# US 10,480,942 B2 · Micromechanical detection structure of a MEMS multi-axis gyroscope, with reduced drifts of corresponding electrical parameters

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- Number: US 10,480,942 B2
- Document ID: US10480942B2
- Status: Granted
- Kind: B2
- Application number: 15/273,312
- Filed: 2016-09-22
- Published: 2017-10-05
- Granted: 2019-11-19
- Earliest claimed: 2016-03-31
- Assignees: STMicroelectronics S.r.l.
- Applicants: Stmicroelectronics S.R.L.
- Inventors: Gabriele Gattere; Carlo Valzasina; Luca Giuseppe Falorni
- Web page: https://patentgrep.com/patent/US10480942B2

## CPC

- G01C 19/5747: each sensing mass being connected to a driving mass, e.g. driving frames
- B81C 1/00158: {Diaphragms, membranes (manufacture process for semi-permeable inorganic membranes B01D67/0039)}
- G01C 19/5712: the devices involving a micromechanical structure
- 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)
- H01G 5/011: Electrodes
- G01C 19/58: Turn-sensitive devices without moving masses
- Y10T 29/49169: Assembling electrical component directly to terminal or elongated conductor
- G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S)
- B81C: PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS (making microcapsules or microballoons B01J13/02; processes or apparatus specially adapted for the manufacture or treatment of piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/01)
- H01G: CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE (selection of specified materials as dielectric H01B3/00; capacitors having potential barriers H10D1/62, H10K10/10)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A multi-axis MEMS gyroscope includes a micromechanical detection structure having a substrate, a driving-mass arrangement, a driven-mass arrangement with a central window, and a sensing-mass arrangement which undergoes sensing movements in the presence of angular velocities about a first horizontal axis and a second horizontal axis. A sensing-electrode arrangement is fixed with respect to the substrate and is set underneath the sensing-mass arrangement. An anchorage assembly is set within the central window for constraining the driven-mass arrangement to the substrate at anchorage elements. The anchorage assembly includes a rigid structure suspended above the substrate that is elastically coupled to the driven mass by elastic connection elements at a central portion, and is coupled to the anchorage elements by elastic decoupling elements at end portions thereof.

## Claims

### Claim 1

A multi-axis MEMS gyroscope, comprising:
a micromechanical detection structure having a main extension in a horizontal plane, the micromechanical detection structure including:
a substrate including semiconductor material;
a driving-mass arrangement configured to be driven in a driving movement;
a driven-mass arrangement having a central window, the driven-mass arrangement coupled elastically to said driving-mass arrangement and configured to be driven in motion by said driving movement;
a sensing-mass arrangement configured to perform, in response to motion of the driven-mass arrangement and in the presence of a first angular velocity about a first horizontal axis of the horizontal plane, a first detection movement of rotation out of the horizontal plane about a second horizontal axis of the horizontal plane, perpendicular to the first horizontal axis, and further configured to perform, in response to motion of the driven-mass arrangement and in the presence of a second angular velocity about the second horizontal axis of the horizontal plane, a second detection movement of rotation out of the horizontal plane about the first horizontal axis;
a sensing-electrode arrangement fixed with respect to the substrate and capacitively coupled to the sensing-mass arrangement; and
an anchorage assembly arranged within the central window of the driven-mass arrangement, the anchorage assembly elastically coupled to the driven-mass arrangement, and configured to constrain the driven-mass arrangement to the substrate at anchorage elements, wherein
said anchorage assembly includes a rigid structure that is suspended above said substrate,
the rigid structure includes a pair of rigid elements that extend along the second horizontal axis and that are arranged symmetrically with respect to the second horizontal axis in the central window,
each of the pair of rigid elements is elastically coupled to the driven-mass arrangement by a respective elastic connection element that extends from a central portion of a respective rigid element to the driven-mass arrangement,
and each of the pair of rigid elements is coupled, at respective terminal ends of the rigid element, to respective anchorage elements by respective elastic decoupling elements, and
said anchorage elements are positioned at a distance from said elastic connection elements and proximate to said sensing-electrode arrangement in the horizontal plane.

### Claim 2 (depends on 1)

The multi-axis MEMS gyroscope according to claim 1, wherein said elastic decoupling elements are configured to elastically decouple said rigid structure from deformations of said substrate due to one or more of thermal drifts, mechanical stresses, and humidity absorption.

### Claim 3 (depends on 1)

The multi-axis MEMS gyroscope according to claim 1, wherein the anchorage elements are positioned proximate to said sensing-electrode arrangement to minimize a mean of the variations of gaps between said sensing-mass arrangement and said sensing-electrode arrangement.

### Claim 4 (depends on 1)

The multi-axis MEMS gyroscope according to claim 1, wherein said anchorage assembly is configured so that said rigid structure is substantially immobile with respect to said first and second angular velocities.

### Claim 5 (depends on 1)

The multi-axis MEMS gyroscope according to claim 1, wherein said driven-mass arrangement comprises a driven mass having internally a first pair of lateral windows set laterally with respect to the central window and aligned along the first horizontal axis; and wherein said sensing-mass arrangement comprises a first pair of sensing masses, each of which is set within a respective lateral window of said first pair of lateral windows, is suspended above the substrate, and is coupled to the driven mass by respective elastic suspension elements; and wherein said elastic suspension elements, of a torsional type, extend parallel to the second horizontal axis on opposite sides of a terminal portion of the respective sensing masses so that said sensing masses are set in cantilever fashion above said substrate.

### Claim 6 (depends on 5)

The multi-axis MEMS gyroscope according to claim 5, wherein said sensing-electrode arrangement comprises a first pair of sensing electrodes set on the substrate underneath said first pair of sensing masses.

### Claim 7 (depends on 6)

The gyroscope according to claim 6, wherein said driven mass further has internally a second pair of lateral windows set laterally with respect to the central window and aligned along the second horizontal axis; and wherein said sensing-mass arrangement comprises a second pair of sensing masses, each of which is set within a respective lateral window of said second pair of lateral windows and is coupled to the driven mass by respective elastic suspension elements suspended in cantilever fashion above said substrate.

### Claim 8 (depends on 7)

The multi-axis MEMS gyroscope according to claim 7, wherein said sensing-electrode arrangement comprises a second pair of sensing electrodes set on the substrate underneath said second pair of sensing masses.

### Claim 9 (depends on 1)

The multi-axis MEMS gyroscope according to claim 1, wherein said driving-mass arrangement is coupled to a set of driving electrodes and is configured to be driven in said driving movement based upon electrical biasing of said set of driving electrodes; wherein said driving movement is a movement of translation along the second horizontal axis such as to drive said driven-mass arrangement into rotation about said vertical axis.

### Claim 10 (depends on 1)

The multi-axis MEMS gyroscope according to claim 1, wherein the elastic connection elements extend within said central window and are aligned to define an axis of rotation out of the horizontal plane for said driven-mass arrangement.

### Claim 11

An electronic device, comprising:
a MEMS gyroscope including a micromechanical detection structure having a main extension in a horizontal plane, the micromechanical detection structure including:
a substrate including a surface parallel to the horizontal plane;
a driving-mass structure positioned over the surface of the substrate and configured to oscillate in the horizontal plane;
a driven-mass structure positioned over the surface of the substrate and including a central window, the driven-mass structure elastically coupled to the driving-mass structure and configured oscillate, responsive to oscillations of the driving-mass structure in the horizontal plane, in a rotational motion about a vertical axis orthogonal to the horizontal plane;
a sensing-mass structure positioned over the surface of the substrate and configured to detect rotational movement of the driven-mass structure about first and second horizontal axes in the horizontal plane;
a sensing-electrode structure arranged on the surface of the substrate, the sensing-electrode structure capacitively coupled to the sensing-mass structure;
an anchorage assembly arranged within the central window of the driven-mass structure, the anchorage assembly including,
a rigid structure suspended over the surface of the substrate, the rigid structure including a pair of rigid elements that extend along the second horizontal axis and that are arranged symmetrically with respect to the second horizontal axis in the central window;
elastic coupling elements coupling the pair of rigid elements to the driven-mass arrangement, each of the elastic coupling elements extending from a central portion of a respective rigid element to the driven-mass arrangement;
anchorage elements on the surface of the substrate, each anchorage element proximate to the sensing-electrode structure and spaced apart in the horizontal plane from the elastic coupling elements; and
elastic decoupling elements coupled between end portions of the pair of rigid elements and the anchorage elements;
a reading-interface circuit electrically coupled to said micromechanical structure; and
a microprocessor unit electrically coupled to said reading-interface circuit.

### Claim 12 (depends on 11)

The electronic device of claim 11, wherein the sensing-electrode structure comprises a plurality of sensing electrodes formed on the surface of the substrate adjacent the driven-mass structure, and wherein the anchorage elements are positioned on the surface of the substrate within an envelope region of each of the plurality of sensing electrodes.

### Claim 13 (depends on 11)

The electronic device of claim 11, wherein the electronic device comprises one of a mobile-communication portable device and a wearable type of electronic device.

### Claim 14 (depends on 11)

The electronic device of claim 11, wherein the sensing-mass structure is further configured to perform a first detection of rotational movement out of the horizontal plane along a vertical axis in the presence of a first angular velocity about the first horizontal axis of the horizontal plane, and further configured to perform a second detection of rotational movement out of the horizontal plane in the presence of a second angular velocity about the second horizontal axis of the horizontal plane.

### Claim 15 (depends on 11)

The electronic device of claim 11, wherein the substrate comprises a semiconductor material and wherein the driven-mass structure comprises polysilicon.

### Claim 16

A gyroscope, comprising:
a detection structure having a main extension in a horizontal plane and including:
a substrate;
a driving mass;
a driven mass having a central window and being elastically coupled to the driving mass, the driving mass in operation of the gyroscope moving in a first detection movement of rotation out of the horizontal plane along a vertical axis in response to a first angular velocity about a first horizontal axis of the horizontal plane, and in operation of the gyroscope moving in a second detection movement of rotation out of the horizontal plane in response to a second angular velocity about a second horizontal axis of the horizontal plane;
a sensing electrode attached to the substrate and capacitively coupled to the sensing mass;
anchorage elements fixed to the substrate at a position proximate the sensing electrode in the horizontal plane; and
an anchorage assembly in the central window of the driven mass, the anchorage assembly elastically coupled to the driven mass and to the anchorage elements, the anchorage assembly including a pair of rigid elements that extend along the second horizontal axis and that are arranged symmetrically with respect to the second horizontal axis in the central window, each of the pair of rigid elements elastically coupled to the driven mass by a respective elastic connection element that extends from a central portion of a respective rigid element to the driven mass, and each of the pair of rigid elements coupled, at respective terminal ends of the rigid element, to respective anchorage elements by elastic decoupling elements, the elastic connection elements being a distance on the substrate from the anchorage elements.

### Claim 17 (depends on 16)

The gyroscope of claim 16, wherein the substrate is a semiconductor substrate and wherein the elastic decoupling elements in operation decouple the rigid element from deformations of the substrate.

### Claim 18 (depends on 16)

The gyroscope of claim 16, wherein the anchorage elements are positioned proximate to the sensing electrode to minimize a mean of changes in the gap responsive to deformations of the substrate.

### Claim 19

A multi-axis MEMS gyroscope, comprising:
a micromechanical detection structure having a main extension in a horizontal plane, the micromechanical detection structure including:
a substrate including semiconductor material;
a driving-mass arrangement configured to be driven in a driving movement;
a driven-mass arrangement having a central window and a driven mass, the driven-mass arrangement coupled elastically to said driving-mass arrangement and configured to be driven in motion by said driving movement, the driven mass having internally a first pair of lateral windows set laterally with respect to the central window and aligned along a first horizontal axis;
a sensing-mass arrangement configured to perform, in response to motion of the driven-mass arrangement and in the presence of a first angular velocity about the first horizontal axis of the horizontal plane, a first detection movement of rotation out of the horizontal plane about a second horizontal axis of the horizontal plane, perpendicular to the first horizontal axis, and further configured to perform, in response to motion of the driven-mass arrangement and in the presence of a second angular velocity about the second horizontal axis of the horizontal plane, a second detection movement of rotation out of the horizontal plane about the first horizontal axis, wherein
the sensing-mass arrangement includes a first pair of sensing masses, each of which is set within a respective lateral window of the first pair of lateral windows, is suspended above the substrate, and is coupled to the driven mass by respective elastic suspension elements of a torsional type, and
each of the elastic suspension elements extend parallel to the second horizontal axis on opposite sides of a terminal portion of a respective sensing mass of the first pair of sensing masses so that the first pair of sensing masses are set in cantilever fashion above said substrate;
a sensing-electrode arrangement fixed with respect to the substrate and capacitively coupled to the sensing-mass arrangement; and
an anchorage assembly arranged within the central window of the driven-mass arrangement, the anchorage assembly elastically coupled to the driven-mass arrangement, and configured to constrain the driven-mass arrangement to the substrate at anchorage elements, wherein
said anchorage assembly includes a rigid structure, suspended above said substrate and elastically coupled to said driven mass by elastic connection elements at a central portion of the rigid structure, and coupled to said anchorage elements by elastic decoupling elements at end portions of the rigid structure, and
said anchorage elements are positioned at a distance from said elastic connection elements and proximate said sensing-electrode arrangement in the horizontal plane to reduce, in response to deformations of said substrate, variations of gaps between said sensing-mass arrangement and said sensing-electrode arrangement.

### Claim 20 (depends on 19)

The multi-axis MEMS gyroscope according to claim 19, wherein said sensing-electrode arrangement includes a first pair of sensing electrodes that are on the substrate and are aligned with the first pair of sensing masses.

### Claim 21 (depends on 20)

The gyroscope according to claim 20, wherein
said driven mass includes a second pair of lateral windows set laterally with respect to the central window and aligned along the second horizontal axis,
the sensing-mass arrangement includes a second pair of sensing masses, each of which is set within a respective lateral window of the second pair of lateral windows and is coupled to the driven mass by respective elastic suspension elements, and
the sensing-electrode arrangement includes a second pair of sensing electrodes that are on the substrate and are aligned with the second pair of sensing masses.