Method of fabricating a reflection type liquid crystal display in which the surface of a substrate is roughened, a metal film is formed on the roughened surface, and a non-polarizing, transparent dielectric film is form on the metal film

• US 6,061,112 A
• Filed: 01/12/1999
• Issued: 05/09/2000
• Est. Priority Date: 11/05/1996
• Status: Expired due to Term

• Current Assignee: NLT Technologies, Ltd.
• Original Assignee: NEC Corporation
• Inventors: Koide, Shin, Ukita, Tooru
• Primary Examiner(s): Dudek, James A.
• Application Number:
  US09/228,396
• Time in Patent Office: 483 Days
• Field of Search: 349/113, 349/114, 349/158, 349/160
• US Class Current: 349/113
• CPC Class Codes: G02F 1/133357 Planarisation layers
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/133565 inside the LC elements, i.e. between the cell substrates
• CPC Class Codes: G02F 1/1362 Active matrix addressed cells G02F1/134336, G02F1/134363 take precedence

Abstract

There is provided a reflection type liquid crystal display including (a) a first substrate having a roughened surface, (b) a second substrate spaced away from the first substrate in opposing relation to the roughened surface of the first substrate, (c) a liquid crystal layer sandwiched between the first and second substrates, (d) a metal film formed on the roughened surface of the first substrate for reflecting lights therefrom, (e) a transparent dielectric film formed on the metal film, the transparent dielectric film having a planarized upper surface, (f) a plurality of transparent pixel electrodes formed on the transparent dielectric film, and (g) a plurality of switching devices formed on the transparent dielectric film, each of the switching devices being electrically connected with each of the transparent pixel electrodes, the transparent pixel electrodes and the switching devices being arranged in a matrix. The above-mentioned reflection type liquid crystal display makes it possible to provide an excellent light diffusion and reflection function without special technique. In particular, it is possible to reduce the number of photolithography steps for fabricating an active matrix type substrate, ensuring lower fabrication costs and a higher fabrication yield.

Claims

1. A method of fabricating a substrate for a reflection type liquid crystal display, comprising the steps of:

(a) roughening a surface of a substrate;

(b) forming a metal film on the thus roughened surface of said substrate for reflecting lights therefrom;

(c) forming a non-polarizing, transparent dielectric film on said metal film so that said transparent dielectric film has a planarized upper surface; and

(d) forming at least one transparent pixel electrode on said transparent dielectric film;

wherein said transparent dielectric film is formed by spin-coating polymer on said metal film.

2. The method as set forth in claim 1, wherein said transparent dielectric film is formed by the steps of:

(a) applying liquid prepolymer on said metal film;

(b) spreading said prepolymer on said metal film so that said prepolymer has an almost uniform thickness; and

(c) curing said prepolymer.

3. The method as set forth in claim 1, wherein said polymer includes at least one of polyamide, polyimide, polyester, acrylic resin, epoxy resin, silicone resin, and polysilazane.

4. A method of fabricating a substrate for a reflection type liquid crystal display, comprising the steps of:

(a) roughening a surface of a substrate;

(b) forming a metal film on the thus roughened surface of said substrate for reflecting lights therefrom;

(c) forming a non-polarizing, transparent dielectric film on said metal film so that said transparent dielectric film has a planarized upper surface;

(d) forming a plurality of transparent pixel electrodes on said transparent dielectric film; and

(e) forming a plurality of switching devices on said transparent dielectric film so that each of said switching devices is electrically connected with each of said transparent pixel electrodes, and that said transparent pixel electrodes and said switching devices are arranged in a matrix;

wherein said transparent dielectric film is formed by spin-coating polymer on said metal film.

5. The method as set forth in claim 4, wherein said transparent dielectric film is formed by the steps of:

(a) applying liquid prepolymer on said metal film;

(b) spreading said prepolymer on said metal film so that said prepolymer has an almost uniform thickness; and

(c) curing said prepolymer.

6. The method as set forth in claim 4, wherein said polymer includes at least one of polyamide, polyimide, polyester, acrylic resin, epoxy resin, silicone resin, and polysilazane.

7. A method of fabricating a substrate for a reflection type liquid crystal display, comprising the steps of:

(a) roughening a surface of a substrate;

(b) forming a metal film on the thus roughened surface of said substrate for reflecting lights therefrom;

(c) forming a non-polarizing, transparent dielectric film on said metal film so that said transparent dielectric film has a planarized upper surface;

(d) forming a plurality of transparent pixel electrodes on said transparent dielectric film; and

(e) forming a plurality of switching devices on said transparent dielectric film so that each of said switching devices is electrically connected with each of said transparent pixel electrodes, and that said transparent pixel electrodes and said switching devices are arranged in a matrix;

wherein said surface is roughened in said step (a) so that there are formed projections and recesses having a difference in height in the range of 0.1 μ

m to 5 μ

m both inclusive.

8. A method of fabricating a substrate for a reflection type liquid crystal display, comprising the steps of:

(a) roughening a surface of a substrate;

(b) forming a metal film on the thus roughened surface of said substrate for reflecting lights therefrom;

(c) forming a non-polarizing, transparent dielectric film on said metal film so that said transparent dielectric film has a planarized upper surface;

(d) forming a plurality of transparent pixel electrodes on said transparent dielectric film; and

(e) forming a plurality of switching devices on said transparent dielectric film so that each of said switching devices is electrically connected with each of said transparent pixel electrodes, and that said transparent pixel electrodes and said switching devices are arranged in a matrix;

wherein said metal film is formed partially on said roughened surface of said first substrate in said step (b).

9. The method as set forth in claim 8, wherein said metal film is formed almost only below said transparent pixel electrodes.

10. The method as set forth in claim 8, wherein said metal film is formed on said roughened surface of said first substrate so as not to exist below said switching devices.

11. The method as set forth in claim 8, wherein unnecessary portions of said metal film is removed by photolithography and etching.

12. A method of fabricating a substrate for a reflection type liquid crystal display, comprising the steps of:

(a) roughening a surface of a substrate;

(b) forming a metal film on the thus roughened surface of said substrate for reflecting lights therefrom;

(c) forming a non-polarizing, transparent dielectric film on said metal film so that said transparent dielectric film has a planarized upper surface;

(d) forming a film on said transparent dielectric film;

(e) forming a plurality of transparent pixel electrodes on said film; and

(f) forming a plurality of switching devices on said film so that each of said switching devices is electrically connected with each of said transparent pixel electrodes, and that said transparent pixel electrodes and said switching devices are arranged in a matrix;

wherein said transparent dielectric film is formed by spin-coating polymer on said metal film.

13. The method as set forth in claim 12, wherein said transparent dielectric film is formed by the steps of:

(a) applying liquid prepolymer on said metal film;

(b) spreading said prepolymer on said metal film so that said prepolymer has an almost uniform thickness; and

(c) curing said prepolymer.

14. The method as set forth in claim 12, wherein said polymer includes at least one of polyamide, polyimide, polyester, acrylic resin, epoxy resin, silicone resin, and polysilazane.

15. A method of fabricating a substrate for a reflection type liquid crystal display, comprising the steps of:

(a) roughening a surface of a substrate;

(b) forming a metal film on the thus roughened surface of said substrate for reflecting lights therefrom;

(c) forming a non-polarizing, transparent dielectric film on said metal film so that said transparent dielectric film has a planarized upper surface;

(d) forming a film on said transparent dielectric film;

(e) forming a plurality of transparent pixel electrodes on said film; and

(f) forming a plurality of switching devices on said film so that each of said switching devices is electrically connected with each of said transparent pixel electrodes, and that said transparent pixel electrodes and said switching devices are arranged in a matrix;

wherein said metal film is formed partially on said roughened surface of said first substrate in said step (b).

16. The method as set forth in claim 15, wherein said metal film is formed almost only below said transparent pixel electrodes.

17. The method as set forth in claim 15, wherein said metal film is formed on said roughened surface of said first substrate so as not to exist below said switching devices.

18. The method as set forth in claim 15, wherein unnecessary portions of said metal film is removed by photolithography and etching.