/09/2013
• Issued: 05/13/2014
• Est. Priority Date: 08/27/2001
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Tanaka, Koichiro, Moriwaka, Tomoaki
• Primary Examiner(s): Heinrich, Samuel M
• Application Number:
  US13/962,984
• Publication Number:
  US 20130323866A1
• Time in Patent Office: 277 Days
• Field of Search: 438/166, 438/487, 438/795, 257/E21.134, 219/121.65, 219/121.66, 219/121.85
• US Class Current: 438/487
• CPC Class Codes: B23K 26/06 Shaping the laser beam, e.g. by masks or multi-focusing
• CPC Class Codes: B23K 26/0604 by a combination of beams
• CPC Class Codes: B23K 26/064 by means of optical elements, e.g. lenses, mirrors or prisms
• CPC Class Codes: B23K 26/0732 into a rectangular shape
• CPC Class Codes: B23K 26/0736 into an oval shape, e.g. elliptic shape
• CPC Class Codes: B23K 26/0738 into a linear shape
• CPC Class Codes: G02B 27/09 Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for adapting the beam shape of a laser diode G02B19/0052; adapting the beam shape of an LED G02B19/0061; coupling into light guides using intermediate optical elements G02B6/4204; beam shaping specially adapted for lasers H01S3/005
• CPC Class Codes: G02B 27/095 Refractive optical elements
• CPC Class Codes: G02B 27/0955 Lenses lenses per se G02B3/00
• CPC Class Codes: H01L 21/02422 Non-crystalline insulating materials, e.g. glass, polymers
• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02678 Beam shaping, e.g. using a mask
• CPC Class Codes: H01L 21/02683 Continuous wave laser beam
• CPC Class Codes: H01L 21/02686 Pulsed laser beam
• CPC Class Codes: H01L 21/268 using electromagnetic radiation, e.g. laser radiation
• CPC Class Codes: H01L 21/28017 the insulator being formed after the semiconductor body, the semiconductor being silicon
• 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 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• 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
• CPC Class Codes: H01S 5/4012 Beam combining, e.g. by the use of fibres, gratings, polarisers, prisms
• CPC Class Codes: H01S 5/4025 : Array arrangements, e.g. constituted by discrete laser diodes or laser bar H01S5/42 takes precedence
• CPC Class Codes: H10K 50/84 : Passivation; Containers; Encapsulations
• CPC Class Codes: H10K 50/8426 : Peripheral sealing arrangements, e.g. adhesives, sealants
• CPC Class Codes: H10K 59/12 : Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 59/122 : Pixel-defining structures or layers, e.g. banks
• CPC Class Codes: H10K 59/87 : Passivation; Containers; Encapsulations

Abstract

If an optical path length of an optical system is reduced and a length of a laser light on an irradiation surface is increased, there occurs curvature of field which is a phenomenon that a convergent position deviates depending on an incident angle or incident position of a laser light with respect to a lens. To avoid this phenomenon, an optical element having a negative power such as a concave lens or a concave cylindrical lens is inserted to regulate the optical path length of the laser light and a convergent position is made coincident with a irradiation surface to form an image on the irradiation surface.

Claims

1. A method of manufacturing an active matrix display device comprising:

forming a semiconductor film over a substrate;

emitting a laser beam having a first cross section perpendicular to a propagation direction of the laser beam;

expanding the laser beam along a first direction to increase the cross section of the laser beam along the first direction;

regulating an optical path length of the expanded laser beam along the first direction using a concave lens;

condensing the laser beam along a second direction orthogonal to the first direction; and

increasing crystallinity of the semiconductor film by scanning the semiconductor film with the laser beam along a third direction orthogonal to the first direction wherein the laser beam has a second cross section on a surface of the semiconductor film, the second cross section being larger than the first cross section along the first direction and shorter than the first direction along the third direction;

after increasing the crystallinity, patterning the semiconductor film into a plurality of semiconductor layers, each including a region to become a channel forming region of a thin film transistor;

forming an insulating layer over the plurality of semiconductor layers; and

forming a plurality of pixel electrodes over the insulating layer.

2. The method according to claim 1, wherein the step of expanding the laser beam along the first direction is performed by using an optical system including at least a cylindrical lens array and a cylindrical convex lens.

3. The method according to claim 1, wherein the laser beam is a solid laser or gas laser of a continuous oscillation type or pulse oscillation type.

4. The method according to claim 1, wherein the laser beam is one selected from the group consisting of a continuous oscillation or pulse oscillation YAG laser, YVO₄ laser, YLF laser, YAlO₃ laser, glass laser, ruby laser, alexandrite laser, and Ti:

sapphire laser.

5. The method according to claim 1, wherein the laser beam is one selected from the group consisting of a continuous oscillation or pulse oscillation excimer laser, Ar laser and Kr laser.

6. The method according to claim 1, wherein the concave lens is at least one selected from a concave cylindrical lens, a toroidal lens, or a Crossed Cylindrical Lens.

7. The method according to claim 1, wherein the concave lens is one selected from a concave cylindrical lens, a toroidal lens, and a Crossed Cylindrical Lens, combined with a convex cylindrical lens.

8. The method according to claim 1, further comprising a step of forming a light emitting layer comprising an organic compound over the plurality of pixel electrodes.

9. The method according to claim 1, wherein the active matrix display device is a liquid crystal display device.

21. The method according to claim 1, wherein the step of increasing crystallinity of the semiconductor film includes crystallizing the semiconductor film.

10. A method of manufacturing an active matrix display device comprising:

forming a semiconductor film over a substrate;

emitting a laser beam having a first cross section perpendicular to a propagation direction of the laser beam;

expanding the laser beam along a first direction by dividing the laser beam into a plurality of laser beams and superposing the plurality of laser beams along the first direction whereby a uniformity of the laser beam is homogenized along the first direction;

regulating an optical path length of the expanded laser beam along the first direction using a concave lens;

condensing the laser beam along a second direction orthogonal to the first direction; and

increasing crystallinity of the semiconductor film by scanning the semiconductor film with the laser beam in a third direction orthogonal to the first direction wherein the laser beam has a second cross section on a surface of the semiconductor film, the second cross section being larger than the first cross section along the first direction and shorter than the first direction along the third direction;

after increasing the crystallinity, patterning the semiconductor film into a plurality of semiconductor layers, each including a region to become a channel forming region of a thin film transistor;

forming an insulating layer over the plurality of semiconductor layers; and

forming a plurality of pixel electrodes over the insulating layer.

11. The method according to claim 10, wherein the step of expanding the laser beam along the first direction is performed by using an optical system including at least a cylindrical lens array and a cylindrical convex lens.

12. The method according to claim 10, wherein the laser beam is a solid laser or gas laser of a continuous oscillation type or pulse oscillation type.

13. The method according to claim 10, wherein the laser beam is one selected from the group consisting of a continuous oscillation or pulse oscillation YAG laser, YVO₄ laser, YLF laser, YAlO₃ laser, glass laser, ruby laser, alexandrite laser, and Ti:

sapphire laser.

14. The method according to claim 10, wherein the laser beam is one selected from the group consisting of a continuous oscillation or pulse oscillation excimer laser, Ar laser and Kr laser.

15. The method according to claim 10, wherein the laser beam is converted into a harmonic by a non-linear optical element.

16. The method according to claim 10, wherein the concave lens is at least one selected from a concave cylindrical lens, a toroidal lens, or a Crossed Cylindrical Lens.

17. The method according to claim 10, wherein the concave lens is one selected from a concave cylindrical lens, a toroidal lens, and a Crossed Cylindrical Lens, combined with a convex cylindrical lens.

18. The method according to claim 10, further comprising a step of forming a light emitting layer comprising an organic compound over the plurality of pixel electrodes.

19. The method according to claim 10, wherein the active matrix display device is a liquid crystal display device.

22. The method according to claim 10, wherein the step of increasing crystallinity of the semiconductor film includes crystallizing the semiconductor film.

20. A method of manufacturing an active matrix display device comprising:

forming a semiconductor film over a substrate;

emitting a laser beam having a first cross section perpendicular to a propagation direction of the laser beam;

expanding the laser beam along a first direction by dividing the laser beam into a plurality of laser beams using a first cylindrical lens array and superposing the plurality of laser beams along the first direction using a first cylindrical lens whereby a uniformity of the laser beam is homogenized along the first direction;

regulating an optical path length of the expanded laser beam along the first direction using a concave lens;

dividing the laser beam along a second direction orthogonal to the first direction into a plurality of laser beams using a second cylindrical lens array and superposing the plurality of laser beams along the second direction using a second cylindrical lens whereby a uniformity of the laser beam along the second direction is homogenized;

condensing the laser beam along a second direction orthogonal to the first direction; and

increasing crystallinity of the semiconductor film by scanning the semiconductor film with the laser beam along a third direction orthogonal to the first direction wherein the laser beam has a second cross section on a surface of the semiconductor film, the second cross section being larger than the first cross section along the first direction and shorter than the first direction along the third direction;

after increasing the crystallinity, patterning the crystallized semiconductor film into a plurality of semiconductor layers, each including a region to become a channel forming region of a thin film transistor;

forming an insulating layer over the plurality of semiconductor layers; and

forming a plurality of pixel electrodes over the insulating layer.