Hermetic conductive feedthroughs for a semiconductor wafer
A glass wafer has an internal surface and an opposing external surface separated by a wafer thickness. A hermetic, electrically conductive feedthrough extends through the wafer from the internal surface to the opposing external surface. The feedthrough includes a feedthrough member having an inner face exposed along the internal surface for electrically coupling to an electrical circuit. The feedthrough member extends from the inner face partially through the wafer thickness to an exteriorly-facing outer face hermetically embedded within the wafer.
1. A method for manufacturing a hermetic feedthrough in a glass wafer, the method comprising:
depositing a first feedthrough member in a via in a base layer of a glass wafer, wherein a top surface of the base layer defines an internal surface of the glass wafer;
depositing an electrically conductive trace along the top surface of the base layer so that the trace and an exteriorly-facing outer face of the first feedthrough member are in direct electrical connection;
depositing a second electrically conductive trace on a bottom surface of a top layer, wherein a top surface of the top layer defines an external surface of the glass wafer;
embedding the exteriorly-facing outer face of the first feedthrough member and at least a portion of the electrically conductive trace and the second electrically conductive trace in the glass wafer such that the electrically conductive trace and the second electrically conductive trace overlap, wherein embedding the exteriorly-facing outer face of the first feedthrough member comprises fusion bonding the top surface of the base layer to the bottom surface of the top layer along an interface; and
electrically coupling the exteriorly-facing outer face of the first feedthrough member to an electrical connection point located along the external surface of the glass wafer by the electrically conductive trace and the second electrically conductive trace extending away from the embedded exteriorly-facing outer face.
2. The method of claim 1 , further comprising positioning the electrical connection point spaced apart laterally from the embedded exteriorly-facing outer face of the first feedthrough member.
3. The method of claim 1 , further comprising depositing the first feedthrough member in the base layer to extend from the internal surface of the glass wafer to the top surface of the base layer.
4. The method of claim 1 , further comprising:
forming an interior sidewall in the top layer that defines a cavity that extends from the wafer external surface to the bottom surface of the top layer; and
exposing an end of the electrically conductive trace or the second electrically conductive trace within the cavity.
5. The method of claim 4 , further comprising positioning a sensor in the cavity and electrically coupling the sensor to the electrically conductive trace and the second electrically conductive trace.
6. The method of claim 5 , further comprising depositing a second feedthrough member in the top layer extending from the bottom surface of the top layer to the wafer external surface, the second feedthrough member spaced apart laterally from the first feedthrough member; and
electrically coupling the first feedthrough member and the second feedthrough member utilizing the electrically conductive trace and the second electrically conductive trace.
7. The method of claim 6 , further comprising embedding an interiorly-facing inner face of the second feedthrough member within the glass wafer.
8. The method of claim 6 , further comprising electrically coupling an external component to the embedded face of the first feedthrough member via an exposed external face of the second feedthrough member.
9. The method of claim 8 , wherein the external component comprises at least one of an electrode, contact pad, or sensor.
10. The method of claim 6 , further comprising grinding the top layer to a first thickness after depositing the second feedthrough member in the top layer, wherein the base layer has a second thickness greater than the first thickness.
11. The method of claim 1 , further comprising grinding the top layer to a first thickness, wherein the base layer has a second thickness greater than the first thickness.
12. The method of claim 1 , further comprising forming a via in the base layer prior to depositing the first feedthrough member in the via in the base layer.
13. The method of claim 12 , wherein forming the via comprises laser drilling or sandblasting the base layer to form the via.
14. The method of claim 1 , wherein depositing the first feedthrough member comprises electroplating or metallizing the first feedthrough member in the via in the base layer.
15. The method of claim 1 , wherein depositing the first feedthrough member comprises positioning a solid pre-formed member in the via in the base layer.
16. The method of claim 1 , wherein depositing the electrically conductive trace comprises printing, sputtering, evaporating, or electroplating the electrically conductive trace along the top surface of the base layer so that the trace and the exteriorly-facing outer face of the first feedthrough member are in direct electrical connection.
17. The method of claim 1 , further comprising depositing solder bumps at the bottom surface of the base layer and in contact with the first feedthrough member.
18. A method for manufacturing an implantable medical device that comprises a recessed package and a glass lid, the method comprising:
forming the glass lid, comprising:
depositing a first feedthrough member in a via in a base layer of a glass wafer, wherein the base layer defines an internal surface of the glass wafer;
depositing an electrically conductive trace along the internal surface of the glass wafer so that the trace and an exteriorly-facing outer face of the first feedthrough member are in direct electrical connection;
embedding the exteriorly-facing outer face of the first feedthrough member and at least a portion of the electrically conductive trace in the glass wafer, wherein embedding the exteriorly-facing outer face of the first feedthrough member comprises fusion bonding the base layer to a top layer along an interface, wherein the top layer defines an external surface of the glass wafer; and
electrically coupling the exteriorly-facing outer face of the first feedthrough member to an electrical connection point located along the external surface of the glass wafer by the electrically conductive trace extending away from the embedded exteriorly-facing outer face.
19. The method of claim 18 , further comprising sealing the glass lid to the recessed package to form an enclosure.
20. The method of claim 19 , further comprising:
disposing electrical circuitry within the enclosure; and
electrically coupling the electrical circuitry to the first feedthrough member.