Liquid crystal display device

• US 10,678,107 B2
• Filed: 05/14/2019
• Issued: 06/09/2020
• Est. Priority Date: 07/06/2007
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Suzuki, Yukie, Kuwabara, Hideaki, Kimura, Hajime
• Primary Examiner(s): Kianni, Kaveh C
• Application Number:
  US16/411,594
• Publication Number:
  US 20190265528A1
• Time in Patent Office: 392 Days
• Field of Search: 349156
• CPC Class Codes: G02F 1/133345 Insulating layers G02F1/1335, G02F1/1337, G02F1/135, G02F1/136 take precedence
• CPC Class Codes: G02F 1/1339 Gaskets; Spacers; Sealing of cells
• CPC Class Codes: G02F 1/134309 characterised by their geometrical arrangement
• 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: H01L 27/1214 comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs
• CPC Class Codes: H01L 27/1222 with a particular composition, shape or crystalline structure of the active layer
• CPC Class Codes: H01L 27/1288 employing particular masking sequences or specially adapted masks, e.g. half-tone mask
• CPC Class Codes: H01L 29/04 characterised by their crystalline structure, e.g. polycrystalline, cubic or particular orientation of crystalline planes characterised by physical imperfections H01L29/30
• CPC Class Codes: H01L 29/458 for thin film silicon, e.g. source or drain electrode
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT
• CPC Class Codes: H01L 29/66765 Lateral single gate single channel transistors with inverted structure, i.e. the channel layer is formed after the gate
• CPC Class Codes: H01L 29/78678 with inverted-type structure, e.g. with bottom gate
• CPC Class Codes: H01L 29/78696 characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel H01L29/78612 takes precedence; transistors having a drain offset region or a lightly doped drain [LDD] H01L29/78621

Abstract

A method of manufacturing, with high mass productivity, liquid crystal display devices having highly reliable thin film transistors with excellent electric characteristics is provided. In a liquid crystal display device having an inverted staggered thin film transistor, the inverted staggered thin film transistor is formed as follows: a gate insulating film is formed over a gate electrode; a microcrystalline semiconductor film which functions as a channel formation region is formed over the gate insulating film; a buffer layer is formed over the microcrystalline semiconductor film; a pair of source and drain regions are formed over the buffer layer; and a pair of source and drain electrodes are formed in contact with the source and drain regions so as to expose a part of the source and drain regions.

Claims

1. A liquid crystal display device comprising:

a transistor comprising;

a gate electrode;

a gate insulating film over the gate electrode;

a first semiconductor film over the gate insulating film;

a second semiconductor film over and overlapping with the first semiconductor film;

a third semiconductor film over and overlapping with the second semiconductor film, the third semiconductor film containing phosphorus; and

a first conductive film over and overlapping with the third semiconductor film;

an insulating film over the first conductive film;

a first electrode electrically connected to the first conductive film;

a second electrode including a first region overlapping with the first electrode with the insulating film therebetween and a second region below the first conductive film; and

a liquid crystal over the first electrode and the second electrode,

wherein an alignment of the liquid crystal is controlled by an electric field between the first electrode and the second electrode, and

wherein an end portion of the third semiconductor film is located outside an end portion of the first conductive film.

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

wherein both of the gate electrode and the first electrode are provided on and in contact with an insulating surface.

3. The liquid crystal display device according to claim 1, further comprising an alignment film in contact with the insulating film and the first electrode.

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

wherein the first electrode is provided with a slit.

5. A liquid crystal display device comprising:

a transistor comprising;

a gate electrode;

a gate insulating film over the gate electrode;

a first semiconductor film over the gate insulating film;

a second semiconductor film over and overlapping with the first semiconductor film;

a third semiconductor film over and overlapping with the second semiconductor film, the third semiconductor film containing phosphorus; and

a first conductive film over and overlapping with the third semiconductor film;

an insulating film over the first conductive film;

a first electrode over the insulating film;

a second electrode including a first region overlapping with the first electrode with the insulating film therebetween and a second region below the first conductive film; and

a liquid crystal over the first electrode and the second electrode,

wherein an alignment of the liquid crystal is controlled by an electric field between the first electrode and the second electrode, and

wherein an end portion of the third semiconductor film is located outside an end portion of the first conductive film.

6. The liquid crystal display device according to claim 5,

wherein both of the gate electrode and the first electrode are provided on and in contact with an insulating surface.

7. The liquid crystal display device according to claim 5, further comprising an alignment film in contact with the insulating film and the first electrode.

8. The liquid crystal display device according to claim 5,

wherein the first electrode is provided with a slit.