Method of manufacturing a hermetic chamber with electrical feedthroughs

• US 20060177956A1
• Filed: 12/20/2005
• Published: 08/10/2006
• Est. Priority Date: 02/10/2005
• Status: Active Grant

• Current Assignee: St. Jude Medical Luxembourg Holdings Ii S.A.R.L.
• Original Assignee: CardioMEMS Incorporated
• Inventors: Park, Jin Woo, O'Brien, David, Allen, Mark, You, Liang, Cros, Florent, Fonseca, Michael
• Granted Patent: US 7,662,653 B2
• Time in Patent Office: Days
• US Class Current: 438/50
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 5/03 Detecting, measuring or recording fluid pressure within the body other than blood pressure, e.g. cerebral pressure; Measuring pressure in body tissues or organs A61B5/205 takes precedence
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• CPC Class Codes: B81B 2201/06 Bio-MEMS
• CPC Class Codes: B81B 2207/096 through the substrate
• CPC Class Codes: B81B 7/007 Interconnections between the MEMS and external electrical signals
• CPC Class Codes: B81C 1/00301 Connecting electric signal lines from the MEMS device with external electrical signal lines, e.g. through vias
• CPC Class Codes: G01L 9/0073 using a semiconductive diaphragm
• CPC Class Codes: G01L 9/0075 using a ceramic diaphragm, e.g. alumina, fused quartz, glass

Abstract

A method of manufacturing a hermetically-sealed chamber with an electrical feedthrough includes the step of hermetically fixing an electrode to a substrate in a predetermined location on the substrate. A passage is formed through the substrate through the predetermined location such that at least a portion of the electrode is exposed to the passage. The passage is then at least partially filled with an electrically conductive material. A housing is then formed including the substrate such that the housing defines a chamber, with the electrode being disposed within the housing and the chamber being hermetically sealed. The electrode within the chamber can be placed in electrical communication with an exterior electrical component by way of the electrically conductive material in the passage.

Claims

1. A method of manufacturing a hermetically-sealed chamber with an electrical feedthrough, comprising the steps of:

hermetically fixing an electrode to a substrate in a predetermined location on said substrate;

forming a passage through said substrate through said predetermined location such that at least a portion of said electrode is exposed to said passage;

at least partially filling said passage with an electrically conductive material; and

forming a housing comprising said substrate such that said housing defines a chamber, said electrode being disposed within said chamber, and said chamber being hermetically sealed;

whereby said electrode within said chamber can be placed in electrical communication with an exterior electrical component by way of said electrically conductive material in said passage.

2. The method of claim 1, wherein said step of forming a passage through said substrate comprises the step of forming a passage having a cross section at said predetermined location of from 10⁻

6 to 10<sup>−

12</sup> meters².

3. The method of claim 2, wherein said step of forming a passage through said substrate comprises the step of forming a passage having a surface area of from 10⁻

6 to 10<sup>−

9</sup> meters².

4. The method of claim 1, wherein said step of forming a housing comprising said substrate comprises the step of forming a housing having a volume of from 10⁻

8 to 10<sup>−

15</sup> meters³.

5. The method of claim 1, wherein said step of hermetically fixing an electrode to a substrate comprises the step of depositing said electrode onto said substrate using a method selected from the group consisting of fusion bonding, low pressure plasma spray, laser welding, electroplating, chemical vapor deposition, and physical vapor deposition.

6. The method of claim 1, wherein said substrate comprises a first substrate, and wherein said step of forming a chamber comprising said first substrate comprises the step of:

providing a second substrate;

mutually imposing said first and second substrates such that said electrode is disposed within a chamber defined by said substrates; and

cutting said first and second substrates with a laser so as to fuse said first and second substrates together.

7. The method of claim 1, wherein said step of hermetically fixing an electrode to a substrate comprises the step of hermetically fixing a non-refractory metal to said substrate.

8. The method of claim 7, wherein said step of hermetically fixing a non-refractory metal to said substrate comprises the step of hermetically fixing a metal selected from the group consisting of gold, platinum, nickel, silver and alloys thereof.

9. The method of claim 1, wherein said step of hermetically fixing an electrode to a substrate comprises the step of hermetically fixing a refractory metal to said substrate.

10. The method of claim 9, wherein said step of hermetically fixing a refractory metal to said substrate comprises the step of hermetically fixing a metal selected from the group consisting of niobium, titanium, tungsten, tantalum, molybdenum, chromium, platinum/iridium alloy, and alloys thereof.

11. The method of claim 1, comprising the further steps of:

prior to said step of hermetically fixing an electrode to a substrate, forming a recess in a surface of said substrate; and

wherein said step of fixing an electrode to a substrate comprises the step of fixing an electrode to said substrate within said recess thereof.

12. The method of claim 6, wherein said electrode comprises a first electrode, wherein said passage comprises a first passage, wherein said predetermined location comprises a first predetermined location, and wherein said method comprises the further steps of:

prior to said step of mutually imposing said first and second substrates, hermetically fixing a second electrode to said first substrate in a second predetermined location on said substrate;

forming a second passage through said first substrate through said second predetermined location such that at least a portion of said second electrode is exposed to said second passage; and

at least partially filling said second passage with an electrically conductive material.

13. The method of claim 12, comprising the further step of:

prior to said step of mutually imposing said first and second substrates, fixing a third electrode to said second substrate such that when said first and second substrates are mutually imposed, said third electrode is arranged within said chamber in parallel, spaced apart relation to said first electrode so as to form a capacitor structure; and

placing said second electrode in electrical communication with said third electrode, whereby said third electrode can be placed in electrical communication with an exterior electrical component by way of said electrically conductive material in said second passage.

14. The method of claim 12, comprising the further step of:

disposing a piezoresistor within said chamber in electrical communication with said first and second electrodes and operatively coupled to a deflective region of said first substrate.

15. The method of claim 1, wherein said step of hermetically fixing an electrode to a substrate comprises the step of forming an intermetallic compound between the electrode and the substrate such that a chemical reaction takes place that results in the formation of covalent bonds between two or more elements, with at least one of the elements coming from the substrate and one from the electrode.

16. The method of claim 15, wherein said step of forming an intermetallic compound comprises the step of annealing said electrode and said substrate.

17. The method of claim 16, wherein said step of annealing said electrode and said substrate comprises the steps of:

providing an electrode comprising a refractory material and providing a substrate comprising fused silica; and

protecting the exposed surface of said electrode against oxidation.

18. The method of claim 16, wherein said step of protecting the exposed surface of said electrode against oxidation comprises the step of annealing said electrode and said substrate in an inert environment.

19. The method of claim 16, wherein said step of protecting the exposed surface of said electrode against oxidation comprises the step of applying a protective layer over said exposed surfaces of said electrode.

20. The method of claim 16, wherein said step of annealing said electrode and said substrate comprises the step of heating said electrode and said substrate to approximately 700-1100°

C.

21. The method of claim 16, wherein said step of annealing said electrode and said substrate comprises the step of increasing the heat at a ramp rate of approximately three to ten °

C. per minute.

22. The method of claim 17, wherein said step of annealing said electrode and said substrate comprises the further step of heating said electrode and said substrate to approximately 1100°

C. at a ramp rate of approximately 4°

C. per minute.

23. A method of manufacturing a hermetically-sealed chamber with an electrical feedthrough, comprising the steps of:

hermetically fixing two electrodes to a first substrate;

forming first and second passages through said substrate underlying said electrode such that at least a portion of said electrode is exposed to said passage;

at least partially filling said first and second passages with an electrically conductive material;

imposing said first substrate together with second and third substrates to form a housing defining first and second chambers, said passage being disposed in a common wall separating said first and second chambers, and said first and second electrodes being disposed within said first chamber;

whereby said first chamber is hermetically sealed; and

whereby said first and second electrodes within said first chamber can be placed in electrical communication with said second chamber by way of said electrically conductive material in said passage.

24. The method of claim 23, comprising the further step, subsequent to said step of imposing said first substrate together with second and third substrates, of cutting said first, second, and third substrates with a laser so as to fuse said substrates together hermetically.

25. The method of claim 23, comprising the further step of:

mounting an electrical component onto said first substrate in electrical communication with said first electrode such that when said first, second, and third substrates are mutually imposed, said electrical component resides within said second chamber.

26. The method of claim 25, wherein said step of mounting an electrical component comprises the step of mounting an electrical circuit operative to process a signal received from said first chamber.

27. The method of claim 26, wherein said step of mounting an electrical circuit comprises the step of mounting an integrated circuit.

28. The method of claim 25, wherein said step of mounting an electrical component comprises the step of mounting an electrical circuit operative to process a signal passing to said first chamber.

29. The method of claim 28, wherein said step of mounting an electrical circuit comprises the step of mounting an integrated circuit.