Activated iridium oxide electrodes and methods for their fabrication

• US 20060148254A1
• Filed: 01/05/2005
• Published: 07/06/2006
• Est. Priority Date: 01/05/2005
• Status: Abandoned Application

• Current Assignee: IMI Intelligent Medical Implants AG (Pixium Vision SA)
• Original Assignee: IMI Intelligent Medical Implants AG (Pixium Vision SA)
• Inventors: McLean, George Y.
• Application Number:
  US11/031,669
• Publication Number:
  US 20060148254A1
• Time in Patent Office: Days
• US Class Current: 438/686
• CPC Class Codes: C23C 14/5853 Oxidation
• CPC Class Codes: C25D 11/34 of metals or alloys not provided for in groups C25D11/04 - C25D11/32
• CPC Class Codes: H01L 21/02244 of a metallic layer
• CPC Class Codes: H01L 21/31683 of metallic layers, e.g. Al deposited on the body, e.g. formation of multi-layer insulating structures
• CPC Class Codes: H01L 21/76888 By rendering at least a portion of the conductor non conductive, e.g. oxidation

Abstract

A technique for activating iridium to produce iridium oxide is provided. In a device in which an iridium layer is electrically coupled to a semiconductor junction, a current is generated within the junction and an activation current is applied to the iridium layer via the conductive semiconductor junction. In a presently preferred embodiment, the junction current is generated via illumination of the semiconductor junction.

Claims

1. A method for oxidizing an iridium layer electrically coupled to a semiconductor junction, the method comprising:

generating a junction current within the semiconductor junction sufficient to permit an activation current to be applied to the iridium layer; and

applying the activation current to the iridium layer through the semiconductor junction to oxidize the iridium.

2. The method of claim 1, wherein the semiconductor junction comprises a diode.

3. The method of claim 1, wherein the semiconductor junction is formed in a doped silicon substrate.

4. The method of claim 1, wherein generating the junction current further comprises applying illumination to the semiconductor junction.

5. A method for forming an iridium oxide electrode that is electrically coupled to a semiconductor junction on a substrate, the method comprising:

depositing an iridium layer on the substrate and in electrical communication with the semiconductor junction;

applying illumination to the semiconductor junction to generate a junction current sufficient to permit an activation current to be applied to the iridium layer; and

applying the activation current to the iridium layer through the semiconductor junction to oxidize the film.

6. The method of claim 5, wherein the semiconductor junction comprises a diode.

7. The method of claim 5, wherein the semiconductor junction is formed in a doped silicon substrate.

8. The method of claim 5, further comprising:

annealing the iridium layer prior to applying the activation current.

9. The method of claim 5, wherein applying the activation current further comprises:

immersing the substrate in an electrochemical cell, wherein the activation current is applied via the electrochemical cell.

10. The method of claim 9, wherein the electrochemical cell comprises a Na₂HPO₄ electrolyte, an Ag/AgCl reference electrode, a counter electrode and a working electrode connected to the substrate in series with the semiconductor junction.

11. In a retinal prosthesis comprising a plurality of microphotodiodes formed in a semiconductor substrate, each of the plurality of microphotodiodes comprising an electrical connection to a corresponding iridium layer formed on a surface of the semiconductor substrate and another electrical connection to a common ground electrode formed on another surface of the semiconductor substrate, a method for activating the iridium layer corresponding to each of the plurality of microphotodiodes, the method comprising:

immersing the substrate in an electrochemical cell;

coupling the common ground electrode to a working electrode of the electrochemical cell;

applying illumination to the plurality of microphotodiodes; and

applying an activation current to the corresponding iridium layer of each of the plurality of microphotodiodes via the working electrode.

12. The method of claim 11, wherein the electrochemical cell comprises a Na₂HPO₄ electrolyte, an Ag/AgCl reference electrode and a counter electrode.