Metallizing MEMS Devices

• US 20170166439A1
• Filed: 12/09/2015
• Published: 06/15/2017
• Est. Priority Date: 12/09/2015
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Kaanta, Bradley C.
• Granted Patent: US 9,758,367 B2
• Time in Patent Office: Days
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 2203/0118 Cantilevers
• CPC Class Codes: B81B 2207/015 the micromechanical device and the control or processing electronics being integrated on the same substrate
• CPC Class Codes: B81B 2207/07 Interconnects
• CPC Class Codes: B81B 7/0006 Interconnects
• CPC Class Codes: B81C 1/0015 Cantilevers switches using MEMS H01H1/0036; electrostatic relays using micromechanics H01H59/0009; microelectro-mechanical resonators H03H9/02244
• CPC Class Codes: B81C 1/00682 Treatments for improving mechanical properties, not provided for in B81C1/00658 - B81C1/0065
• CPC Class Codes: B81C 1/00698 Electrical characteristics, e.g. by doping materials
• CPC Class Codes: B81C 2201/0161 Controlling physical properties of the material
• CPC Class Codes: B81C 2201/0176 Chemical vapour Deposition

Abstract

Various embodiments produce a semiconductor device, such a MEMS device, having metallized structures formed by replacing a semiconductor structure with a metal structure. Some embodiments expose a semiconductor structure to one or more a reacting gasses, such as gasses including tungsten or molybdenum.

Claims

1. A method of fabricating a micromachined device having a metal interconnection structure, comprising:

fabricating a substrate having at least one semiconductor interconnection structure, the semiconductor interconnection structure having an electrical resistance;

fabricating a micromachined structure on the substrate; and

after fabricating the micromachined structure, metallizing the semiconductor interconnection structure to form a conductive metal interconnection structure having an electrical resistance that is lower than the electrical resistance of the semiconductor interconnection structure.

2. The method of fabricating a micromachined device having a metal interconnection structure according to claim 1, further comprising, prior to metallizing the semiconductor interconnection structure, releasing the micromachined structure, so that the micromachined structure is movable relative to the substrate and remains movable relative to the substrate during the process of metallizing the semiconductor interconnection structure.

3. The method of fabricating a micromachined device having a metal interconnection structure according to claim 1, wherein metallizing the semiconductor interconnection structure to form a conductive metal interconnection structure comprises:

forming a seed layer of metal on the semiconductor interconnection structure in which semiconductor atoms within the semiconductor interconnection structure are replaced by metal.

4. The method of fabricating a micromachined device having a metal interconnection structure according to claim 1, wherein metallizing the semiconductor interconnection structure to form a conductive metal interconnection structure occurs at a temperature of less than 500 degrees Celsius.

5. The method of fabricating a micromachined device having a metal interconnection structure according to claim 1, wherein metallizing the semiconductor interconnection structure to form a conductive metal interconnection structure occurs at a temperature of less than 300 degrees Celsius.

6. The method of fabricating a micromachined device having a metal interconnection structure according to claim 1, wherein the conductive metal interconnection structure has a sheet resistance of less than 10 Ω

/sq.

7. The method of fabricating a micromachined device having a metal interconnection structure according to claim 1, wherein the conductive metal interconnection structure has a sheet resistance of less than 1 Ω

/sq.

8. The method of fabricating a micromachined device having a metal interconnection structure according to claim 1, wherein metallizing the semiconductor interconnection structure to form a conductive metal interconnection structure comprises exposing the semiconductor interconnection structure to a reacting gas.

9. The method of fabricating a micromachined device having a metal interconnection structure according to claim 8, wherein the reacting gas comprises tungsten, and the conductive metal interconnection structure comprises tungsten.

10. The method of fabricating a micromachined device having a metal interconnection structure according to claim 8, wherein the reacting gas comprises WF₆.

11. The method of fabricating a micromachined device having a metal interconnection structure according to claim 10, wherein the reacting gas comprises SiH₄.

12. The method of fabricating a micromachined device having a metal interconnection structure according to claim 1, further comprising covering the conductive metal interconnection structure with a passivating layer.

21. The method of fabricating a micromachined device having a metal interconnection structure according to claim 8, wherein the reacting gas comprises molybdenum, and the conductive metal interconnection structure comprises molybdenum.

22. The method of fabricating a micromachined device having a metal interconnection structure according to claim 21, wherein the reacting gas comprises MoF₆.

23. The method of fabricating a micromachined device having a metal interconnection structure according to claim 22, wherein the reacting gas comprises SiH₄.

13. A MEMS device comprising:

a substrate having a surface;

a movable MEMS structure movably suspended from the substrate;

a metallized interconnection structure, the metallized interconnection structure comprising a metal-infused semiconductor and having a sheet resistance of less than 5 Ω

/sq.

14. The MEMS device of claim 13, wherein the metal-infused semiconductor is a tungsten-infused semiconductor.

24. The MEMS device of claim 13, wherein the metallized interconnection structure has a sheet resistance of less than 1 Ω

/sq.

25. The MEMS device of claim 13, wherein the metal-infused semiconductor is a molybdenum-infused semiconductor.

26. The MEMS device of claim 13, further comprising:

a passivating layer on the metallized interconnection structure.

15. A method of fabricating a micromachined device, comprising:

fabricating a micromachined structure on a substrate;

fabricating at least one semiconductor interconnection structure at a surface of the substrate; and

simultaneously metallizing the micromachined structure and the at least one semiconductor interconnection structure to form a metallized micromachined structure and at least one conductive metal interconnection structure.

16. The method of fabricating a micromachined device according to claim 15, wherein the micromachined structure is movable with respect to the substrate during metallizing the micromachined structure.

17. The method of fabricating a micromachined device according to claim 16, wherein the micromachined structure is a beam of a MEMS device, and metallizing the micromachined structure comprises metallizing four sides of the beam.

19. The method of fabricating a micromachined device according to claim 15, further comprising:

covering the conductive metal interconnection structure with a passivating layer.

20. The method of fabricating a micromachined device according to claim 15, wherein simultaneously metallizing the micromachined structure and the at least one semiconductor interconnection structure comprises:

forming a seed layer of metal on the micromachined structure and the at least one semiconductor interconnection structure in which semiconductor atoms within the micromachined structure and the at least one semiconductor interconnection structure are replaced by metal.

27. The method of fabricating a micromachined device according to claim 15, wherein simultaneously metallizing the micromachined structure and the at least one semiconductor interconnection structure comprises exposing the micromachined structure and the at least one semiconductor interconnection structure to a reacting gas.

28. The method of fabricating a micromachined device according to claim 27, wherein the reacting gas comprises tungsten, and the conductive metal interconnection structure comprises tungsten.

29. The method of fabricating a micromachined device according to claim 28, wherein the reacting gas comprises WF₆.

30. The method of fabricating a micromachined device according to claim 29, wherein the reacting gas comprises SiH₄.

31. The method of fabricating a micromachined device according to claim 27, wherein the reacting gas comprises molybdenum, and the conductive metal interconnection structure comprises molybdenum.

32. The method of fabricating a micromachined device according to claim 31, wherein the reacting gas comprises MoF₆.

33. The method of fabricating a micromachined device according to claim 32, wherein the reacting gas comprises SiH₄.

18. (canceled)

34. A method of fabricating a micromachined device, comprising:

fabricating a micromachined structure on a substrate; and

metallizing the micromachined structure, wherein metallizing the micromachined structure comprises forming a seed layer of metal on the micromachined structure in which semiconductor atoms within the micromachined structure are replaced by metal.

35. The method of fabricating a micromachined device according to claim 34, wherein the micromachined structure is movable with respect to the substrate during metallizing the micromachined structure.

36. The method of fabricating a micromachined device according to claim 35, wherein the micromachined structure is a beam of a MEMS device, and metallizing the micromachined structure comprises metallizing four sides of the beam.

37. The method of fabricating a micromachined device according to claim 34, further comprising fabricating at least one semiconductor interconnection structure at a surface of the substrate, wherein metallizing the micromachined structure comprises simultaneously metallizing the at least one semiconductor interconnection structure to form a conductive metal interconnection structure including forming the seed layer of metal on the at least one semiconductor interconnection structure in which semiconductor atoms within the at least one semiconductor interconnection structure are replaced by metal.

38. The method of fabricating a micromachined device according to claim 34, further comprising:

covering the conductive metal interconnection structure with a passivating layer.

39. The method of fabricating a micromachined device according to claim 34, wherein the seed layer comprises tungsten.

40. The method of fabricating a micromachined device according to claim 34, wherein the seed layer comprises molybdenum.