# US 7,277,563 B2 · Capacitive micro pressure sensing member and fingerprint sensor using the same

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- Number: US 7,277,563 B2
- Document ID: US7277563B2
- Status: Granted
- Kind: B2
- Application number: 10/638,371
- Filed: 2003-08-12
- Published: 2004-03-11
- Granted: 2007-10-02
- Earliest claimed: 2002-08-13
- Assignees: Lightuning Tech. Inc.
- Inventors: Bruce C. S. Chou
- Web page: https://patentgrep.com/patent/US7277563B2

## CPC

- G01L 1/146: {for measuring force distributions, e.g. using force arrays (G01L1/148 takes precedence)}
- G01L 1/148: {using semiconductive material, e.g. silicon}
- G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G)

## Abstract

A capacitive micro pressure sensing member and a fingerprint sensor using the same. The sensing member includes a substrate, a first suspended structure, a first protrusion structure, and a second suspended structure. The first suspended structure is located above the substrate and includes a suspended thin plate and at least one compliant suspension arm connected to the suspended thin plate, which is movable so that a distance from the suspended thin plate to the substrate is changed. The first protrusion structure is arranged at a center portion of a top surface of the suspended thin plate. The second suspended structure is arranged on a top surface of the first protrusion structure with a center portion of the second suspended structure contacting the first protrusion structure. The second suspended structure covers the first suspended structure to form a sealed chamber together with the substrate.

## Claims

### Claim 1

A capacitive micro pressure sensing member, comprising:
a substrate;
a first suspended structure located above the substrate and including a suspended thin plate and at least one compliant suspension arm connected to the suspended thin plate;
a first protrusion structure arranged at a center portion of a top surface of the suspended thin plate; and
a second suspended structure arranged on a top surface of the first protrusion structure with a center portion of the second suspended structure contacting the first protrusion structure, the second suspended structure covering the first suspended structure to form a sealed chamber together with the substrate, wherein the suspended thin plate is movable in the sealed chamber relative to the substrate so that a distance from the suspended thin plate to the substrate is changed.

### Claim 2 (depends on 1)

The capacitive micro pressure sensing member according to claim 1, wherein a floating electrode is included in the suspended thin plate to form a sense capacitor between the substrate and the floating electrode.

### Claim 3 (depends on 1)

The capacitive micro pressure sensing member according to claim 1, wherein the second suspended structure is a diaphragm structure.

### Claim 4 (depends on 1)

The capacitive micro pressure sensing member according to claim 1, further comprising a second protrusion structure arranged on a top surface of the second suspended structure to serve as a stress concentration point for pressure application.

### Claim 5

A fingerprint sensor, comprising:
a sensor substrate; and
a plurality of capacitive micro pressure sensing members arranged on a top surface of the sensor substrate to form a pressure sensing members array, wherein each of the capacitive micro pressure sensing members comprises:
a member substrate;
a first suspended structure located above the member substrate and including a suspended thin plate and at least one compliant suspension and connected to the suspended thin plate;
a first protrusion structure arranged at a center portion of a top surface of the suspended thin plate; and
a second suspended structure arranged on a top surface of the first protrusion structure with a center portion of the second suspended structure contacting the first protrusion structure, the second suspended structure covering the first suspended structure to form a sealed chamber together with the member substrate, wherein the suspended thin plate is movable in the sealed chamber relative to the member substrate so that a distance from the suspended thin plate to the member substrate is changed.

### Claim 6 (depends on 5)

The fingerprint sensor according to claim 5, wherein the sensor substrate is a silicon substrate.

### Claim 7 (depends on 5)

The fingerprint sensor according to claim 5, wherein a floating electrode is included in the suspended thin plate to form a sense capacitor between the member substrate and the floating electrode.

### Claim 8 (depends on 5)

The fingerprint sensor according to claim 5, wherein the second suspended structure is a diaphragm structure.

### Claim 9 (depends on 5)

The fingerprint sensor according to claim 5, wherein each of the capacitive micro pressure sensing members further comprises a second protrusion structure arranged on a top surface of the second suspended structure to serve as a stress concentration point for pressure application.