# US 7,746,528 B2 · Beam irradiation apparatus, beam irradiation method, and method for manufacturing thin film transistor

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- Number: US 7,746,528 B2
- Document ID: US7746528B2
- Status: Granted
- Kind: B2
- Application number: 12/213,511
- Filed: 2008-06-20
- Published: 2008-11-06
- Granted: 2010-06-29
- Earliest claimed: 2003-04-21
- Assignees: Semiconductor Energy Laboratory Co., Ltd.
- Inventors: Koichiro Tanaka
- Web page: https://patentgrep.com/patent/US7746528B2

## CPC

- G02B 26/105: {with one or more pivoting mirrors or galvano-mirrors (G02B26/101 takes precedence)}
- Y10S 359/90: Methods
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A galvanometer mirror rotates in one direction when the galvanometer mirror is used. A spot can be scanned on an irradiated surface at a more constant speed by rotating the galvanometer mirror and by using the inertia. Moreover, it is preferable to make the galvanometer mirror heavy because the inertia becomes higher so that the spot is scanned at a more constant speed. In addition, in a polygon mirror of this invention, mirrors are arranged so as not to contact each other because a change time of the scanning position between the mirrors is provided. By moving the irradiated object with timing together when the laser light is not irradiated, the laser process can be performed efficiently.

## Claims

### Claim 1

A method for manufacturing a semiconductor device comprising the steps of:
emitting a laser beam by an oscillator;
reflecting the laser beam by a galvanometer mirror; and
crystallizing a semiconductor film by irradiating with the reflected laser beam;
wherein the galvanometer mirror is fixed to a shaft, and
wherein the galvanometer mirror fully rotates around an axis constituted by the shaft.

### Claim 2 (depends on 1)

The method for manufacturing a semiconductor device according to claim 1 further comprising:
forming a gate electrode over the crystalline semiconductor film, and
forming an impurity region in the semiconductor film using the gate electrode as a mask.

### Claim 3 (depends on 1)

The method for manufacturing a semiconductor device according to claim 1, wherein the laser beam is a beam emitted from any one of a YVO4 laser, a YAG laser, a YLF laser, a YAlO3 laser, and an Ar laser.

### Claim 4

A method for manufacturing a semiconductor device comprising the steps of:
emitting a laser beam by an oscillator;
reflecting the laser beam by a galvanometer mirror; and
crystallizing a semiconductor film by irradiating with the reflected laser beam;
wherein the galvanometer mirror is fixed to a shaft,
wherein the galvanometer mirror fully rotates around an axis constituted by the shaft, and
wherein the laser beam is a pulse beam.

### Claim 5 (depends on 4)

The method for manufacturing a semiconductor device according to claim 4 further comprising:
forming a gate electrode over the crystalline semiconductor film, and
forming an impurity region in the semiconductor film using the gate electrode as a mask.

### Claim 6 (depends on 4)

The method for manufacturing a semiconductor device according to claim 4, wherein the laser beam is a beam emitted from any one of a YVO4 laser, a YAG laser, a YLF laser, a YAlO3 laser, and an Ar laser.