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US 8,786,793 B2Granted
Display device and manufacturing method thereof
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorShunpei Yamazaki
Life of this patent
Estimating the term…
Abstract
A gate insulating film is formed over a gate electrode; a microcrystalline semiconductor is formed over the gate insulating film; an impurity element for controlling the threshold value is added into the microcrystalline semiconductor film by an ion implantation method; the microcrystalline semiconductor film is irradiated with a laser beam so that the crystallinity of the microcrystalline semiconductor film is improved; and then, a buffer layer is formed over the microcrystalline semiconductor film, whereby a channel-etched thin film transistor is formed. Further, a display device including the thin film transistor is manufactured.
Claims16
A method for manufacturing a display device, comprising the steps of:
- forming a gate electrode over a substrate;
- forming a first insulating film over the gate electrode;
- forming a first semiconductor film over the first insulating film;
- adding a first impurity into the first semiconductor film, the first impurity imparting a first conductivity type or a second conductivity type;
- irradiating the first semiconductor film with laser light at a region in which the first semiconductor film and the gate electrode are overlapped, after adding the first impurity into the first semiconductor film;
- forming a buffer layer over the first semiconductor film after irradiating the first semiconductor film with laser light;
- forming a second semiconductor film over the buffer layer, the second semiconductor film including a second impurity which imparts the first conductivity type;
- etching the first semiconductor film, the buffer layer, and the second semiconductor film;
- forming a conductive film over the second semiconductor film so that the conductive film is in contact with the first insulating film and side surfaces of the first semiconductor film, the buffer layer, and the second semiconductor film;
- and
- etching the conductive film to form a source electrode and a drain electrode over the second semiconductor film,
- wherein the first semiconductor film is a microcrystalline semiconductor film, and
- wherein the buffer layer is an amorphous semiconductor film.
10 more elements
A method for manufacturing a display device, comprising the steps of:
- forming a gate electrode over a substrate;
- forming a first insulating film over the gate electrode;
- forming a first semiconductor film over the first insulating film;
- adding a first impurity into the first semiconductor film;
- irradiating the first semiconductor film with laser light after adding the first impurity into the first semiconductor film;
- forming a buffer layer over the first semiconductor film after irradiating the first semiconductor film with laser light;
- forming a second semiconductor film over the buffer layer;
- etching the first semiconductor film, the buffer layer, and the second semiconductor film;
- forming a conductive film over the second semiconductor film;
- etching the conductive film to form a source electrode over a first portion of the second semiconductor film and a drain electrode over a second portion of the second semiconductor film;
- etching a first portion of the buffer layer between the first portion of the second semiconductor film and the second portion of the second semiconductor film;
- and
- forming a second insulating film over the source electrode and the drain electrode so that the second insulating film is in contact with the first portion of the buffer layer,
- wherein the first semiconductor film is a microcrystalline semiconductor film, and
- wherein the buffer layer is an amorphous semiconductor film.
12 more elements
A method for manufacturing a display device, comprising the steps of:
- forming a gate electrode over a substrate;
- forming a first insulating film over the gate electrode;
- forming a first semiconductor film over the first insulating film;
- adding a first impurity into the first semiconductor film;
- cleaning a surface of the first semiconductor film;
- irradiating the first semiconductor film with laser light after cleaning the surface of the first semiconductor film;
- forming a buffer layer over the first semiconductor film after irradiating the first semiconductor film with laser light;
- forming a second semiconductor film comprising a second impurity over the buffer layer;
- forming a conductive film over the second semiconductor film;
- wet etching the conductive film to form a source electrode over a first portion of the second semiconductor film and a drain electrode over a second portion of the second semiconductor film;
- etching a first portion of the buffer layer between the first portion of the second semiconductor film and the second portion of the second semiconductor film;
- and
- forming a second insulating film over the source electrode and the drain electrode so that the second insulating film is in contact with the first portion of the buffer layer,
- wherein the first semiconductor film is a microcrystalline semiconductor film, and
- wherein the buffer layer is an amorphous semiconductor film.
12 more elements
Dependencies are inferred from the claim text.