TRANSISTOR, LIQUID CRYSTAL DISPLAY DEVICE, AND MANUFACTURING METHOD THEREOF

• US 20120062813A1
• Filed: 09/07/2011
• Published: 03/15/2012
• Est. Priority Date: 09/10/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: KOYAMA, Jun
• Granted Patent: US 8,797,487 B2
• Time in Patent Office: Days
• US Class Current: 349/43
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G02F 1/136231 for reducing the number of lithographic steps
• CPC Class Codes: G02F 1/136286 Wiring, e.g. gate line, drain line
• 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: 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 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• CPC Class Codes: H01L 27/124 with a particular composition, shape or layout of the wiring layers specially adapted to the circuit arrangement, e.g. scanning lines in LCD pixel circuits wiring structures per se H01L23/52
• 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 29/24 including, apart from doping materials or other impurities, only semiconductor materials not provided for in groups H01L29/16, H01L29/18, H01L29/20, H01L29/22 including organic materials H10K99/00
• CPC Class Codes: H01L 29/41733 for thin film transistors with insulated gate
• CPC Class Codes: H01L 29/66969 of devices having semiconductor bodies not comprising group 14 or group 13/15 materials comprising selenium or tellurium in uncombined form other than as impurities in semiconductor bodies of other materials, comprising cuprous oxide or cuprous iodide H01L21/02365
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate

Abstract

Photolithography and etching steps for forming an island-shaped semiconductor layer are omitted, and a liquid crystal display device is manufactured with four photolithography steps: a step of forming a gate electrode (including a wiring formed using the same layer as the gate electrode), a step of forming source and drain electrodes (including a wiring formed using the same layer as the source and drain electrodes), a step of forming a contact hole (including the removal of an insulating layer and the like in a region other than the contact hole), and a step of forming a pixel electrode (including a wiring formed using the same layer as the pixel electrode). By the reduction in the number of photolithography steps, a liquid crystal display device can be provided at low cost and high productivity. Formation of a parasitic channel is prevented by an improvement in shape and potential of a wiring.

Claims

1. A liquid crystal display device comprising:

a transistor comprising a gate electrode, a source electrode, a drain electrode, and a semiconductor layer;

a first wiring electrically connected to the gate electrode;

a second wiring electrically connected to the source electrode;

a pixel electrode electrically connected to the drain electrode; and

a capacitor wiring,

wherein the semiconductor layer overlaps with the first wiring, the second wiring, the pixel electrode, and the capacitor wiring, and

wherein part of the capacitor wiring extends beyond an end portion of the pixel electrode in a direction parallel to a direction in which the second wiring extends.

2. The liquid crystal display device according to claim 1,

wherein the capacitor wiring comprises an extending portion along the second wiring, and

wherein the extending portion extends beyond the end portion of the pixel electrode in the direction parallel to the direction in which the second wiring extends.

3. The liquid crystal display device according to claim 2, wherein the part of the capacitor wiring or the extending portion overlaps with the pixel electrode.

4. The liquid crystal display device according to claim 1,

wherein at least part of the first wiring is provided with a region extending beyond both end portions of the first wiring in a line width direction and covering the first wiring, and

wherein the semiconductor layer does not exist in the region.

5. The liquid crystal display device according to claim 1, wherein the semiconductor layer comprises an oxide semiconductor.

6. The liquid crystal display device according to claim 5, wherein the oxide semiconductor comprises indium and zinc.

7. The liquid crystal display device according to claim 2, wherein the extending portion comprises a bent portion or a curved portion.

8. A method for manufacturing a liquid crystal display device, comprising the steps of:

forming a gate electrode over a substrate by a first photolithography step;

forming a gate insulating layer over the gate electrode;

forming a semiconductor layer over the gate insulating layer;

forming a source electrode and a drain electrode over the semiconductor layer by a second photolithography step;

forming an insulating layer over the source electrode and the drain electrode;

forming a contact hole by selectively removing part of the insulating layer overlapping with the drain electrode and removing part of the insulating layer, part of the semiconductor layer, and part of the gate insulating layer, by a third photolithography step; and

forming a pixel electrode over the insulating layer by a fourth photolithography step.

9. The method for manufacturing a liquid crystal display device, according to claim 8,

wherein a base layer is formed between the substrate and the gate electrode.

10. The method for manufacturing a liquid crystal display device, according to claim 8,

wherein the semiconductor layer comprises an oxide semiconductor.

11. The liquid crystal display device according to claim 10, wherein the oxide semiconductor comprises indium and zinc.

12. The method for manufacturing a liquid crystal display device, according to claim 8,

wherein the gate electrode, the source electrode, or the drain electrode is formed using a material containing copper.

13. The method for manufacturing a liquid crystal display device, according to claim 12,

wherein a highest temperature in a process after the gate electrode, the source electrode, or the drain electrode is formed is lower than or equal to 450°

C.

14. The method for manufacturing a liquid crystal display device, according to claim 8,

wherein the gate electrode, the source electrode, or the drain electrode is formed using a material containing aluminum.

15. The method for manufacturing a liquid crystal display device, according to claim 14,

wherein a highest temperature in a process after the gate electrode, the source electrode, or the drain electrode is formed is lower than or equal to 380°

C.

16. The method for manufacturing a liquid crystal display device, according to claim 8,

wherein the first photolithography step, the second photolithography step, the third photolithography step, and the fourth photolithography step each comprise a step of forming a resist mask, a step of etching a conductive layer or an insulating layer, and a step of removing the resist mask.