Micro electro-mechanical system with one or more moving parts method and apparatus

• US 20030210116A1
• Filed: 05/08/2002
• Published: 11/13/2003
• Est. Priority Date: 05/08/2002
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Lane, Spencer A., Jonnalagadda, Krishna, Eliacin, Manes
• Granted Patent: US 6,777,629 B2
• Time in Patent Office: Days
• US Class Current: 335/78
• CPC Class Codes: B81B 2201/045 Optical switches
• CPC Class Codes: B81B 2203/0315 Cavities
• CPC Class Codes: B81C 1/00182 Arrangements of deformable or non-deformable structures, e.g. membrane and cavity for use in a transducer
• CPC Class Codes: B81C 2201/0108 Sacrificial polymer, ashing of organics
• CPC Class Codes: B81C 2203/0136 Growing or depositing of a covering layer
• CPC Class Codes: H01H 2001/0073 Solutions for avoiding the use of expensive silicon technologies in micromechanical switches
• CPC Class Codes: H01H 59/0009 making use of micromechanics

Abstract

A meso-scale MEMS device having a movable member (51) is formed using standard printed wiring board and high density interconnect technologies and practices. In one embodiment, sacrificial material disposed about the movable member (51) is removed through openings (101, 102) as formed through a cover (91) to form a cavity (121) that retains and limits the freedom of movement of the movable member (51). The movable member can support a reflective surface (224) to thereby provide a mechanism that will support a projection display and/or image scanner (such as a bar code scanner).

Claims

1. A meso-scale MEMS apparatus comprising:

a printed wiring board comprised at least in part of polymer material;

a meso-scale structure disposed on the printed wiring board; and

at least one meso-scale separate structure that is movably disposed proximal to and fully non-integrally with respect to the meso-scale structure and that is substantially restrained to no more than a predetermined range of movement with respect to the meso-scale structure.

2. The meso-scale MEMS apparatus of claim 1 wherein the meso-scale structure comprises an electric switch.

3. The meso-scale MEMS apparatus of claim 2 wherein the at least one meso-scale separate structure includes at least one conductive surface.

4. The meso-scale MEMS apparatus of claim 1 wherein the at least one meso-scale separate structure is comprised of conductive material.

5. The meso-scale MEMS apparatus of claim 4 wherein the conductive material comprises copper.

6. The meso-scale MEMS apparatus of claim 1 wherein the meso-scale structure has a largest dimension that is no greater than about 300 mils.

7. The meso-scale MEMS apparatus of claim 1 wherein the at least one meso-scale separate structure has at least one hole disposed therethrough.

8. The meso-scale MEMS apparatus of claim 7 wherein the meso-scale structure includes a post disposed through the meso-scale separate structure hole.

9. The meso-scale MEMS apparatus of claim 8 wherein the post is at least partially comprised of conductive material.

10. The meso-scale MEMS apparatus of claim 1 wherein the meso-scale structure includes at least one conductive surface disposed to at least occasionally be contacted by the at least one meso-scale separate structure.

11. The meso-scale MEMS apparatus of claim 10 wherein the meso-scale structure includes at least two conductive surfaces disposed to at least occasionally be both contacted simultaneously by the at least one meso-scale separate structure, wherein the at least two conductive surfaces and the at least one meso-scale separate structure comprises an electric circuit.

12. The meso-scale MEMS apparatus of claim 1 and further comprising at least a second meso-scale separate structure that is movably disposed proximal to and fully non-integrally with respect to the meso-scale structure and that is substantially restrained to no more than a predetermined range of movement with respect to the meso-scale structure.

13. The meso-scale MEMS apparatus of claim 1 wherein the at least one meso-scale separate structure comprises an electrical ground.

14. The meso-scale MEMS apparatus of claim 13 wherein the meso-scale structure includes at least one electrode disposed proximal to the at least one meso-scale separate structure.

15. The meso-scale MEMS apparatus of claim 14 wherein the meso-scale structure includes at least one conductive contact that is disposed to contact the at least one meso-scale separate structure when the at least one meso-scale separate structure is biased towards the at least one electrode.

16. The meso-scale MEMS apparatus of claim 13 wherein the meso-scale structure includes:

at least a first and second electrode disposed proximal to and on opposite sides of the at least one meso-scale structure; and

at least a first and second electrode disposed proximal to the at least one meso-scale structure;

such that the first electrode is disposed to contact the at least one meso-scale separate structure when the at least one meso-scale separate structure is biased towards the first electrode and the second electrode is disposed to contact the at least one meso-scale separate structure when the at least one meso-scale separate structure is biased towards the second electrode.

17. The meso-scale MEMS apparatus of claim 1 wherein the at least one meso-scale separate structure is disposed within a cavity that is formed in the meso-scale structure.

18. The meso-scale MEMS apparatus of claim 1 wherein the at least one meso-scale separate structure has a substantially reflective surface.

19. The meso-scale MEMS apparatus of claim 18 wherein the substantially reflective surface includes at least one of copper, silver, and chrome.

20. The meso-scale MEMS apparatus of claim 18 wherein the reflective surface is deflectable with respect to the printed wiring board.

21. The meso-scale MEMS apparatus of claim 20 wherein the reflective surface is pivotable about a pivot, which pivot is substantially fixed with respect to the printed wiring board.

22. The meso-scale MEMS apparatus of claim 21 wherein the reflective surface is laterally pivotable with respect to the pivot through substantially 360 degrees.

23. The meso-scale MEMS apparatus of claim 20 wherein the reflective surface is deflectable by assuming at least one of a concave and a convex shape.

24. The meso-scale MEMS apparatus of claim 20 wherein the meso-scale structure includes at least one electrode.

25. The meso-scale MEMS apparatus of claim 24 wherein the at least one electrode selectively acts upon the reflective surface to thereby selectively deflect the reflective surface with respect to the printed wiring board.

26. The meso-scale MEMS apparatus of claim 25 and further including a plurality of electrodes, wherein at least a plurality of the plurality of electrodes selectively act upon the reflective surface to thereby selectively deflect the reflective surface with respect to the printed wiring board.

27. A method of forming a meso-scale MEMS apparatus comprising:

providing a printed wiring board substrate;

forming a meso-scale structure on the printed wiring board substrate;

providing at least one meso-scale separate structure that is movably disposed proximal to and fully non-integrally with respect to the meso-scale structure such that the at least one meso-scale separate structure is substantially restrained to no more than a predetermined range of movement with respect to the meso-scale structure.

28. The method of claim 27 wherein the printed wiring board substrate is comprised of at least one of FR-2 through FR-6, polyimide, Teflon, CEM-1 through CEM-8, G-10, a modified epoxy, BT epoxy, cyanate ester, and polytetrafluoroethylene.

29. The method of claim 27 wherein providing at least one meso-scale separate structure includes providing at least one meso-scale separate structure substantially comprised of conductive material.

30. The method of claim 27 wherein providing at least one meso-scale separate structure includes providing at least one meso-scale separate structure substantially comprised of both conductive and non-conductive material.

31. The method of claim 27 wherein providing at least one meso-scale separate structure includes providing at least one meso-scale separate structure having a hole disposed therethrough.

32. The method of claim 31 forming a meso-scale structure includes forming a meso-scale structure having a post that is disposed through the meso-scale separate structure hole.

33. The method of claim 32 wherein the post has a conductive surface disposed thereon.

34. The method of claim 27 wherein forming a meso-scale structure includes forming a meso-scale structure having meso-scale separate structure contactable conductive switch surfaces.

35. The method of claim 27 wherein forming a meso-scale structure includes forming a meso-scale structure having at least one meso-scale separate structure controlling conductive electrode surface.

36. The method of claim 27 wherein providing at least one meso-scale separate structure includes providing at least one meso-scale separate structure having a substantially reflective surface.

37. The method of claim 36 wherein providing at least one meso-scale separate structure having a substantially reflective surface includes providing at least one meso-scale separate structure having a substantially reflective surface comprised of at least one of copper, silver, and chrome.

38. The method of claim 36 wherein providing at least one meso-scale separate structure includes providing at least one meso-scale separate structure having a substantially reflective surface wherein the reflective surface is pivotable about a pivot, which pivot is substantially fixed with respect to the printed wiring board.

39. A method of forming a meso-scale structure on a printed wiring board having a movable member, comprising:

providing a printed wiring board;

disposing first sacrificial polymer material overlying the printed wiring board;

forming a member overlying the first polymer material;

disposing second sacrificial polymer material overlying the member;

disposing a cover overlying the second sacrificial polymer material;

removing at least portions of the first and second sacrificial polymer material such that the member can move within a substantially limited range of movement with respect to the printed wiring board and such that the member is not integrally connected to any other portion of the meso-scale structure.

40. The method of claim 39 wherein:

disposing first sacrificial polymer material includes disposing a first polymer material overlying the printed wiring board and not curing at least a first part of the first polymer material to form the first sacrificial polymer material; and

disposing second sacrificial polymer material includes disposing a second polymer material overlying the printed wiring board and not curing at least a first part of the second polymer material to form the second sacrificial polymer material.

41. The method of claim 39 wherein:

disposing a cover includes disposing a cover having at least one opening disposed therethrough; and

removing at least portions of the first and second sacrificial polymer material includes removing at least portions of the first and second sacrificial polymer material by exposing the first and second sacrificial polymer material to at least a first solvent as introduced through the at least one opening in the cover.

42. The method of claim 39 wherein removing at least portions of the first and second sacrificial polymer material includes forming a cavity bounded at least in part by at least one of cured polymer material and conductive material.