Hermetic feedthrough for an implantable device

• US 6,516,808 B2
• Filed: 06/14/2001
• Issued: 02/11/2003
• Est. Priority Date: 09/12/1997
• Status: Expired due to Term

• Current Assignee: Alfred E. Mann Foundation For Scientific Research
• Original Assignee: Alfred E. Mann Foundation For Scientific Research
• Inventors: Schulman, Joseph H.
• Primary Examiner(s): Schaetzle, Kennedy
• Application Number:
  US09/882,712
• Publication Number:
  US 20010039374A1
• Time in Patent Office: 607 Days
• Field of Search: 607/36, 128/899, 600/347, 600/323, 600/325, 600/327, 600/365, 600/372, 600/373, 600/309, 206/438, 174/52.4
• US Class Current: 128/899
• CPC Class Codes: A61B 2560/0219 of externally powered implanted units
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/01 Measuring temperature of body parts ; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue clinical contact thermometers G01K13/20
• CPC Class Codes: A61B 5/145 Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissuemeasuring of blood pressure or blood flow A61B5/02; non-radiation detecting or locating of foreign bodies in blood A61B5/06
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/1473 invasive, e.g. introduced into the body by a catheter A61B5/1482 takes precedence
• CPC Class Codes: A61B 5/14865 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors
• CPC Class Codes: A61B 5/4839 combined with drug delivery
• CPC Class Codes: A61M 2205/0244 Micromachined materials, e.g. made from silicon wafers, microelectromechanical systems [MEMS] or comprising nanotechnology
• CPC Class Codes: A61N 1/05 for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• CPC Class Codes: A61N 1/3754 Feedthroughs
• CPC Class Codes: H01L 23/3107 the device being completely enclosed
• CPC Class Codes: H01L 23/5387 Flexible insulating substrates H01L23/5388 takes precedence
• CPC Class Codes: H01L 29/0657 characterised by the shape of the body
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/19041 being a capacitor

Abstract

The present invention provides an implantable substrate sensor comprising electronic circuitry formed within, or on, a substrate. A protective coating then covers the substrate, forming a hermetically sealed package having the circuitry under the coating. The circuitry has electrically conductive pads for communicating and/or providing power to the circuitry. Electrical pathways provide hermetic electrical connection to the conductive pads for external connection to the sealed circuitry. In a first embodiment, the pathway is a via that is made from a biocompatible material that is made hermetic by either increasing its thickness or by ion beam deposition. Alternatively, the pathways are formed from metal traces, surrounded by a biocompatible insulation material, essentially parallel to the surface of the substrate that are connected to the conductive pads by first vias and have second ends externally accessible to the sealed package to provide external electrical connection to the hermetically sealed circuitry within.

Claims

1. A hermetically sealed package suitable for implantation in living tissue, said package comprising:

a semiconductor substrate having a plurality of surfaces and having an integrated circuit formed as an integral portion of at least one of said surfaces, said integrated circuit having one or more electrically conductive pads for communicating and/or providing power to said integrated circuit;

one or more electrical pathways formed as an integral portion of said semiconductor substrate for providing electrical connection to said one or more electrically conductive pads, said pathways having first ends coupled to said one or more pads and second ends exposed for external electrical connection from said sealed package, wherein said second ends are formed from biocompatible material having sufficient uniformity and/or thickness to ensure hermeticity of said electrical pathways; and

an insulating coating material for encapsulating said integrated circuit and said semiconductor substrate surfaces except for selected portions of said second ends of said electrical pathways wherein said hermetically sealed package is thereby suitable for implantation in living tissue without further packaging.

2. The hermetically sealed package of claim 1 wherein said electrical pathways are comprised of platinum.

3. The hermetically sealed package of claim 2 wherein said platinum electrical pathways are made hermetic by using ion beam deposition to ensure sufficient uniformity.

4. The hermetically sealed package of claim 2 wherein said platinum electrical pathways are made hermetic by having the thickness of the platinum via being at least 5 microns.

5. The hermetically sealed package of claim 1 wherein said integrated circuit is formed on a first surface of the semiconductor substrate and said electrical pathways from said integrated circuit extend outward from said first surface.

6. The hermetically sealed package of claim 5 wherein said semiconductor substrate has a second surface on a side opposite of said first surface of said substrate and said second surface of said substrate and is formed without electrical pathways or an integrated circuit, thereby facilitating connection of said second surface to a second substrate surface of an additional one of said packages.

7. A hermetically sealed package suitable for implantation in living tissue, said package comprising:

a semiconductor substrate having a plurality of surfaces and having an integrated circuit formed on at least one of said surfaces, said integrated circuit having one or more electrically conductive pads for communicating and/or providing power to said integrated circuit;

one or more electrical pathways for providing electrical connection to said one or more electrically conductive pads, said pathways having first ends coupled to said one or more pads and second ends exposed for external electrical connection from said sealed package;

an insulating material for encapsulating said integrated circuit and said semiconductor substrate surfaces except for selected portions of said second ends of said electrical pathways; and

wherein each of said electrical pathways comprises;

a first electrically conductive via electrically coupled to one of said pads;

a metal trace having first and second ends oriented essentially parallel to the surface of the semiconductor substrate and electrically coupled at said first end to said first via, wherein said second end is at least partially externally exposed; and

wherein

said electrical pathway is surrounded by a biocompatible insulation material.

8. The hermetically sealed package of claim 7 wherein said biocompatible insulation material is selected from the group of alumina, zirconia, or an alloy of alumina and zirconia.

9. The hermetically sealed package of claim 7 wherein said second end of said metal trace is biocompatible.

10. The hermetically sealed package of claim 9 wherein said second end of said metal trace is platinum.

11. A hermetically sealed package suitable for implantation in living tissue, said package comprising:

a semiconductor substrate having a plurality of surfaces and having an integrated circuit formed on at least one of said surfaces, said integrated circuit having one or more electrically conductive pads for communicating and/or providing power to said integrated circuit;

one or more electrical pathways for providing electrical connection to said one or more electrically conductive pads, said pathways having first ends coupled to said one or more pads and second ends exposed for external electrical connection from said sealed package;

an insulating material for encapsulating said integrated circuit and said semiconductor substrate surfaces except for selected portions of said second ends of said electrical pathways; and

wherein at least one of said electrically conductive pathways is comprised of;

a plurality of metal traces having first and second ends, including at least an innermost trace closest to said semiconductor substrate and an outermost trace furthest from said semiconductor substrate, each adjacent pair of metal traces separated by an insulating material sandwiched in-between so as to form a hermetic seal between said metal traces;

at least one interconnection via surrounded by said insulating material for interconnecting said adjacent pairs of metal traces;

at least one innermost via for interconnecting said innermost trace to at least one of said pads on said integrated circuit;

an insulating material for encapsulating said plurality of metal traces, said integrated circuit and said semiconductor substrate, wherein the second end of at least one outermost metal trace is at least partially exposed through the encapsulating insulating material for external communication; and

wherein

said combination of metal traces, sandwiched insulating material, encapsulating material and vias provides a hermetic communication path to said integrated circuit from a location external to said implantable package.

12. A method of forming an electrically conductive hermetic connection to a hermetically sealed integrated circuit, said method comprising the steps of:

forming an integrated circuit as an integral portion of the face of a semiconductor substrate, said integrated circuit having one or more electrically conductive pads for communicating and/or providing power to said integrated circuit;

forming one or more electrical pathways as an integral portion of said semiconductor substrate for providing electrical connection to said one or more electrically conductive pads;

said pathways having first ends coupled to said one or more pads and second ends exposed for external electrical connection from said sealed integrated circuit, wherein said second ends are formed from biocompatible material having sufficient uniformity and/or thickness to ensure hermeticity of said electrical pathways; and

encapsulating said semiconductor substrate and said integrated circuit except for selected portions of said second ends of said electrical pathways with an insulating coating material wherein said hermetically sealed circuit is thereby suitable for implantation in living tissue without further packaging.

13. The method of claim 12 wherein the step of forming one or more electrical pathways comprises the step of forming said electrical pathways from platinum such that said electrical pathways are biocompatible.

14. The method of claim 13 wherein the step of forming said electrical pathways from platinum comprises depositing said platinum using ion beam deposition to ensure sufficient uniformity.

15. The method of claim 13 wherein the step of forming said electrical pathways from platinum comprises depositing a layer of platinum of at least 5 microns to cause said platinum electrical pathways to be hermetic.

16. The method of claim 12 additionally comprising the step of rounding at least one corner of said encapsulated integrated circuit.

17. The method of claim 16 wherein said rounding step comprises sandblasting.

18. The method of claim 16 wherein said rounding step comprises acid etching.

19. A method of forming an electrically conductive hermetic connection to a hermetically sealed integrated circuit, said method comprising the steps of:

forming an integrated circuit on a face of a semiconductor substrate, said integrated circuit having one or more electrically conductive pads for communicating and/or providing power to said integrated circuit;

forming one or more electrical pathways for providing electrical connection to said one or more electrically conductive pads;

said pathways having first ends coupled to said one or more pads and second ends exposed for external electrical connection from said sealed integrated circuit;

encapsulating said semiconductor substrate and said integrated circuit except for selected portions of said second ends of said electrical pathways; and

wherein the step of forming one or more electrical pathways comprises at least in part the steps of;

forming a first electrically conductive via electrically coupled to one of said pads;

forming a metal trace having first and second ends oriented essentially parallel to the surface of the semiconductor substrate and electrically coupled at said first end to said first via, wherein said second end of said metal trace is at least partially externally exposed; and

surrounding said electrical pathway by a biocompatible insulation material.

20. The method of claim 19 wherein the step of surrounding said electrical pathway comprises depositing alumina to surround said electrical pathway.

21. The method of claim 19 wherein the step of forming a second electrically coupled via comprises forming said second via from a biocompatible material.

22. The method of claim 19 wherein the step of forming a second electrically coupled via comprises forming said second via from platinum such that said second via is biocompatible.

23. A method of forming an electrically conductive hermetic connection to a hermetically sealed integrated circuit, said method comprising the steps of:

forming an integrated circuit on a face of a semiconductor substrate, said integrated circuit having one or more electrically conductive pads for communicating and/or providing power to said integrated circuit;

forming one or more electrical pathways for providing electrical connection to said one or more electrically conductive pads;

said pathways having first ends coupled to said one or more pads and second ends exposed for external electrical connection from said sealed integrated circuit;

encapsulating said semiconductor substrate and said integrated circuit except for selected portions of said second ends of said electrical pathways; and

wherein the step of forming one or more electrical pathways comprises at least in part the steps of;

forming a plurality of metal traces having first and second ends, including at least an innermost trace closest to said semiconductor substrate and an outermost trace furthest from said semiconductor substrate, each adjacent pair of metal traces separated by an insulating material sandwiched in-between so as to form a hermetic seal between said metal traces;

forming at least one interconnection via surrounded by said insulating material for interconnecting said adjacent pairs of metal traces;

forming at least one innermost via for interconnecting said innermost trace to at least one of said pads on said integrated circuit;

depositing an insulating material for encapsulating said plurality of metal traces, said integrated circuit and said semiconductor substrate;

enabling at least a portion of one said second end of an outermost metal trace to be partially externally exposed through the encapsulating insulating material for external communication; and

wherein

said combination of metal traces, sandwiched insulating material, encapsulating material and vias provides a hermetic communication path to said integrated circuit from a location external to said implantable package.