Display units having two insolating films and a planarizing film and process for producing the same

• US 5,721,601 A
• Filed: 09/22/1995
• Issued: 02/24/1998
• Est. Priority Date: 09/29/1994
• Status: Expired due to Term

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Suzuki, Koji, Yamaji, Toshifumi, Masahara, Kou, Abe, Hisashi, Yoneda, Kiyoshi, Nakanishi, Shiro, Morimoto, Yoshihiro, Oda, Nobuhiko
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Dudek, James A.
• Application Number:
  US08/532,484
• Time in Patent Office: 886 Days
• Field of Search: 349/122, 349/138, 349/149
• US Class Current: 349/138
• CPC Class Codes: G02F 1/133357 Planarisation layers
• CPC Class Codes: G02F 1/136227 Through-hole connection of the pixel electrode to the active element through an insulation layer

Abstract

A liquid crystal display unit is described, which includes a first substrate, a second substrate opposing to the first substrate, pixel driving elements, first and second insulation layers, a planarizing film and a liquid crystal layer. The pixel driving elements are disposed on the first substrate and between the first and second substrates. The first insulation layer is deposited over the first substrate and the pixel driving elements. The planarizing film is formed on the first insulation layer. This planarizing film provides a substantially flat surface over the first substrate to minimize a height of a step present between an area corresponding to each pixel driving element and an area locating adjacent to the pixel driving element on the first substrate. The second insulation layer is formed on the planarizing film. The display electrodes are formed on the second insulation layer and electrically connected to the pixel driving elements, respectively. The liquid crystal layer is located between the first substrate and said second substrate.

Claims

1. A liquid crystal display unit comprising:

a first substrate;

a second substrate opposing to said first substrate;

pixel driving elements disposed on said first substrate and between said first and second substrates;

a first insulation layer deposited over said first substrate and said pixel driving elements;

a planarizing film, formed on said first insulation layer, for providing a substantially flat surface over said first substrate to minimize a height of a step present between an area corresponding to each pixel driving element and an area locating adjacent to said pixel driving element on said first substrate;

a second insulation layer formed on said planarizing film;

display electrodes formed on said second insulation layer and electrically connected to said pixel driving elements, respectively; and

a liquid crystal layer located between said first and second substrates.

2. The liquid crystal display unit according to claim 1, wherein said first insulation layer is formed over said first substrate only at the portions corresponding to the locations of said pixel driving elements;

said second insulation layer is formed on said planarizing film only at the portions corresponding to the locations of said pixel driving elements.

3. The liquid crystal display unit according to claim 1, wherein each of said first and said second insulation layers is a film selected from the group consisting of silicon oxide film, silicon nitride film and silicon nitride oxide film.

4. The liquid crystal display unit according to claim 1, wherein each of said first and second insulation layers is a film selected from the group consisting of plasma TEOS film, plasma oxide film and ECR oxide film.

5. The liquid crystal display unit according to claim 1, wherein said planarizing film is colored.

6. The liquid crystal display unit according to claim 1, further comprising auxiliary capacitances which are formed on said first substrate and are electrically connected to said display electrodes, respectively.

7. A built-in driver type liquid crystal display unit comprising a first substrate, a second substrate opposing to the first substrate, a pixel portion and a driving circuit adjacent to the pixel potion, said pixel portion and said driving circuit being formed on said first substrate,

wherein said pixel portion includes:

pixel driving elements disposed on said first substrate and between said first and second substrate;

a first insulation layer deposited over said first substrate;

a planarizing film, formed on said first insulation layer, for providing a substantially flat surface over said first substrate to minimize a height of a step present between an area corresponding to each pixel driving element and an area located adjacent to said pixel driving element on said first substrate;

a second insulation layer formed on said planarizing film;

display electrodes formed on said second insulation layer and electrically connected to said pixel driving elements, respectively; and

a liquid crystal layer located between said first and second substrates; and

wherein said driving circuit includes;

circuit elements disposed on said first substrate;

a first insulation layer deposited over said circuit elements; and

a second insulation layer formed on said first insulation layer of said driving circuit.

8. The liquid crystal display unit according to claim 7, wherein said first insulation layer in said pixel portion is formed over said first substrate only at the portions corresponding to the locations of said pixel driving elements;

said second insulation layer is formed on said planarizing film only at the portions corresponding to the locations of said pixel driving elements.

9. The liquid crystal display unit according to claim 7, wherein each of said first and second insulation layers of said pixel portion and said driving circuit is a film selected from the group consisting of silicon oxide film, silicon nitride film and silicon nitride oxide film.

10. The liquid crystal display unit according to claim 7, wherein each of said first and second insulation layers of said pixel portion and said driving circuit is a film selected from the group consisting of plasma TEOS film, plasma oxide film and ECR oxide film.

11. The liquid crystal display unit according to claim 7, wherein said planarizing film is colored.

12. The liquid crystal display unit according to claim 7, further comprising auxiliary capacitances which are formed on said first substrate and are electrically connected to said display electrodes, respectively.

13. A process for producing a liquid crystal display unit having a pixel portion containing pixel driving elements, said process comprising the steps of:

forming the pixel driving elements on a substrate;

forming a first insulation film over an entire surface of said substrate and over said pixel driving elements;

forming a planarizing film to provide a substantially flat surface on said first insulation film;

forming a second insulation film on said planarizing film; and

forming, on said second insulation film, display electrodes which are connected to said pixel driving elements respectively.

14. The process according to claim 13, wherein each of said steps of forming said first and second insulation films includes a substep of forming one of TEOS film and silicon oxide film by means of plasma CVD;

and a substep of subjecting the formed film to ion implantation in order to increase the number of dangling bonds.

15. The process according to claim 13, wherein each of said steps of forming said first and second insulation films includes a substep of forming one of TEOS film and silicon oxide film by means of plasma CVD;

and a substep of subjecting the formed film to hydrogen plasma treatment in order to cause the film to have Si--H bonds.

16. The process according to claim 13, further comprising the step of coloring said planarizing film before the formation of said second insulation film.

17. The process according to claim 13, further comprising the step of forming auxiliary capacitances on said substrate during the formation of said pixel driving elements.

18. The process according to claim 13, wherein said planarizing film is formed by using spin-on-glass technique.

19. The process according to claim 13, further comprising the step of removing a portion of said first insulation film where said display electrodes are to be formed before the formation of said planarizing film;

and the step of removing a portion of said second insulation film where said display electrodes are to be formed.

20. A process for producing a built-in driver type display unit having a pixel portion and a driving circuit therefor which are formed on a substrate, said process comprising the steps of:

forming the pixel driving elements on said substrate within the area corresponding to said pixel portion;

forming circuit elements on said substrate within the area corresponding to said drive circuit;

forming a first insulation film over the entire surface of said substrate and over said pixel driving elements and said circuit elements;

forming a planarizing film to provide a substantially flat surface on said first insulation film;

removing a portion of said planarizing film at the area corresponding to said driving circuit to expose said first insulation film;

forming a second insulation film on the remaining planarizing film and on said first insulation film thus exposed; and

forming display electrodes on said second insulation film within the area corresponding to said pixel portion, said display electrodes being connected to said pixel driving elements respectively.

21. The process according to claim 20, wherein each of said steps of forming said first and second insulation films includes a substep of forming one of TEOS film and silicon oxide film by means of plasma CVD;

and a substep of subjecting the formed film to ion implantation in order to increase the number of dangling bonds.

22. The process according to claim 20, wherein each of said steps of forming said first and second insulation films includes a substep of forming one of TEOS film and silicon oxide film by means of plasma CVD;

and a substep of subjecting the formed film to hydrogen plasma treatment in order to the film to have Si--H bonds.

23. The process according to claim 20, further comprising the step of coloring said planarizing film before the formation of said second insulation film.

24. The process according to claim 20, further comprising the step of forming auxiliary capacitances on said substrate during the formation of said pixel driving elements.

25. The process according to claim 20, wherein said planarizing film is formed by using spin-on-glass technique.

26. The process according to claim 20, further comprising the step of removing a portion of said first insulation film where said display electrodes are to be formed before the formation of said planarizing film;

and the step of removing a portion of said second insulation film where said display electrodes are to be formed.