Micromechanical switch with insulated switch contact

• US 5,638,946 A
• Filed: 01/11/1996
• Issued: 06/17/1997
• Est. Priority Date: 01/11/1996
• Status: Expired due to Term

• Current Assignee: Northeastern University
• Original Assignee: Northeastern University
• Inventors: Zavracky, Paul M.
• Primary Examiner(s): SCOTT, JAMES R
• Application Number:
  US08/585,407
• Time in Patent Office: 523 Days
• Field of Search: 200/16 B, 200/16 D, 200/83 N, 200/181, 200/512, 200/61.48, 200/262-270, 200/275, 73/514.16, 73/514.36, 73/514.37, 257/414-467, 361/283.1-283.4
• US Class Current: 200/181
• CPC Class Codes: G11C 23/00 Digital stores characterised by movement of mechanical parts to effect storage, e.g. using balls; Storage elements therefor
• CPC Class Codes: H01H 1/0036 Switches making use of microelectromechanical systems [MEMS] for electromagnetic relays H01H50/005; for electrostatic relays H01H59/0009
• CPC Class Codes: H01H 2001/0057 the contact materials containing refractory materials, e.g. tungsten
• CPC Class Codes: H01H 59/0009 making use of micromechanics
• CPC Class Codes: H02H 5/005 responsive to ionising radiation; Nuclear-radiation circumvention circuits radiation detectors G01T; nuclear-explosion detection G21J5/00

Abstract

A micromechanical switch and a method of making the switch. The micromechanical switch of the invention is made by surface micromachining techniques and include an isolated contact located on the beam and separated from the main body of the beam by an insulated connector. The isolated contact provides the advantage that the current flow caused by the circuit being switched does not alter the fields or currents used to actuate the switch. Thus, the present invention allows the actuation functions to be unaffected by the signals that are being switched.

Claims

1. An insulated micromechanical switch comprising:

a substrate;

a source contact mounted on said substrate;

a gate contact mounted on said substrate;

a drain contact having a first drain electrode and a second drain electrode, said drain contact mounted on said substrate;

a deflectable beam comprising;

a conductive beam body having a first end and a second end, said first end of said beam body attached to said source contact, said second end of said beam body overhanging said gate contact;

a beam contact overhanging said drain contact; and

an insulator joining and electrically insulating said second end of said beam body and said beam contact; and

wherein said beam is deflectable between a first position in which said beam contact is in electrical communication with said drain contact in response to an electrical field of a first strength established between said gate electrode and said conductive beam body, to a second position in which said beam contact is isolated from said drain contact in response to an electrical field of a second strength established between said gate electrode and said conductive beam body.

2. The insulated micromechanical switch of claim 1, wherein said substrate comprises silicon or glass.

3. The insulated micromechanical switch of claim 1, wherein said beam body comprises nickel, gold, chrome, chromium, copper or iron.

4. The insulated micromechanical switch of claim 1, wherein said insulator comprises polyimide, PMMA, silicon nitride or silicon oxide.

5. The insulated micromechanical switch of claim 1, wherein said contacts comprise platinum, palladium, titanium/tungsten, rhodium or gold.

6. The insulated micromechanical switch of claim 1, wherein said beam has a length of between 5 μ

m and 20 μ

m.

7. The insulated micromechanical switch of claim 1, wherein said insulated micromechanical switch is incorporated into an electrical circuit.

8. An insulated micromechanical switch, comprising:

a substrate;

a source electrode mounted on said substrate;

a gate contact comprising a first gate electrode and a second gate electrode, said gate contact mounted on said substrate adjacent said source electrode, said first gate electrode and said second gate electrode separated by a channel;

a drain contact comprising a first drain electrode and a second drain electrode mounted on said substrate adjacent said gate contact;

a non-conductive deflectable beam mounted on said source electrode and overhanging said gate contact and said drain electrodes, said beam comprising an upper electrode layer and an upper contact layer, said upper electrode layer positioned on said beam over said gate contact and said upper contact layer positioned on said beam over said drain contact, said beam electrically insulating said upper contact layer from said upper electrode layer; and

wherein said beam is deflectable between a first position wherein said upper contact layer is in electrical communication with said drain electrodes in response to an electrical field of a first strength established between said first gate electrode and said second gate electrode, to a second position wherein said upper contact layer is isolated from said drain electrodes in response to an electrical field of a second strength established between said first gate electrode and said second gate electrode.

9. The insulated micromechanical switch of claim 8, wherein said substrate comprises silicon or glass.

10. The insulated micromechanical switch of claim 8, wherein said beam body comprises nickel, gold, chrome, chromium, copper or iron.

11. The insulated micromechanical switch of claim 8, wherein said insulator comprises polyimide, PMMA, silicon nitride or silicon oxide.

12. The insulated micromechanical switch of claim 8, wherein said contacts comprise platinum, palladium, titanium/tungsten, rhodium or gold.

13. The insulated micromechanical switch of claim 8, wherein said beam has a length of between 5 μ

m and 20 μ

m.

14. The insulated micromechanical switch of claim 8, wherein said insulated micromechanical switch is incorporated into an electrical circuit.