Transmissive liquid crystal display apparatus and method for producing the same

• US 5,859,683 A
• Filed: 09/27/1996
• Issued: 01/12/1999
• Est. Priority Date: 09/29/1995
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Shimada, Takayuki, Tagusa, Yasunobu, Katayama, Mikio, Kanemori, Yuzuru
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): NGUYEN, TIEP HUU
• Application Number:
  US08/722,827
• Time in Patent Office: 837 Days
• Field of Search: 349/138, 349/39, 349/44
• US Class Current: 349/138
• CPC Class Codes: G02F 1/136227 Through-hole connection of the pixel electrode to the active element through an insulation layer
• CPC Class Codes: H01L 27/1255 integrated with passive devices, e.g. auxiliary capacitors

Abstract

A transmissive liquid crystal display apparatus includes a liquid crystal layer interposed between a first substrate and a second substrate. The first substrate includes gate lines, source lines and switching devices provided in a vicinity of intersectional portions of the gate lines and the source lines. The switching devices include gate electrodes connected to the gate lines, source electrodes connected to the source lines and drain electrodes connected to pixel electrodes for applying a voltage to the liquid crystal layer. An interlayer insulating film having high transparency is provided above the switching devices, the gate lines and the source lines. The interlayer insulating film has roughness on its surface. A height difference of the roughness is 50 nm or less. The pixel electrode formed of a transparent conductive material is provided on the interlayer insulating film.

Claims

1. A transmissive liquid crystal display apparatus comprising:

a liquid crystal layer interposed between a first substrate and a second substrate, the first substrate including gate lines, source lines and switching devices provided in a vicinity of intersectional portions of the gate lines and the source lines, the switching devices including gate electrodes connected to the gate lines, source electrodes connected to the source lines and drain electrodes connected to pixel electrodes for applying a voltage to the liquid crystal layer,

wherein an interlayer insulating film having high transparency is provided above the switching devices, the gate lines and the source lines, the interlayer insulating film having roughness on its surface, a height difference of the roughness being 50 nm or less, and

the pixel electrodes formed of a transparent conductive material are provided on the interlayer insulating film.

2. A transmissive liquid crystal display apparatus according to claim 1, wherein a thickness of the interlayer insulating film is in the range of about 1.5 μ

m to about 5 μ

m.

3. A transmissive liquid crystal display apparatus according to claim 1, wherein a transmittance of light with a wavelength of about 400 nm to about 800 nm of the interlayer insulating film is about 90% or more.

4. A transmissive liquid crystal display apparatus according to claim 1, wherein a dielectric constant of the interlayer insulating film is in the range of about 2 to about 5.

5. A transmissive liquid crystal display apparatus according to claim 1, further comprising interconnecting electrodes for connecting the pixel electrodes and the drain electrodes,

wherein the interlayer insulating film is provided above the switching devices, the gate lines, the source lines and the interconnecting electrodes,

the pixel electrodes are provided in the interlayer insulating film so as to at least partially overlap at least either the gate lines or the source lines, and

the interconnecting electrodes and the pixel electrodes are connected to each other via contact holes penetrating the interlayer insulating film.

6. A transmissive liquid crystal display apparatus according to claim 5, further comprising capacitor lines formed substantially parallel to the gate lines in central portions of the pixel electrodes, and

wherein the contact holes are formed over the capacitor lines.

7. A transmissive liquid crystal display apparatus according to claim 6, wherein a width of the contact hole in a direction lateral to the capacitor line does not exceed a width of the capacitor line by more than 2 μ

m.

8. A transmissive liquid crystal display apparatus according to claim 5, wherein the interconnecting electrodes are formed of a transparent conductive film.

9. A transmissive liquid crystal display apparatus according to claim 5, wherein a metal nitride layer for connecting the interconnecting electrodes and the pixel electrodes is provided below the contact holes.

10. A transmissive liquid crystal display apparatus according to claim 1, further comprising a micro prism sheet on a substrate side opposite to another substrate side that faces the liquid crystal layer.

11. A transmissive liquid crystal display apparatus according to claim 1, wherein a line-like patterned light-shielding layer for defining a size of a pixel is provided on at least one of the first substrate and the second substrate, the light-shielding layer being provided so as not to extend beyond the gate lines and the source lines.

12. A transmissive liquid crystal display apparatus according to claim 1, being a direct sight type, wherein a ratio of a shorter side of the display apparatus to a longer side of the display apparatus is substantially 9:

16.

13. A method for producing a transmissive liquid crystal display apparatus comprising the steps of:

on the first substrate including gate lines, source lines and switching devices provided in a vicinity of intersectional portions of the gate lines and the source lines, the switching devices including gate electrodes connected to the gate lines, source electrodes connected to the source lines and drain electrodes connected to pixel electrodes for applying a voltage to a liquid crystal layer,

forming an interlayer insulating film having roughness of a height difference of about 50 nm or less by applying a material of an initial viscosity of about 100 cps or less onto the switching devices, the gate lines and the source lines; and

forming pixel electrodes formed of a transparent conductive material on the interlayer insulating film.

14. A method for producing a transmissive liquid crystal display apparatus according to claim 13, wherein a thickness of the interlayer insulating film is in a range of about 1.5 μ

m to 5 μ

m.

15. A method for producing a transmissive liquid crystal display apparatus according to claim 13, wherein a transmittance of light with a wavelength of about 400 nm to about 800 nm of the interlayer insulating film is about 90% or more.

16. A method for producing a transmissive liquid crystal display apparatus according to claim 13, wherein a dielectric constant of the interlayer insulating film is in the range of about 2 to about 5.

17. A method for producing a transmissive liquid crystal display apparatus according to claim 13, the first substrate further including interconnecting electrodes for connecting the pixel electrodes and the drain electrodes,

the interlayer insulating film forming step being a step of forming the interlayer insulating film above the switching devices, the gate lines, the source lines and the interconnecting electrodes,

further comprising the step of forming contact holes penetrating the interlayer insulating film,

the pixel electrode forming step being a step wherein the pixel electrodes are provided in the interlayer insulating film so as to at least partially overlap at least either the gate lines or the source lines, and the interconnection electrodes and the pixel electrodes are electrically connected to each other via the contact holes.

18. A method for producing a transmissive liquid crystal display apparatus according to claim 13, wherein the interlayer insulating film is formed of a photosensitive material and is patterned by exposure and alkali development.

19. A method for producing a transmissive liquid crystal display apparatus according to claim 13, wherein the step of applying the material formed into the interlayer insulating film is performed by a spin coating method, a roll coating method or a slot coating method.

20. A method for producing a transmissive liquid crystal display apparatus according to claim 19, wherein a rotation rate in the spin coating method is in a range of about 800 rpm to about 1500 rpm.