Method of manufacturing a hermetic chamber with electrical feedthroughs

• US 7,662,653 B2
• Filed: 12/20/2005
• Issued: 02/16/2010
• 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
• Primary Examiner(s): PHAM, THANHHA S
• Application Number:
  US11/314,696
• Publication Number:
  US 20060177956A1
• Time in Patent Office: 1,519 Days
• Field of Search: 438/15, 438/25, 438/26, 438/33, 438/51, 438/55, 438/107, 438/108, 438/113, 257/E21.499, 257/E21.597
• US Class Current: 438/51
• 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:

providing a first substrate;

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

forming a passage through said first 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;

providing a second substrate;

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

cutting said first and second substrates with a laser so as to fuse said first and second substrates together to form a unitary housing and to hermetically seal said chamber.

2. The method of claim 1, wherein said step of-forming a passage through said first 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 1, wherein said step of forming a passage through said first 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 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 first substrate comprises the step of depositing said electrode onto said first 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 step of hermetically fixing an electrode to a first substrate comprises the step of hermetically fixing an electrode consisting of a metal selected from the group consisting of gold, platinum, nickel, silver and alloys thereof to said first substrate.

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

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

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

8. The method of claim 1, 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 first 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.

9. The method of claim 7, 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.

10. The method of claim 1, wherein said step of hermetically fixing an electrode to a first substrate comprises the step of forming an intermetallic compound between the electrode and the first 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 first substrate and one from the electrode.

11. The method of claim 10, wherein said step of forming an intermetallic compound comprises the step of annealing said electrode and said first substrate.

12. The method of claim 11, wherein said step of annealing said electrode and said first substrate comprises the steps of:

annealing a metal electrode to a first substrate comprising fused silica such that said metal electrode has an exposed surface; and

protecting said exposed surface of said electrode against oxidation.

13. The method of claim 12, wherein said step of protecting the exposed surface of said electrode against oxidation comprises the step of annealing said electrode and said first substrate in an inert environment.

14. The method of claim 12, wherein said step of protecting the exposed surface of said electrode against oxidation comprises the step of applying a protective layer over said exposed surface of said electrode.

15. The method of claim 11, wherein said step of annealing said electrode and said first substrate comprises the step of heating said electrode and said first substrate to approximately 700-1100°

C.

16. The method of claim 11, wherein said step of annealing said electrode and said first substrate comprises the step of increasing the heat at a ramp rate of approximately three to ten °

C. per minute.

17. The method of claim 12, wherein said step of annealing said electrode and said first substrate comprises the further step of heating said electrode and said first substrate to approximately 100°

C. at a ramp rate of approximately 4°

C. per minute.

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

hermetically fixing first and second electrodes to a first substrate;

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

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

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

mounting an electrical component onto said first substrate in electrical communication with said first electrode;

mutually imposing said first substrate together with a second substrate and a third substrate to form a housing defining a first chamber and a second chamber, said first and second passages being disposed in a common wall separating said first and second chambers, said first and second electrodes being disposed within said first chamber, and said electrical component residing within said second chamber;

wherein said first chamber is hermetically sealed; and

wherein said first and second electrodes within said first chamber are placed in electrical communication with said second chamber by way of said electrically conductive material in said first and second passages.

19. The method of claim 18, comprising the further step, subsequent to said step of imposing said first substrate together with second and third substrates, of using a laser to apply a heat that is sufficiently high to simultaneously cut and hermetically fuse together said first, second, and third substrates while being sufficiently low so as not to damage said electrical component.

20. The method of claim 18, 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.

21. The method of claim 20, wherein said step of mounting an electrical circuit comprises the step of mounting an integrated circuit.

22. The method of claim 18, 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.

23. The method of claim 22, wherein said step of mounting an electrical circuit comprises the step of mounting an integrated circuit.

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

providing a first substrate of a material selected from the group consisting of fused silica, sapphire, or quartz;

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

forming a passage through said first 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;

providing a second substrate of a material selected from the group consisting of fused silica, sapphire, or quartz;

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

cutting said first and second substrates with a laser so as to fuse said first and second substrates together to form a unitary housing and to hermetically seal said chamber.

25. The method of claim 24, wherein said step of forming a passage through said first 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.

26. The method of claim 24, wherein said step of forming a passage through said first substrate comprises the step of forming a passage having a surface area of from 10⁻

6 to 10<sup>−

9</sup> meters².

27. The method of claim 24, wherein said step of forming a housing comprises the step of forming a housing having a volume of from 10⁻

8 to 10<sup>−

15</sup> meters³.

28. The method of claim 24, wherein said step of hermetically fixing an electrode to a first substrate comprises the step of depositing said electrode onto said first 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.

29. The method of claim 24, wherein said step of hermetically fixing an electrode to a first substrate comprises the step of hermetically fixing a metal selected from the group consisting of gold, platinum, nickel, silver and alloys thereof to said first substrate.

30. The method of claim 24, comprising the further steps of:

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

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

31. The method of claim 24, 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 first 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.

32. The method of claim 31, 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.

33. The method of claim 24, wherein said step of hermetically fixing an electrode to a first substrate comprises the step of forming an intermetallic compound between the electrode and the first 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 first substrate and one from the electrode.

34. The method of claim 33, wherein said step of forming an intermetallic compound comprises the step of annealing said electrode and said first substrate.

35. The method of claim 34, wherein said step of annealing said electrode and said first substrate comprises the steps of:

providing an electrode comprising a metal and providing a first substrate comprising fused silica; and

protecting the exposed surface of said electrode against oxidation.

36. The method of claim 34, wherein said step of protecting the exposed surface of said electrode against oxidation comprises the step of annealing said electrode and said first substrate in an inert environment.

37. The method of claim 34, 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.

38. The method of claim 34, wherein said step of annealing said electrode and said first substrate comprises the step of heating said electrode and said first substrate to approximately 700-1100°

C.

39. The method of claim 34, wherein said step of annealing said electrode and said first substrate comprises the step of increasing the heat at a ramp rate of approximately three to ten °

C. per minute.

40. The method of claim 35, wherein said step of annealing said electrode and said first substrate comprises the further step of heating said electrode and said first substrate to approximately 1100°

C. at a ramp rate of approximately 4°

C. per minute.