Implantable electrode and method of making the same
An implantable electrode system of is disclosed that includes a conductive electrode layer, an interconnect coupled to the electrode layer, an insulator that insulates the interconnect, and an anchor that more securely fixes the electrode layer in place. This structure is particularly useful with the electrode layer being a neural interface that is configured to provide either a recording or stimulating function. A method for forming such an implantable electrode system includes forming an interconnect over a base layer, forming an anchoring structure over the base layer, depositing an insulating material layer over the interconnect structure and over the anchoring structure, exposing a portion of the interconnect structure, forming an electrode layer over the insulating layer, the electrode layer contacting the exposed portion of the interconnect structure.
1. A method for controlling charge distribution of an implantable electrode comprising:
forming an interconnect structure over a base layer;
forming an anchoring structure over the base layer;
depositing an insulating material layer over the interconnect structure and over the anchoring structure;
exposing a portion of the interconnect structure through the insulating material layer;
exposing a portion of the anchoring structure through the insulating material layer;
forming a first plug over the exposed portion of the interconnect structure;
forming a second plug over the exposed portion of the anchoring structure; and
forming an electrode site that extends over the insulating material layer, the first plug, and the second plug, the electrode site being electrically coupled to the exposed portion of the interconnect structure via the first plug and to the exposed portion of the anchoring structure via the second plug.
2. The method of claim 1 , wherein the electrode site is a thin film of metal comprised of gold, iridium, or platinum.
3. The method of claim 1 , wherein the exposed portion of the interconnect structure has a ring geometry.
4. The method of claim 1 , wherein exposing the portion of the interconnect structure comprises:
exposing a central portion of the interconnect structure without exposing an edge portion of the interconnect structure.
5. The method of claim 1 , wherein an edge portion of the interconnect structure is separated from the electrode site by a portion of the insulating layer.
6. The method of claim 1 , wherein forming the electrode site comprises:
forming a metal-to-metal bond between a material of the electrode site and a material of the second plug.
7. The method of claim 1 , wherein the anchoring structure and the interconnect structure are formed on a common plane.
8. The method of claim 7 , wherein the electrode site is circular and the exposed portion of the anchoring structure has a ring geometry that coincides with a perimeter portion of the electrode site.
9. The method of claim 1 , wherein depositing the insulating material layer comprises:
depositing a first insulating material layer over and in contact with the interconnect structure; and
depositing a second insulating material layer over and in contact with the first insulating material layer.