INERTIAL OR RESONATING SENSOR IN SURFACE TECHNOLOGY, WITH OUT OF PLANE DETECTION BY STRAIN GAUGE

• US 20100186510A1
• Filed: 01/22/2010
• Published: 07/29/2010
• Est. Priority Date: 01/23/2009
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (French Alternative Energies and Atomic Energy Commission)
• Original Assignee: Commissariat a L'Energie Atomique (French Alternative Energies and Atomic Energy Commission)
• Inventors: ROBERT, Philippe
• Granted Patent: US 8,371,166 B2
• Time in Patent Office: Days
• US Class Current: 73/514.290
• CPC Class Codes: G01C 19/5656 the devices involving a micromechanical structure
• CPC Class Codes: G01C 19/5769 Manufacturing; Mounting; Housings
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/097 by vibratory elements

Abstract

The invention involves a surface type MEMS sensor, characterized by that fact that it has:

• • a) a first zone in semi-conductor material, called thick zone, which has a first thickness forming at least one mobile mass,
  • b) a second zone in semi-conductor material, forming at least a pivot link for the mobile mass in relation to a substrate, with the axis of the pivot link running parallel to the substrate plane,
  • c) a third one, called thin zone, with a lesser thickness than that of the second zone forming at least a suspended type strain gauge for the detection of the movement of the mobile mass around the axis of the pivot link and with this third area:
    • extending in a plane parallel to the substrate plane which does not contain the axis of the pivot link,
    • extending in a plane perpendicular to the rotation axis of the pivot link,
    • being linked to the mobile mass on one side and to the substrate on the other.

Claims

1. MEMS surface type sensor, made in a substrate the surface of which defines a plane, known as substrate plane, this sensor comprising:

a) a first zone, called thick zone, having a first thickness (T), of which two surfaces form a first plane (N1) and a second plane (N2) parallel in relation to one another and to the plane of the substrate, this zone forming at least one mobile mass with movement outside the plane of the substrate,

b) a second zone, linked to a fixed zone of the substrate, this second zone forming at least a pivot link of the mobile mass in relation to said substrate, and having a thickness less or equal to that of the mobile mass and being linked to it, the axis (H) of the pivot link being placed between the first plane (N1) and the second plane (N2), and parallel to each of them, this second zone having, along a direction perpendicular to the substrate plane, a lower part and an upper part, at least one of these parts being in the first plane (N1) or in the second plane (N2), known as plane common to the first and second zones,

c) a third zone, called thin zone area, of a lesser thickness than that of the second zone, forming at least a suspended type strain gauge, for the detection of the movement of the mobile mass around the axis of the pivot link, this third zone having, along a direction perpendicular to the substrate plane, a lower part and an upper part, one of these parts being in the plane common to the first and second zones, and this third zone;

extending in a plane parallel to the substrate plane not containing the axis of the pivot link,

extending perpendicularly to the rotation axis of the pivot link,

being linked to the mobile mass on the one side and to the substrate on the other.

2. Sensor according to claim 1, the second zone:

having a width, along the direction of the pivot axis H, less than the width of the mobile mass along this direction;

or including two extended arms, placed on either side of the mobile mass or in a gap made in this mobile mass.

3. Sensor according to claim 1, the mobile mass having a thickness strictly greater than that of the pivot zone.

4. Sensor according to claim 1, the third zone and the first zone:

having a common plane, which is the second plane of the mass and being situated on the same side in relation to this plane,

or having a common plane, which is the second plane of the mass, and being situated on both sides of this plane.

5. Sensor according to claim 1, the axis (H) of the pivot link being in a plane parallel to the first plane (N1) and to the second plane (N2) of the sensor, going through the center of gravity (G) of the mobile mass.

6. Sensor according to claim 1, the application points (P) of the strains produced by the mobile mass on each of the gauges being vertical to the pivot axis (H), i.e. in a perpendicular plane to each of the first plane (N1) and second plane (N) and containing the axis (H) of the pivot link.

7. Sensor according to claim 1, the third zone including at least two strain gauges, situated in an anti-symmetrical fashion in relation to each other and in relation:

to a plane perpendicular to the first and second planes (N1, N2) of the mobile mass and containing the torsion axis (H),

and to a plane perpendicular to the torsion axis.

8. Sensor according to claim 1, the strain gauge(s) being made of a piezo-resistant material such as monocrystalline silicon or polycrystalline silicon or of silicon nanowires or carbon nanotubes or of monocrystalline or polycrystalline SiGe.

9. Sensor according to claim 8, the gauge(s) being of the single branch or double branch type.

10. Sensor according to claim 1, the strain gauge(s) including at least a detection resonator, including at least a vibrating blade vibrating in a plane parallel to the first and second planes (N1, N2), a means of excitation and a means of detecting the vibration.

11. Sensor according to claim 10, the strain gauge(s) including electrostatic means to excite the vibrating blade and/or to detect of the resonance.

12. Sensor according to claim 11, the strain gauge(s) including at least one electrode placed, in relation to the vibrating blade, in the direction of the vibration.

13. Sensor according to claim 10, the strain gauge(s) including piezo-resistive means of resonance detection, placed on the vibrating blade.

14. Sensor according to claim 1, also including means to trigger movement of the mobile mass.

15. Sensor according to claim 14, with the means to trigger movement of the mobile mass including:

an electrode present on, or in, the substrate with regard to one of the sides of the mobile mass,

or a layer of conductive material placed on the mobile mass and linked to the substrate, electrically insulated from the mobile mass by an insulation layer, forming a bimetal with the mobile mass;

or a layer of piezo-electric material deposited on the mobile mass and linked to the substrate, electrically insulated from the mobile mass by an insulation layer.

16. Sensor according to claim 1, the mobile mass also comprising on its surface means to select at least a type of molecule capable of being surface adsorbed or absorbed, for example radicals of given molecules or a layer of material sensitive to a single type of molecule.