Micromachined monolithic 3-axis gyroscope with single drive

• US 10,050,155 B2
• Filed: 01/25/2016
• Issued: 08/14/2018
• Est. Priority Date: 09/18/2010
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Fairchild Semiconductor Corporation (ON Semiconductor Corporation)
• Inventors: Acar, Cenk
• Primary Examiner(s): Caputo, Lisa
• Assistant Examiner(s): Woodward, Nathaniel T
• Application Number:
  US15/005,783
• Publication Number:
  US 20160264404A1
• Time in Patent Office: 932 Days
• Field of Search: 73 137
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 2203/051 Translation according to an axis parallel to the substrate
• CPC Class Codes: B81B 2203/053 Translation according to an axis perpendicular to the substrate
• CPC Class Codes: B81B 2203/055 Translation in a plane parallel to the substrate, i.e. enabling movement along any direction in the plane
• CPC Class Codes: B81B 2203/056 Rotation in a plane parallel to the substrate
• CPC Class Codes: B81B 2203/058 Rotation out of a plane parallel to the substrate
• CPC Class Codes: B81B 2207/094 Feed-through, via
• CPC Class Codes: B81B 7/04 Networks or arrays of similar microstructural devices
• CPC Class Codes: G01C 19/5755 the devices having a single sensing mass
• 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 2015/0848 using a plurality of mechanically coupled spring-mass systems, the sensitive direction of each system being different
• CPC Class Codes: H01L 29/84 controllable by variation of applied mechanical force, e.g. of pressure

Abstract

This document discusses, among other things, a cap wafer and a via wafer configured to encapsulate a single proof-mass 3-axis gyroscope formed in an x-y plane of a device layer. The single proof-mass 3-axis gyroscope can include a main proof-mass section suspended about a single, central anchor, the main proof-mass section including a radial portion extending outward towards an edge of the 3-axis gyroscope sensor, a central suspension system configured to suspend the 3-axis gyroscope from the single, central anchor, and a drive electrode including a moving portion and a stationary portion, the moving portion coupled to the radial portion, wherein the drive electrode and the central suspension system are configured to oscillate the 3-axis gyroscope about a z-axis normal to the x-y plane at a drive frequency.

Claims

1. An inertial measurement system, comprising:

a device layer including;

a 3-axis gyroscope including a single proof mass formed in an x-y plane of a device layer, the single proof mass of the 3-axis gyroscope including;

symmetrical x-axis proof mass sections; and

a z-axis gyroscope coupling flexure coupled to the symmetric x-axis proof mass sections;

a sense electrode included within the single proof mass of the 3-axis gyroscope; and

a 3-axis accelerometer including a single proof mass formed in the x-y plane of the device layer adjacent the 3-axis gyroscope,

the 3-axis gyroscope including a central suspension configured to suspend the single proof mass of the 3-axis gyroscope about a single, central gyroscope anchor, and

the 3-axis accelerometer including separate x, y, and z-axis flexure bearings configured to suspend a single proof mass of the 3-axis accelerometer about a single, central accelerometer anchor.

2. The system of claim 1, including:

a cap wafer bonded to a first surface of the device layer; and

a via wafer bonded to a second surface of the device layer,

wherein the cap wafer and the via wafer are configured to encapsulate the 3-axis accelerometer and the 3-axis gyroscope in the same cavity.

3. The system of claim 1, including a via wafer bonded to a perimeter of a surface of the device layer, and

wherein the single proof masses of the 3-axis gyroscope and the 3-axis accelerometer are anchored to the via wafer using the single, central gyroscope anchor and the single, central accelerometer anchor.

4. The system of claim 1, wherein the 3-axis gyroscope includes:

a drive electrode including a moving portion and a stationary portion, the moving portion coupled to the single proof mass of the 3-axis gyroscope, wherein the drive electrode and the central suspension are configured to oscillate the 3-axis gyroscope about a z-axis normal to the x-y plane at a drive frequency.

5. The system of claim 1, wherein the x and y-axis flexure bearings are symmetrical about the single, central accelerometer anchor and the z-axis flexure is not symmetrical about the single, central accelerometer anchor.

6. The system of claim 1, wherein the symmetrical x-axis proof mass sections are configured to move anti-phase along an x-axis of the x-y plane in response to a z-axis angular motion.

7. The system of claim 6, wherein the z-axis gyroscope coupling flexure bearing is configured to couple the symmetric x-axis proof mass sections and to resist in-phase motion between the x-axis proof mass sections.

8. The system of claim 1, including:

a via wafer bonded to a surface of the device layer, the via wafer including;

x-axis and y-axis gyroscope sense electrodes out-of-plane with the device layer configured to detect x-axis and y-axis angular rotation of the single proof mass of the 3-axis gyroscope; and

z-axis accelerometer sense electrodes out-of-plane with the device layer configured to detect z-axis acceleration of the single proof mass of the 3-axis accelerometer; and

wherein the sense electrode includes a z-axis gyroscope sense electrode, the device layer includes;

x-axis and y-axis accelerometer sense electrodes in-plane with the device layer and configured to detect x-axis and y-axis acceleration of the single proof mass of the 3-axis accelerometer; and

the z-axis gyroscope sense electrodes in-plane with the device layer and configured to detect z-axis angular rotation of the single proof mass of the 3-axis gyroscope.

9. An inertial measurement system, comprising:

a device layer including;

a 3-axis gyroscope including a single proof mass formed in an x-y plane of a device layer, the single proof mass of the 3-axis gyroscope including;

symmetrical x-axis proof mass sections; and

a z-axis gyroscope coupling flexure coupled to the symmetric x-axis proof sections;

a drive electrode included in the single proof mass of the 3-axis gyroscope; and

a 3-axis accelerometer including a single proof mass formed in the x-y plane of the device layer adjacent the 3-axis gyroscope;

a cap wafer bonded to a first surface of the device layer; and

a via wafer bonded to a second surface of the device layer,

the 3-axis gyroscope including a central suspension configured to suspend the single proof mass of the 3-axis gyroscope about a single, central gyroscope anchor,

the 3-axis accelerometer including separate x, y, and z-axis flexure bearings configured to suspend a single proof mass of the 3-axis accelerometer about a single, central accelerometer anchor, and

the cap wafer and the via wafer being configured to encapsulate the 3-axis accelerometer and the 3-axis gyroscope in the same cavity.

10. The system of claim 9, wherein the via wafer is bonded to a perimeter of the second surface of the device layer, and

wherein the single proof masses of the 3-axis gyroscope and the 3-axis accelerometer are anchored to the via wafer using the single, central gyroscope anchor and the single, central accelerometer anchor.

11. The system of claim 9, wherein the symmetrical x-axis proof mass sections are configured to move anti-phase along an x-axis of the x-y plane in response to a z-axis angular motion.

12. The system of claim 11, wherein the z-axis gyroscope coupling flexure bearing is configured to couple the x-axis proof mass sections and to resist in-phase motion between the x-axis proof mass sections.

13. The system of claim 9, including:

a via wafer bonded to a surface of the device layer, the via wafer including;

x-axis and y-axis gyroscope sense electrodes out-of-plane with the device layer configured to detect x-axis and y-axis angular rotation of the single proof mass of the 3-axis gyroscope; and

z-axis accelerometer sense electrodes out-of-plane with the device layer configured to detect z-axis acceleration of the single proof mass of the 3-axis accelerometer; and

wherein the device layer includes;

x-axis and y-axis accelerometer sense electrodes in-plane with the device layer and configured to detect x-axis and y-axis acceleration of the single proof mass of the 3-axis accelerometer; and

a z-axis gyroscope sense electrode in-plane with the device layer and configured to detect z-axis angular rotation of the single proof mass of the 3-axis gyroscope.

14. The system of claim 9, wherein the drive electrode includes a moving portion and a stationary portion, the moving portion is coupled to the single proof mass of the 3-axis gyroscope, the drive electrode and the central suspension are configured to oscillate the 3-axis gyroscope about a z-axis normal to the x-y plane at a drive frequency.

15. The system of claim 9, wherein the x- and y-axis flexure bearings are symmetrical about the single, central accelerometer anchor and the z-axis flexure is not symmetrical about the single, central accelerometer anchor.

16. The system of claim 9, wherein the single proof mass of the 3-axis gyroscope includes symmetrical x-axis proof mass sections configured to move anti-phase along an x-axis of the x-y plane in response to a z-axis angular motion.

17. An inertial measurement system, comprising:

a device layer including;

a 3-axis gyroscope including a single proof mass formed in an x-y plane of a device layer, the single proof mass of the 3-axis gyroscope including;

symmetrical x-axis proof mass sections; and

a z-axis gyroscope coupling flexure coupled to the symmetric x-axis proof sections;

a drive electrode included in the single proof mass of the 3-axis gyroscope; and

a 3-axis accelerometer including a single proof mass formed in the x-y plane of the device layer adjacent the 3-axis gyroscope;

a cap wafer bonded to a first surface of the device layer; and

a via wafer bonded to a second surface of the device layer,

the cap wafer and the via wafer being configured to encapsulate the 3-axis accelerometer and the 3-axis gyroscope in the same cavity.

18. The system of claim 17, wherein the 3-axis gyroscope includes a central suspension configured to suspend the single proof mass of the 3-axis gyroscope about a single, central gyroscope anchor, and

wherein the 3-axis accelerometer including separate x-, y-, and z-axis flexure bearings is configured to suspend a single proof mass of the 3-axis accelerometer about a single, central accelerometer anchor.

19. The system of claim 18, wherein the via wafer is bonded to a perimeter of the second surface of the device layer, and

wherein the single proof masses of the 3-axis gyroscope and the 3-axis accelerometer are anchored to the via wafer using the single, central gyroscope anchor and the single, central accelerometer anchor.

20. The system of claim 17, wherein:

the symmetrical x-axis proof mass sections are configured to move anti-phase along an x-axis of the x-y plane in response to a z-axis angular motion; and

the z-axis gyroscope coupling flexure bearing is configured to couple the x-axis proof mass sections and to resist in-phase motion between the x-axis proof mass sections.