Single-Pole Double-Throw Mems Switch

• US 20070205087A1
• Filed: 04/12/2005
• Published: 09/06/2007
• Est. Priority Date: 04/12/2004
• Status: Active Grant

• Current Assignee: Siverta, Inc.
• Original Assignee: Siverta, Inc.
• Inventors: Gottlieb, Glenn, Slater, Timothy, Pashby, Gary
• Granted Patent: US 7,816,999 B2
• Time in Patent Office: Days
• US Class Current: 200/181
• CPC Class Codes: H01H 59/0009 making use of micromechanics

Abstract

MEMS switches of varying configurations provide individu-ally acutatable contacts. The MEMS switches are sealed by an improved anodic bonding technique.

Claims

1. A single-pole, double-throw (“

SPDT”

) micro-electro mechanical systems (“

MEMS”

) switch adapted for selectively coupling an electrical signal present on an input conductor connected to the SPDT MEMS switch to an output conductor selected from a group which includes at least a first output conductor and a second output conductor, both output conductors being connected to the SPDT MEMS switch, the SPDT MEMS switch comprising;

a monolithic layer of material having micro-machined therein;

a. at least a pair of toggles configured in an arrangement selected from a group which includes a pair of confronting toggles and a pair of conrearing toggles;

b. pairs of torsion bars no fewer in number than the number of toggles, each pair of torsion bars being;

i. respectively disposed on opposite sides of and coupled to one of the toggles; and

ii. establishing an axis about which such toggle is rotatable; and

c. a frame to which ends of torsion bars furthest from the toggle are coupled, the frame supporting through the torsion bars the toggle for rotation about the axis established by the torsion bars;

electrically conductive shorting bars no fewer in number than the number of toggles, one shorting bar being respectively carried at an end of each toggle distal from the rotation axis of such toggle;

a base that is joined to a first surface of the monolithic layer; and

a substrate that is bonded to a second surface of the monolithic layer which is distal from the first surface thereof to which the base is joined, the substrate having formed thereon;

a. electrodes no fewer in number than the number of toggles, each electrode being juxtaposed with a surface of the toggle that is displaced to one side of the rotation axis thereof, application of an electrical potential between the electrode and the toggle urging the toggle to rotate about the rotation axis established by the torsion bars coupled thereto; and

b. pairs of switch contacts no fewer in number than the number of toggles, each pair of switch contacts being adapted to be connectable respectively to the input conductor and to one of the output conductors, and each pair of switch contacts;

i. being disposed adjacent to but spaced apart from the shorting bar carried by one of the toggles when no force is applied to the toggle;

ii. when no force is applied to the toggle being electrically insulated from each other; and

iii. being contacted by the adjacent shorting bar upon application of a sufficiently strong force to the toggle which urges the toggle to rotate about the rotation axis established by each pair of torsion bars;

whereby upon rotation of each toggle about the rotation axis established by the torsion bars coupled thereto to such an extent that the shorting bar contacts the switch contacts, the contacting shorting bar electrically coupling together the switch contacts that are adjacent to the shorting bar carried by the toggle.

2. The SPDT MEMS switch of claim 1 wherein the electrodes have a stepped cross-sectional shape thereby reducing voltage which must be applied for generating a sufficiently strong force which causes the toggle to rotate about the rotation axis established by each pair of torsion bars.

3. The SPDT MEMS switch of claim 1 wherein frit material bonds the monolithic layer to the substrate, the frit material being disposed to enclose the frame, the torsion bars and the pair of toggles, during bonding the frit material being compressed by a projecting rail located about the frame, the torsion bars and the toggles.

4. The SPDT MEMS switch of claim 3 wherein the rail is disposed within a frit trench that receives the frit material.

5. The SPDT MEMS switch of claim 3 wherein the rail is formed within the monolithic layer.

6. The SPDT MEMS switch of claim 1 wherein a fusion bond joins the monolithic layer and the base.

7. The SPDT MEMS switch of claim 1 wherein material forming the monolithic layer is single crystal silicon (Si).

8. The SPDT MEMS switch of claim 1 wherein a sheet of electrically insulating material is interposed between the toggle and the shorting bar(s) carried thereon.

9. The SPDT MEMS switch of claim 1 wherein the base includes a cavity formed therein which abuts the first surface of the monolithic layer.

10. The SPDT MEMS switch of claim 1 wherein:

the substrate has formed thereon electrical conductors that respectively carry electrical signals between the switch contacts and input and output conductors; and

the SPDT MEMS switch includes ground plate(s) which are disposed adjacent to and are electrically insulated from the electrical conductors.

11. The SPDT MEMS switch of claim 10 wherein the ground plate(s) are disposed on the monolithic layer.

12. The SPDT MEMS switch of claim 10 wherein the ground plate(s) are disposed on the substrate.

13. A MEMS device comprising:

a first layer of material; and

a second layer of material wherein frit material bonds the first layer of material to the second layer of material, during bonding the frit material being compressed by a rail located within a layer of material selected from a group which includes the first layer of material and the second layer of material.

14. The MEMS device of claim 13 wherein the rail is disposed within a frit trench that receives the frit material.

15. The MEMS device of claim 13 wherein the frit material is anodically bonded between the first layer of material and the second layer of material.

16. The MEMS device of claim 15 wherein while establishing the frit bond between the first layer of material and the second layer of material a voltage of less than one-hundred (100) volts is applied across the first layer of material and the second layer of material.

17. A method for bonding together layers of a MEMS device comprising the steps of:

disposing frit material between a mated first layer of material and second layer of material of a MEMS device;

applying pressure across the mated first layer of material and second layer of material;

heating the mated first layer of material and second layer of material; and

applying an electrical potential across the mated first layer of material and second layer of material.

18. The method of claim 17 wherein the pressure applied across the mated first layer of material and second layer of material is at least 1800 Newtons.

19. The method of claim 17 wherein the mated first layer of material and second layer of material are heated to at least 400°

C.

20. The method of claim 17 wherein the frit material is compressed by a rail located within a layer of material selected from a group which includes the first layer of material and the second layer of material.

21. The method of claim 20 wherein the rail is disposed within a frit trench that receives the frit material.

22. The method of claim 17 wherein the electrical potential applied across the mated first layer of material and second layer of material is less than 100 volts.