Etching process for making electrodes

• US 6,838,013 B2
• Filed: 06/12/2002
• Issued: 01/04/2005
• Est. Priority Date: 05/12/2000
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Ram, Jyothsna, Lennhoff, Nancy S.
• Primary Examiner(s): Hassanzadeh, Parviz
• Application Number:
  US10/170,105
• Publication Number:
  US 20020182386A1
• Time in Patent Office: 937 Days
• Field of Search: 216/23, 216/95, 216/100, 216/101, 216/103, 216/108, 156/345.11, 428/472, 428/1.51, 428/333
• US Class Current: 216/103
• CPC Class Codes: C09K 13/04 containing an inorganic acid
• CPC Class Codes: C09K 2323/051 Inorganic, e.g. glass or silicon oxide
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: H01L 21/32134 by liquid etching only
• CPC Class Codes: H01L 31/1884 Manufacture of transparent electrodes, e.g. TCO, ITO
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy
• CPC Class Codes: Y10T 428/24917 including metal layer
• CPC Class Codes: Y10T 428/261 In terms of molecular thickness or light wave length
• CPC Class Codes: Y10T 428/31529 Next to metal
• CPC Class Codes: Y10T 428/31678 Of metal

Abstract

Substantially transparent electrodes are formed on a substrate by a process including forming on the substrate, in order, a bottom high index layer, a metallic conductive layer, and a top high index layer with a conductivity of at least about 400 Ω/square; and chemically etching the bottom high index layer, the top high index layer and the conductive layer to form discrete electrodes in the metallic conductive layer.

Claims

1. A process for forming an electrode, the process comprising:

forming on a substrate, in order, a bottom high index layer, a conductive layer, and a top high index layer with a conductivity of at least about 400 Ω

/square; and

chemically etching the bottom high index layer, the top high index layer and the conductive layer with an etching solution comprising H₂SO₄ and FeCl₃ to form an electrode in the conductive layer.

2. The process of claim 1, wherein the etching step is performed in a single bath comprising H₂SO₄ and FeCl₃.

3. The process of claim 2, wherein the bath comprises a 3% solution of H₂SO₄ and a 0.01% solution of FeCl₃ at a ratio of about 2:

1 to about 5;

1.

4. The process of claim 2, wherein the ratio in the bath is about 4:

1 to about 5;

1.

5. The process of claim 2, wherein the top and bottom high index layers and the conductive layer are resident in the bath for a residence time of about 1 minute to about 5 minutes.

6. The process of claim 2, wherein the top and bottom high index layers and the conductive layer are in the bath for a residence time of about 1 minute to about 5 minutes.

7. The process of claim 2, wherein the top and bottom high index layers and the conductive layer are in the bath for a residence time of about 3 minutes to about 5 minutes.

8. The process of claim 2, wherein the temperature of the bath is about 30°

C. to about 40°

C.

9. The process of claim 2, further comprising agitating the bath.

10. The process of claim 2, wherein the bath is an ultrasonic bath.

11. The process of claim 1, wherein the etching step forms a plurality of discrete electrodes in the conductive layer, further comprising connecting a plurality of conductors to portions of the top index layer overlying the discrete electrodes.

12. The process of claim 1, wherein the substrate is a material selected from the group consisting of polyether sulfones, poly(alkyl)acrylates, cellulose diacetate, polycarbonates, polyesters, polycarbonate copolymers and poly(bis(cyclopentadiene) condensate).

13. The process of claim 1, wherein the substrate further comprises a silica layer on at least one surface thereof.

14. The process of claim 1, wherein the substrate comprises on a surface thereof the following layers, in order:

a first silica layer, a hardcoat layer, and a second silica layer.

15. A process for forming a substantially transparent electrode, the process comprising:

depositing on a substrate, in order, a bottom high index layer, a conductive layer, and a top high index layer with a conductivity of at least about 400 Ω

/square,

chemically etching in a single bath the bottom high index layer, the top high index layer and the conductive layer to form an electrode in the conductive layer, wherein the bath comprises H₂SO₄ and FeCl₃.