Bibliographic Details
| Title: |
MAGNETORESISTIVE SENSOR AND MANUFACTURING METHOD THEREOF |
| Document Number: |
20130000136 |
| Publication Date: |
January 3, 2013 |
| Appl. No: |
13/608965 |
| Application Filed: |
September 10, 2012 |
| Abstract: |
A magnetoresistive element formed by a strip of magnetoresistive material which extends on a substrate of semiconductor material having an upper surface. The strip comprises at least one planar portion which extends parallel to the upper surface, and at least one transverse portion which extends in a direction transverse to the upper surface. The transverse portion is formed on a transverse wall of a dig. By providing a number of magnetoresistive elements perpendicular to one another it is possible to obtain an electronic compass that is insensitive to oscillations with respect to the horizontal plane parallel to the surface of the Earth. |
| Inventors: |
Vigna, Benedetto (Pietrapertosa, IT); Sassolini, Simone (Vidigulfo, IT); Baldo, Lorenzo (Bareggio, IT); Procopio, Francesco (Sedriano, IT) |
| Assignees: |
STMICROELECTRONICS S.R.L. (Agrate Brianza, IT) |
| Claim: |
1. A sensor, comprising: a substrate of semiconductor material having an upper surface, a first sloping wall inclined with respect to said upper surface and extending longitudinally in a first direction, and a second sloping wall inclined with respect to said upper surface and extending longitudinally in a second direction substantially perpendicular to the first direction; a first plurality of magnetoresistive elements including a plurality of planar portions extending substantially parallel to said upper surface, and a plurality of transverse portions extending on said first sloping wall, transversally to said upper surface; and a second plurality of magnetoresistive elements including a plurality of planar portions extending substantially parallel to said upper surface, and a plurality of transverse portions extending on said second sloping wall, transversally to said upper surface. |
| Claim: |
2. A sensor according to claim 1, wherein the magnetoresistive elements of said first plurality are connected to form a first Wheatstone bridge for detecting a magnetic field parallel to said upper surface and perpendicular to said second direction. |
| Claim: |
3. A sensor according to claim 2, wherein the magnetoresistive elements of said second plurality are connected to form a second Wheatstone bridge for detecting a magnetic field parallel to said upper surface and to said second direction. |
| Claim: |
4. A sensor according to claim 1, wherein said planar portions and said transverse portions each have a respective area, a ratio of the areas of the transverse portions and the areas of the planar portions being selected to cause said sensor to be insensitive to a magnetic field directed in a third direction, perpendicular to said first and second directions. |
| Claim: |
5. A sensor according to claim 1, further comprising an inertial sensor formed in a wafer of semiconductor material bonded to said substrate, the substrate being configured to be a protective cap for the inertial sensor. |
| Claim: |
6. A sensor according to claim 1, wherein the magnetoresistive elements of said first plurality are arranged substantially parallel to the second direction and the magnetoresistive elements of said second plurality are arranged substantially parallel to the first direction. |
| Claim: |
7. An electronic compass, comprising: a sensor that includes: a substrate of semiconductor material having an upper surface, a first sloping wall inclined with respect to said upper surface and extending longitudinally in a first direction, and a second sloping wall inclined with respect to said upper surface and extending longitudinally in a second direction substantially perpendicular to the first direction; a first plurality of magnetoresistive elements including a plurality of planar portions extending substantially parallel to said upper surface, and a plurality of transverse portions extending on said first sloping wall, transversally to said upper surface; and a second plurality of magnetoresistive elements including a plurality of planar portions extending substantially parallel to said upper surface, and a plurality of transverse portions extending on said second sloping wall, transversally to said upper surface; and a calculation unit coupled to said sensor and configured to calculate an angle of a magnetic field component parallel to said upper surface. |
| Claim: |
8. A compass according to claim 7, wherein the magnetoresistive elements of said first plurality are connected to form a first Wheatstone bridge for detecting a magnetic field parallel to said upper surface and perpendicular to said second direction. |
| Claim: |
9. A compass according to claim 8, wherein the magnetoresistive elements of said second plurality are connected to form a second Wheatstone bridge for detecting a magnetic field parallel to said upper surface and to said second direction. |
| Claim: |
10. A compass according to claim 7, wherein said planar portions and said transverse portions each have a respective area, a ratio of the areas of the transverse portions and the areas of the planar portions being selected to cause said sensor to be insensitive to a magnetic field directed in a third direction, perpendicular to said first and second directions. |
| Claim: |
11. A compass according to claim 7, further comprising an inertial sensor formed in a wafer of semiconductor material bonded to said substrate, the substrate being configured to be a protective cap for the inertial sensor. |
| Claim: |
12. A compass according to claim 7, wherein the magnetoresistive elements of said first plurality are arranged substantially parallel to the second direction and the magnetoresistive elements of said second plurality are arranged substantially parallel to the first direction. |
| Claim: |
13. A process, comprising: forming a substrate of semiconductor material having a upper surface; forming in the substrate a first sloping wall inclined with respect to said upper surface and extending longitudinally in a first direction; forming in the substrate a second sloping wall inclined with respect to said upper surface and extending longitudinally in a second direction substantially perpendicular to the first direction; forming a first plurality of magnetoresistive elements including a plurality of planar portions extending substantially parallel to said upper surface, and a plurality of transverse portions extending on said first sloping wall, transversally to said upper surface; and forming a second plurality of magnetoresistive elements including a plurality of planar portions extending substantially parallel to said upper surface, and a plurality of transverse portions extending on said second sloping wall, transversally to said upper surface. |
| Claim: |
14. A process according to claim 13, wherein forming the first sloping wall comprises forming a recess in said substrate. |
| Claim: |
15. A process according to claim 14, wherein forming the recess comprises etching the substrate using TMAH (tetramethylammonium hydroxide). |
| Claim: |
16. A process according to claim 14, wherein forming the first plurality of magnetoresistive elements: depositing a mask having windows extending on said recess and on said upper surface; depositing a magnetoresistive layer on said mask and in said recess, wherein said magnetoresistive layer penetrates into said windows; and lifting off said mask and said magnetoresistive layer except at portions of said magnetoresistive layer in said windows. |
| Claim: |
17. A process according to claim 13, wherein said magnetoresistive layer is of a Fe—Ni alloy. |
| Current U.S. Class: |
33/355/R |
| Current International Class: |
01; 01; 01 |
| Accession Number: |
edspap.20130000136 |
| Database: |
USPTO Patent Applications |
