# US 10,312,351 B2 · Laser annealing method, laser annealing apparatus, and manufacturing process for thin film transistor

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- Number: US 10,312,351 B2
- Document ID: US10312351B2
- Status: Granted
- Kind: B2
- Application number: 15/786,482
- Filed: 2017-10-17
- Published: 2018-02-08
- Granted: 2019-06-04
- Earliest claimed: 2015-05-19
- Assignees: V Technology Co., Ltd.
- Applicants: V Technology Co., Ltd.
- Inventors: Michinobu Mizumura
- Web page: https://patentgrep.com/patent/US10312351B2

## CPC

- H10P 14/3411: {Silicon, silicon germanium or germanium}
- H10D 30/0314: {of lateral top-gate TFTs comprising only a single gate}
- H10D 30/0316: {of lateral bottom-gate TFTs comprising only a single gate}
- H10D 30/0321: {comprising silicon, e.g. amorphous silicon or polysilicon}
- H10D 30/6731: {Top-gate only TFTs}
- H10D 30/674: {characterised by the active materials}
- H10D 30/6745: {Polycrystalline or microcrystalline silicon}
- H10D 30/6757: {characterised by the structure of the channel, e.g. transverse or longitudinal shape or doping profile (TFTs having channel structures for preventing kink or snapback effects H10D30/6708; TFTs having lightly-doped source or drain extensions H10D30/6715)}
- H10D 86/0229: {characterised by control of the annealing or irradiation parameters}
- H10D 86/425: {having different crystal properties in different TFTs or within an individual TFT}
- H10D 86/60: wherein the TFTs are in active matrices
- H10P 14/20: of semiconductor materials
- H10P 14/3456: {Polycrystalline}
- H10P 14/381: {Beam shaping, e.g. using a mask}
- H10P 14/3816: {Pulsed laser beam}
- H10P 14/382: {Scanning of a beam}
- H10P 34/42: with electromagnetic radiation, e.g. laser annealing (laser cutting H10P54/20)
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

The present invention provides a laser annealing method for irradiating laser light L to an amorphous silicon thin film deposited on a substrate to obtain polysilicon, the method including: multiply irradiating the laser light L while changing an irradiation area of the laser light L on the amorphous silicon thin film to achieve such a grain size distribution that a crystal grain size of the polysilicon decreases from a central portion to a side edge portion at least along a center line C of the irradiation area of the laser light L. The above laser annealing method can reduce a leak current through a simple process.

## Claims

### Claim 1

A laser annealing method for irradiating laser light to an amorphous silicon thin film deposited on gate electrodes formed in a matrix at regular array pitches on a substrate so as to crystallize the amorphous silicon thin film into polysilicon as semiconductor layers on the gate electrodes,
the method comprising:
the step of multiply irradiating the laser light while changing an irradiation area of the laser light on the amorphous silicon thin film to achieve such a grain size distribution that a crystal grain size of the polysilicon decreases from a central portion to a side edge portion at least along a center line of the irradiation area of the laser light, wherein
the step of multiply irradiating the laser light is performed
by using a photo mask having a plurality of apertures formed in a matrix at the array pitches of the gate electrodes, the matrix having rows each including apertures of the same size and extending in a direction crossing a conveyance direction of the substrate and columns each including apertures of different sizes and extending in the conveyance direction, and
by irradiating the laser light sequentially through the rows of apertures by moving the substrate stepwise so that the laser light is irradiated through the apertures of different sizes in the photo mask and an irradiation width of the laser light changes in stages.

### Claim 2 (depends on 1)

The laser annealing method according to claim 1, wherein the apertures of different sizes in the photo mask have different widths in the conveyance direction but have the same width as each other in the direction crossing the conveyance direction.

### Claim 3 (depends on 1)

The laser annealing method according to claim 1, wherein the apertures of different sizes in the photo mask have different widths in the direction crossing the conveyance direction but have the same width as each other in the conveyance direction.