Display Device and Method for Manufacturing the Same

• US 20090242888A1
• Filed: 03/30/2009
• Published: 10/01/2009
• Est. Priority Date: 03/31/2008
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Hosoya, Kunio
• Granted Patent: US 8,138,500 B2
• Time in Patent Office: Days
• US Class Current: 257/59
• CPC Class Codes: G02F 1/133345 Insulating layers G02F1/1335, G02F1/1337, G02F1/135, G02F1/136 take precedence
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G02F 1/136227 Through-hole connection of the pixel electrode to the active element through an insulation layer

Abstract

In a pixel portion, a scan signal line and an auxiliary capacitor line are formed using a second conductive film, and a data signal line is formed using a first conductive film. In a TFT portion, a gate electrode is formed using the first conductive film and electrically connected to the scan signal line formed using the second conductive film through an opening in a gate insulating film. Further, a source electrode and a drain electrode are formed using the second conductive film. In the auxiliary capacitor portion, the auxiliary capacitor line formed using the second conductive film serves as a lower electrode, the pixel electrode serves as an upper electrode, and the passivation film used as a dielectric film is interposed between the capacitor electrodes.

Claims

1. A display device comprising:

a gate electrode which is formed using a first conductive film over a light-transmitting substrate;

a data signal line which is formed using the first conductive film and extends in one direction;

a first insulating film over the gate electrode and the data signal line;

a semiconductor film over the first insulating film;

a source electrode and a drain electrode which are formed using a second conductive film over the first insulating film and the semiconductor film;

a scan signal line which is formed using the second conductive film and extends in a direction intersecting with the one direction;

an auxiliary capacitor line which is formed using the second conductive film and extends in the direction intersecting with the one direction;

a second insulating film over the first insulating film, the source electrode and the drain electrode, the scan signal line and the auxiliary capacitor line;

a third insulating film having an opening over the second insulating film; and

a pixel electrode over the third insulating film, the pixel electrode being in contact with a portion of the second insulating film in the opening,

wherein one of the source electrode and the drain electrode is electrically connected to the semiconductor film and the data signal line,

wherein the other of the source electrode and the drain electrode is electrically connected to the semiconductor film and the pixel electrode,

wherein the gate electrode is electrically connected to the scan signal line; and

wherein the auxiliary capacitor line and the pixel electrode are included in an auxiliary capacitor portion where the portion of the second insulating film is used as a dielectric film.

2. The display device according to claim 1, wherein a peripheral edge portion of the pixel electrode overlaps with the data signal line and the auxiliary capacitor line.

3. The display device according to claim 1, wherein the semiconductor film has a portion that is recessed when seen in cross section.

4. The display device according to claim 3, further comprising:

a first impurity semiconductor film and a second impurity semiconductor film, to which an impurity element imparting one conductivity type is added, over the semiconductor film,

wherein one of the source electrode and the drain electrode is in contact with the first impurity semiconductor film and the data signal line; and

wherein the other of the source electrode and the drain electrode is in contact with the second impurity semiconductor film and the pixel electrode.

5. The display device according to claim 1, wherein the third insulating film is formed using a photosensitive organic resin material.

6. The display device according to claim 1, wherein the data signal line and the auxiliary capacitor line intersect with each other with the first insulating film interposed therebetween.

7. An electronic device comprising the display device according to claim 1 in a display portion.

8. A display device comprising:

a gate electrode which is formed using a first conductive film over a light-transmitting substrate;

a data signal line which is formed using the first conductive film and extends in one direction;

a first insulating film over the gate electrode and the data signal line;

a microcrystalline semiconductor film over the first insulating film;

a buffer layer over the microcrystalline semiconductor film and has a portion that is recessed when seen in cross section;

a first impurity semiconductor film and a second impurity semiconductor film, to which an impurity element imparting one conductivity type is added, and which are provided over the buffer layer;

a source electrode and a drain electrode which are formed using a second conductive film which is formed over the first insulating film, the first impurity semiconductor film and the second impurity semiconductor film;

a scan signal line which is formed using the second conductive film and extends in a direction intersecting with the one direction;

an auxiliary capacitor line which is formed using the second conductive film and extends in the direction intersecting with the one direction;

a second insulating film over the first insulating film, the source electrode and the drain electrode, the scan signal line and the auxiliary capacitor line;

a third insulating film having an opening over the second insulating film; and

a pixel electrode over the third insulating film, the pixel electrode being in contact with a portion of the second insulating film in the opening,

wherein one of the source electrode and the drain electrode is electrically connected to the first impurity semiconductor film and the data signal line,

wherein the other of the source electrode and the drain electrode is electrically connected to the second impurity semiconductor film and the pixel electrode, and

wherein the gate electrode is electrically connected to the scan signal line; and

wherein the auxiliary capacitor line and the pixel electrode are included in an auxiliary capacitor portion where the portion of the second insulating film is used as a dielectric film.

9. The display device according to claim 8, wherein a peripheral edge portion of the pixel electrode overlaps with the data signal line and the auxiliary capacitor line.

10. The display device according to claim 8, wherein the third insulating film is formed using a photosensitive organic resin material.

11. The display device according to claim 8, wherein the data signal line and the auxiliary capacitor line intersect with each other with the first insulating film interposed therebetween.

12. An electronic device comprising the display device according to claim 8 in a display portion.

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

forming a gate electrode and a data signal line using a first conductive film over a light-transmitting substrate;

forming a first insulating film and a first semiconductor film in this order over the gate electrode and the data signal line;

etching the first semiconductor film to form a second semiconductor film over the gate electrode;

etching the first insulating film to form a first opening which reaches the gate electrode and a second opening which reaches the data signal line;

forming a second conductive film over the first insulating film and the second semiconductor film;

etching the second conductive film to form a scan signal line which is electrically connected to the gate electrode through the first opening, a source electrode and a drain electrode, one of which is electrically connected to the data signal line through the second opening, and an auxiliary capacitor line;

forming a second insulating film over the first insulating film, the second semiconductor film, the source electrode and the drain electrode, the scan signal line, and the auxiliary capacitor line;

forming a third insulating film over the second insulating film;

removing part of the second insulating film and part of the third insulating film to form a third opening which reaches the drain electrode;

removing part of the third insulating film to form a fourth opening by which the second insulating film formed over the auxiliary capacitor line is exposed; and

forming, over the third insulating film, a pixel electrode which is in contact with the drain electrode in the third opening and is in contact with the second insulating film in the fourth opening.

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

forming a gate electrode and a data signal line which are formed using a first conductive film over a light-transmitting substrate;

forming a first insulating film, a first semiconductor film, and a first impurity semiconductor film to which an impurity element imparting one conductivity type is added in this order over the gate electrode and the data signal line;

forming a first mask layer over the first impurity semiconductor film by photolithography using a multi-tone mask;

etching the first insulating film, the first semiconductor film, and the first impurity semiconductor film using the first mask layer to form a first opening which reaches the gate electrode and a second opening which reaches the data signal line;

performing ashing on the first mask layer to form a second mask layer;

etching the first semiconductor film and the first impurity semiconductor film using the second mask layer to form a second semiconductor film and a second impurity semiconductor film;

forming a second conductive film over the first insulating film and the second impurity semiconductor film;

forming a third mask layer over the second conductive film;

etching the second conductive film and the second impurity semiconductor film using the third mask layer to form a scan signal line which is electrically connected to the gate electrode through the first opening, a source electrode and a drain electrode one of which is electrically connected to the data signal line through the second opening, an auxiliary capacitor line, a third impurity semiconductor film, and a fourth impurity semiconductor film;

forming a second insulating film over the first insulating film, the second semiconductor film, the third impurity semiconductor film, the fourth impurity semiconductor film, the source electrode and the drain electrode, the scan signal line, and the auxiliary capacitor line;

forming a third insulating film over the second insulating film;

forming, in the third insulating film, a third opening by which the second insulating film is exposed and a recessed portion which is recessed when seen in cross section and in which the third insulating film remains, by performing photolithography using a multi-tone mask;

etching the second insulating film in the third opening to form a fourth opening which reaches the drain electrode;

performing ashing on the third insulating film in the recessed portion to form a fifth opening by which the second insulating film formed over the auxiliary capacitor line is exposed; and

forming, over the third insulating film, a pixel electrode which is in contact with the drain electrode in the fourth opening and is in contact with the second insulating film in the fifth opening.