Three axis magnetic field sensor

Abstract

Three bridge circuits ( 101, 111, 121 ), each include magnetoresistive sensors coupled as a Wheatstone bridge ( 100 ) to sense a magnetic field ( 160 ) in three orthogonal directions ( 110, 120, 130 ) that are set with a single pinning material deposition and bulk wafer setting procedure. One of the three bridge circuits ( 121 ) includes a first magnetoresistive sensor ( 141 ) comprising a first sensing element ( 122 ) disposed on a pinned layer ( 126 ), the first sensing element ( 122 ) having first and second edges and first and second sides, and a first flux guide ( 132 ) disposed non-parallel to the first side of the substrate and having an end that is proximate to the first edge and on the first side of the first sensing element ( 122 ). An optional second flux guide ( 136 ) may be disposed non-parallel to the first side of the substrate and having an end that is proximate to the second edge and the second side of the first sensing element ( 122 ).

The invention claimed is: 
     
       1. A ferromagnetic thin-film based magnetic field sensor comprising:
 a substrate having a planar surface; and 
 a first magnetoresistive sensor comprising:
 a first sensing element having a first side and second sides lying parallel to the planar surface of the substrate, the first sensing element having a second side opposed to the first side and having wherein the first side is defined by at least first and second opposed edges; and 
 a first flux guide comprising a soft ferromagnetic material, a first flux guide side, and a second flux guide side, wherein the second flux guide side is orthogonal to the first flux guide side, the second flux guide side is disposed non-parallel to the first side of the first sensing element, and having the second flux guide side includes an end that is proximate to the first edge and the first side of the first sensing element, 
 
 wherein the first side of the first sensing element extends in a first plane, the planar surface of the substrate extends in a second plane parallel to the first plane, and the first flux guide side extends in a third plane parallel to and spaced apart from each of the first and second planes; and 
 a second magnetoresistive sensor comprising:
 a second sensing element having first and second sides lying parallel to the planar surface of the substrate, wherein the first side of the second sensing element extends in the first plane, 
 
 wherein the first magnetoresistive sensor detects a magnetic field in a first direction orthogonal to the planar surface, and the second magnetoresistive sensor detects a magnetic field in a second direction parallel to the planar surface. 
 
     
     
       2. The ferromagnetic thin-film based magnetic field sensor of  claim 1  wherein the first magnetoresistive sensor further comprises:
 a second flux guide comprising a soft ferromagnetic material disposed non-parallel to the first side of the first sensing element and having an end that is proximate to the second edge and the second side of the first sensing element. 
 
     
     
       3. The ferromagnetic thin-film based magnetic field sensor of  claim 1  wherein the first magnetoresistive sensor comprises one of an array of ferromagnetic thin-film based magnetic field sensors. 
     
     
       4. The ferromagnetic thin-film based magnetic field sensor of  claim 1  wherein the first flux guide comprises a high aspect ratio structure non-parallel to the first sense element. 
     
     
       5. The ferromagnetic thin-film based magnetic field sensor of  claim 1  wherein the first flux guide comprises a U shaped element. 
     
     
       6. The ferromagnetic thin-film based magnetic field sensor of  claim 1  wherein the first flux guide includes a flared end. 
     
     
       7. The ferromagnetic thin-film based magnetic field sensor of  claim 1  further comprising a material disposed adjacent the first flux guide and comprising one of the group consisting of a high conductivity metal and a dielectric material. 
     
     
       8. The ferromagnetic thin-film based magnetic field sensor of  claim 1  wherein the first flux guide comprises a box shaped structure. 
     
     
       9. The ferromagnetic thin-film based magnetic field sensor of  claim 1  wherein at least one of the first and second flux guides is disposed substantially orthogonal to the plane of the substrate. 
     
     
       10. The ferromagnetic thin-film based magnetic field sensor of  claim 1  wherein at least one of the first and second flux guides is disposed at an angle of between 45 degrees and 90 degrees to the plane of the substrate. 
     
     
       11. The ferromagnetic thin-film based magnetic field sensor of  claim 1  further comprising: a second magnetoresistive sensor having a second sensing element for detecting a magnetic field in a second direction orthogonal to the first direction; and, wherein the magnetic field sensor further comprises:
 a third magnetoresistive sensor having a third sensing element orthogonal to the second sensing element for detecting comprising:
 a third sensing element having first and second sides lying parallel to the planar surface of the substrate, wherein the first side of the third sensing element extends in the first plane, and 
 wherein the third magnetoresistive sensor detects a magnetic field in a third direction orthogonal to the first and second directions, wherein the third sensing element is in a plane with the first and second sensing elements direction is parallel to the planar surface. 
 
 
     
     
       12. The ferromagnetic thin-film based magnetic field sensor of  claim 11 , wherein each of the first, second, and third sensor sensing elements each comprise an imbalanced synthetic antiferromagnet formed with first and second ferromagnetic layers separated by a spacer layer, where wherein the first and second ferromagnetic layers have different magnetic moments. 
     
     
       13. The ferromagnetic thin-film based magnetic field sensor of  claim 1  further comprising:, wherein the first magnetoresistive sensor comprising: further comprises a first pinned layer; a,
 wherein the second magnetoresistive sensor comprising: further comprises a second pinned layer;, and a the second sensing element is formed on the second pinned layer;, and 
 wherein the magnetic field sensor further comprises: 
 a third magnetoresistive sensor comprising:
 a third pinned layer; and 
 a third sensing element formed on the third pinned layer and, which is orthogonal to a pinned layer of the second sensing element;, wherein the third sensing element includes first and second sides lying parallel to the planar surface of the substrate, and wherein the first side of the third sensing element extends in the first plane, and  
 
 
 wherein the second and third pinned layers are oriented about 45 degrees to the first pinned layer. 
 
     
     
       14. The ferromagnetic thin-film based magnetic field sensor of claim  13  1, wherein the first magnetic tunnel junction magnetoresistive sensor further comprises:
 a second flux guide having a first flux guide side and a second flux guide side, wherein the second flux guide side is orthogonal to the first flux guide side, the second flux guide side is disposed non-parallel to the first side of the first sensing element, and having an end that of the second flux guide side is proximate to the second edge and the second side of the first sensing element, 
 wherein the first flux guide side of the second flux guide is disposed in a fourth plane parallel to and spaced apart from each of the first, second, and third planes. 
 
     
     
       15. The ferromagnetic thin-film based magnetic field sensor of  claim 14 , wherein the first and second flux guides each comprise an aspect ratio greater than 10. 
     
     
       16. A ferromagnetic thin-film based magnetic field sensor comprising:
 a first bridge circuit comprising first, second, third, and fourth magnetic tunnel junction sensors coupled as a Wheatstone bridge for sensing a magnetic field orthogonal to the a plane of the sensors; 
 the first magnetic tunnel junction sensor comprising:
 a first reference layer; and 
 a first sensing element formed on the first reference layer, the first sensing element having first and second edges and first and second sides; and 
 a first flux guide comprising a soft ferromagnetic material disposed orthogonal to and spaced from the first edge and the first side of the first sensing element; 
 
 the second magnetic tunnel junction sensor comprising:
 a second reference layer; and 
 a second sensing element formed on the second reference layer, the second sensing element having first and second edges and first and second sides; and 
 a second flux guide comprising a soft ferromagnetic material disposed orthogonal to and spaced from the first edge and the first side of the second sensing element; 
 
 the third magnetic tunnel junction sensor comprising:
 a third reference layer; and 
 a third sensing element formed on the third reference layer, the third sensing element having first and second edges and first and second sides; and 
 a third flux guide comprising a soft ferromagnetic material disposed orthogonal to and spaced from the first edge and the first side of the third sensing element; 
 
 the fourth magnetic tunnel junction sensor comprising:
 a fourth reference layer; and 
 a fourth sensing element formed on the fourth reference layer, the fourth sensing element having first and second edges and first and second sides; and 
 a fourth flux guide disposed orthogonal to and spaced from the first edge and the first side of the fourth sensing element. 
 
 
     
     
       17. The ferromagnetic thin-film based magnetic field sensor of  claim 16 , wherein the first, second, third, and fourth magnetic tunnel junction sensors further comprise fifth, sixth, seventh, and eighth flux guides disposed orthogonal to and spaced from the second edge and the second side of the first, second, third, and fourth sensing elements, respectively. 
     
     
       18. The ferromagnetic thin-film based magnetic field sensor of  claim 16 , further comprising:
 a second bridge circuit comprising fifth, sixth, seventh, and eighth magnetic tunnel junction sensors coupled as a second Wheatstone bridge for sensing a magnetic field in a second direction orthogonal to the first direction; and 
 a third bridge circuit comprising ninth, tenth, eleventh, and twelfth magnetic tunnel junction sensors coupled as a third Wheatstone bridge for sensing a magnetic field in a third direction orthogonal to the first and second directions. 
 
     
     
       19. The ferromagnetic thin-film based magnetic field sensor of  claim 16  wherein each of the first, second, third, and fourth sensors comprises an array of sense elements. 
     
     
       20. A method of testing the functionality and sensitivity of a response of the Z axis of a ferromagnetic thin-film magnetic field sensor including a substrate having a planar surface, and a first magnetoresistive sensor comprising a sensing element having a first side lying parallel to the planar surface of the substrate, the sensing element having a second side opposed to the first side and having first and second opposed edges, a first flux guide comprising a soft ferromagnetic material disposed non-parallel to the first side of the substrate and having an end that is proximate to the first edge and the first side of the sensing element, and a metal line formed adjacent contiguous to the flux guide, the method comprising:
 applying a current through the metal line to provide a magnetic field with a component parallel to the plane of the flux guides.   
     
     
       21. The method of  claim 20 , further comprising:
 applying a current pulse through the metal line to reset the flux guide domain structure.   
     
     
       22. The ferromagnetic thin-film based magnetic field sensor of claim 14, wherein the first flux guide is disposed closer to the first side of the first sensing element than the second side of the first sensing element, and the second flux guide is disposed closer to the second side of the first sensing element than the first side of the first sensing element. 
     
     
       23. The ferromagnetic thin-film based magnetic field sensor of claim 1, wherein the first flux guide side includes a first dimension and a second dimension longer than the first dimension, the second flux guide side includes a third dimension and a fourth dimension longer than the third dimension, and the third dimension is orthogonal to the first dimension. 
     
     
       24. The ferromagnetic thin-film based magnetic field sensor of claim 23, wherein the second dimension and the fourth dimension are equal. 
     
     
       25. The ferromagnetic thin-film based magnetic field sensor of claim 1, wherein the first flux guide includes a width dimension, a height dimension greater than the width dimension, and a depth dimension greater than the height dimension. 
     
     
       26. The ferromagnetic thin-film based magnetic field sensor of claim 25, wherein the second flux guide side is defined by the height dimension and the depth dimension. 
     
     
       27. The ferromagnetic thin-film based magnetic field sensor of claim 26, wherein the first flux guide side is defined by the width dimension and the depth dimension. 
     
     
       28. The ferromagnetic thin-film based magnetic field sensor of claim 1, wherein the third plane is in between the first and second planes. 
     
     
       29. The ferromagnetic thin-film based magnetic field sensor of claim 1, wherein the first plane is spaced apart from the second plane. 
     
     
       30. The ferromagnetic thin-film based magnetic field sensor of claim 1, wherein the first flux guide side is closer to the first side of the sensing element than the second side of the sensing element. 
     
     
       31. The ferromagnetic thin-film based magnetic field sensor of claim 1, wherein an entirety of the first flux guide is positioned closer to the first side of the first sensing element than the second side of the first sensing element. 
     
     
       32. The ferromagnetic thin-film based magnetic field sensor of claim 1, wherein the end of the second flux guide side is closer to the first side of the first sensing element than the second side of the first sensing element. 
     
     
       33. The ferromagnetic thin-film based magnetic field sensor of claim 1, wherein the end of the second flux guide side is closer to the first edge of the first sensing element than the second edge of the first sensing element. 
     
     
       34. The ferromagnetic thin-film based magnetic field sensor of claim 1, wherein an entirety of the first flux guide includes a one-piece construction. 
     
     
       35. The ferromagnetic thin-film based magnetic field sensor of claim 1, wherein the first flux guide is configured to guide a magnetic field orthogonal to the first side of the first sensing element into a plane parallel to the first side of the first sensing element. 
     
     
       36. The ferromagnetic thin-film based magnetic field sensor of claim 1, wherein the first magnetoresistive sensor is formed within a thickness of the substrate. 
     
     
       37. The ferromagnetic thin-film based magnetic field sensor of claim 1, further comprising:
 a third magnetoresistive sensor including:
 a third sensing element having first and second sides lying parallel to the planar surface of the substrate, wherein the first side of the third sensing element extends in the first plane. 
   
     
     
       38. The ferromagnetic thin-film based magnetic field sensor of claim 1, wherein the soft ferromagnetic material includes nickel iron. 
     
     
       39. The magnetic field sensor of claim 1, wherein an entirety of the first flux guide is in between the planar surface and the first sensing element. 
     
     
       40. A ferromagnetic thin-film based magnetic field sensor comprising:
 a substrate having a planar surface;   a first magnetoresistive sensor comprising:
 a first sensing element having first and second sides lying parallel to the planar surface of the substrate, wherein the first side is defined by at least first and second opposed edges; and 
 a first flux guide comprising a high permeability magnetic material, a first flux guide side, and a second flux guide side, wherein the second flux guide side is orthogonal to the first flux guide side, the second flux guide side is disposed non-parallel to the first side of the first sensing element, and the second flux guide side includes an end that is proximate to the first edge and the first side of the first sensing element, 
 wherein the first side of the first sensing element extends in a first plane, the planar surface of the substrate extends in a second plane parallel to the first plane, and the first flux guide side extends in a third plane parallel to and spaced apart from each of the first and second planes; and 
   a second magnetoresistive sensor comprising:
 a second sensing element having first and second sides lying parallel to the planar surface of the substrate, wherein the first side of the second sensing element extends in the first plane, 
 wherein the first magnetoresistive sensor detects a magnetic field in a first direction orthogonal to the planar surface, and the second magnetoresistive sensor detects a magnetic field in a second direction parallel to the planar surface. 
   
     
     
       41. The ferromagnetic thin-film based magnetic field sensor of claim 40, wherein the high permeability magnetic material includes nickel iron. 
     
     
       42. The ferromagnetic thin-film based magnetic field sensor of claim 40, further comprising:
 a third magnetoresistive sensor comprising:
 a third sensing element having first and second sides lying parallel to the planar surface of the substrate, wherein the first side of the third sensing element extends in the first plane, and 
 wherein the third magnetoresistive sensor detects a magnetic field in a third direction orthogonal to the first and second directions. 
   
     
     
       43. The ferromagnetic thin-film based magnetic field sensor of claim 42, wherein each of the first, second, and third sensing elements comprise an imbalanced synthetic antiferromagnet formed with first and second ferromagnetic layers separated by a spacer layer, where the first and second ferromagnetic layers have different magnetic moments. 
     
     
       44. The ferromagnetic thin-film based magnetic field sensor of claim 40, wherein the first magnetoresistive sensor further comprises a first pinned layer,
 wherein the second magnetoresistive sensor further comprises a second pinned layer, and the second sensing element is formed on the second pinned layer, and   wherein the magnetic field sensor further comprises:
 a third magnetoresistive sensor comprising:
 a third pinned layer; and 
 a third sensing element formed on the third pinned layer, which is orthogonal to a pinned layer of the second sensing element, wherein the third sensing element includes first and second sides lying parallel to the planar surface of the substrate, and wherein the first side of the third sensing element extends in the first plane, 
 
   wherein the second and third pinned layers are oriented about 45 degrees to the first pinned layer.   
     
     
       45. The ferromagnetic thin-film based magnetic field sensor of claim 40, wherein the first magnetoresistive sensor further comprises:
 a second flux guide having a first flux guide side and a second flux guide side, wherein the second flux guide side is orthogonal to the first flux guide side, the second flux guide side is disposed non-parallel to the first side of the first sensing element, and an end of the second flux guide side is proximate to the second edge and the second side of the first sensing element,   wherein the first flux guide side of the second flux guide extends in a fourth plane parallel to and spaced apart from each of the first, second, and third planes.   
     
     
       46. The ferromagnetic thin-film based magnetic field sensor of claim 45, wherein the first and second flux guides each comprise an aspect ratio greater than 10. 
     
     
       47. The ferromagnetic thin-film based magnetic field sensor of claim 45, wherein the first flux guide is disposed closer to the first side of the first sensing element than the second side of the first sensing element, and the second flux guide is disposed closer to the second side of the first sensing element than the first side of the first sensing element. 
     
     
       48. The ferromagnetic thin-film based magnetic field sensor of claim 40, wherein the first flux guide side includes a first dimension and a second dimension longer than the first dimension, the second flux guide side includes a third dimension longer than a fourth dimension, wherein the third dimension is orthogonal to the first dimension. 
     
     
       49. The ferromagnetic thin-film based magnetic field sensor of claim 48, wherein the second dimension and the fourth dimension are equal. 
     
     
       50. The ferromagnetic thin-film based magnetic field sensor of claim 40, wherein the third plane is in between the first and second planes. 
     
     
       51. A ferromagnetic thin-film based magnetic field sensor comprising:
 a first bridge circuit comprising first, second, third, and fourth magnetic tunnel junction sensors coupled as a Wheatstone bridge for sensing a magnetic field orthogonal to a plane of the sensors;   the first magnetic tunnel junction sensor comprising:
 a first reference layer; and 
 a first sensing element formed on the first reference layer, the first sensing element having first and second edges and first and second sides; and 
 a first flux guide comprising a high permeability magnetic material disposed orthogonal to and spaced from the first edge and the first side of the first sensing element; 
   the second magnetic tunnel junction sensor comprising:
 a second reference layer; and 
 a second sensing element formed on the second reference layer, the second sensing element having first and second edges and first and second sides; and 
 a second flux guide comprising a high permeability magnetic material disposed orthogonal to and spaced from the first edge and the first side of the second sensing element; 
   the third magnetic tunnel junction sensor comprising:
 a third reference layer; and 
 a third sensing element formed on the third reference layer, the third sensing element having first and second edges and first and second sides; and 
 a third flux guide comprising a high permeability magnetic material disposed orthogonal to and spaced from the first edge and the first side of the third sensing element; 
   the fourth magnetic tunnel junction sensor comprising:
 a fourth reference layer; and 
 a fourth sensing element formed on the fourth reference layer, the fourth sensing element having first and second edges and first and second sides; and 
 a fourth flux guide disposed orthogonal to and spaced from the first edge and the first side of the fourth sensing element. 
   
     
     
       52. The magnetic field sensor of claim 51, wherein the first, second, third, and fourth magnetic tunnel junction sensors further comprise fifth, sixth, seventh, and eighth flux guides disposed orthogonal to and spaced from the second edge and the second side of the first, second, third, and fourth sensing elements, respectively. 
     
     
       53. The ferromagnetic thin-film based magnetic field sensor of claim 51, further comprising:
 a second bridge circuit comprising fifth, sixth, seventh, and eighth magnetic tunnel junction sensors coupled as a second Wheatstone bridge for sensing a magnetic field in a second direction orthogonal to the first direction; and   a third bridge circuit comprising ninth, tenth, eleventh, and twelfth magnetic tunnel junction sensors coupled as a third Wheatstone bridge for sensing a magnetic field in a third direction orthogonal to the first and second directions.   
     
     
       54. The ferromagnetic thin-film based magnetic field sensor of claim 53, wherein the second and third directions are parallel to the plane of sensors. 
     
     
       55. A ferromagnetic thin-film based magnetic field sensor comprising:
 a substrate having a planar surface;   a first magnetoresistive sensor comprising:
 a first sensing element having first and second sides lying parallel to the planar surface of the substrate; and 
 a first flux guide comprising a soft ferromagnetic material, having a first flux guide side and a second flux guide side, wherein the second flux guide side is orthogonal to the first flux guide side, the second flux guide side is disposed non-parallel to the first side of the first sensing element, and the second flux guide side includes an end that is proximate to an edge of the first side of the first sensing element; 
   a second magnetoresistive sensor comprising:
 a second sensing element having first and second sides lying parallel to the planar surface of the substrate; and 
   a third magnetoresistive sensor comprising:
 a third sensing element having first and second sides lying parallel to the planar surface of the substrate, 
   wherein the first magnetoresistive sensor detects a magnetic field in a first direction, the second magnetoresistive sensor detects a magnetic field in a second direction orthogonal to the first direction, and the third magnetoresistive sensor detects a magnetic field in a third direction orthogonal to the first and second directions, wherein the first direction is orthogonal to the planar surface, and the second and third directions are parallel to the planar surface, and   wherein each of the first, second, and third sensing elements includes a sense axis parallel to the planar surface.   
     
     
       56. The ferromagnetic thin-film based magnetic field sensor of claim 55, wherein the first side of the first sensing element is in a first plane, the planar surface of the substrate is in a second plane parallel to the first plane, and the first flux guide side is in a third plane parallel to and spaced apart from each of the first and second planes, and wherein the third plane is in between the first and second planes. 
     
     
       57. The ferromagnetic thin-film based magnetic field sensor of claim 55, wherein an entirety of the first flux guide is positioned closer to the first side of the first sensing element than the second side of the first sensing element. 
     
     
       58. The ferromagnetic thin-film based magnetic field sensor of claim 57, wherein the first magnetoresistive sensor further comprises:
 a second flux guide positioned non-parallel to the first side of the first sensing element,   wherein an entirety of the second flux guide is positioned closer to the second side of the first sensing element than the first side of the first sensing element.   
     
     
       59. The ferromagnetic thin-film based magnetic field sensor of claim 55, wherein an entirety of the first flux guide is positioned in between the first side of the first sensing element and the planar surface of the substrate. 
     
     
       60. The ferromagnetic thin-film based magnetic field sensor of claim 55, wherein the soft ferromagnetic material includes nickel iron. 
     
     
       61. The ferromagnetic thin-film based magnetic field sensor of claim 55, wherein the first flux guide is configured to guide a magnetic field orthogonal to the first side of the first sensing element into a plane parallel to the first side of the first sensing element. 
     
     
       62. The ferromagnetic thin-film based magnetic field sensor of claim 55, wherein the first magnetoresistive sensor is formed within a thickness of the substrate. 
     
     
       63. The ferromagnetic thin-film based magnetic field sensor of claim 55, wherein each of the first, second, and third sensing elements includes an imbalanced synthetic antiferromagnet formed with first and second ferromagnetic layers separated by a spacer layer, where the first and second ferromagnetic layers have different magnetic moments. 
     
     
       64. The ferromagnetic thin-film based magnetic field sensor of claim 55, wherein an entirety of the first flux guide includes a one-piece construction. 
     
     
       65. A ferromagnetic thin-film based magnetic field sensor comprising:
 a substrate having a planar surface;   a first magnetoresistive sensor comprising:
 a first sensing element having first and second sides lying parallel to the planar surface of the substrate; and 
 a first flux guide comprising a high permeability magnetic material, having a first flux guide side and a second flux guide side, wherein the second flux guide side is orthogonal to the first flux guide side, the second flux guide side is disposed non-parallel to the first side of the first sensing element, and the second flux guide side includes an end that is proximate to an edge of the first side of the first sensing element; 
   a second magnetoresistive sensor comprising:
 a second sensing element having first and second sides lying parallel to the planar surface of the substrate; and 
   a third magnetoresistive sensor comprising:
 a third sensing element having first and second sides lying parallel to the planar surface of the substrate, 
   wherein the first magnetoresistive sensor detects a magnetic field in a first direction, the second magnetoresistive sensor detects a magnetic field in a second direction orthogonal to the first direction, and the third magnetoresistive sensor detects a magnetic field in a third direction orthogonal to the first and second directions, wherein the first direction is orthogonal to the planar surface, and the second and third directions are parallel to the planar surface, and   wherein each of the first, second, and third sensing elements includes a sense axis parallel to the planar surface.   
     
     
       66. The ferromagnetic thin-film based magnetic field sensor of claim 65, wherein the first side of the first sensing element is in a first plane, the planar surface of the substrate is in a second plane parallel to the first plane, and the first flux guide side is in a third plane parallel to and spaced apart from each of the first and second planes, and wherein the third plane is in between the first and second planes. 
     
     
       67. The ferromagnetic thin-film based magnetic field sensor of claim 65, wherein an entirety of the first flux guide is positioned closer to the first side of the first sensing element than the second side of the first sensing element. 
     
     
       68. The ferromagnetic thin-film based magnetic field sensor of claim 67, wherein the first magnetoresistive sensor further comprises:
 a second flux guide positioned non-parallel to the first side of the first sensing element,   wherein an entirety of the second flux guide is positioned closer to the second side of the first sensing element than the first side of the first sensing element.   
     
     
       69. The ferromagnetic thin-film based magnetic field sensor of claim 65, wherein an entirety of the first flux guide is positioned in between the first side of the first sensing element and the planar surface of the substrate. 
     
     
       70. The ferromagnetic thin-film based magnetic field sensor of claim 65, wherein the high permeability magnetic material includes nickel iron. 
     
     
       71. The ferromagnetic thin-film based magnetic field sensor of claim 65, wherein the first flux guide is configured to guide a magnetic field orthogonal to the first side of the first sensing element into a plane parallel to the first side of the first sensing element. 
     
     
       72. The ferromagnetic thin-film based magnetic field sensor of claim 65, wherein the first magnetoresistive sensor is formed within a thickness of the substrate.