# US 7,410,848 B2 · Crystallization method, crystallization apparatus, processed substrate, thin film transistor and display apparatus

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- Number: US 7,410,848 B2
- Document ID: US7410848B2
- Status: Granted
- Kind: B2
- Application number: 10/878,331
- Filed: 2004-06-29
- Published: 2004-12-30
- Granted: 2008-08-12
- Earliest claimed: 2003-06-30
- Assignees: Advanced LCD Technologies Development Center Co., Ltd.
- Inventors: Masayuki Jyumonji; Hiroyuki Ogawa; Masakiyo Matsumura; Masato Hiramatsu; Yoshinobu Kimura; Yukio Taniguchi; Tomoya Kato
- Web page: https://patentgrep.com/patent/US7410848B2

## CPC

- B23K 26/0622: by shaping pulses
- B23K 26/064: by means of optical elements, e.g. lenses, mirrors or prisms
- B23K 26/0648: {comprising lenses}
- B23K 26/066: by using masks
- C30B 13/24: using electromagnetic waves
- H10D 30/0314: {of lateral top-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 30/6745: {Polycrystalline or microcrystalline silicon}
- H10D 86/0229: {characterised by control of the annealing or irradiation parameters}
- H10P 14/2921: {being crystalline insulating materials}
- 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 14/3456: {Polycrystalline}
- H10P 14/381: {Beam shaping, e.g. using a mask}
- H10P 14/3816: {Pulsed laser beam}
- H10P 14/382: {Scanning of a beam}
- Y10T 117/1004: with means for measuring, testing, or sensing
- Y10T 117/1008: with responsive control means
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

There are provided a crystallization method which can design laser beam having a light intensity and a distribution optimized on an incident surface of a substrate, form a desired crystallized structure while suppressing generation of any other undesirable structure area and satisfy a demand for low-temperature processing, a crystallization apparatus, a thin film transistor and a display apparatus. When crystallizing a non-single-crystal semiconductor thin film by irradiating laser beam thereto, irradiation light beam to the non-single-crystal semiconductor thin film have a light intensity with a light intensity distribution which cyclically repeats a monotonous increase and a monotonous decrease and a light intensity which melts the non-single-crystal semiconductor. Further, at least a silicon oxide film is provided on a laser beam incident surface of the non-single-crystal semiconductor film.

## Claims

### Claim 1

A projection type crystallization method for a non-single-crystal semiconductor film, comprising:
homogenizing pulse laser light by making the pulse laser beam incident on a homogenizer, in which the pulse laser beam is transformed into a plurality of light fluxes incident at different angles, and emitting pulse laser beam homogenized in light intensity by these plurality of light fluxes;
modulating the pulse laser beam by making the plurality of the light fluxes of the different angles incident on a phase modulation optical system including a plurality of phase modulation sections to form a repetitious pattern in which the light intensity of the pulse laser beam homogenized in the homogenizing repeats a monotonous increase and a monotonous decrease, in a light intensity distribution in which maximum peaks of the light intensity of the repetitious pattern are equal to each other and so are minimum peaks, and emitting the modulated pulse laser beam therefrom;
melting the non-single-crystal semiconductor film of an image-forming region, the image-forming region being formed as the pulse laser beam modulated in the modulating, forms an image on the laser beam incident surface by an image formation optical system; and
crystallizing the image formation region melted with the pulse laser beam in a lateral direction.

### Claim 2 (depends on 1)

The crystallization method according to claim 1, further comprising:
providing a cap film on the laser beam incident surface of the non-single-crystal semiconductor film, and wherein the crystallizing grows the image-forming region melted with the pulse laser beam into crystals in the lateral direction by a thermal storage effect of the cap film.

### Claim 3 (depends on 2)

The crystallization method according to claim 2, further comprising:
dehydrogenating the non-single-crystal semiconductor film after providing the cap film.

### Claim 4 (depends on 1)

The crystallization method according to claim 1, wherein the crystallizing in the lateral direction starts from a location corresponding to the minimum value of the light intensity distribution of the repetitious pattern.

### Claim 5 (depends on 2)

The crystallization method according to claim 2, wherein the cap film includes a silicon oxide film and a thickness of the silicon oxide film in a range of not less than 30 nm and not more than 500 nm.

### Claim 6 (depends on 2)

The crystallization method according to claim 2, wherein the cap film includes a silicon oxide film and a thickness of the silicon oxide film in a range of not less than 100 nm and not more than 370 nm.

### Claim 7 (depends on 1)

The crystallization method according to claim 1, wherein the repetitious pattern comprises an isosceles triangle.

### Claim 8 (depends on 1)

The crystallization method according to claim 1, wherein the light intensity of the pulse laser light is, in a relative value, 0.9 or higher and no more than 1.0.