Display Device and Method for Manufacturing the Same

• US 20090146150A1
• Filed: 12/03/2008
• Published: 06/11/2009
• Est. Priority Date: 12/05/2007
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Hosoya, Kunio
• Granted Patent: US 8,039,840 B2
• Time in Patent Office: Days
• US Class Current: 257/59
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: H01L 27/12 the substrate being other than a semiconductor body, e.g. an insulating body
• CPC Class Codes: H01L 27/1214 comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs
• CPC Class Codes: H01L 27/1255 integrated with passive devices, e.g. auxiliary capacitors
• CPC Class Codes: H01L 27/1288 employing particular masking sequences or specially adapted masks, e.g. half-tone mask
• CPC Class Codes: H01L 27/13 combined with thin-film or thick-film passive components

Abstract

A display device having the high aperture ratio and a storage capacitor with high capacitance is to be obtained. The present invention relates to a display device and a manufacturing method thereof. The display device includes a thin film transistor which includes a gate electrode, a gate insulating film, a first semiconductor layer, a channel protective film, a second semiconductor having conductivity which is divided into a source region and a drain region, and a source electrode and a drain electrode; a third insulating layer formed over the second conductive film; a pixel electrode formed over the third insulating layer, which is connected to one of the source electrode and the drain electrode; and a storage capacitor formed in a region where a capacitor wiring over the first insulating layer and the pixel electrode are overlapped with the third insulating layer over the capacitor wiring interposed therebetween.

Claims

1. A display device comprising:

a thin film transistor comprising;

a gate electrode formed of a first conductive film;

a gate insulating film formed of a first insulating layer over the gate electrode;

a first semiconductor layer over the first insulating layer, wherein the first semiconductor layer is overlapped with the gate electrode;

a channel protective film which is formed of a second insulating layer over the first semiconductor layer, wherein the channel protective film is overlapped with the gate electrode;

a second semiconductor layer having an impurity element imparting one conductivity type, wherein the second semiconductor layer is overlapped with the first semiconductor layer, wherein the second semiconductor layer is divided into a source region and a drain region, wherein one end portion of the source region and one end portion of the drain region is provided over the channel protective film; and

a source electrode over the source region and a drain electrode over the drain region, wherein the source electrode and the drain electrode are formed of a second conductive film;

a third insulating layer formed over the source electrode and the drain electrode;

a pixel electrode formed of a third conductive film over the third insulating layer, wherein the pixel electrode is electrically connected to one of the source electrode and the drain electrode through a contact hole formed in the third insulating layer;

a capacitor wiring formed of a stacked body which includes the first semiconductor layer, the second semiconductor layer, and the second conductive film over the first insulating layer; and

a storage capacitor formed of a stacked body which includes the capacitor wiring, the third insulating layer, and the pixel electrode.

3. The display device according to claim 1, wherein the third conductive film is a light-transmitting conductive film.

2. A display device comprising:

a thin film transistor comprising;

a gate electrode formed of a first conductive film;

a gate insulating film formed of a first insulating layer over the gate electrode;

a first semiconductor layer over the first insulating layer, wherein the first semiconductor layer is overlapped with the gate electrode;

a channel protective film which is formed of a second insulating layer over the first semiconductor layer, wherein the channel protective film is overlapped with the gate electrode;

a second semiconductor layer having an impurity element imparting one conductivity type, wherein the second semiconductor layer is overlapped with the first semiconductor layer, wherein the second semiconductor layer is divided into a source region and a drain region, wherein one end portion of the source region and one end portion of the drain region is provided over the channel protective film; and

a source electrode over the source region and a drain electrode over the drain region, wherein the source electrode and the drain electrode are formed of a second conductive film;

a third insulating layer formed over the source electrode and the drain electrode;

a pixel electrode formed of a third conductive film over the third insulating layer, wherein the pixel electrode is electrically connected to one of the source electrode and the drain electrode through a contact hole formed in the third insulating layer;

a capacitor wiring formed of a stacked body which includes the first semiconductor layer, the second semiconductor layer, and the second conductive film over the first insulating layer;

a storage capacitor formed of a stacked body which includes the capacitor wiring, the third insulating layer, and the pixel electrode; and

a connection region comprising;

a wiring formed of the first conductive film; and

an electrode which is formed of the third conductive film over the wiring and which is in contact with a top surface and a side surface of the other one of the source electrode and the drain electrode.

4. The display device according to claim 2, wherein the third conductive film is a light-transmitting conductive film.

5. A method for manufacturing a display device comprising the steps of:

forming a first conductive film over a substrate;

forming a first resist mask over the first conductive film;

etching the first conductive film with use of the first resist mask, so that a gate wiring and a source wiring are formed;

forming a first insulating film that is to be a gate insulating film, an i-type semiconductor layer, and a second insulating film over the gate wiring and the source wiring;

forming a second resist mask over the second insulating film;

etching the second insulating film with use of the second resist mask, so that a channel protective film is formed;

forming a conductivity type semiconductor layer which has an impurity element imparting one conductivity type and a second conductive film over the i-type semiconductor layer and the channel protective film;

forming a third resist mask over the second conductive film;

etching the second conductive film, the conductivity type semiconductor layer, and the i-type semiconductor layer with use of the third resist mask,

so that the channel protective film is exposed by the etching of the second conductive film and the conductivity type semiconductor layer,

so that a source electrode, a drain electrode, and a wiring of a capacitor wiring are formed by the etching of the second conductive film,

so that a source region, a drain region, and a conductivity type semiconductor layer of the capacitor wiring are formed by the etching of the conductivity type semiconductor layer, and

so that an i-type semiconductor layer including a channel formation region and an i-type semiconductor layer of the capacitor wiring are formed by the etching of the i-type semiconductor layer;

forming a protective film to cover the source electrode, the drain electrode, the channel protective film, and the wiring of the capacitor wiring;

forming a fourth resist mask over the protective film;

etching the protective film with use of the fourth resist mask, so that a third contact hole reaching the drain electrode is formed in the protective film;

forming a third conductive film to cover the protective film, and the third contact hole;

forming a fifth resist mask over the third conductive film; and

etching the third conductive film with use of the fifth resist mask,

so that a pixel electrode is formed, which is electrically connected to the drain electrode through the third contact hole and which extends over the capacitor wiring.

7. The method for manufacturing a display device according to claim 5, wherein the third conductive film is a light-transmitting conductive film.

6. A method for manufacturing a display device comprising the steps of:

forming a first conductive film over a substrate;

forming a first resist mask over the first conductive film;

etching the first conductive film with use of the first resist mask, so that a gate wiring and a source wiring are formed;

forming a first insulating film that is to be a gate insulating film, an i-type semiconductor layer, and a second insulating film over the gate wiring and the source wiring;

forming a second resist mask over the second insulating film;

etching the second insulating film with use of the second resist mask, so that a channel protective film is formed;

forming a conductivity type semiconductor layer which has an impurity element imparting one conductivity type and a second conductive film over the i-type semiconductor layer and the channel protective film;

forming a third resist mask over the second conductive film;

etching the second conductive film, the conductivity type semiconductor layer, and the i-type semiconductor layer with use of the third resist mask,

so that the channel protective film is exposed by the etching of the second conductive film and the conductivity type semiconductor layer,

so that a source electrode, a drain electrode, and a wiring of a capacitor wiring are formed by the etching of the second conductive film,

so that a source region, a drain region, and a conductivity type semiconductor layer of the capacitor wiring are formed by the etching of the conductivity type semiconductor layer,

so that an i-type semiconductor layer including a channel formation region and an i-type semiconductor layer of the capacitor wiring are formed by the etching of the i-type semiconductor layer, and

so that a first contact hole is formed over the source wiring and the gate insulating film by the etching of the second conductive film, the conductivity type semiconductor layer, and the i-type semiconductor layer;

forming a protective film to cover the source electrode, the drain electrode, the channel protective film, and the wiring of the capacitor wiring;

forming a fourth resist mask over the protective film;

etching the protective film and the gate insulating film with use of the fourth resist mask,

so that a second contact hole with a larger diameter than the first contact hole is formed by the etching of the protective film,

so that the gate insulating film in the first contact hole is removed and the source wiring is exposed by the etching of the gate insulating film,

so that a stepwise-shaped contact hole is formed in the protective film, the source electrode, the source region, the i-type semiconductor layer, and the gate insulating film by the first contact hole and the second contact hole where the gate insulating film is removed, and

so that a third contact hole reaching the drain electrode is formed in the protective film by the etching of the protective film;

forming a third conductive film to cover the protective film, the stepwise-shaped contact hole, and the third contact hole;

forming a fifth resist mask over the third conductive film; and

etching the third conductive film with use of the fifth resist mask,

so that a pixel electrode is formed, which is electrically connected to the drain electrode through the third contact hole and which extends over the capacitor wiring, and

so that an electrode which electrically connects the source wiring and the source electrode is formed in the stepwise-shaped contact hole by the etching of the third conductive film.

8. The method for manufacturing a display device according to claim 6, wherein the third conductive film is a light-transmitting conductive film.