US5372836A
Expired / Lapsed
US
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Method of forming polycrystalling silicon film in process of manufacturing LCD
Assignee: Tokyo Electron Ltd
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Filing: 1993-03-26
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Granted: 1994-12-13
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Expires: 2013-03-26
Abstract
Abstract In a method of forming a polycrystalline silicon film in a process of manufacturing an LCD, a hydrogenated amorphous silicon film is formed on a glass substrate by plasma CVD throughout areas serving as the pixel portion and driver unit of the LCD. A laser beam is radiated on a selected region of the film on the area serving as the driver unit. The energy of the laser beam is set such that hydrogen in the film is discharged without crystallizing the film and damaging the film. The energy of the laser beam is gradually increased to gradually discharge hydrogen from the film. The energy of the laser beam is finally set such that the film is transformed into a polycrystalline silicon film. The amorphous silicon film can be poly-crystallized without damaging the film by the discharge of hydrogen.
Inventors
- 👤 Issei Imahashi
- 👤 Kiichi Hama
- 👤 Jiro Hata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 17:05
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/136; G02F1/1362; H; H10; H10P; H10P14/00; H10P14/20; H10P14/34; H10P14/3451; H10P14/3452; H10P14/3454; C; C23; C23C; C23C16/00; C23C16/22; C23C16/24; C23C16/56; H10D; H10D30/00; H10D30/60; H10D30/67; H10D86/00; H10D86/01; H10D86/021; H10D86/0221; H10D86/0223; H10D86/40; H10P14/29; H10P14/2901; H10P14/2922; H10P14/3402; H10P14/3404; H10P14/3411; H10P14/38; H10P14/3802; H10P14/3808; H10P14/381; H10P14/3816; H10P14/382; G02F1/1333; G02F1/1345; G02F1/13454
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
200 words
A method of forming polycrystalline silicon film for the manufacture of a liquid crystal display (LCD) having a pixel portion and a driver unit, comprising: (a) forming a hydrogenated amorphous silicon film (α-Si:H film) on a surface of a glass substrate in areas of said substrate corresponding to said pixel portion and said driver unit, (b) determining a minimum energy density of a laser beam which, when irradiated on the surface of said α-Si:H film causes hydrogen therein to explosively discharge from said α-Si:H film, which energy density value is termed a ceiling value, (c) repeatedly irradiating said α-Si:H film corresponding to said driver unit with a laser beam having an energy density value below said ceiling value, measuring the amount of hydrogen released after each said irradiation, and increasing the energy density of said repeated laser beam irradiations whenever consecutive irradiations give a measured amount of hydrogen released which decreases after said consecutive irradiations, and (d) crystallizing said repeatedly irradiated α-Si:H film corresponding to said driver unit by irradiation with a laser beam having an energy density above said ceiling value and sufficient to cause silicon in said repeatedly irradiated α-Si:H film to crystallize into a polycrystalline silicon film.
Claim 2
Independent Claim
200 words
A method of forming polycrystalline silicon film for the manufacture of a liquid crystal display (LCD) having a pixel portion and a driver unit, comprising: (a) forming a hydrogenated amorphous silicon film (α-Si:H film) on a surface of a glass substrate in areas of said substrate corresponding to said pixel portion and said driver unit, (b) determining a minimum energy density of a laser beam which, when irradiated on the surface of said α-Si:H film causes hydrogen therein to explosively discharge from said α-Si:H film, which energy density value is termed a ceiling value, (c) repeatedly irradiating said α-Si:H film corresponding to said driver unit with a laser beam having an energy density value below said ceiling value, measuring the amount of hydrogen released after each said irradiation, and increasing the energy density of said repeated laser beam irradiations whenever consecutive irradiations give a measured amount of hydrogen released which decreases after said consecutive irradiations, and (d) crystallizing said repeatedly irradiated α-Si:H film corresponding to said driver unit by irradiation with a laser beam having an energy density above said ceiling value and sufficient to cause silicon in said repeatedly irradiated α-Si:H film to crystallize into a polycrystalline silicon film.
Claim 3
Dependent Claim
17 words
A method according to claim 1, wherein all laser beams are emitted from a single light source.
Claim 4
Dependent Claim
20 words
A method according to claim 1, wherein said glass substrate is heated to about 300° C. during the crystallizing step.
Claim 5
Dependent Claim
33 words
A method according to claim 1, wherein all laser beams are constituted by a beam having a square section smaller than said repeatedly irradiated film and operated to scan said repeatedly irradiated film.
Claim 6
Dependent Claim
38 words
A method according to claim 4, wherein said all laser beams pass through a homogenizer comprising an expand lens and a biprism lens while the laser beam is radiated from said light source on said repeatedly irradiated film.
Claim 7
Dependent Claim
15 words
A method according to claim 5, wherein the laser beams are emitted as a pulse.
Claim 8
Dependent Claim
27 words
A method according to claim 6, wherein an energy of at least one of said laser beams is adjusted by adjusting an output of a laser source.
Claim 9
Dependent Claim
29 words
A method according to claim 6, wherein an energy of at least one of said laser beams per unit area is adjusted by changing an interval of the pulse.
Claim 10
Dependent Claim
27 words
A method according to claim 6, wherein an energy of at least one of the laser beams is adjusted by changing a scanning speed of the beam.
Claim 11
Dependent Claim
35 words
A method according to claim 6, wherein the ceiling value is set such that an energy density on a surface of said repeatedly irradiated film is set to be lower than 173 mJ/cm 2 .
Claim 12
Dependent Claim
44 words
A method according to claim 6, wherein the energy density of said laser beam for crystallizing said film is set such that an energy density on a surface of said repeatedly irradiated film is set to be not less than 795 mJ/cm 2 .
Claim 13
Dependent Claim
88 words
A method according to claim 4, wherein the crystallizing further comprises the steps of: radiating a test light on said repeatedly irradiated film; spectroscopically detecting a reflected light of the test light from said repeatedly irradiated film to obtain detection data concerning a band gap spectroscopic reflectance distribution of said repeatedly irradiated film and comparing reference data concerning a band gap spectroscopic reflectance distribution of a polysilicon film and responding to the detection data with the detection data to evaluate a crystallized state of said repeatedly irradiated film.
Claim 14
Dependent Claim
23 words
A method according to claim 12, wherein the detection and the reference data are peak values of the band gap spectroscopic reflectance distribution.
Claim 15
Dependent Claim
22 words
A method according to claim 12, wherein the detection and the reference data are profiles of the band gap spectroscopic reflectance distribution.
Claim 16
Dependent Claim
28 words
A method according to claim 12, further comprising the step of adjusting an energy of said crystallizing laser beam on the basis of evaluation of the crystallized state.
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