Integrated gyroscope of semiconductor material

• US 20020189354A1
• Filed: 04/23/2002
• Published: 12/19/2002
• Est. Priority Date: 04/27/2001
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Zerbini, Sarah, Durante, Guido Spinola, Gardella, Simone
• Granted Patent: US 6,766,689 B2
• Time in Patent Office: Days
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5747 each sensing mass being connected to a driving mass, e.g. driving frames

Abstract

The gyroscope is formed by a driving system including a driving mass having an open concave shape; an accelerometer including a sensing mass and comprising mobile sensing electrodes; a linkage connecting the driving mass to the sensing mass. The sensing mass is surrounded on three sides by the driving mass and has a peripheral portion not facing the sensing mass. The mobile sensing electrodes extend integral with the sensing mass from the peripheral portion not facing the driving mass and are interleaved with fixed sensing electrodes. Thereby, there are no passing electrical connections extending below the sensing mass. Moreover the linkage includes springs placed equidistant from the center of gravity of the accelerometer, and the gyroscope is anchored to the substrate with anchoring springs placed equidistant from the center of gravity of the assembly formed by the driving system and by the accelerometer.

Claims

1. An integrated gyroscope, comprising:

a driving group including a driving mass having an open concave shape;

an acceleration sensor including a sensing mass having a peripheral portion not facing said driving mass and a sensing group of a capacitive type, said sensing mass being surrounded by said driving mass and said sensing group comprising mobile sensing electrodes integral with said sensing mass and extending from said peripheral portion of said sensing mass; and

a linkage connecting said driving mass to said sensing mass.

2. A gyroscope according to claim 1 wherein said driving mass has a concave polygonal shape.

3. A gyroscope according to claim 2 wherein said driving mass has substantially the shape of a squared letter C and said sensing mass has a substantially rectangular shape.

4. A gyroscope according to claim 1 wherein said driving mass and said sensing mass are formed in a same structural layer).

5. A gyroscope according to claim 1 wherein said driving mass and said sensing mass are formed in a same epitaxial layer.

6. A gyroscope according to claim 1 wherein said driving mass and said sensing mass form masses completely suspended above a fixed body.

7. A gyroscope according to claim 6 wherein an anchoring group connects said driving mass to the fixed body.

8. A gyroscope according to claim 7 wherein said anchoring group comprises a plurality of anchoring springs extending from said driving mass to the outside.

9. A gyroscope according to claim 8 wherein said driving group further comprises a plurality of mobile driving electrodes extending integral from said driving mass, said driving system, said acceleration sensor and said linkage having a gyroscope center of gravity, said anchoring springs being arranged in a position equidistant from said gyroscope center of gravity.

10. A gyroscope according to claim 8 wherein said acceleration sensor has a sensing center of gravity and said linkage comprises a plurality of coupling springs arranged in a position equidistant from said sensing center of gravity.

11. A gyroscope according to claim 10 wherein said anchoring springs and said coupling springs are of the folded type.

12. A gyroscope according to claim 11 wherein said driving group determines an oscillation of said driving mass and of said acceleration sensor in a first direction and said sensing group senses a movement of said sensing mass in a second direction, perpendicular to said first direction, and wherein said anchoring springs extend in a direction prevalently parallel to said first direction and said coupling springs extend in a direction prevalently parallel to said second direction.

13. A gyroscope according to claim 1 comprising two symmetrical parts connected by central springs and each including an own driving group, its own acceleration sensor and an own linkage.

15. The sensor of claim 14, further comprising a plurality of anchoring springs configured to couple the driving mass to the substrate and to permit motion of the driving mass in the first direction.

16. The sensor of claim 15 wherein the anchoring springs are disposed symmetrically around the driving mass and balanced thereto with reference to a center of gravity of the driving mass.

17. The sensor of claim 14, further comprising a plurality of coupling springs configured to couple the sensing mass to the driving mass and to permit motion of the sensing mass in the second direction.

18. The sensor of claim 17 wherein the coupling springs are disposed symmetrically around the sensing mass and balanced thereto with reference to a center of gravity of the sensing mass.

19. The sensor of claim 14 wherein the driving mass and the sensing mass are formed in a same structural layer.

20. The sensor of claim 14 wherein the driving mass, the sensing mass, the mobile sensing electrode and the fixed sensing electrodes comprise a first gyroscope, and wherein the sensor further comprises a second gyroscope, functionally identical to the first gyroscope and coupled in the same manner to the substrate.

21. The sensor of claim 20 wherein the sensor is configured such that the concavities of the driving masses of the first and second gyroscopes face away from each other.

22. The sensor of claim 21 wherein the driving mass of the second gyroscope oscillates in the first direction.

23. The sensor of claim 22 wherein the sensing mass of the second gyroscope is configured to move in a third direction, parallel to the second direction.

25. The method of claim 24 wherein the substrate includes a pair of fixed sensing electrodes fixed to the substrate and capacitively coupled to a mobile sensing electrode coupled to the second mass, the fixed and mobile sensing electrodes being positioned on a side of the second mass facing away from the first mass.

14. An acceleration sensor, comprising:

a semiconductor substrate;

a driving mass coupled to the substrate and configured to oscillate in a first direction parallel to an upper surface of the substrate, the driving mass having a concavity;

a sensing mass coupled to the driving mass and suspended within the concavity;

a mobile sensing electrode coupled to the sensing mass and extending in a direction away from the driving mass; and

a pair of fixed sensing electrodes coupled to the substrate and positioned on opposite sides of the mobile sensing electrode and configured to detect motion of the mobile sensing electrode in a direction perpendicular to the first direction and parallel to the upper surface of the substrate.

24. A method, comprising:

oscillating a first mass in a first direction relative to a substrate, the first mass being coupled resiliently to the substrate;

measuring acceleration of the substrate by sensing motion in a second direction relative to the substrate of a second mass perpendicular to the first direction, the second mass being coupled resiliently within a concave opening of the first mass;