Light emitting device and manufacturing method thereof
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorsShunpei Yamazaki, Takeshi Fukunaga, Jun Koyama, Kazutaka Inukai
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Abstract
The light emitting device according to the present invention is characterized in that a gate electrode comprising a plurality of conductive films is formed, and concentrations of impurity regions in an active layer are adjusted with making use of selectivity of the conductive films in etching and using them as masks. The present invention reduces the number of photolithography steps in relation to manufacturing the TFT for improving yield of the light emitting device and shortening manufacturing term thereof, by which a light emitting device and an electronic appliance are inexpensively provided.
Claims24
A light emitting device comprising an n-channel TFT and a light emitting element in each of pixels, the n-channel TFT comprising:
- an active layer including:
- a channel forming region;
- an n-type impurity region (c) adjacent to the channel forming region;
- an n-type impurity region (b) adjacent to the n-type impurity region (c);
- and
- an n-type impurity region (a) adjacent to the n-type impurity region (b);
- a gate insulating layer provided over the active layer;
- and
- a gate electrode provided over the gate insulating layer including:
- a first gate electrode provided over the gate insulating layer;
- and
- a second gate electrode provided over the first gate,
- wherein the first gate electrode overlaps the channel forming region and the n-type impurity region (c) with the gate insulating layer therebetween, and
- wherein the second gate electrode overlaps the channel forming region with the gate insulating layer therebetween.
A light emitting device comprising a driver circuit comprising a n-channel TFT, and pixel portion comprising a light emitting element, the n-channel TFT comprising:
- an active layer including:
- a channel forming region;
- an n-type impurity region (c) adjacent to the channel forming region;
- an n-type impurity region (b) adjacent to the n-type impurity region (c);
- and
- an n-type impurity region (a) adjacent to the n-type impurity region (b);
- a gate insulating layer provided over the active layer;
- and
- a gate electrode provided over the gate insulating layer including:
- a first gate electrode provided over the gate insulating layer;
- and
- a second gate electrode provided over the first gate,
- wherein the first gate electrode overlaps the channel forming region and the n-type impurity region (c) with the gate insulating layer therebetween, and
- wherein the second gate electrode overlaps the channel forming region with the gate insulating layer therebetween.
A method of manufacturing a light emitting device comprising:
- a first step of forming a semiconductor film on a insulating material;
- a second step of forming an insulating film covering the semiconductor film;
- a third step of forming a conductive film on the insulation film by laminating two or more conductive layers;
- a fourth step of forming a gate electrode by etching the conductive film;
- a fifth step of adding an n-type impurity element to the semiconductor film using the gate electrode as a mask;
- a sixth step of etching a side face of the gate electrode before selectively etching a first portion of the gate electrode;
- a seventh step of adding an n-type impurity element to the semiconductor film after the sixth step through a second part of the gate electrode using the gate electrode except the second portion as a mask;
- a eighth step of forming an insulating film covering the gate electrode;
- a ninth step of forming wirings on the insulating film formed in the eighth step to be in contact with the semiconductor film;
- and
- a tenth step of forming a light emitting element on the insulating film formed in the eighth step.
A method of manufacturing a light emitting device comprising:
- a first step of forming a semiconductor film on a insulating material;
- a second step of forming an insulating film covering the semiconductor film;
- a third step of forming a conductive film on the insulation film by laminating a first conductive film and a second conductive film;
- a fourth step of forming a gate electrode which comprises a first gate electrode comprising the first conductive film and a second gate electrode comprising the second conductive film by etching the conductive film;
- a fifth step of adding an n-type impurity element to the semiconductor film using the first gate electrode and the second gate electrode as a mask;
- a sixth step of etching the first gate electrode and the second gate electrode before selectively etching the second gate electrode;
- a seventh step of adding an n-type impurity element to the semiconductor film after the sixth step through a part of the first gate electrode using the selectively etched second gate electrode as a mask;
- a eighth step of forming an insulating film covering the gate electrode;
- a ninth step of forming wirings on the insulating film formed in the eighth step to be in contact with the semiconductor film;
- and
- a tenth step of forming a light emitting element on the insulating film formed in the eighth step.
Dependencies are inferred from the claim text.