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US 6,548,370 B1Granted
Method of crystallizing a semiconductor layer by applying laser irradiation that vary in energy to its top and bottom surfaces
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorsKenji Kasahara, Ritsuko Kawasaki, Hisashi Ohtani, Shunpei Yamazaki
Life of this patent
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Abstract
A laser annealing method for obtaining a crystalline semiconductor film having a large grain size is provided. Laser light is irradiated to the top surface and the bottom surface of an amorphous semiconductor film when crystallizing the amorphous semiconductor film by laser light irradiation. Furthermore, a relationship of 0<(I0′/I0)<1, or 1<(I0′/I0) is achieved for the ratio (I0/I0′) between the effective energy strength of the laser light when irradiated to the top surface (I0) and the effective energy strength of the laser light when irradiated to the bottom surface (I0′)
Claims12
A method of manufacturing a semiconductor device comprising the steps of:
- forming a semiconductor film over a substrate;
- crystallizing said semiconductor film by irradiating a laser light on a top surface and a bottom surface of said semiconductor film;
- and
- forming a thin film transistor having said crystallized semiconductor film as an active layer,
- wherein an effective energy strength of the laser light irradiated on the top surface of the semiconductor film (I0) differs from an effective energy strength of the laser light irradiated on the bottom surface of the semiconductor film (I0′) during irradiation of the top surface and the bottom surface of the semiconductor film.
2 more elements
A method of manufacturing a semiconductor device comprising the steps of:
- forming a semiconductor film over a substrate;
- crystallizing said semiconductor film by irradiating a laser light on a top surface and a bottom surface of said semiconductor film;
- and
- forming a thin film transistor having said crystallized semiconductor film as an active layer,
- wherein a relationship of 0<(I0′/I0)<1, or a relationship of 1<(I0′/I0) exists between an effective energy strength of the laser light irradiated on the top surface of the semiconductor film (I0) and an effective energy strength of the laser light irradiated on the bottom surface of the semiconductor film (I0′) during irradiation of the top surface and the bottom surface of the semiconductor film.
2 more elements
A method of manufacturing a semiconductor device comprising the steps of:
- forming a semiconductor film over a substrate;
- crystallizing said semiconductor film by irradiating a laser light on a top surface and a bottom surface of said semiconductor film;
- and
- forming a thin film transistor having said crystallized semiconductor film as an active layer,
- wherein said laser light irradiated on the bottom surface of the semiconductor film is reflected by a reflecting body formed on the bottom surface side of the semiconductor film and then irradiated on the bottom surface of the semiconductor film.
2 more elements
A method of manufacturing a semiconductor device comprising the steps of:
- forming a semiconductor film over a substrate;
- crystallizing said semiconductor film by irradiating a laser light on a top surface and a bottom surface of said semiconductor film;
- and
- forming a thin film transistor having said crystallized semiconductor film as an active layer,
- wherein said laser light irradiated on the bottom surface. of the semiconductor film is reflected by a reflecting body formed on the bottom surface side of the semiconductor film and then irradiated on the bottom surface of the semiconductor film, and
- wherein an effective energy strength of the laser light irradiated on the top surface of the semiconductor film (I0) differs from an effective energy strength of the laser light irradiated on the bottom surface of the semiconductor film (I0′).
3 more elements
A method of manufacturing a semiconductor device comprising the steps of:
- forming a semiconductor film over a substrate;
- crystallizing said semiconductor film by irradiating a laser light on a top surface and a bottom surface of said semiconductor film;
- and
- forming a thin film transistor having said crystallized semiconductor film as an active layer,
- wherein said laser light irradiated on the bottom surface of the semiconductor film is reflected by a reflecting body formed on the bottom surface side of the semiconductor film and then irradiated on the bottom surface of the semiconductor film, and
- wherein a relationship of 0<(I0′/I0)<1, or a relationship of 1<(I0′/I0) exists between an effective energy strength of the laser light irradiated on the top surface of the semiconductor film (I0) and an effective energy strength of the laser light irradiated on the bottom surface of the semiconductor film (I0′).
3 more elements
A method of manufacturing a semiconductor device comprising the steps of:
- forming a semiconductor film over a substrate;
- crystallizing said semiconductor film by irradiating a laser light on a top surface and a bottom surface of said semiconductor film;
- and
- forming a thin film transistor having said crystallized semiconductor film as an active layer,
- wherein said laser light is separated by an optical system into said laser light irradiated on the top surface of the semiconductor film, and into said laser light irradiated on the bottom surface of the semiconductor film.
2 more elements
A method of manufacturing a semiconductor device comprising the steps of:
- forming a semiconductor film over a substrate;
- crystallizing said semiconductor film by irradiating a laser light on a top surface and bottom surface of said semiconductor film;
- and
- forming a thin film transistor having said crystallized semiconductor film as an active layer,
- wherein said laser light is separated by an optical system into said laser light irradiated on the top surface of the semiconductor film, and into said laser light irradiated on the bottom surface of the semiconductor film, and
- wherein an effective energy strength of the laser light irradiated on the top surface of the semiconductor film (I0) differs from an effective energy strength of the laser light irradiated on the bottom surface of the semiconductor film (I0′).
3 more elements
A method of manufacturing a semiconductor device comprising the steps of:
- forming a semiconductor film over a substrate;
- crystallizing said semiconductor film by irradiating a laser light on a top surface and a bottom surface of said semiconductor film;
- and
- forming a thin film transistor having said crystallized semiconductor film as an active layer,
- wherein said laser light is separated by an optical system into said laser light irradiated on the top surface of the semiconductor film, and into said laser light irradiated on the bottom surface of the semiconductor film, and
- wherein a relationship of 0<(I0′/I0)<1, or a relationship of 1<(I0′/I0) exists between an effective energy strength of the laser light irradiated on the top surface of the semiconductor film (I0) and an effective energy strength of the laser light irradiated on the bottom surface of the semiconductor film (I0′).
3 more elements
Dependencies are inferred from the claim text.