US 2007/0181890 A1 · Light emitting device

Abstract

An object of the invention is to provide a technique for improving the characteristics of a TFT and realizing an optimum structure of the TFT for the driving conditions of a pixel section and a driving circuit by a small number of photo masks. Therefore, a light emitting device has a semiconductor film, a first electrode and a first insulating film nipped between the semiconductor film and the first electrode. Further, the light emitting device has a second electrode and a second insulating film nipped between the semiconductor film and the second electrode. The first and second electrodes are overlapped with each other through a channel forming area arranged in the semiconductor film. In the case of a TFT in which a reduction in off-electric current is considered important in comparison with an increase in on-electric current, a constant voltage (common voltage) is applied to the first electrode at any time. In the case of a TFT in which the increase in on-electric current is considered important in comparison with the reduction in off-electric current, the same voltage is applied to the first and second electrodes.

Claims26

Dependent claims

A light emitting device comprising:

a first wiring;
a second wiring;
a third wiring;
a fourth wiring;
a first thin film transistor comprising at least two impurity regions;
and
a second thin film transistor comprising at least two impurity regions,
wherein said first thin film transistor comprises a first electrode, a first insulating film over said first electrode, a semiconductor film over said first insulating film, a second insulating film over said semiconductor film, and a second electrode over said second insulating film,
wherein said first insulating film is formed so as to cover said first wiring, said third and fourth wirings are formed over said second insulating film, a third insulating film is formed so as to cover said third and fourth wirings, and said second wiring is formed over said third insulating film,
wherein said first wiring is connected to said first electrode of said first thin film transistor, and said second wiring is connected to said second electrode of said first thin film transistor,
wherein one of two impurity regions of said first thin film transistor is connected to said third wiring, and the other is connected to a gate electrode of said second thin film transistor, and
wherein one of two impurity regions of said second thin film transistor is connected to said fourth wiring, and the other is connected to a pixel electrode.

9 more elements

A light emitting device comprising:

a first wiring;
a second wiring;
a third wiring;
a fourth wiring;
a first thin film transistor comprising at least two impurity regions;
and
a second thin film transistor comprising at least two impurity regions,
wherein said first thin film transistor comprises a first electrode, a first insulating film over said first electrode, a semiconductor film over said first insulating film, a second insulating film over said semiconductor film, and a second electrode over said second insulating film,
wherein said first insulating film is formed so as to cover said first wiring, said third wiring is formed over said second insulating film, a third insulating film is formed so as to cover said third wiring, and said second and fourth wirings are formed over said third insulating film,
wherein said first wiring is connected to said first electrode of said first thin film transistor, and said second wiring is connected to said second electrode of said first thin film transistor,
wherein one of two impurity regions of said first thin film transistor is connected to said third wiring, and the other is connected to a gate electrode of said second thin film transistor, and
wherein one of two impurity regions of said second thin film transistor is connected to said fourth wiring, and the other is connected to a pixel electrode.

9 more elements

A light emitting device comprising:

a first wiring;
a second wiring;
a third wiring;
a fourth wiring;
a first thin film transistor comprising at least two impurity regions;
and
a second thin film transistor comprising at least two impurity regions,
wherein said first thin film transistor comprises a first electrode, a first insulating film over said first electrode, a semiconductor film over said first insulating film, a second insulating film over said semiconductor film, and a second electrode over said second insulating film,
wherein said first insulating film is formed so as to cover said first and fourth wirings, said third wiring is formed over said second insulating film, a third insulating film is formed so as to cover said third wiring, and said second wiring is formed over said third insulating film,
wherein said first wiring is connected to said first electrode of said first thin film transistor, and said second wiring is connected to said second electrode of said first thin film transistor,
wherein one of two impurity regions of said first thin film transistor is connected to said third wiring, and the other is connected to a gate electrode of said second thin film transistor, and
wherein one of two impurity regions of said second thin film transistor is connected to said fourth wiring, and the other is connected to a pixel electrode.

9 more elements

A light emitting device comprising:

a first wiring;
a second wiring;
a third wiring;
a fourth wiring;
a first thin film transistor comprising at least two impurity regions;
and
a second thin film transistor comprising at least two impurity regions,
wherein said first thin film transistor comprises a first electrode, a first insulating film over said first electrode, a semiconductor film over said first insulating film, a second insulating film over said semiconductor film, and a second electrode over said second insulating film,
wherein said first insulating film is formed so as to cover said first wiring, said third wiring is formed over said second insulating film, a third insulating film is formed so as to cover said third wiring, and said second wiring is formed over said third insulating film,
wherein said first wiring is connected to said first electrode of said first thin film transistor, and said second wiring is connected to said second electrode of said first thin film transistor,
wherein one of two impurity regions of said first thin film transistor is connected to said third wiring, and the other is connected to a gate electrode of said second thin film transistor, and
wherein one of two impurity regions of said second thin film transistor is connected to said fourth wiring, and the other is connected to a pixel electrode.

9 more elements

Dependencies are inferred from the claim text.

Light emitting device

Life of this patent

Light emitting device

Life of this patent

Abstract

Claims26