MEMS device having contact and standoff bumps and related methods

• US 6,876,482 B2
• Filed: 11/08/2002
• Issued: 04/05/2005
• Est. Priority Date: 11/09/2001
• Status: Expired due to Term

• Current Assignee: AAC Technologies Pte Limited (AAC Technologies Holdings Inc.)
• Original Assignee: WiSpry, Inc (AAC Technologies Holdings Inc.), Turnstone Systems, Inc.
• Inventors: DeReus, Dana Richard
• Primary Examiner(s): Ben, Loha
• Application Number:
  US10/291,107
• Publication Number:
  US 20030116417A1
• Time in Patent Office: 879 Days
• Field of Search: 359/290, 359/291, 359/295, 359/298, 359/247, 359/214, 359/221, 359/847, 359/848, 359/230, 359/224, 200/181, 250/214.1, 250/214.LS, 250/227.22, 310/306, 310/307, 310/309, 216/13, 216/83, 257/415, 257/417, 257/747, 356/519, 333/101, 333/105, 333/262, 438/52, 338/200, 337/36, 337/85, 427/162, 427/534
• US Class Current: 359/290
• CPC Class Codes: B81B 2201/014 having a cantilever fixed on one side connected to one or more dimples
• CPC Class Codes: B81B 2201/018 Switches not provided for in B81B2201/014 - B81B2201/016
• CPC Class Codes: B81B 2203/0118 Cantilevers
• CPC Class Codes: B81B 2203/04 Electrodes
• CPC Class Codes: B81B 2207/07 Interconnects
• CPC Class Codes: B81B 3/0024 Transducers for transforming thermal into mechanical energy or vice versa, e.g. thermal or bimorph actuators electric motors using thermal effects H02N10/00
• CPC Class Codes: B81B 3/0051 For defining the movement, i.e. structures that guide or limit the movement of an element mechanical arrangements for preventing or damping vibration or shock H01H3/60
• 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 2201/0107 Sacrificial metal
• CPC Class Codes: B81C 2201/0108 Sacrificial polymer, ashing of organics
• CPC Class Codes: B81C 2201/0109 Sacrificial layers not provided for in B81C2201/0107 - B81C2201/0108
• CPC Class Codes: H01H 1/04 Co-operating contacts of different material
• CPC Class Codes: H01H 1/504 by thermal means
• CPC Class Codes: H01H 2001/0042 Bistable switches, i.e. having two stable positions requiring only actuating energy for switching between them, e.g. with snap membrane or by permanent magnet
• CPC Class Codes: H01H 2001/0063 having electrostatic latches, i.e. the activated position is kept by electrostatic forces other than the activation force
• CPC Class Codes: H01H 2001/0089 Providing protection of elements to be released by etching of sacrificial element; Avoiding stiction problems, e.g. of movable element to substrate
• CPC Class Codes: H01H 2059/0072 with stoppers or protrusions for maintaining a gap, reducing the contact area or for preventing stiction between the movable and the fixed electrode in the attracted position
• CPC Class Codes: H01H 2061/006 Micromechanical thermal relay
• CPC Class Codes: H01H 59/0009 making use of micromechanics
• CPC Class Codes: H01H 61/04 wherein the thermally-sensitive member is only heated directly
• CPC Class Codes: H01L 23/3735 : Laminates or multilayers, e.g. direct bond copper ceramic substrates
• CPC Class Codes: H01L 23/522 : including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body
• CPC Class Codes: H01L 27/1203 : the substrate comprising an insulating body on a semiconductor body, e.g. SOI three-dimensional layout H01L27/0688
• 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 2924/09701 : Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H02N 1/006 : of the gap-closing type H02N1/004 takes precedence
• CPC Class Codes: H02N 10/00 : Electric motors using thermal effects motors using expansion or contraction of bodies due to heating or cooling F03G7/06
• CPC Class Codes: Y10T 29/49222 : forming array of contacts or terminals

Abstract

MEMS Device Having Contact and Standoff Bumps and Related Methods. According to one embodiment, a movable MEMS component suspended over a substrate is provided. The component can include a structural layer having a movable electrode separated from a substrate by a gap. The component can also include at least one standoff bump attached to the structural layer and extending into the gap for preventing contact of the movable electrode with conductive material when the component moves.

Claims

1. A movable, MEMS component suspended over a substrate, the component comprising:

(a) a structural layer having a movable electrode separated from the substrate by a gap; and

(b) at least one standoff bump attached to the structural layer and protruding through the movable electrode and extending into the gap for preventing contact of the movable electrode with a conductive material on the substrate when the component moves.

2. The MEMS component according to claim 1, wherein the structural layer comprises a nonconductive, resilient material.

3. The MEMS component according to claim 1, wherein the movable electrode comprises a metal material.

4. The MEMS component according to claim 1, wherein the movable electrode comprises a semiconductive material.

5. The MEMS component according to claim 1, further including an electrode interconnect attached to a side of the structural layer opposing the movable electrode and having electrical communication with the movable electrode.

6. The MEMS component according to claim 5, wherein the movable electrode and electrode interconnect have substantially equal respective coefficients of thermal expansion.

7. The MEMS component according to claim 1, wherein the at least one standoff bump comprises a nonconductive material.

8. The MEMS component according to claim 1, wherein the at least one standoff bump is attached to the movable electrode.

9. The MEMS component according to claim 1, wherein the structural layer includes at least one end fixed with respect to the substrate, and wherein the at least one standoff bump is attached to an end portion of the movable electrode distal the at least one fixed end.

10. The MEMS component according to claim 1, wherein the at least one standoff bump includes a first and second standoff bump, wherein the first standoff bump and the second standoff bump are attached to an end of the movable electrode distal the at least one fixed end.

11. The MEMS component according to claim 10, wherein the first standoff bump and the second standoff bump are positioned a substantially equal distance from the at least one fixed end.

12. The MEMS component according to claim 1, wherein the structural layer includes a movable contact for contacting a stationary contact when the movable component moves towards the stationary contact.

13. The MEMS component according to claim 12, wherein the movable contact includes at least one contact bump extending into the gap, whereby the movable contact contacts the stationary contact before the movable electrode contacts a conductive material.

14. A MEMS device having standoff bumps, the device comprising:

(a) a substrate having a stationary electrode and a first stationary contact; and

(b) a movable component suspended above the substrate, the component comprising;

(i) a structural layer having a movable electrode and a movable contact, wherein the movable electrode is spaced from the stationary electrode by a first gap and the movable contact is spaced from the first stationary contact by a second gap; and

(ii) at least one standoff bump attached to the structural layer and protruding through the movable electrode and extending into the first gap for preventing the contact of the movable electrode with the stationary electrode.

15. The MEMS device according to claim 14, wherein the structural layer comprises a nonconductive, resilient material.

16. The MEMS device according to claim 14, wherein the movable electrode comprises a metal material.

17. The MEMS device according to claim 14, wherein the movable electrode comprises a semiconductive material.

18. The MEMS device according to claim 14, wherein the component further includes an electrode interconnect attached to a side of the structural layer opposing the movable electrode and having electrical communication with the movable electrode.

19. The MEMS device according to claim 18, wherein the movable electrode and electrode interconnect have substantially equal respective coefficients of thermal expansion.

20. The MEMS device according to claim 14, wherein the at least one standoff bump comprises a nonconductive material.

21. The MEMS device according to claim 14, wherein the at least one standoff bump is positioned adjacent the movable electrode.

22. The MEMS device according to claim 14, wherein the at least one standoff bump is attached to the movable electrode.

23. The MEMS device according to claim 14, wherein the structural layer includes at least one end fixed with respect to the substrate, and wherein the at least one standoff bump is attached to an end portion of the movable electrode distal the at least one fixed end.

24. The MEMS device according to claim 14, wherein the at least one standoff bump includes a first and second standoff bump, wherein the first standoff bump and the second standoff bump are attached to an end of the movable electrode distal the at least one fixed end.

25. The MEMS device according to claim 24, wherein the first standoff bump and the second standoff bump are positioned a substantially equal distance from the at least one fixed end.

26. The MEMS device according to claim 14, wherein the movable contact is positioned at a distal end of the structural layer.

27. The MEMS device according to claim 26, wherein the movable electrode is positioned on the structural layer between the movable contact and at a fixed end of the structural layer.

28. The MEMS device according to claim 14, wherein the movable electrode includes a portion substantially surrounding the movable contact.

29. The MEMS device according to claim 28, wherein the at least one standoff bump is attached to the portion of the movable electrode substantially surrounding the movable contact.

30. The MEMS device according to claim 14, wherein the component further includes a contact interconnect attached to a side of the structural layer opposing the movable contact and having electrical communication with the movable contact.

31. The MEMS device according to claim 14, wherein the movable contact includes a contact bump extending into the second gap, whereby the movable contact contacts the first stationary contact before the movable electrode contacts the stationary electrode.

32. The MEMS device according to claim 14, wherein the movable contact includes a first and second set of contact bumps extending into the second gap, the substrate further includes a second stationary contact, whereby the first and second set of contact contacts the first stationary contact and the second stationary contact, respectively, before the movable electrode contacts the stationary electrode.

33. The MEMS device according to claim 14, wherein the component further includes at least one compliance cut extending into the structural layer.

34. The MEMS device according to claim 14, wherein the structural layer includes a first and second end fixed with respect to the substrate.

35. A MEMS switch having standoff bumps, the switch comprising:

(a) a substrate including a first and second stationary electrode and a stationary contact, wherein the stationary contact is positioned between the first and second stationary electrodes;

(b) a structural layer including a first and second end fixed with respect to the substrate and including first, second, and third portions having bottom surfaces, the bottom surfaces suspended over the substrate;

(c) a first movable electrode attached to the bottom surface of the first portion and spaced from the first stationary electrode by a first gap;

(d) a first standoff bump attached to the structural layer and extending into the first gap for preventing the contact of the first movable electrode with the first stationary electrode;

(e) a second movable electrode attached to the bottom surface of the second portion and spaced from the second stationary electrode by a second gap;

(f) a second standoff bump attached to the structural layer and extending into the second gap for preventing the contact of the second movable electrode with the second stationary electrode; and

(g) a movable contact attached to the bottom surface of the third portion and suspended over the stationary contact.

36. The switch according to claim 35, wherein the structural layer comprises a nonconductive, resilient material.

37. The switch according to claim 35, wherein the structural layer further includes:

(a) a top surface opposing the bottom surface and including first, second, and third portions opposing the first, second, and third portions, respectively, of the structural layer; and

(b) a first and second electrode interconnect attached to the first and second portions, respectively, of the top surface of the structural layer.

38. The switch according to claim 35, wherein the first and second standoff bumps comprise a nonconductive material.

39. The switch according to claim 35, wherein the first and second standoff bumps are attached to the first and second movable electrodes, respectively.

40. The switch according to claim 35, wherein the first and second standoff bumps are attached to portions of the first and second movable electrodes, respectively, positioned adjacent the movable contact.

41. A MEMS switch having standoff bumps, the switch comprising:

(a) a substrate having a stationary electrode and a stationary contact;

(b) a movable, folded component suspended above the substrate, the component comprising;

(i) a structural layer having a bottom surface and including a first and second folded beam and a cantilever attached to attachment ends of the first and second folded beams;

(ii) a movable electrode separated from the substrate by a first gap;

(iii) at least one standoff bump attached to the structural layer and extending into the first gap for preventing contact of the movable electrode with conductive material on the substrate when the component moves toward the substrate; and

(iv) a movable contact spaced from the stationary contact by a second gap.

42. The switch according to claim 41, wherein the at least one standoff bump is attached to the movable electrode.

43. The switch according to claim 41, wherein the at least one standoff bump is attached to e attachment ends of the first and second folded beams.

44. A method of implementing an actuation function in a MEMS device having standoff bumps, the method comprising:

(a) providing a MEMS device having standoff bumps, the device comprising;

(i) a substrate having a stationary electrode;

(ii) a structural layer having a movable electrode spaced from the stationary electrode by a gap; and

(iii) at least one standoff bump attached to the structural layer and protruding through the movable electrode and extending into the first gap for preventing the contact of the movable electrode with the stationary electrode when the structural layer moves towards the stationary electrode; and

(b) applying a voltage between the movable electrode and the stationary electrode to electrostatically couple the movable electrode with the stationary electrode across the gap, whereby the structural layer is moved toward the substrate and the at least one standoff bump contacts the stationary electrode.

45. A method for fabricating a movable, MEMS component having a standoff bump, comprising:

(a) depositing a sacrificial layer on a conductive component;

(b) forming a movable electrode on the sacrificial layer for spacing the movable electrode and the conductive component by a gap upon the removal of the sacrificial layer;

(c) forming a standoff bump in the sacrificial layer whereby the standoff bump extends into the gap between the movable electrode and the conductive component;

(d) depositing a structural layer on the movable electrode and the standoff bump; and

(e) removing the sacrificial layer to form a gap spacing the conductive component from the movable electrode whereby the standoff bump extends into the gap for preventing contact of the movable electrode with the conductive component when the moveable electrode moves.

46. The method according to claim 45, wherein the movable electrode is composed of conductive material.

47. The method according to claim 45, wherein the movable electrode is composed of semiconductive material.

48. The method according to claim 45, wherein the standoff bump is composed of a nonconductive material.

49. A method for fabricating a MEMS device having a standoff bump, the method comprising:

(a) forming a stationary electrode on a substrate;

(b) depositing a sacrificial layer on the stationary electrode and the substrate;

(c) forming a movable electrode on the sacrificial layer for spacing the movable electrode and the stationary electrode by a gap upon the removal of the sacrificial layer;

(d) forming a standoff bump in the sacrificial layer whereby the standoff bump extends into the gap between the movable electrode and the stationary electrode formed by the removal of the a sacrificial layer;

(e) depositing a structural layer on the movable electrode and the standoff bump; and

(f) removing the sacrificial layer to form a gap spacing the stationary electrode and the movable electrode whereby the standoff bump extends into the gap for preventing contact of the movable electrode with a conductive material on the substrate when the structural layer moves towards the stationary electrode.

50. The method according to claim 49, wherein the movable electrode is composed of conductive material.

51. The method according to claim 49, wherein the movable electrode is composed of semiconductive material.

52. The method according to claim 49, wherein the standoff bump is composed of a nonconductive material.

53. The method according to claim 49, further including forming a stationary contact on the substrate.

54. The method according to claim 49, further including forming a movable contact on the sacrificial layer.

55. The method according to claim 49, wherein forming a standoff bump further includes forming the standoff bump adjacent the movable electrode.