Chip level sensor with multiple degrees of freedom

• US 9,638,524 B2
• Filed: 11/30/2012
• Issued: 05/02/2017
• Est. Priority Date: 11/30/2012
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Feyh, Ando, Chen, Po-Jui
• Primary Examiner(s): Caputo, Lisa
• Assistant Examiner(s): Megna Fuentes, Anthony W
• Application Number:
  US13/690,932
• Publication Number:
  US 20140150552A1
• Time in Patent Office: 1,614 Days
• Field of Search: 7350401-50416, 7351417-51418, 7351413, 7351438, 29 2535
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 2207/053 of movable structures
• CPC Class Codes: B81B 7/02 containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS] B81B7/04 takes precedence
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure
• CPC Class Codes: G01C 19/5755 the devices having a single sensing mass
• CPC Class Codes: G01C 19/5769 Manufacturing; Mounting; Housings
• CPC Class Codes: G01C 25/00 Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass testing, calibrating or compensating compasses G01C17/38
• CPC Class Codes: G01P 15/123 by piezo-resistive elements, e.g. semiconductor strain gauges
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/0808 for defining in-plane movement of the mass, i.e. movement of the mass in the plane of the substrate
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type
• CPC Class Codes: G01P 2015/0848 using a plurality of mechanically coupled spring-mass systems, the sensitive direction of each system being different
• CPC Class Codes: G01P 2015/0882 for providing damping of vibrations
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

A sensing assembly device includes a substrate, a chamber above the substrate, a first piezoelectric gyroscope sensor positioned within the chamber, and a first accelerometer positioned within the chamber.

Claims

1. A sensing assembly device comprising:

a substrate;

a chamber above the substrate;

a first piezoelectric gyroscope sensor positioned within the chamber; and

a first accelerometer positioned within the chamber, wherein the chamber is pressurized to a pressure sufficient to provide damping for the first accelerometer;

the first piezoelectric gyroscope comprises;

a first and second support beam, each of the first and second support beams having a respective pair of piezoelectric drive elements;

a first and second secondary support beams supported by the first support beam;

a third and a fourth secondary support beam supported by the second support beam;

a seismic mass supported by the first, second, third, and fourth secondary support beams; and

four piezoelectric sense elements, each of the four piezoelectric sense elements located on a respective one of the first, second, third, and fourth secondary support beams.

2. The device of claim 1, further comprising:

a second piezoelectric gyroscope sensor positioned within the chamber; and

a second accelerometer positioned within the chamber.

3. The device of claim 2, further comprising:

a third piezoelectric gyroscope sensor positioned within the chamber; and

a third accelerometer positioned within the chamber, wherein;

the first piezoelectric gyroscope sensor is configured to sense rotation about a first axis;

the second piezoelectric gyroscope sensor is configured to sense rotation about a second axis;

the third piezoelectric gyroscope sensor is configured to sense rotation about a third axis; and

each of the first, second and third axis is orthogonal to each of the other of the first, second and third axis.

4. The device of claim 2, wherein the first accelerometer is a piezoelectric accelerometer.

5. The device of claim 4, the first accelerometer comprising:

a body portion movable with respect to the substrate; and

a plurality of first plates fixedly extending from the body portion and interdigitated with a plurality of second plates which are fixed with respect to the substrate.

6. The device of claim 5, further comprising:

a control system operably connected to the plurality of first plates and the plurality of second plates and configured to adjust the stiffness of the first accelerometer.

7. The device of claim 2, wherein the first accelerometer is a capacitive accelerometer.

8. The device of claim 1, further comprising a cap, wherein:

an inside surface of the cap defines a portion of the chamber;

the first accelerometer is attached to the substrate; and

the first piezoelectric gyroscope is attached to the inside surface of the cap.

9. The device of claim 1, further comprising a cap, wherein:

an inside surface of the cap defines a portion of the chamber;

the first accelerometer is attached to the inside surface of the cap; and

the first piezoelectric gyroscope is attached to the substrate.

10. The device of claim 1, wherein:

the first accelerometer is attached to the substrate; and

the first piezoelectric gyroscope is attached to the substrate.

11. The device of claim 1, wherein the first accelerometer is a multiple-axis sensor.

12. The device of claim 1, wherein the first piezoelectric gyroscope sensor is a multiple-axis sensor.

13. A method of forming a sensing assembly device comprising:

providing a substrate;

forming a first piezoelectric gyroscope sensor above the substrate;

forming a first accelerometer positioned above the substrate; and

forming a chamber above the substrate such that the first piezoelectric gyroscope sensor and the first accelerometer are within the chamber;

wherein forming the first piezoelectric gyroscope sensor comprises;

forming a first and a second support beam;

forming a first pair of piezoelectric drive elements on the first support beam;

forming a second pair of piezoelectric drive elements on the second support beam;

supporting a first and a second secondary support beam with the first support beam;

supporting a third and a fourth secondary support beam with the second support beam;

supporting a seismic mass with the first, second, third, and fourth secondary support beams;

positioning a first piezoelectric sense element on the first secondary support beam;

positioning a second piezoelectric sense element on the second secondary support beam;

positioning a third piezoelectric sense element on the third secondary support beam; and

positioning a fourth piezoelectric sense element on the fourth secondary support beam.

14. The method of claim 13, further comprising;

establishing an environment within the chamber, the environment selected to provide damping to the first accelerometer.

15. The method of claim 14, further comprising:

forming a plurality of first plates on a body portion of the first accelerometer; and

forming a plurality of second fixed plates interdigitated with the plurality of first plates, such that the plurality of second fixed plates are located within the chamber and fixed with respect to the chamber while the body portion is movable with respect to the chamber when the chamber is formed.

16. The method of claim 13, further comprising:

forming a second piezoelectric gyroscope sensor above the substrate; and

forming a second accelerometer above the substrate, wherein forming a chamber above the substrate comprises forming the chamber such that the second piezoelectric gyroscope sensor and the second accelerometer are within the chamber.

17. The method of claim 16, wherein:

the first piezoelectric gyroscope sensor is configured to sense rotation about a first axis;

the second piezoelectric gyroscope sensor is configured to sense rotation about a second axis; and

the first axis is orthogonal to the second axis.

18. The method of claim 13, wherein:

forming a first piezoelectric gyroscope sensor comprises supporting the first piezoelectric gyroscope sensor with a cap defining a portion of the chamber; and

forming a first accelerometer comprises supporting the first accelerometer with the substrate.