Temperature-compensated micro-electromechanical device, and method of temperature compensation in a micro-electromechanical device

Patent metadata

Field	Value
Publication number	US-10894713-B2
Application number	US-201815863051-A
Country	US
Kind code	B2
Filing date	Jan 5, 2018
Priority date	Oct 8, 2004
Publication date	Jan 19, 2021
Grant date	Jan 19, 2021

Abstract

A micro-electromechanical device includes a semiconductor substrate, in which a first microstructure and a second microstructure of reference are integrated. The first microstructure and the second microstructure are arranged in the substrate so as to undergo equal strains as a result of thermal expansions of the substrate. Furthermore, the first microstructure is provided with movable parts and fixed parts with respect to the substrate, while the second microstructure has a shape that is substantially symmetrical to the first microstructure but is fixed with respect to the substrate. By subtracting the changes in electrical characteristics of the second microstructure from those of the first, variations in electrical characteristics of the first microstructure caused by changes in thermal expansion or contraction can be compensated for.

First claim

The invention claimed is:

1. A device, comprising:
a substrate;
a first detection structure including:
a first plurality of electrodes, the first plurality of electrodes being fixed to the substrate;
a first suspended mass elastically coupled to the substrate, the first suspended mass being movable relative to the substrate;
a second plurality of electrodes extending from the first suspended mass, the second plurality of electrodes being movable relative to the substrate, the second plurality of electrodes configured to be capacitively coupled to the first plurality of electrodes;

a second detection structure including:
a third plurality of electrodes, the third plurality of electrodes being fixed to the substrate;
a second suspended mass rigidly coupled to the substrate, the second suspended mass having a fixed position relative to the substrate, the first suspended mass and the second suspended mass being configured to undergo substantially equal strains as a result of thermal expansion of the substrate; and
a fourth plurality of electrodes extending from the second suspended mass, the fourth plurality of electrodes having a fixed position relative to the substrate, the fourth plurality of electrodes configured to be capacitively coupled to the third plurality of electrodes.

2. The device of claim 1 wherein the first plurality of electrodes are symmetrical with the third plurality of electrodes with respect to an axis of the substrate.

3. The device of claim 1 wherein the second plurality of electrodes are symmetrical with the fourth plurality of electrodes with respect to an axis of the substrate.

4. The device of claim 1 , further comprising:
a first stator structure coupled to the substrate, the first suspended mass being elastically coupled to the first stator structure; and
a second stator structure coupled to the substrate, the second suspended mass rigidly coupled to the second stator structure.

5. The device of claim 1 wherein the first suspended mass and the second suspended mass have substantially the same shape and dimensions.

6. The device of claim 1 wherein the first suspended mass is symmetrical with the second suspended mass with respect to a first axis.

7. The device of claim 6 wherein the first suspended mass is movable relative to the substrate along a second axis that is transverse to the first axis.

8. A device, comprising:
a substrate;
a first detection structure on the substrate, the first detection structure including:
a first plurality of electrodes rigidly coupled to the substrate, the first plurality of electrodes having a fixed position relative to the substrate;
a first suspended mass elastically coupled to the substrate, the first suspended mass being movable relative to the substrate along a first axis; and
a second plurality of electrodes coupled to the first suspended mass, the second plurality of electrodes being movable relative to the substrate along the first axis, the second plurality of electrodes configured to be capacitively coupled to the first plurality of electrodes; and

a second detection structure on the substrate, the second detection structure including:
a third plurality of electrodes rigidly coupled to the substrate, the third plurality of electrodes having a fixed position relative to the substrate;
a second suspended mass rigidly coupled to the substrate, the second suspended mass having a fixed position relative to the substrate, the first suspended mass and the second suspended mass being configured to undergo substantially equal strains as a result of thermal expansion of the substrate; and
a fourth plurality of electrodes coupled to the second suspended mass, the fourth plurality of electrodes having a fixed position relative to the substrate, the fourth plurality of electrodes configured to be capacitively coupled to the third plurality of electrodes, the first detection structure being symmetrical with the second detection structure with respect to a second axis that is transverse to the first axis.

9. The device of claim 8 , further comprising:
a first stator structure coupled to the substrate, the first suspended mass being elastically coupled to the first stator structure; and
a second stator structure coupled to the substrate, the second suspended mass rigidly coupled to the second stator structure.

10. The device of claim 8 wherein the first plurality of electrodes are rigidly coupled to the first stator structure, and the third plurality of electrodes are rigidly coupled to the second stator structure.

11. The device of claim 8 wherein the first suspended mass and the second suspended mass have substantially the same shape and dimensions.

12. The device of claim 8 wherein the second plurality of electrodes includes a first set of electrodes and a second set of electrodes, the first set of electrodes are couples to a first side of the first suspended mass, the second set of electrodes are coupled to a second side, opposite to the first side, of the first suspended mass.

13. A method, comprising:
forming a first detection structure on a substrate, the forming of the first detection structure including:
forming a first plurality of electrodes that are rigidly coupled to the substrate, the first plurality of electrodes having a fixed position relative to the substrate;
forming a first suspended mass that is elastically coupled to the substrate, the first suspended mass being movable relative to the substrate along a first axis;
forming a second plurality of electrodes that are coupled to the first suspended mass, the second plurality of electrodes being movable relative to the substrate along the first axis, the second plurality of electrodes configured to be capacitively coupled to the first plurality of electrodes;

forming a second detection structure on the substrate, the forming of the second detection structure including:
forming a third plurality of electrodes that are rigidly coupled to the substrate, the third plurality of electrodes having a fixed position relative to the substrate;
forming a second suspended mass that is rigidly coupled to the substrate, the second suspended mass having a fixed position relative to the substrate, the first suspended mass and the second suspended mass being configured to undergo substantially equal strains as a result of thermal expansion of the substrate; and
forming a fourth plurality of electrodes that are coupled to the second suspended mass, the fourth plurality of electrodes having a fixed position relative to the substrate, the fourth plurality of electrodes configured to be capacitively coupled to the third plurality of electrodes, the first detection structure being symmetrical with the second detection structure with respect to a second axis that is transverse to the first axis.

14. The method of claim 13 wherein the first suspended mass and the second suspended mass have substantially the same shape and dimensions.

15. The method of claim 13 wherein the second plurality of electrodes includes a first set of electrodes and a second set of electrodes, the first set of electrodes are couples to a first side of the first suspended mass, the second set of electrodes are coupled to a second side, opposite to the first side, of the first suspended mass.

16. The method of claim 13 wherein the first plurality of electrodes are symmetrical with the third plurality of electrodes with respect to the second axis.

17. The method of claim 13 wherein the second plurality of electrodes are symmetrical with the fourth plurality of

Assignees

• St Microelectronics Srl

Inventors

• Lasalandra Ernesto
• Merassi Angelo
• Zerbini Sarah

Classifications

• B81B3/0081 Primary

  Thermal properties · CPC title

• B81B2201/025

  Inertial sensors not provided for in B81B2201/0235 - B81B2201/0242 · CPC title

• H03H2009/02496

  Horizontal, i.e. parallel to the substrate plane · CPC title

• G01P15/125

  by capacitive pick-up · CPC title

• B81C1/00666

  Treatments for controlling internal stress or strain in MEMS structures · CPC title