Magnetoresistive semiconductor pressure sensors and fingerprint identification/verification sensors using same

• US 20050199071A1
• Filed: 05/05/2005
• Published: 09/15/2005
• Est. Priority Date: 07/20/1999
• Status: Active Grant

• Current Assignee: Lenovo PC International Limited (Lenovo Group Ltd.)
• Original Assignee: Fidelica Microsystems, Inc. (Petters Group Worldwide LLC)
• Inventors: Ganapathi, Srinivasan K.
• Granted Patent: US 7,073,397 B2
• Time in Patent Office: Days
• US Class Current: 73/754
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G01L 1/125 by using magnetostrictive means magnetostrictive sensors H10N35/101

Abstract

The invention provides an apparatus for sensing pressure that comprises a substrate and a sensor formed on the substrate. The sensor is adapted to sense pressure applied thereto and includes a support structure smaller than the substrate to result in a cavity above a portion of the substrate and a magnetoresistive sensor formed over the support structure.

Claims

1. An apparatus for sensing pressure comprising:

a substrate;

a sensor formed on the substrate that is adapted to sense pressure applied thereto, the sensor including;

a support structure that is smaller than the substrate, thereby providing a cavity above a portion of the substrate; and

a magnetoresistive sensor formed over the support structure.

2. An apparatus according to claim 1 wherein the magnetoresistive sensor is an AMR sensor.

3. An apparatus according to claim 1 wherein the magnetoresistive sensor is a GMR sensor.

4. An apparatus according to claim 1 wherein the support structure is a deformable beam.

5. An apparatus according to claim 4 wherein the deformable beam is formed of semiconductor or insulator layers.

6. An apparatus according to claim 4 wherein the deformable beam is formed of a conductor.

7. An apparatus according to claim 4 wherein the deformable beams has a length of between 2 microns to several hundred microns.

8. An apparatus according to claim 7 wherein the deformable beam has a thickness ranging from 0.1 micron to 20 microns.

9. An apparatus according to claim 7 wherein the width of the beam ranges from 1 microns to several microns

10. An apparatus according to claim 1 wherein a plurality of sensors arranged in an array are formed on the substrate, each of the plurality of sensors including:

a support structure that is smaller than the substrate, thereby providing a cavity above a portion of the substrate; and

a magnetoresistive sensor formed over the support structure.

11. An apparatus according to claim 10 wherein each magnetoresistive sensor is an AMR sensor.

12. An apparatus according to claim 10 wherein each magnetoresistive sensor is a GMR sensor.

13. An apparatus according to claim 10 wherein each of the support structures is a deformable beam.

14. An apparatus according to claim 13 wherein each magnetoresistive sensor is an AMR sensor.

15. An apparatus according to claim 13 wherein each magnetoresistive sensor is a GMR sensor.

16. An apparatus according to claim 1 wherein a change in resistance upon the application of pressure is measured using a current that is adapted to detect the change in resistance.

17. An apparatus according to claim 10 wherein the plurality of sensors each detect pressure applied during the obtaining of a fingerprint and the resistance sensed by each of the plurality of sensors is used to determine the fingerprint, certain of the sensors detecting ridges of the fingerprint, and other ones of the sensors detecting valleys of the fingerprint.