BAW Gyroscope with Bottom Electrode

• US 20120111113A1
• Filed: 01/03/2011
• Published: 05/10/2012
• Est. Priority Date: 11/05/2010
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Sammoura, Firas N., Yang, Kuang L.
• Granted Patent: US 8,616,056 B2
• Time in Patent Office: Days
• US Class Current: 73/514.01
• CPC Class Codes: G01C 19/5698 using acoustic waves, e.g. surface acoustic wave gyros
• CPC Class Codes: H01L 21/4846 Leads on or in insulating or insulated substrates, e.g. metallisation H01L21/4821 takes precedence; metallisation of ceramics in general C04B41/51; printed circuits H05K3/00
• CPC Class Codes: H01L 21/84 the substrate being other than a semiconductor body, e.g. being an insulating body
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

A bulk acoustic wave gyroscope has a primary member in a member plane, and an electrode layer in an electrode plane spaced from the member plane. The electrode layer has a first portion that is electrically isolated from a second portion. The first portion, however, is mechanically coupled with the second portion and faces the primary member (e.g., to actuate or sense movement of the primary member). For support, the second portion of the electrode is directly coupled with structure in the member plane.

Claims

1. A bulk acoustic wave gyroscope comprising:

a primary member in a member plane; and

an electrode layer in an electrode plane spaced from the member plane,

the electrode layer having a first portion and a second portion, the first portion being electrically isolated from the second portion, the first portion being mechanically coupled with the second portion,

the first portion of the electrode layer facing the primary member,

the second portion of the electrode being directly coupled with structure in the member plane.

2. The gyroscope as defined by claim 1 further comprising a conductive path extending from the member plane and into the second portion of the electrode layer.

3. The gyroscope as defined by claim 2 wherein the conductive path comprises a via.

4. The gyroscope as defined by claim 1 wherein an oxide directly couples the second portion of the electrode with the structure in the member plane.

5. The gyroscope as defined by claim 1 wherein the second portion of the electrode layer is grounded.

6. The gyroscope as defined by claim 1 further comprising a trench separating the first portion of the electrode layer from the second portion of the electrode layer, the trench being at least partly filled with a dielectric material.

7. The gyroscope as defined by claim 1 further comprising a side electrode in the member plane, the side electrode being radially spaced from the primary member.

8. The gyroscope as defined by claim 1 wherein the primary member and electrode layer are formed at least in part from a silicon-on-insulator wafer.

9. The bulk acoustic wave gyroscope as defined by claim 1 wherein the primary member forms a disk that resonates in a flexure mode in response to receipt of an electrostatic signal from the first portion of the electrode layer.

10. A bulk acoustic wave gyroscope comprising:

a resonating member in a member plane; and

an electrode layer in an electrode plane, the member and electrode planes being spaced apart,

the resonating member being formed at least in part from a first layer of a silicon on insulator wafer, the bottom electrode layer at least in part being formed from a second layer of the silicon on insulator wafer,

the bottom electrode layer having a first portion and a second portion, the first portion being electrically isolated from the second portion, the first portion facing the resonating member and configured to electrostatically actuate the resonating member when subjected to a voltage,

the first portion of the electrode layer being mechanically secured to the second portion of the electrode layer,

the second portion of the electrode layer being anchored to structure in the member plane.

11. The gyroscope as defined by claim 10 further comprising a via anchoring the second portion of the electrode layer to structure in the electrode plane.

12. The gyroscope as defined by claim 10 wherein an oxide directly couples the second portion of the electrode with the structure in the member plane.

13. The gyroscope as defined by claim 10 further comprising a trench separating the first portion of the electrode layer from the second portion of the electrode layer, the trench being at least partly filled with a dielectric material.

14. The gyroscope as defined by claim 10 further comprising a side electrode in the member plane, the side electrode being radially spaced from the primary member.

15. The gyroscope as defined by claim 10 wherein the second portion of the electrode layer is configured to be grounded when a voltage is applied to the first portion of the electrode layer.

16. A method of forming a bulk acoustic wave gyroscope, the method comprising:

forming a primary member in a member plane;

forming an electrode layer in an electrode plane that is longitudinally spaced from the member plane;

removing a portion of the electrode layer to form a trench; and

filling the trench with a non-conductive material to produce a first portion of the electrode layer and a second portion of the electrode layer, the non-conductive material mechanically connecting the first portion of the electrode layer and the second portion of the electrode layer, the nonconductive material electrically isolating the first portion of the electrode layer from the second portion of the electrode layer.

17. The gyroscope as defined by claim 16 further comprising forming an anchor through the second portion of the electrode layer and into structure in the member plane.

18. The gyroscope as defined by claim 16 wherein forming the primary member and forming the electrode layer comprises processing a silicon-on-insulator wafer.

19. The gyroscope as defined by claim 16 further comprising releasing the primary member to form a space between the primary member and the electrode layer.

20. The gyroscope as defined by claims 19 wherein releasing comprises timing the release to maintain insulator material between the member plane and the electrode plane.