CAPACITIVE SENSOR DEVICE AND A METHOD OF SENSING ACCELERATIONS

• US 20110169109A1
• Filed: 09/14/2009
• Published: 07/14/2011
• Est. Priority Date: 09/15/2008
• Status: Active Grant

• Current Assignee: III Holdings 12, LLC (Intellectual Ventures LLC)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Langereis, Geert
• Granted Patent: US 9,128,114 B2
• Time in Patent Office: Days
• US Class Current: 257/418
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type

Abstract

The invention relates to a capacitive sensor device 100. The capacitive sensor device (100) comprises a substrate (401), a first electrode (101) coupled to the substrate (401, a second electrode (102) coupled to the substrate (401) and a movable element (103). The movable element (103) is capacitively coupled to the first electrode (101), the moveable element (103) and the first electrode (101) representing a first capacitor (104). The movable element (103) is capacitively coupled to the second electrode (102), the moveable element (103) and the second electrode (102) representing a second capacitor (105). The movable element (103) is movable between the first electrode (101) and the second electrode (102) in such a manner, that an electrical impedance between the first electrode (101) and the second electrode (102) is changeable due to a change of a position of the movable element (103). The movable element (103) is decoupled from the substrate (401), in particular to a signal line.

Claims

1. A capacitive sensor device, comprising:

a substrate;

a first electrode coupled to the substrate;

a second electrode coupled to the substrate; and

a movable element;

wherein the movable element is capacitively coupled to the first electrode, the moveable element and the first electrode effecting a first capacitor;

wherein the movable element is capacitively coupled to the second electrode, the moveable element and the second electrode effecting a second capacitor;

wherein the movable element is movable between the first electrode and the second electrode in such a manner, that an electrical impedance between the first electrode and the second electrode is changeable due to a change of a position of the movable element;

wherein the movable element is decoupled from the substrate.

2. The capacitive sensor device of claim 1;

wherein the movable element is galvanically decoupled from the substrate.

3. The capacitive sensor device of claim 1;

wherein a first distance between the first electrode and the movable element corresponds to the position of the movable element.

4. The capacitive sensor device of claim 1;

wherein a second distance between the second electrode and the movable element corresponds to the position of the movable element.

5. The capacitive sensor device of claim 1;

wherein the first capacitor and the second capacitor are connected in series.

6. The capacitive sensor device of claim 1;

wherein at least one of the first capacitor and the second capacitor comprises a first partial capacitor and a second partial capacitor;

wherein the first partial capacitor and the second partial capacitor are connected in parallel.

7. The capacitive sensor device of claim 1;

wherein at least a portion of the moveable element and a portion of at least one of the first electrode and the second electrode interidigitate with each other.

8. The capacitive sensor device of claim 7;

wherein at least one of the first electrode and the second electrode comprise at least one electrode finger protruding in the direction to the movable element;

wherein the movable element comprises at least one movable finger protruding in the direction of the first electrode or in the direction of the second electrode;

wherein the electrode finger and the movable finger interdigitate with each other;

wherein the electrode finger and the movable finger are capacitively coupled with each other.

9. Method of producing a capacitive sensor device, the method comprising:

providing a substrate;

forming a buried oxide layer on the substrate;

forming a top silicon layer on the buried oxide layer;

etching holes and trenches in the top silicon layer, wherein a pattern of the holes and trenches are defined by a mask;

removing the buried oxide layer located below the top silicon layer according to the pattern.

10. A method of sensing accelerations, the method comprising:

capacitively coupling a movable element to a first electrode, the moveable element and the first electrode effecting a first capacitor;

capacitively coupling the movable element to a second electrode, the moveable element and the second electrode effecting a second capacitor;

moving the movable element between the first electrode and the second electrode in such a manner, that an electrical impedance between the first electrode and the second electrode is changeable due to a change of a position of the movable element; and

decoupling the movable element from a substrate of the sensor device.

11. The method according to claim 10,

wherein the movable element is galvanically decoupled from the substrate.