# US 7,410,889 B2 · Method of fabricating a poly-silicon thin film

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- Number: US 7,410,889 B2
- Document ID: US7410889B2
- Status: Granted
- Kind: B2
- Application number: 11/393,747
- Filed: 2006-03-31
- Published: 2007-06-14
- Granted: 2008-08-12
- Earliest claimed: 2005-12-12
- Assignees: Industrial Technology Research Institute
- Inventors: Yu-Cheng Chen; Jia-Xing Lin; Hung-Tse Chen
- Web page: https://patentgrep.com/patent/US7410889B2

## CPC

- H10P 14/3816: {Pulsed laser beam}
- H10D 86/0227: {using structural arrangements to control crystal growth, e.g. placement of grain filters}
- H10P 14/2922: {being non-crystalline insulating materials, e.g. glass or polymers}
- H10P 14/3238: {being insulating materials}
- H10P 14/3411: {Silicon, silicon germanium or germanium}
- H10P 14/381: {Beam shaping, e.g. using a mask}
- H10P 14/382: {Scanning of a beam}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A silicon layer and a heat-retaining layer are formed on a substrate in turn, and a laser beam with a sharp energy density gradient is next utilized to perform a laser heating process for inducing super lateral growth crystallization occurred in part of the Si layer. The heat-retaining layer provides additional heating-enhancement function for the Si layer in crystallization so as to increase the super lateral growth length. Then, the laser beam is repeatedly moved to irradiate the substrate to finish the crystallization process for the full substrate.

## Claims

### Claim 1

A method of fabricating a polysilicon (poly-Si) thin film, comprising the steps of:
forming a silicon layer on a substrate;
forming a heat-retaining layer directly on the silicon layer, wherein the entire bottom surface of the heat-retaining layer is in direct contact with the entire top surface of the silicon layer;
patterning at least one laser beam to produce a patterned laser beam with an energy density gradient occurring at the edges of the patterned laser beam, wherein the range of the energy density gradient is between 400 J/cm3 and 3000 J/cm3;
irradiating the patterned laser beam with the energy density gradient to the heat-retaining layer so as to perform a laser heating process for inducing super lateral growth crystallization occurred in part of the silicon layer; and
repeatedly moving the patterned laser beam to irradiate different positions of the substrate until the crystallization process for the full substrate is finished.

### Claim 2 (depends on 1)

The method of claim 1, wherein the step of forming the silicon layer is preceded by the step of forming a buffer layer on the substrate.

### Claim 3 (depends on 1)

The method of claim 1, wherein the material of the substrate is glass.

### Claim 4 (depends on 1)

The method of claim 1, wherein the heat-retaining layer is SiOxNy.

### Claim 5 (depends on 1)

The method of claim 1, wherein the patterned laser beam with the energy density gradient is an excimer laser using the ultraviolet light of XeCl.

### Claim 6 (depends on 1)

The method of claim 1, wherein the patterned laser beam with the energy density gradient is formed by using a pattern photo mask to block part of the laser beam.

### Claim 7 (depends on 1)

The method of claim 1, wherein the patterned laser beam with the energy density gradient has a long strip pattern.

### Claim 8 (depends on 1)

The method of claim 1, wherein step of moving the patterned laser beam is achieved by moving the patterned laser beam directly or moving the substrate.

### Claim 9 (depends on 1)

The method of claim 1, wherein the patterned laser beam with the energy density gradient is formed by using an optical system to adjust the laser beam to a narrower width.

### Claim 10 (depends on 1)

The method of claim 1, wherein the patterned laser beam with the energy density gradient has a hollow square region.