COLLAPSED MODE CAPACITIVE SENSOR

• US 20120133005A1
• Filed: 06/30/2010
• Published: 05/31/2012
• Est. Priority Date: 07/02/2009
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Van Lippen, Twan, Woltjer, Reinout, Langeries, Geert
• Granted Patent: US 8,742,517 B2
• Time in Patent Office: Days
• US Class Current: 257/416
• CPC Class Codes: B06B 1/0292 Electrostatic transducers, e.g. electret-type
• CPC Class Codes: G01L 9/0072 using variations in capacitance
• CPC Class Codes: H04R 19/04 Microphones H04R19/01 takes precedence
• CPC Class Codes: H04R 31/006 Interconnection of transducer parts of diaphragm and outer suspension by moulding H04R31/003
• CPC Class Codes: H04R 7/12 Non-planar diaphragms or cones

Abstract

A capacitive sensor is configured for collapsed mode, e.g. for measuring sound or pressure, wherein the moveable element is partitioned into smaller sections. The capacitive sensor provides increased signal to noise ratio.

Claims

1. Capacitive sensor for measuring a physical parameter, comprising:

a moveable membrane forming an upper electrode, and

a bottom layer forming a bottom electrode,

wherein the sensor is configured to be driven in a collapsed mode in which the moveable membrane is brought into contact with the bottom layer, a magnitude of an area of contact between the moveable membrane and the bottom layer being configured to depend on the physical parameter, an output signal of the sensor depending on the magnitude of the contact area, and

wherein the moveable membrane is partitioned into a plurality of smaller segments, each segment being configured for contact with the bottom layer, the magnitude of the contact area of each of the smaller segments depending on the physical parameter, the output signal of the sensor depending on the total amount of magnitudes of the areas of contact between the segments of the moveable membrane and the bottom layer.

2. Capacitive sensor according to claim 1,

wherein each segment of the moveable membrane is formed as an upper part of a blister shaped part surrounding a closed space.

3. Capacitive sensor according to claim 1,

further comprising a plurality of supports for supporting the moveable membrane, the segments of the membrane being formed in the sections between the supports.

4. Capacitive sensor according to claim 1,

wherein the moveable membrane comprises the upper electrode as one of a conductive layer arranged internally and at the upper or lower outside of the membrane.

5. Capacitive sensor according to claim 1,

further comprising an electrically insulating layer provided between the upper electrode and the bottom electrode.

6. Capacitive sensor according to claim 1,

wherein the sensor is an electro-acoustical transducer.

7. Capacitive sensor according to claim 1,

wherein the sensor is a pressure sensor.

8. Method for fabricating a capacitive sensor for measuring a physical parameter, comprising

generating a bottom layer forming a bottom electrode,

generating a layer part serving as a plurality of membrane supports and a sacrificial layer on top of the bottom layer,

generating an upper layer serving as a membrane forming an upper electrode, and

etching the sacrificial layer between the membrane support so as to provide a plurality of cavities below the membrane serving as membrane segments.

9. A method of fabricating a capacitive sensor as in claim 8 which is fabricated using thin-film silicon processing techniques