Structure and system for simultaneous sensing a magnetic field and mechanical stress
First Claim
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1. A magnetic field sensor comprising:
- a substrate having a bottom surface and a top surface;
an epitaxial layer disposed over the top surface of the substrate, the epitaxial layer having a top surface and a bottom surface, the bottom surface of the epitaxial layer proximate to and parallel to the top surface of the substrate; and
a dual Hall element, comprising;
a first planar Hall element disposed within or over the epitaxial layer, the first planar Hall element having a first plurality of pickups with a first center between the first plurality of pickups; and
a second planar Hall element disposed within or over the epitaxial layer, the second planar Hall element having a second different plurality of pickups with a second center between the second plurality of pickups, wherein a line intersecting the first and second centers is perpendicular to the top surface of the epi layer,wherein the first planar Hall element has a first sensitivity to a magnetic field and a first sensitivity to mechanical stress in the substrate, the first planar Hall element for generating a first output signal responsive to the magnetic field, the first magnetic field sensitivity, mechanical stress in the substrate, and the first mechanical stress sensitivity,and wherein the second planar Hall element has a second sensitivity to the magnetic field and a second sensitivity to mechanical stress in the substrate, the second planar Hall element for generating a second output signal responsive to the magnetic field, the second magnetic field sensitivity, the mechanical stress in the substrate, and the second mechanical stress sensitivity.
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Abstract
A structure having collocated magnetic field sensing elements can be used to simultaneously determine magnetic field and mechanical stress. A primary magnetic field sensing element generates a primary signal responsive to a magnetic field and a secondary magnetic field sensing element generates a secondary signal responsive to mechanical stress. A system includes a stress compensation module to receive the primary and signals, and to compensate for mechanical stress in the primary signal.
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Citations
17 Claims
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1. A magnetic field sensor comprising:
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a substrate having a bottom surface and a top surface; an epitaxial layer disposed over the top surface of the substrate, the epitaxial layer having a top surface and a bottom surface, the bottom surface of the epitaxial layer proximate to and parallel to the top surface of the substrate; and a dual Hall element, comprising; a first planar Hall element disposed within or over the epitaxial layer, the first planar Hall element having a first plurality of pickups with a first center between the first plurality of pickups; and a second planar Hall element disposed within or over the epitaxial layer, the second planar Hall element having a second different plurality of pickups with a second center between the second plurality of pickups, wherein a line intersecting the first and second centers is perpendicular to the top surface of the epi layer, wherein the first planar Hall element has a first sensitivity to a magnetic field and a first sensitivity to mechanical stress in the substrate, the first planar Hall element for generating a first output signal responsive to the magnetic field, the first magnetic field sensitivity, mechanical stress in the substrate, and the first mechanical stress sensitivity, and wherein the second planar Hall element has a second sensitivity to the magnetic field and a second sensitivity to mechanical stress in the substrate, the second planar Hall element for generating a second output signal responsive to the magnetic field, the second magnetic field sensitivity, the mechanical stress in the substrate, and the second mechanical stress sensitivity. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A magnetic field sensor comprising:
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a first magnetic field sensing element supported by a substrate, the first magnetic field sensing element having a first sensitivity to a magnetic field and a first sensitivity to mechanical stress in the substrate, the first magnetic field sensing element for generating a first output signal responsive to the magnetic field, the first magnetic field sensitivity, mechanical stress in the substrate, and the first mechanical stress sensitivity; a second magnetic field sensing element supported by the substrate, the second magnetic field sensing element having a second sensitivity to the magnetic field and a second sensitivity to mechanical stress in the substrate, the second magnetic field sensing element for generating a second output signal responsive to the magnetic field, the second magnetic field sensitivity, the mechanical stress in the substrate, and the second mechanical stress sensitivity; a stress compensation module operatively coupled to receive a first stress compensation input signal responsive to the first output signal and a second stress compensation input signal responsive to the second output signal and to generate a stress compensation signal; and an adjustable gain stage coupled to amplify the first output signal with a gain in accordance with the stress compensation signal to generate a stress-compensated output signal, wherein the stress-compensated output signal is responsive to the magnetic field, and is not responsive to the mechanical stress in the substrate, wherein the first and second magnetic field sensing elements are provided as a dual Hall element comprising; a substrate having a bottom surface and a top surface; an N-type epitaxial layer disposed over the substrate top surface, the epitaxial layer having a top surface and a bottom surface; a barrier structure disposed over the substrate and extending perpendicular from the epitaxial layer top surface so as to form a barrier to electrical charges within the epitaxial layer and resulting in a bounded region of the epitaxial layer having a generally octagonal shape; a P-well region diffused into the epitaxial layer, and a plurality of pickups implanted and diffused into the epitaxial layer, opposing pairs of the plurality of pickups separated by the P-well region, each one of the plurality of pickups comprising an N+ type diffusion, wherein a first set of the plurality of pickups is operable to form the first magnetic field sensing element as a first Hall element and a second different set of the plurality of pickups is operable to form the second magnetic field sensing element as a second Hall element.
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Specification