Acceleration and angular velocity resonant detection integrated structure, and related MEMS sensor device

Patent metadata

Field	Value
Publication number	US-9389077-B2
Application number	US-201314032052-A
Country	US
Kind code	B2
Filing date	Sep 19, 2013
Priority date	Sep 28, 2012
Publication date	Jul 12, 2016
Grant date	Jul 12, 2016

Abstract

An integrated detection structure has a first inertial mass and a second inertial mass, each of which is elastically anchored to a substrate and has a linear movement along a first horizontal axis, a first detection movement of rotation about a first axis of rotation parallel to a second horizontal axis and a second detection movement of translation along the second horizontal axis; driving electrodes cause linear movement of the inertial masses, in opposite directions of the first horizontal axis; a pair of flexural resonator elements and a pair of torsional resonator elements are elastically coupled to the inertial masses, the torsional resonator elements having a resonant movement of rotation about a second axis of rotation and a third axis of rotation, parallel to one another and to the first axis of rotation.

First claim

The invention claimed is:

1. An integrated detection structure comprising:
a substrate;
first elastic anchorage elements;
second elastic anchorage elements;
a first inertial mass suspended over the substrate in a plane and anchored to the substrate by the first elastic anchorage elements;
a second inertial mass suspended over the substrate in the plane and anchored to the substrate by the second elastic anchorage elements;
a first set of driving electrodes operatively coupled to each of said first and second inertial masses and configured to drive the first and second inertial masses with driving movements, in opposite directions along a first axis of said plane; and
first, second, third, and fourth elastic supporting elements;
a first pair of first resonator elements elastically coupled to said first inertial mass by the first and second elastic supporting elements, respectively, said first and second elastic supporting elements being configured to enable independent resonant movements of the first resonator elements of the first pair with respect to each other;
a second pair of first resonator element elastically coupled to said second inertial mass by the third and fourth elastic supporting elements, respectively, said third and fourth elastic supporting elements being configured to enable independent resonant movements of the first resonator elements of the second pair with respect to each other; wherein:
said first elastic anchorage elements are configured to allow the first inertial mass to perform a first linear driving movement along the first axis in said plane, allow a first detection movement of rotation about a first rotation axis parallel to a second axis transverse to said first axis and in said plane as a function of a first angular velocity or a first linear acceleration to be detected and cause corresponding variations of resonance frequency of said first pair first resonator elements; and
said second elastic anchorage elements are configured to allow the second inertial mass to perform a second linear driving movement along the first axis in said plane, allow a second detection movement of rotation about a second rotation axis parallel to the second axis in said plane as a function of the first angular velocity or the first linear acceleration to be detected and cause a corresponding variations of resonance frequency of said second pair of first resonator elements.

2. The structure according to claim 1 , wherein:
said first resonator elements of said first and second pairs of first resonator elements are of a torsional type, and said independent resonant movement of each of said first and second pairs is an independent movement of rotation of the first resonator elements about a respective second axis of rotation and third axis of rotation that are parallel to one another and parallel to the respective first axis of rotation of said first and second inertial masses;
said respective first detection movement for said first and second inertial masses is the same direction of rotation, as a result of a respective Coriolis force, in response to a first angular velocity about said second axis, and in opposite directions of rotation, as a result of a respective inertial force, in response to a first linear acceleration directed along a vertical axis transverse to said plane.

3. The structure according to claim 2 , comprising a first set of detection electrodes arranged on said substrate and operatively coupled to said first resonator elements to enable detection of corresponding variations of resonance frequency as the electrical stiffness varies as a function of a variation of distance from said substrate as a result of said first detection movement of said first and second inertial masses.

4. The structure according to claim 3 , wherein said respective first detection movement of said first and second inertial masses is configured to cause opposite variations of distance from said substrate, in the first resonator elements of first and second pairs, and different variations of resonance frequency in the first resonator elements of at least one of the first and second pairs in response to said first angular velocity or of said first linear acceleration.

5. The structure according to claim 2 , wherein:
the first resonator elements of said first and second pairs are arranged in a first opening and in a second opening, respectively, provided in the respective inertial mass; and
said first opening and said second opening are set symmetrically with respect to said first axis of rotation, said second opening being open towards an outside of the respective inertial mass, centrally with respect to said integrated detection structure.

6. The structure according to claim 5 , wherein said first resonator elements are contained in overall dimensions of the respective inertial mass in said plane and are set symmetrically with respect to said first axis of rotation, said second axis of rotation and said third axis of rotation being arranged at a same distance from said first axis of rotation.

7. The structure according claim 2 , further comprising a second set of driving electrodes operatively coupled to said first resonator elements and configured to cause driving thereof, in a resonance condition, in rotation about said second axis of rotation and said third axis of rotation, respectively, at a nominal torsional resonance frequency.

8. The structure according to claim 1 , further comprising a median axis parallel to the second axis; wherein said first and second inertial masses are arranged symmetrically with respect to said median axis.

9. The structure according to claim 1 , wherein:
the respective first and second elastic anchorage elements couple said first and second inertial masses to respective external anchorages; and
said first and second inertial masses have a distribution of mass that is asymmetrical with respect to said respective first axis of rotation, and are constrained in an eccentric way to said substrate via the respective elastic anchorage elements.

10. The structure according to claim 9 , wherein said first resonator elements of the first and second pairs are of a torsional type; the structure further comprising first and second pairs of second resonator elements of a flexural type, the first and second pairs of second resonator elements coupled to each of said first and second inertial masses, each of said second resonator elements having a first end constrained to an anchorage towards said substrate and a second end constrained to a respective one of said elastic anchorage elements, in the proximity of a respective one of said external anchorages; wherein said elastic anchorage elements are further configured to allow the respective inertial mass to perform a respective second linear detection movement along said second axis; said respective second detection movement being designed to cause axial stresses in said second resonator elements and vary the resonance frequency.

11. The structure according to claim 10 , further comprising a second set of detection electrodes operatively coupled to said second resonator elements and enable detection of corresponding variations of resonance frequency.

12. The structure according to claim 10 , wherein said respective second detection movement for said first and second inertial masses is in the same direction of said second axis in response to a second linear acceleration directed along said second axis, and in opposite directions of said second axis in the presence of a second angular velocity about said vertical axis.

13. The structure according to claim 12 , wherein the structure is co

Assignees

• St Microelectronics Srl

Inventors

• Comi Claudia
• Corigliano Alberto
• Baldasarre Leonardo

Classifications

• G01P2015/0831

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