Display substrate electrodes with auxiliary metal layers for enhanced conductivity

• US 6,037,005 A
• Filed: 05/12/1998
• Issued: 03/14/2000
• Est. Priority Date: 05/12/1998
• Status: Expired due to Term

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Padiyath, Raghunath, Moshrefzadeh, Robert S.
• Primary Examiner(s): King, Roy V.
• Application Number:
  US09/076,165
• Time in Patent Office: 672 Days
• Field of Search: 427/286, 427/287, 427/259, 427/261, 427/269, 427/250, 427/124, 156/643.1, 216/40, 216/101
• US Class Current: 427/286
• CPC Class Codes: C09K 2323/061 Inorganic, e.g. ceramic, metallic or glass
• CPC Class Codes: G02F 1/134336 Matrix
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: H10K 50/814 combined with auxiliary electrodes, e.g. ITO layer combined with metal lines
• CPC Class Codes: H10K 59/80516 combined with auxiliary electrodes, e.g. ITO layer combined with metal lines

Abstract

A method for enhancing the conductivity of transparent conductive electrodes on display substrates by providing patterned auxiliary metallic layers adjacent to the transparent conductive material. The method of the present invention eliminates the need for aligning the auxiliary metal layers with preexisting transparent conductive electrodes by providing for simultaneous patterning of the auxiliary metal layers and formation of the independently addressable electrodes.

Claims

1. A method for enhancing the conductivity of transparent conductive electrodes comprising the steps of:

providing a substantially transparent substrate having a transparent conductive layer thereon;

forming parallel strips of resist material on the transparent conductive layer, thereby leaving areas of the transparent conductive layer uncovered by the resist material;

depositing a metal coating on the transparent conductive layer and strips of resist material using a collimated beam of metallic material, whereby the collimated beam is incident at such an angle as to be partially blocked by the parallel strips of resist material, thereby leaving portions of the uncovered transparent conductive layer exposed;

removing the exposed portions of the transparent conductive layer; and

removing the strips of resist material and any metal coating thereon to form a plurality of independently addressable electrodes on the substrate.

2. The method of claim 1, further comprising the step of depositing an opaque insulating material on the substrate after the step of removing the exposed portions of the transparent conductive layer and before the step of removing the strips of resist material.

3. The method of claim 1, wherein the step of removing the exposed portions of the transparent conductive layer comprises selectively etching the exposed portions of the transparent conductive layer.

4. The method of claim 1, wherein the step of removing the strips of resist material comprises removing the strips of resist material by a lift-off method.

5. The method of claim 1, wherein the transparent conductive layer is a transparent conductive oxide.

6. The method of claim 5, wherein the transparent conductive oxide is indium tin oxide.

7. The method of claim 1, wherein the metallic material is Cr, Cu, Ag, Au, Ni, W, Al, Pt, Ti, Fe, Sn, or combinations and alloys thereof.

8. A method for enhancing the conductivity of transparent conductive electrodes comprising the steps of:

providing a substantially transparent substrate having a first major surface;

patterning strips of resist material on the smooth major surface of the substrate to thereby leave areas of the substrate exposed, each said strip of resist material having a bottom edge adjacent to the substrate, a top edge opposing the bottom edge, and two opposing side edges;

depositing a metal to cover at least a portion of the resist strips and the exposed areas of the substrate;

forming continuous metal strips along the side edges of the resist strips by selectively removing portions of the metal;

depositing a transparent conductive film to substantially cover the resist strips, the metal strips, and the exposed areas of the substrate; and

removing the resist strips and any portions of metal and transparent conductive film adjacent to the top edges of said strips to thereby form independently addressable electrodes on the substrate, wherein at least a portion of the electrodes comprise strips of the transparent conductive film each having side edges bordered by the remaining continuous metal strips.

9. The method of claim 8, wherein the step of forming continuous metal strips along the side edges of the resist strips by selectively removing portions of the metal comprises the steps of:

(a) coating a liquid material over the metal so that excess liquid material resides on the metal near the side edges of the resist strips;

(b) hardening the liquid material to form a second resist;

(c) back etching the second resist so that only the excess material near the side edges of the resist strips remains;

(d) removing the exposed metal by etching; and

(e) removing the remaining second resist.

10. The method of claim 8, wherein the transparent conductive layer is a transparent conductive oxide.

11. The method of claim 10, wherein the transparent conductive oxide is indium tin oxide.

12. The method of claim 8, wherein the metallic material is Cr, Cu, Ag, Au, Ni, W, Al, Pt, Ti, Fe, Sn, or combinations and alloys thereof.

13. A method for enhancing the conductivity of transparent conductive electrodes comprising the steps of:

providing a substantially transparent substrate having a first major surface;

providing a transparent conductive layer adjacent the first major surface of the substrate;

forming a contiguous metallic coating adjacent the transparent conductive layer, wherein at least a portion of the metallic coating has a periodic array of holes therein; and

removing portions of the transparent conductive layer and any metallic coating thereon to thereby form a plurality of independently addressable electrodes on the substrate.

14. The method of claim 13, wherein the step of forming a contiguous metallic coating having a periodic array of holes comprises depositing a metallic film, coating the film with a photoresist material, exposing the resist material to light having an appropriate wavelength and at an appropriate intensity to activate those areas of the photoresist adjacent to the areas of the metallic coating to be removed, removing the activated areas of the photoresist to expose areas of the metallic coating, etching the exposed areas of the metallic coating, and removing the remaining photoresist material.

15. The method of claim 13, wherein the step of removing portions of the transparent conductive layer and any metallic coating thereon comprises forming strips of photoresist material adjacent to the transparent conductive layer and metallic coating, selectively etching substantially parallel strip-like areas of the transparent conductive layer and any metallic coating thereon through the photoresist strips to thereby form independently addressable electrodes on the substrate, and removing the photoresist material.

16. The method of claim 13, wherein the transparent conductive layer is a transparent conductive oxide.

17. The method of claim 16, wherein the transparent conductive oxide is indium tin oxide.

18. The method of claim 13, wherein the metallic material is Cr, Cu, Ag, Au, Ni, W, Al, Pt, Ti, Fe, Sn, or combinations and alloys thereof.

19. The method of claim 13, wherein the periodic array of holes is selected from the group consisting of:

(a) a two-dimensional array of diamond-shaped holes,

(b) a hexagonal array of circular holes,

(c) a square array of square holes,

(d) a two-dimensional array of triangular hole pairs, and

(e) a hexagonal array of hexagonal holes,

and combinations thereof.