DISPLAY DEVICE AND ELECTRONIC DEVICE INCLUDING THE DISPLAY DEVICE

• US 20170229488A1
• Filed: 04/24/2017
• Published: 08/10/2017
• Est. Priority Date: 05/10/2013
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: MIYAKE, Hiroyuki, YAMAZAKI, Shunpei
• Granted Patent: US 10,373,980 B2
• Time in Patent Office: Days
• CPC Class Codes: G02F 1/133345 Insulating layers G02F1/1335, G02F1/1337, G02F1/135, G02F1/136 take precedence
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G02F 2201/123 pixel
• CPC Class Codes: G02F 2202/10 semiconductor
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• CPC Class Codes: H01L 27/1248 with a particular composition or shape of the interlayer dielectric specially adapted to the circuit arrangement
• CPC Class Codes: H01L 27/1255 integrated with passive devices, e.g. auxiliary capacitors
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
• CPC Class Codes: H10K 59/1213 the pixel elements being TFTs
• CPC Class Codes: H10K 59/1216 the pixel elements being capacitors
• CPC Class Codes: H10K 59/123 Connection of the pixel electrodes to the thin film transistors [TFT]

Abstract

To provide a display device including a transistor that includes an oxide semiconductor and has favorable characteristics, a pixel electrode electrically connected to the transistor, and a capacitor electrically connected to the pixel electrode. To provide a display device that can be manufactured at low cost. The display device includes a display element including a pixel electrode, a transistor that performs switching of the display element and includes a first oxide semiconductor layer serving as a channel formation region, a capacitor that is electrically connected to the display element and includes a dielectric layer between a pair of electrodes. The pixel electrode is a second oxide semiconductor layer formed on the same surface as that on which the first oxide semiconductor layer is formed, and also serves as one electrode of the capacitor.

Claims

1. A method for forming a display device comprising the steps of:

forming a conductive layer over a substrate;

forming a first electrode and a second electrode by patterning the conductive layer;

forming a first insulating layer covering the first electrode and the second electrode;

forming an oxide semiconductor layer over the first insulating layer;

forming a first oxide semiconductor layer overlapping with the first electrode and a second oxide semiconductor layer overlapping with the electrode by patterning the oxide semiconductor layer;

forming a source electrode and a drain electrode over and in contact with the first oxide semiconductor layer;

forming an oxide insulating layer over and in contact with the first oxide semiconductor layer, the source electrode, and the drain electrode;

forming a first opening in the oxide insulating layer, the first opening overlaps with the second oxide semiconductor layer and the second electrode; and

forming a pixel electrode from the second oxide semiconductor layer,

wherein the step of forming the pixel electrode comprises a step of;

forming a second insulating layer containing hydrogen over and in contact with the second oxide semiconductor layer in the first opening,

wherein the first oxide semiconductor layer serves as a channel formation region,

wherein the second electrode, a portion of the first insulating layer, and a portion of the pixel electrode form a capacitor, and

wherein the oxide semiconductor layer contains indium, zinc, and a metal element.

2. The method for forming the display device according to claim 1,

wherein the metal element is any one of Al, Ti, Ga, Y, Zr, La, Ce, Nd, and Hf.

3. The method for forming the display device, according to claim 1,

wherein the second insulating layer is a silicon nitride layer with a hydrogen concentration of 1×

10²² atoms/cm³ or higher.

4. The method for forming the display device, according to claim 1, further comprising a step of:

performing first heat treatment on the first oxide semiconductor layer and the second oxide semiconductor layer; and

performing second heat treatment after forming the oxide insulating layer.

5. The method for forming the display device according to claim 1,

wherein an amount of oxygen vacancies of the first oxide semiconductor layer is lower than an amount of oxygen vacancies of the pixel electrode.

6. The method for forming the display device according to claim 1,

wherein a resistivity of the pixel electrode is lower than a resistivity of the first oxide semiconductor layer.

7. A method for forming a display device comprising the steps of:

forming a conductive layer over a substrate;

forming a first electrode and a second electrode by patterning the conductive layer;

forming a first insulating layer covering the first electrode and the second electrode;

forming an oxide semiconductor layer over the first insulating layer;

forming a first oxide semiconductor layer overlapping with the first electrode and a second oxide semiconductor layer overlapping with the electrode by patterning the oxide semiconductor layer;

forming a source electrode and a drain electrode over and in contact with the first oxide semiconductor layer;

forming an oxide insulating layer over and in contact with the first oxide semiconductor layer, the source electrode, and the drain electrode;

forming a first opening in the oxide insulating layer, the first opening overlaps with the second oxide semiconductor layer and the second electrode;

forming a pixel electrode from the second oxide semiconductor layer;

wherein the step of forming the pixel electrode comprises a step of;

forming a second insulating layer containing hydrogen over and in contact with the second oxide semiconductor layer in the first opening, and

forming a liquid crystal layer over the pixel electrode,

wherein the first oxide semiconductor layer serves as a channel formation region,

wherein the second electrode, a portion of the first insulating layer, and a portion of the pixel electrode form a capacitor, and

wherein the oxide semiconductor layer contains indium, zinc, and a metal element.

8. The method for forming the display device according to claim 7,

wherein the metal element is any one of Al, Ti, Ga, Y, Zr, La, Ce, Nd, and Hf.

9. The method for forming the display device, according to claim 7,

wherein the second insulating layer is a silicon nitride layer with a hydrogen concentration of 1×

10²² atoms/cm³ or higher.

10. The method for forming the display device, according to claim 7, further comprising a step of:

performing first heat treatment on the first oxide semiconductor layer and the second oxide semiconductor layer; and

performing second heat treatment after forming the oxide insulating layer.

11. The method for forming the display device according to claim 7,

wherein an amount of oxygen vacancies of the first oxide semiconductor layer is lower than an amount of oxygen vacancies of the pixel electrode.

12. The method for forming the display device according to claim 7,

wherein a resistivity of the pixel electrode is lower than a resistivity of the first oxide semiconductor layer.