Magnetic field angular sensor with a full angle detection

1 . An angular magnetic sensor to determine a magnetic field angle within two axes of a plane, said angular magnetic sensor comprises:

two anisotropic magneto-resistive sensing elements fabricated on a substrate and oriented with respect to each other such that an output voltage of a first of said anisotropic magneto-resistive sensing elements is a function of a first trigonometric function of said magnetic field angle to a reference axis and an output voltage of a second of said anisotropic magneto-resistive sensing elements is a function of a second trigonometric function of said magnetic field angle to said reference axis; and

at least one magneto-resistive sensing element fabricated on said substrate and having a fixed reference magnetization oriented with respect to said reference axis such that an output voltage of said at least one magneto-resistive sensing element provides a quadrant indicator for said magnetic field angle with respect to said reference axis.

2 . The angular magnetic sensor of claim 1 wherein each of said anisotropic magneto-resistive sensing elements comprise four anisotropic magneto-resistive material structures formed on said substrate and connected to form a Wheatstone bridge, one Wheatstone bridge rotated by an orientation angle such that the second trigonometric function is the first trigonometric function shifted by said orientation angle.

3 . The angular magnetic sensor of claim 1 wherein the at least one magneto-resistive sensing element is a giant-magneto-resistive structure formed on said substrate.

4 . The angular magnetic sensor of claim 1 wherein the at least one magneto-resistive sensing element is a magnetic tunnel junction structure formed on said substrate.

5 . The angular magnetic sensor of claim 1 further comprising a magnetic field angle calculator connected to receive said output voltages of said two anisotropic magneto-resistive sensing elements and said output voltage of said at least one magneto-resistive sensing elements to determine the magnetic field angle.

6 . The angular magnetic sensor of claim 5 wherein the first trigonometric function is a sine function and the second trigonometric function is a cosine function.

7 . The angular magnetic sensor of claim 5 wherein the magnetic field angle is a function of a ratio of said first of said anisotropic magneto-resistive sensing elements to said output voltage of said a second of said anisotropic magneto-resistive sensing elements.

8 . The angular magnetic sensor of claim 7 wherein said function is one half an arctangent of said ratio.

9 . The angular magnetic sensor of claim 8 wherein said magnetic field angle calculator determines magnetic field angle as a magnitude of said arctangent of said ratio and a sign from said at least one magneto-resistive sensing element.

10 . A method for fabricating an angular magnetic sensor comprising the steps of:

providing a substrate;

forming two anisotropic magneto-resistive sensing elements fabricated on said substrate and oriented with respect to each other such that an output voltage of a first of said anisotropic magneto-resistive sensing elements is a function of a first trigonometric function of said magnetic field angle to a reference axis and an output voltage of a second of said anisotropic magneto-resistive sensing elements is a function of a second trigonometric function of said magnetic field angle to said reference axis; and

forming at least one magneto-resistive sensing element on said substrate and having a fixed reference magnetization oriented with respect to said reference axis such that an output voltage of said at least one magneto-resistive sensing element provides a quadrant indicator for said magnetic field angle with respect to said reference axis.

11 . The method for fabricating an angular magnetic sensor of claim 10 wherein the step of forming said anisotropic magneto-resistive sensing elements comprises the steps of:

forming four anisotropic magneto-resistive material structures on said substrate for each of said anisotropic magneto-resistive sensing elements;

connecting said four anisotropic magneto-resistive material structures to form a Wheatstone bridge; and

rotating one Wheatstone bridge by an orientation angle such that the second trigonometric function is the first trigonometric function shifted by said orientation angle.

12 . The method for fabricating an angular magnetic sensor of claim 11 wherein forming four anisotropic magneto-resistive material structures on said substrate comprises the steps of:

forming a dielectric layer on said substrate;

depositing a seed layer upon said dielectric layer; and

depositing a ferromagnetic film dielectric layer on said substrate.

13 . The method for fabricating an angular magnetic sensor of claim 10 wherein the at least one magneto-resistive sensing element is a giant-magneto-resistive structure formed on said substrate.

14 . The method for fabricating an angular magnetic sensor of claim 13 wherein forming the at least one magneto-resistive sensing element comprises the steps of:

forming a dielectric layer upon said substrate.

depositing a seed layer upon said dielectric layer;

depositing an anti-ferromagnetic layer upon said seed layer;

depositing a synthetic pinned layer upon said anti-ferromagnetic layer;

depositing a conductive layer upon said synthetic pinned layer; and

depositing a free layer upon said conductive layer.

15 . The method for fabricating an angular magnetic sensor of claim 14 wherein forming said synthetic pinned layer comprises the steps of

depositing a first anti-parallel structure upon said anti-ferromagnetic layer;

depositing a nonmagnetic space layer upon said first anti-parallel structure; and

depositing a second anti-parallel structure upon said nonmagnetic space layer.

16 . The method for fabricating an angular magnetic sensor of claim 15 wherein forming the at least one magneto-resistive sensing element further comprises the steps of:

creating a photo-mask of said at least one magneto-resistive sensing element that is patterned into large rectangle-shaped giant-magneto-resistive stripes with a large aspect ratio and different orientations of long axes, and

forming said at least one magneto-resistive sensing element on said substrate by the step of etching said substrate to define said at least one magneto-resistive sensing element.

17 . The method for fabricating an angular magnetic sensor of claim 16 wherein forming the at least one magneto-resistive sensing element further comprises the steps of:

applying local magnetic fields to said at least one magneto-resistive sensing element; and

thermally annealing said at least one magneto-resistive sensing element to obtain exchange pinning on reference layers with various predetermined directions for each of said giant-magneto-resistive stripes.

18 . The method for fabricating an angular magnetic sensor of claim 17 wherein said local magnetic fields are shape anisotropy fields, stress-induced magnetostrictive anisotropy fields, local hard bias fields, or local flux concentrating fields by adjacent soft magnetic layers.

19 . The method for fabricating an angular magnetic sensor of claim 10 wherein the at least one magneto-resistive sensing element is a magnetic tunnel junction structure formed on said substrate.

20 . The method for fabricating an angular magnetic sensor of claim 19 wherein forming the at least one magneto-resistive sensing element comprises the steps of:

forming a dielectric layer upon said substrate.

depositing a seed layer upon said dielectric layer;

depositing an anti-ferromagnetic layer upon said seed layer;

depositing a synthetic pinned layer upon said anti-ferromagnetic layer;

depositing a tunneling layer upon said synthetic pinned layer; and

depositing a free layer upon said conductive layer.

21 . The method for fabricating an angular magnetic sensor of claim 20 wherein forming said synthetic pinned layer comprises the steps of:

depositing a first anti-parallel structure upon said anti-ferromagnetic layer;

depositing a nonmagnetic space layer upon said first anti-parallel structure; and

depositing a second anti-parallel structure upon said nonmagnetic space layer.

22 . The method for fabricating an angular magnetic sensor of claim 21 wherein forming the at least one magneto-resistive sensing element further comprises the steps of:

creating a photo-mask of said at least one magneto-resistive sensing element that is patterned into large rectangle-shaped giant-magneto-resistive stripes with a large aspect ratio and different orientations of long axes, and

forming said at least one magneto-resistive sensing element on said substrate by the step of etching said substrate to define said at least one magneto-resistive sensing element.

23 . The method for fabricating an angular magnetic sensor of claim 22 wherein forming the at least one magneto-resistive sensing element further comprises the steps of:

applying local magnetic fields to said at least one magneto-resistive sensing element; and

thermally annealing said at least one magneto-resistive sensing element to obtain exchange pinning on reference layers with various predetermined directions for each of said giant-magneto-resistive stripes.

24 . The method for fabricating an angular magnetic sensor of claim 23 wherein said local magnetic fields are shape anisotropy fields, stress-induced magnetostrictive anisotropy fields, local hard bias fields, or local flux concentrating fields by adjacent soft magnetic layers.

25 . The method for fabricating an angular magnetic sensor of claim 10 further comprising the steps of:

forming a magnetic field angle calculator circuit on said substrate by the steps of:

forming and connecting semiconductor devices on said substrate;

providing biasing voltages to said two anisotropic magneto-resistive sensing elements and said at least one magneto-resistive sensing element;

receiving a first output voltage and a second output voltage from said two anisotropic magneto-resistive sensing elements and at least a third output voltage from said at least one magneto-resistive sensing elements to determine a field angle of a magnetic field impinging upon said angular magnetic sensor.

26 . An integrated angular magnetic sensor apparatus for determining a magnetic field angle within two axes of a plane, said integrated angular magnetic sensor apparatus comprising:

a substrate;

two anisotropic magneto-resistive sensing elements fabricated on said substrate and oriented with respect to each other such that an output voltage of a first of said anisotropic magneto-resistive sensing elements is a function of a first trigonometric function of said magnetic field angle to a reference axis and an output voltage of a second of said anisotropic magneto-resistive sensing elements is a function of a second trigonometric function of said magnetic field angle to said reference axis;

at least one magneto-resistive sensing element on said substrate and having a fixed reference magnetization oriented with respect to said reference axis such that an output voltage of said at least one magneto-resistive sensing element provides a quadrant indicator for said magnetic field angle with respect to said reference axis; and

a magnetic field angle calculator connected to receive said output voltages of said two anisotropic magneto-resistive sensing elements and said output voltage of said at least one magneto-resistive sensing elements to determine the magnetic field angle.

27 . The integrated angular magnetic sensor apparatus of claim 26 wherein each of said two anisotropic magneto-resistive sensing elements comprise:

four anisotropic magneto-resistive material structures formed on said substrate and connected to form a Wheatstone bridge, wherein one Wheatstone bridge is rotated by an orientation angle such that the second trigonometric function is the first trigonometric function shifted by said orientation angle.

28 . The integrated angular magnetic sensor apparatus of claim 27 wherein each of said four anisotropic magneto-resistive material structures formed on said substrate comprises:

a dielectric layer formed on said substrate;

a seed layer deposited upon said dielectric layer; and

a ferromagnetic film dielectric layer deposited on said dielectric layer.

29 . The integrated angular magnetic sensor apparatus of claim 26 wherein the at least one magneto-resistive sensing element is a giant-magneto-resistive structure formed on said substrate.

30 . The integrated angular magnetic sensor apparatus of claim 29 wherein the at least one magneto-resistive sensing element comprises:

a dielectric layer formed upon said substrate;

an anti-ferromagnetic layer deposited upon said dielectric layer;

a synthetic pinned layer deposited upon said anti-ferromagnetic layer;

a conductive layer deposited upon said synthetic pinned layer; and

a free layer deposited upon said conductive layer.

31 . The integrated angular magnetic sensor apparatus of claim 30 wherein said synthetic pinned layer comprises:

a first anti-parallel structure deposited upon said anti-ferromagnetic layer;

a nonmagnetic space layer deposited upon said first anti-parallel structure; and

a second anti-parallel structure deposited upon said nonmagnetic space layer.

32 . The integrated angular magnetic sensor apparatus of claim 30 wherein the at least one magneto-resistive sensing element is patterned by a photo-mask into large rectangle-shaped giant-magneto-resistive stripes with a large aspect ratio and different orientations of long axes, which is then etched to define said at least one magneto-resistive sensing element.

33 . The integrated angular magnetic sensor apparatus of claim 32 wherein the at least one magneto-resistive sensing element has local magnetic fields applied to said at least one magneto-resistive sensing element, which is then thermally annealed to obtain exchange pinning on reference layers with various predetermined directions for each of said giant-magneto-resistive stripes.

34 . The integrated angular magnetic sensor apparatus of claim 33 wherein said local magnetic fields are shape anisotropy fields, stress-induced magnetostrictive anisotropy fields, local hard bias fields, or local flux concentrating fields by adjacent soft magnetic layers.

35 . The integrated angular magnetic sensor apparatus of claim 26 wherein the at least one magneto-resistive sensing element is a magnetic tunnel junction structure formed on said substrate.

36 . The integrated angular magnetic sensor apparatus of claim 35 wherein the at least one magneto-resistive sensing element comprises:

a dielectric layer formed upon said substrate.

an anti-ferromagnetic layer deposited upon said dielectric layer;

a synthetic pinned layer deposited upon said anti-ferromagnetic layer;

a tunneling layer deposited upon said synthetic pinned layer; and

a free layer deposited upon said conductive layer.

37 . The integrated angular magnetic sensor apparatus of claim 36 wherein said synthetic pinned layer comprises:

a first anti-parallel structure deposited upon said anti-ferromagnetic layer;

a nonmagnetic space layer deposited upon said first anti-parallel structure; and

a second anti-parallel structure deposited upon said nonmagnetic space layer.

38 . The integrated angular magnetic sensor apparatus of claim 35 wherein the at least one magneto-resistive sensing element is patterned by a photo-mask into large rectangle-shaped giant-magneto-resistive stripes with a large aspect ratio and different orientations of long axes, where the large rectangle-shaped giant-magneto-resistive stripes are etched to define said at least one magneto-resistive sensing element.

39 . The integrated angular magnetic sensor apparatus of claim 38 wherein the at least one magneto-resistive sensing element has local magnetic fields applied to said at least one magneto-resistive sensing element, which is then thermally annealed to obtain exchange pinning on reference layers with various predetermined directions for each of said giant-magneto-resistive stripes.

40 . The integrated angular magnetic sensor apparatus of claim 49 wherein said local magnetic fields are shape anisotropy fields, stress-induced magnetostrictive anisotropy fields, local hard bias fields, or local flux concentrating fields by adjacent soft magnetic layers.

41 . The integrated angular magnetic sensor apparatus of claim 26 wherein said magnetic field angle calculator circuit is connected to provide biasing voltages to said two anisotropic magneto-resistive sensing elements and said at least one magneto-resistive sensing element, and connected to receive a first output voltage and a second output voltage from said two anisotropic magneto-resistive sensing elements and at least a third output voltage from said at least one magneto-resistive sensing elements to determine a field angle of a magnetic field impinging upon said angular magnetic sensor.