Laser irradiation apparatus, laser irradiation method, and method for manufacturing semiconductor device

• US 20070037332A1
• Filed: 10/20/2006
• Published: 02/15/2007
• Est. Priority Date: 02/28/2003
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Tanaka, Koichiro
• Granted Patent: US 7,569,441 B2
• Time in Patent Office: Days
• US Class Current: 438/166
• CPC Class Codes: B23K 26/0604 by a combination of beams
• CPC Class Codes: B23K 26/0608 in the same heat affected zone [HAZ] B23K26/0613, B23K26/0619 take precedence
• CPC Class Codes: H01L 21/268 using electromagnetic radiation, e.g. laser radiation
• CPC Class Codes: H01L 27/12 the substrate being other than a semiconductor body, e.g. an insulating body
• 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 29/78633 with a light shield
• CPC Class Codes: H01L 29/78675 with normal-type structure, e.g. with top gate

Abstract

An aggregation of crystals extending long in the scanning direction (a long crystal grain region) is formed when a continuous wave laser oscillator (a CW laser oscillator) is employed for annealing the semiconductor film in the manufacturing process of a semiconductor device. The long crystal grain region has a characteristic similar to that of single crystal in the scanning direction, but there is restriction for high integration because of the small output of the CW laser oscillator.

In order to solve the problem, a pulsed laser beam 1 having a wavelength absorbed sufficiently in the semiconductor film is used in combination with a laser beam 2 having a high output and having a wavelength absorbed sufficiently in the melted semiconductor film. After irradiating the laser beam 1 to melt the semiconductor widely, the laser beam 2 is irradiated to the melted region. And then the laser beam 2 and the semiconductor film are moved relatively while keeping the melting state so as to form the long crystal grain region. The laser beam 2 keeps to be irradiated to the semiconductor film until the laser beam 1 is irradiated, and the output of the laser beam 2 is attenuated when the laser beam 1 is irradiated so as not to give the energy more than is needed so that the very uniform laser annealing becomes possible. Thus the long crystal grain region having a width 10 times as broad as the conventional one can be formed.

Claims

1. A laser irradiation method comprising;

shaping a first pulsed laser beam having a wavelength not longer than that of visible light into a long beam on a surface, and

moving the surface while irradiating the surface with a second laser beam having a fundamental wave so that a region irradiated with the second laser beam overlap with a region irradiated with the first pulsed laser beam,

wherein an output of the second laser beam is increased when an output of the first pulsed laser beam is decreased.

2. A laser irradiation method according to claim 1, wherein a net energy of the first pulsed laser beam and the second laser beam absorbed in the surface per unit time is controlled to be constant.

3. A laser irradiation method according to claim 1,

wherein the first pulsed laser beam is emitted from an Ar laser, a Kr laser, an excimer laser, a CO₂ laser, a YAG laser, a Y₂O₃ laser, a YVO₄ laser, a YLF laser, a YAlO₃ laser, a glass laser, a ruby laser, an alexandrite laser, a Ti:

Sapphire laser, a copper vapor laser, or a gold vapor laser.

4. A laser irradiation method according to claim 1,

wherein the second laser beam is emitted from an Ar laser, a Kr laser, a CO₂ laser, a YAG laser, a Y₂O₃ laser, a YVO₄ laser, a YLF laser, a YAlO₃ laser, an alexandrite laser, a Ti:

Sapphire laser or a helium-cadmium laser.

5. A laser irradiation method according to claim 1,

wherein the surface is on a film formed over a substrate having a thickness d,

wherein the substrate is transparent to the first pulsed laser beam and the second laser beam, and

wherein an incidence angle φ

1 of the first pulsed laser beam to the surface satisfies an inequality φ

1≧

arctan (W1/2d), when a side of the long beam, which is on an incidence plane and on the surface, is assumed to have a length of W1.

6. A laser irradiation method according to claim 1,

wherein the surface is a film formed over a substrate having a thickness d,

wherein the substrate is transparent to the first pulsed laser beam and the second laser beam, and

wherein an incidence angle φ

2 of the first pulsed laser beam to the surface satisfies an inequality φ

2≧

arctan (W2/2d), when a side of the long beam, which is on an incidence plane and on the surface, is assumed to have a length of W2.

7. A method for manufacturing a semiconductor device comprising;

forming a semiconductor film over a substrate,

shaping a first pulsed laser beam having a wavelength which is absorbed in the semiconductor film into a long beam on a surface of the semiconductor film, and

moving the substrate while irradiating the surface with a second laser beam having a fundamental wave so that a region irradiated with the second laser beam overlap a region irradiated with the first pulsed laser beam,

wherein an output of the second laser beam is increased when an output of the first pulsed laser beam is decreased.

8. A method for manufacturing a semiconductor device according to claim 7, wherein a net energy of the first pulsed laser beam and a second laser beam absorbed in the semiconductor film per unit time is controlled to be constant.

9. A laser irradiation method according to claim 7, wherein a wavelength of the first pulsed laser beam is not longer than that of visible light.

10. A method for manufacturing a semiconductor device according to claim 7,

wherein the first pulsed laser beam is emitted from an Ar laser, a Kr laser, an excimer laser, a CO₂ laser, a YAG laser, a Y₂O₃ laser, a YVO₄ laser, a YLF laser, a YAlO₃ laser, a glass laser, a ruby laser, an alexandrite laser, a Ti:

Sapphire laser, a copper vapor laser, or a gold vapor laser.

11. A method for manufacturing a semiconductor device according to claim 7,

wherein the second laser beam is emitted from an Ar laser, a Kr laser, a CO₂ laser, a YAG laser, a Y₂O₃ laser, a YVO₄ laser, a YLF laser, a YAlO₃ laser, an alexandrite laser, a Ti:

Sapphire laser or a helium-cadmium laser.

12. A method for manufacturing a semiconductor device according to claim 7,

wherein the substrate has a thickness d,

wherein the substrate is transparent to the first pulsed laser beam and the second laser beam, and

wherein an incidence angle φ

1 of the first pulsed laser beam to the surface of the semiconductor film satisfies an inequality φ

1≧

arctan (W1/2d), when a side of the long beam, which is on an incidence plane and on the surface of the semiconductor film, is assumed to have a length of W1.

13. A method for manufacturing a semiconductor device according to claim 7,

wherein the substrate has a thickness d,

wherein the substrate is transparent to the first pulsed laser beam and the second laser beam, and

wherein an incidence angle φ

2 of the first pulsed laser beam to the surface of the semiconductor film satisfies an inequality φ

2≧

arctan (W2/2d), when a side of the long beam, which is on an incidence plane and on the surface of the semiconductor film, is assumed to have a length of W2.