BIMORPHIC STRUCTURES, SENSOR STRUCTURES FORMED THEREWITH, AND METHODS THEREFOR

• US 20080054756A1
• Filed: 08/31/2007
• Published: 03/06/2008
• Est. Priority Date: 08/31/2006
• Status: Active Grant

• Current Assignee: Bellutech LLC
• Original Assignee: Evigia Systems, Inc.
• Inventors: Yazdi, Navid, Gogoi, Bishnu
• Granted Patent: US 7,495,368 B2
• Time in Patent Office: Days
• US Class Current: 310/307
• 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 37/52 actuated due to deflection of bimetallic element
• CPC Class Codes: H02N 11/002 Generators
• CPC Class Codes: Y10T 29/42 Piezoelectric device making
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49004 including measuring or testing of device or component part
• CPC Class Codes: Y10T 29/49005 Acoustic transducer
• CPC Class Codes: Y10T 29/49007 Indicating transducer
• CPC Class Codes: Y10T 29/49105 Switch making

Abstract

A bimorphic structure responsive to changes in an environmental condition, sensor structures incorporating one or more of such bimorphic structures, and a method of forming such bimorphic structures. The sensor structure has an electrically-conductive first contact on a substrate, and a bimorph beam anchored to the substrate so that a portion thereof is suspended above the first contact. The bimorph beam has a multilayer structure that includes first and second layers, with the second layer between the first layer and the substrate. A portion of the first layer projects through an opening in the second layer toward the first contact so as to define an electrically-conductive second contact located on the beam so as to be spaced apart and aligned with the first contact for contact with the first contact when the beam sufficiently deflects toward the substrate.

Claims

1. A sensor structure comprising:

a substrate;

a first contact on the substrate and formed of an electrically conductive material; and

a bimorph beam anchored to the substrate and having a portion thereof suspended above the first contact, the bimorph beam having a multilayer structure comprising first and second layers, the second layer being between the first layer and the substrate, the first layer having a portion that projects through an opening in the second layer toward the first contact, the first layer being formed of an electrically conductive material and the portion of the first layer projecting through the opening defining a second contact, the second contact being located on the beam so as to be spaced apart and aligned with the first contact for contact with the first contact when the beam sufficiently deflects toward the substrate.

2. The sensor structure according to claim 1, wherein the portion of the first layer protrudes from the second layer so as to be closer to the first contact than the first layer.

3. The sensor structure according to claim 1, wherein the second layer is formed of an electrically nonconductive material.

4. The sensor structure according to claim 1, wherein the first layer is formed of a metallic material.

5. The sensor structure according to claim 1, wherein the bimorph beam is one of a plurality of bimorph beams on the substrate.

6. The sensor structure according to claim 1, wherein the bimorph beam deflects in response to changes in an environmental condition selected from the group consisting of temperature and humidity.

7. The sensor structure according to claim 1, wherein the multilayer structure of the bimorph beam consists of the first and second layers.

8. The sensor structure according to claim 1, wherein the bimorph beam is cantilevered above the first contact.

9. The sensor structure according to claim 8, wherein the bimorph beam is anchored to the substrate at a location oppositely disposed from the second contact thereof.

10. The sensor structure according to claim 1, further comprising an integrated circuit on the substrate.

11. The sensor structure according to claim 1, further comprising a third contact disposed opposite the first contact such that the bimorph beam is between the first and third contacts, the third contact being formed of an electrically conductive material.

12. A method of forming a sensor structure, the method comprising:

depositing an electrically conductive material and forming therefrom a first contact on a substrate; and

forming a bimorph beam anchored to the substrate so as to have a portion thereof suspended above the first contact, the bimorph beam being formed to have a multilayer structure comprising first and second layers, the second layer being between the first layer and the substrate, the first layer being formed to have a portion that projects through an opening in the second layer toward the first contact, the first layer being formed of an electrically conductive material and the portion of the first layer projecting through the opening defining a second contact, the second contact being located on the bimorph beam so as to be spaced apart and aligned with the first contact for contact with the first contact when the bimorph beam sufficiently deflects toward the substrate.

13. The method according to claim 12, wherein the step of forming the bimorph beam comprises:

depositing a spacer layer on the substrate;

depositing the second layer of the bimorph beam on the spacer layer so that a portion of the second layer projects through the spacer layer;

forming the opening in the second layer;

depositing the first layer of the bimorph beam on the second layer and in the opening thereof to form the portion of the first layer; and

removing the spacer layer so that the multilayer structure comprising the first and second layers is suspended above the first contact by an anchor comprising the portion of the second layer.

14. The method according to claim 13, further comprising the step of etching a recess into the spacer layer below the opening in the second layer, wherein depositing the first layer in the opening further comprises depositing the first layer in the recess in the spacer layer such that the portion of the first layer is disposed within the opening in the second layer and within the recess in the spacer layer, and wherein removing the spacer layer causes the portion of the first layer to be closer to the first contact than the first layer.

15. The method according to claim 14, wherein a portion of the spacer layer remaining below the recess establishes a gap between the first and second contacts following removal of the spacer layer.

16. The method according to claim 12, wherein the second layer is formed of an electrically nonconductive material.

17. The method according to claim 12, wherein a plurality of bimorph beams are simultaneously formed on the substrate in accordance with the steps of claim 12.

18. The method according to claim 12, wherein the bimorph beam deflects in response to changes in an environmental condition selected from the group consisting of temperature and humidity.

19. The method according to claim 12, further comprising the step of fabricating an integrated circuit on the substrate.

20. The method according to claim 12, further comprising the step of forming a third contact disposed opposite the first contact such that the bimorph beam is between the first and third contacts, the third contact being formed of an electrically conductive material.