Micro electro-mechanical systems relay

• US 5,959,338 A
• Filed: 12/29/1997
• Issued: 09/28/1999
• Est. Priority Date: 12/29/1997
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Youngner, Daniel W., Johnson, Burgess R.
• Primary Examiner(s): Meier, Stephen D.
• Application Number:
  US08/999,420
• Time in Patent Office: 638 Days
• Field of Search: 257/419, 257/415, 338/42
• US Class Current: 257/419
• CPC Class Codes: H01H 1/66 Contacts sealed in an evacuated or gas-filled envelope, e.g. magnetic dry-reed contacts
• CPC Class Codes: H01H 59/0009 making use of micromechanics
• CPC Class Codes: H01H 9/42 Impedances connected with contacts

Abstract

A relay device build using MEMS technology and having a semiconductor wafer base with a surface depression having a first electrically conductive surface pattern. A lower diaphragm is moveably positioned above the depression for contact and has a second electrically conductive surface pattern thereon. An upper diaphragm is positioned above the lower diaphragm, with a central electrode mounted between them to selectively attract and move a diaphragm upon application of voltage. A post connects the upper and lower diaphragms to move a diaphragm when the other is moved electrostatically. The diaphragms define a sealed region enclosing the central electrode. The surface patterns may be tapered at their perimiters to provide a contact contour allowing gradually increasing contact as the diaphragm moves toward the surface. The preferred wafer is a silicon wafer, and the diaphragms are polysilicon. The patterns are formed from highly conductive material like gold, while the outer regions are a high resistive, chemically stable material like CrsiN. The sealed region is evacuated to have a vacuum, or may be filed with an inert gas. In a preferrred embodiment, the sealed region is filled with a fluid having a measurable viscosity, and region is adapted to move the fluid upon electrostatic movement of the diaphragm, such that the viscosity of the fluid is selected to adjust the rate of movement of the diaphragm.

Claims

1. A relay device, comprising:

a semiconductor wafer base, said base having a surface depression having a first electrically conductive surface pattern formed thereon;

a lower diaphragm positioned above said surface depression and moveable for contact therewith, said lower diaphragm having a second electrically conductive surface pattern thereon;

an upper diaphragm positioned above said lower diaphragm, said upper diaphragm having an electrode thereon;

a central electrode mounted between said upper and lower diaphragm, said central electrode being positioned to selectively attract said upper diaphragm electrode upon application of voltage therebetween and to move said upper diaphragm to a lower position, said central electrode further being positioned to selectively attract said lower diaphragm electrode upon application of voltage therebetween and to move said lower diaphragm to an upper position; and

mechanical connection means connectively mounted between said upper diaphragm and said lower diaphragm for moving one of said diaphragms mechanically when the other of said diaphragms is moved by said application of voltage to said central electrode and said other diaphragm;

said upper and lower diaphragms being sealingly mounted on said base to define a sealed region therebetween enclosing said central electrode and said diaphragm electrodes;

said base surface pattern and said lower diaphragm pattern being tapered at their respective perimiters to provide a contact contour allowing initial contact only at the periphery of the depression and increasing contact as said lower diaphragm moves toward said surface to provide full contact between said patterns over a predetermined period of time.

2. The device of claim 1, wherein wherein said wafer is a silicon wafer.

3. The device of claim 1, wherein wherein said diaphragms are formed from polysilicon.

4. The device of claim 1, wherein said first and second patterns include central regions formed from highly conductive material.

5. The device of claim 4, wherein said highly conductive material is selected from gold.

6. The device of claim 1, wherein said first and second patterns include outer regions extending from said central region and are formed from high resistive, chemically stable material.

7. The device of claim 6, wherein wherein said high resistive, chemically stable material is CrsiN.

8. The device of claim 1, wherein each of said diaphragms and the gap at the perimeter of said diaphragms is adjusted to require a voltage of ten volts to move said diaphragms electrostatically.

9. The device of claim 1, wherein said sealed region is evacuated to have a vacuum.

10. The device of claim 1, wherein said sealed region is filed with an inert gas.

11. The device of claim 1, wherein said sealed region is filed with a fluid having a measurable viscosity, and region is adapted to move said fluid upon electrostatic movement of said diaphragm, such that the viscosity of said fluid is selected to adjust the rate of movement of said diaphragm.

12. The device of claim 1, wherein said patterns are substantially identical.

13. The device of claim 12, wherein said patterns are shaped to provide a more conductive center and decreasing spoke-like regions extending from said center.

14. The device of claim 1, wherein said patterns are spiral.

15. In a relay device, said device having a semiconductor wafer base and a pair of diaphragms centered about a central electrode for movement of said diaphragms upon application of a voltage between said central electrode and one of said diaphragms, the improvement comprising:

a surface depression having a first electrically conductive surface pattern formed on the surface of said base;

a second electrically conductive surface pattern on said lower diaphragm; and

mechanical connection means connectively mounted between said upper diaphragm and said lower diaphragm for moving one of said diaphragms mechanically when the other of said diaphragms is moved by said application of voltage to said central electrode and said other diaphragm;

said upper and lower diaphragms being sealingly mounted on said base to define a sealed region therebetween enclosing said central electrode and said diaphragm electrodes;

said base surface pattern and said lower diaphragm pattern being tapered at their respective perimiters to provide a contact contour allowing initial contact only at the periphery of the depression and increasing contact as said lower diaphragm moves toward said surface to provide full contact between said patterns over a predetermined period of time.

16. The device of claim 15, wherein wherein said wafer is a silicon wafer.

17. The device of claim 15, wherein wherein said diaphragms are formed from polysilicon.

18. The device of claim 15, wherein wherein said first and second patterns include central regions formed from highly conductive material.

19. The device of claim 18, wherein said highly conductive material is selected from gold.

20. The device of claim 15, wherein said first and second patterns include outer regions extending from said central region and are formed from high resistive, chemically stable material.

21. The device of claim 20, wherein wherein said high resistive, chemically stable material is CrsiN.

22. The device of claim 15, wherein each of said diaphragms and the gap at the perimeter of said diaphragms is adjusted to require a voltage of ten volts to move said diaphragms electrostatically.

23. The device of claim 15, wherein said sealed region is evacuated to have a vacuum.

24. The device of claim 15, wherein said sealed region is filed with an inert gas.

25. The device of claim 15, wherein said sealed region is filled with a fluid having a measurable viscosity, and region is adapted to move said fluid upon electrostatic movement of said diaphragm, such that the viscosity of said fluid is selected to adjust the rate of movement of said diaphragm.

26. The device of claim 15, wherein said patterns are substantially identical.

27. The device of claim 15, wherein said patterns are shaped to provide a more conductive center and decreasing spoke-like regions extending from said center.

28. The device of claim 15, wherein said patterns are spiral.