CN113945872A - Z-axis gradient magnetic field sensor chip - Google Patents
Z-axis gradient magnetic field sensor chip Download PDFInfo
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- CN113945872A CN113945872A CN202010694311.8A CN202010694311A CN113945872A CN 113945872 A CN113945872 A CN 113945872A CN 202010694311 A CN202010694311 A CN 202010694311A CN 113945872 A CN113945872 A CN 113945872A
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- 230000006698 induction Effects 0.000 claims abstract description 167
- 239000000758 substrate Substances 0.000 claims abstract description 55
- 230000008859 change Effects 0.000 claims abstract description 29
- 230000035945 sensitivity Effects 0.000 claims description 32
- 239000011810 insulating material Substances 0.000 claims description 5
- 239000000463 material Substances 0.000 claims description 3
- 239000002184 metal Substances 0.000 claims description 3
- 238000001514 detection method Methods 0.000 abstract description 12
- 238000010586 diagram Methods 0.000 description 17
- 238000005259 measurement Methods 0.000 description 6
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000004806 packaging method and process Methods 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
- G01R33/09—Magnetoresistive devices
- G01R33/091—Constructional adaptation of the sensor to specific applications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/0005—Geometrical arrangement of magnetic sensor elements; Apparatus combining different magnetic sensor types
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
- G01R33/09—Magnetoresistive devices
- G01R33/093—Magnetoresistive devices using multilayer structures, e.g. giant magnetoresistance sensors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
- G01R33/09—Magnetoresistive devices
- G01R33/096—Magnetoresistive devices anisotropic magnetoresistance sensors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
- G01R33/09—Magnetoresistive devices
- G01R33/098—Magnetoresistive devices comprising tunnel junctions, e.g. tunnel magnetoresistance sensors
Abstract
The embodiment of the invention discloses a Z-axis gradient magnetic field sensor chip, which comprises: a wafer substrate; the longitudinal section of the induction coil is of a concave-convex tooth-shaped structure, and a supporting structure is filled between at least the tooth crest section of the induction coil and the wafer substrate; the magnetoresistive element is connected through a connecting lead to form a magnetoresistive element link, and the magnetoresistive element link is connected with the contact electrode; the induction coil, the magnetic resistance element, the connecting lead and the contact electrode are all positioned on the same surface of the wafer substrate; the tooth bottom section of the induction coil is positioned right above or above two sides of the magnetic resistance element, or the side section of the induction coil is positioned on the side surface of the magnetic resistance element; the induction coil senses the change of the magnetic field in the Z-axis direction to generate induction current, and the magnetic resistance element converts the plane magnetic field generated in the horizontal plane by the induction current of the induction coil into the change of the magnetic resistance value. In the embodiment of the invention, high-precision detection of the magnetic field in the Z-axis direction can be realized.
Description
Technical Field
The embodiment of the invention relates to the technical field of spatial gradient magnetic field measurement, in particular to a Z-axis gradient magnetic field sensor chip.
Background
The Z-axis magnetic field measurement refers to the measurement of the magnetic field in the normal direction of the plane where the magnetic sensor is located. Currently, the Z-axis magnetic field measurement is mainly realized by a detection coil, a Hall element or a magnetic resistance element.
The detection coil has low spatial resolution, limited sensitivity and limited frequency characteristics. The hall element has low sensitivity, high power consumption and poor temperature characteristics. The intrinsic sensitivity direction of the magnetoresistive element is in a plane, and a magnetic flux gathering structure is needed to conduct a Z-axis magnetic field to the plane of the chip, so that the problems of sensitivity loss, high hysteresis, poor time stability and the like are caused.
Therefore, the current situation of low sensitivity and poor precision generally exists in the current Z-axis magnetic field measurement.
Disclosure of Invention
The embodiment of the invention provides a Z-axis gradient magnetic field sensor chip, which solves the problems of low sensitivity and poor precision of the existing Z-axis magnetic field measurement.
The embodiment of the invention provides a Z-axis gradient magnetic field sensor chip, which comprises:
the wafer substrate is positioned in a horizontal plane, and the Z axis is vertical to the horizontal plane;
the vertical section of the induction coil is a concave-convex tooth-shaped structure comprising a tooth bottom surface section, a tooth top surface section and a side surface section, and a support structure is filled between at least the tooth top surface section of the induction coil and the wafer substrate;
the magnetoresistive elements are connected through connecting leads to form a magnetoresistive element link, the magnetoresistive element link is connected with a contact electrode, and the orthographic projection of the contact electrode on the horizontal plane is positioned on the periphery of the induction coil;
the induction coil, the magnetoresistive element, the connecting lead and the contact electrode are all positioned on the same surface of the wafer substrate, and a tooth bottom surface section and a tooth top surface section of the induction coil are all parallel to the surface of the wafer substrate;
the tooth bottom surface section of the induction coil is positioned right above or above two sides of the magnetic resistance element, wherein the current direction in the tooth bottom surface section of the induction coil is vertical to the sensitivity direction of the magnetic resistance element; or, the side section of the induction coil is positioned on the side of the magnetic resistance element, and the current direction in the tooth bottom section of the induction coil is parallel to the sensitivity direction of the magnetic resistance element;
the induction coil senses the change of the magnetic field in the Z-axis direction to generate induction current, and the magnetic resistance element converts the plane magnetic field generated in the horizontal plane by the induction current of the induction coil into the change of the magnetic resistance value.
Further, the tooth bottom surface section of the induction coil is positioned above two sides of the magnetic resistance element, or the side surface section of the induction coil is positioned on the side surface of the magnetic resistance element, and a redundant induction coil is arranged on the outer side of one magnetic resistance element link at the outermost side, which deviates from the induction coil.
Further, the directions of induced currents in the side sections of the induction coil positioned at two sides of the magnetic resistance element are opposite; or the directions of the induced currents in the tooth bottom surface sections of the induction coils positioned at the two sides of the magnetic resistance element are opposite.
Further, the tooth bottom section of the induction coil is located right above the magnetic resistance element, and an insulating material is filled between the magnetic resistance element and the induction coil.
Further, the induction coil is annular.
Further, the induction coil is composed of a non-magnetic metal.
Further, the height of the side section of the induction coil is greater than or equal to the height of the magnetoresistive element.
Further, the magnetoresistive element is an anisotropic magnetoresistive, a giant magnetoresistive, or a tunnel junction magnetoresistive.
Furthermore, a nonmagnetic material packaging shell covers the outside of the Z-axis gradient magnetic field sensor chip.
Further, the output signal of the Z-axis gradient magnetic field sensor chip is output in a single-ended output or differential output mode.
According to the Z-axis gradient magnetic field sensor chip provided by the embodiment of the invention, a magnetic resistance element and an induction coil are compounded, the closed induction coil is used for sensing the change of a magnetic field in the Z-axis direction, the induction coil converts the change of the magnetic field in the Z-axis direction into an induction current, and a plane magnetic field is generated in a horizontal plane by the induction current; the high-sensitivity magnetoresistive element senses the planar magnetic field and converts it into a change in the magnetoresistive value. The Z-axis gradient magnetic field sensor chip measures the magnitude of the magnetic field in the Z-axis direction. The magnetic resistance element has the advantages of high sensitivity and low power consumption, the induction coil has the advantages of high response frequency and no magnetic hysteresis, and the Z-axis gradient magnetic field sensor chip adopting the magnetic resistance element and the induction coil can realize high-precision detection of the magnetic field in the Z-axis direction.
Drawings
To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief description will be given below of the drawings required for the embodiments or the technical solutions in the prior art, and it is obvious that the drawings in the following description, although being some specific embodiments of the present invention, can be extended and extended to other structures and drawings by those skilled in the art according to the basic concepts of the device structure, the driving method and the manufacturing method disclosed and suggested by the various embodiments of the present invention, without making sure that these should be within the scope of the claims of the present invention.
FIG. 1 is a schematic diagram of a Z-axis gradient magnetic field sensor chip according to an embodiment of the present invention;
FIG. 2 is a schematic longitudinal cross-sectional view of the chip shown in FIG. 1;
FIG. 3 is a diagram showing the relationship between the sensitivity of the magnetic sensor element of the chip of FIG. 1 and the direction of the coil current;
FIG. 4 is a schematic diagram of another Z-axis gradient magnetic field sensor chip provided by an embodiment of the present invention;
FIG. 5 is a diagram showing the sensitivity of the magnetic sensor element of the chip of FIG. 4 versus the direction of the coil current;
FIG. 6 is a schematic diagram of another Z-axis gradient magnetic field sensor chip provided by an embodiment of the present invention;
FIG. 7 is a diagram showing the sensitivity of the magnetic sensor element of the chip of FIG. 6 versus the direction of the coil current;
FIG. 8 is another schematic longitudinal cross-sectional view of a chip provided in an embodiment of the present invention;
FIG. 9 is a schematic cross-sectional view of the chip of FIG. 4;
FIG. 10 is a schematic cross-sectional view of the chip of FIG. 6;
FIG. 11 is a schematic diagram of another Z-axis gradient magnetic field sensor chip provided by an embodiment of the present invention;
fig. 12 is a schematic diagram of an output structure of a chip circuit according to an embodiment of the present invention;
FIG. 13 is a schematic diagram of another chip circuit output structure provided by an embodiment of the present invention;
FIG. 14 is a schematic diagram of a further chip circuit output structure according to an embodiment of the present invention;
fig. 15 is a schematic diagram of an output structure of a further chip circuit according to an embodiment of the present invention;
fig. 16 is a schematic structural diagram of a chip package housing according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described through embodiments with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the basic idea disclosed and suggested by the embodiments of the present invention, are within the scope of the present invention.
The embodiment of the invention provides a Z-axis gradient magnetic field sensor chip, which comprises: the wafer substrate is positioned in a horizontal plane, and the Z axis is vertical to the horizontal plane; the vertical section of the induction coil is a concave-convex tooth-shaped structure comprising a tooth bottom surface section, a tooth top surface section and a side surface section, and a supporting structure is filled between at least the tooth top surface section of the induction coil and the wafer substrate; the magnetoresistive element is connected through a connecting lead to form a magnetoresistive element link, the magnetoresistive element link is connected with a contact electrode, and the orthographic projection of the contact electrode on a horizontal plane is positioned on the periphery of the induction coil; the induction coil, the magnetic resistance element, the connecting lead and the contact electrode are all positioned on the same surface of the wafer substrate, and the tooth bottom surface section and the tooth top surface section of the induction coil are parallel to the surface of the wafer substrate; the tooth bottom surface section of the induction coil is positioned right above or above two sides of the magnetic resistance element, wherein the current direction in the tooth bottom surface section of the induction coil is vertical to the sensitivity direction of the magnetic resistance element; or the side surface section of the induction coil is positioned on the side surface of the magnetic resistance element, and the current direction in the tooth bottom surface section of the induction coil is parallel to the sensitivity direction of the magnetic resistance element; the induction coil senses the change of the magnetic field in the Z-axis direction to generate induction current, and the magnetic resistance element converts the plane magnetic field generated in the horizontal plane by the induction current of the induction coil into the change of the magnetic resistance value.
According to the Z-axis gradient magnetic field sensor chip provided by the embodiment of the invention, a magnetic resistance element and an induction coil are compounded, the closed induction coil is used for sensing the change of a magnetic field in the Z-axis direction, the induction coil converts the change of the magnetic field in the Z-axis direction into an induction current, and a plane magnetic field is generated in a horizontal plane by the induction current; the high-sensitivity magnetoresistive element senses the planar magnetic field and converts it into a change in the magnetoresistive value. The Z-axis gradient magnetic field sensor chip measures the magnitude of the magnetic field in the Z-axis direction. The magnetic resistance element has the advantages of high sensitivity and low power consumption, the induction coil has the advantages of high response frequency and no magnetic hysteresis, and the Z-axis gradient magnetic field sensor chip adopting the magnetic resistance element and the induction coil can realize high-precision detection of the magnetic field in the Z-axis direction.
The above is the core idea of the present invention, and the present invention will be described in detail by the following embodiments.
Referring to fig. 1, a schematic diagram of a Z-axis gradient magnetic field sensor chip according to an embodiment of the present invention is shown. Fig. 2 is a schematic longitudinal cross-section of the chip shown in fig. 1.
The Z-axis gradient magnetic field sensor chip provided by the embodiment includes: a wafer substrate 109, the wafer substrate 109 being located in a horizontal plane X-Y, the Z-axis being perpendicular to the horizontal plane; at least one induction coil 10, wherein the induction coil 10 is a closed coil, the longitudinal section of the induction coil 10 is a concave-convex tooth-shaped structure comprising a tooth bottom section 103, a tooth top section 104 and a side section 105, and a support structure 108 is filled between at least the tooth top section 104 of the induction coil 10 and the wafer substrate 109; the magnetoresistive element 101, the magnetoresistive element 101 is connected through connecting the lead wire 102 and forms the magnetoresistive element link, the magnetoresistive element link is connected with contact electrode 106, the orthographic projection of the contact electrode 106 on the horizontal plane is located on the periphery of the induction coil 10; the induction coil 10, the magnetoresistive element 101, the connecting lead 102 and the contact electrode 106 are all located on the same surface of the wafer substrate 109, and the bottom land section 103 and the top land section 104 of the induction coil 10 are all parallel to the surface of the wafer substrate 109; the side section 105 of the induction coil 10 is located at the side of the magnetoresistive element 101, and the direction of the current in the land section 103 of the induction coil 10 is parallel to the sensitivity direction of the magnetoresistive element 101; the induction coil 10 senses a change in the magnetic field in the Z-axis direction to generate an induction current, and the magnetoresistive element 101 converts a planar magnetic field generated in a horizontal plane by the induction current of the induction coil 10 into a change in the magnetoresistive value. The horizontal plane is the X-Y plane. Fig. 1 illustrates that 3 induction coils 10 are included in the Z-axis gradient magnetic field sensor chip, and in other embodiments, other numbers of induction coils may be included in the Z-axis gradient magnetic field sensor chip, which is not limited to this.
In this embodiment, the contact electrode 106, the connecting lead 102, the induction coil 10 and the magnetoresistive element 101 are all disposed on the same surface of the wafer substrate 109, and a supporting structure 108 is disposed in an area surrounded by the tooth top section 104 of the induction coil, the tooth side section 105 of the induction coil and the wafer substrate 109, so as to ensure that the tooth side section 105 of the induction coil is perpendicular to the wafer substrate 109. The magnetoresistive element 101 and the connecting leads 102 may be directly disposed on the surface of the wafer substrate 109. In other embodiments, a support structure is filled below the magnetic resistance element and the connecting lead wire, so that the magnetic resistance element and the connecting lead wire are positioned in the middle of the tooth side surface section of the induction coil; or the support structure is completely filled between the induction coil and the wafer substrate so as to raise the distance between the induction coil and the surface of the wafer substrate.
The height of the optional sensing coil tooth side segment 105 is greater than or equal to the height of the magnetoresistive element 101, where the height is the distance between the top surface of the structure and the surface of the wafer substrate, and the distance between the top surface of the sensing coil tooth side segment 105 and the surface of the wafer substrate is greater than or equal to the distance between the top surface of the magnetoresistive element 101 and the surface of the wafer substrate.
In this embodiment, the side sections 105 of the optional sensing coil 10 are located at the sides of the magneto-resistive elements 101, based on which the magneto-resistive elements in the Z-axis gradient magnetic field sensor chip are classified into two types.
When the front surface of the wafer substrate 109 is orthographically projected, the first type of magnetoresistive element 101 is located in a closed region defined by the induction coil 10, one magnetoresistive element 101 is arranged between two opposite side sections 105 in the induction coil 10, and the orthographically projected part of the magnetoresistive element 101 on the front surface of the wafer substrate 109 is located between the two opposite side sections 105 of the corresponding induction coil 10; for the first type of magnetoresistive element 101, all the magnetoresistive elements 101 in two adjacent induction coils 10 are connected in series in sequence by using the connecting leads 102 to form a U-shaped magnetoresistive element link 21, and two ends of the U-shaped magnetoresistive element link 21 are respectively connected with a contact resistor 106.
When the front surface of the wafer substrate 109 is orthographically projected, the second type of magnetoresistive element 101 is located in a gap region between two adjacent induction coils 10, one magnetoresistive element 101 is arranged between two opposite side sections 105 of two adjacent induction coils 10, and the orthographically projected of the magnetoresistive element 101 on the front surface of the wafer substrate 109 is located between two opposite side sections 105 of two corresponding adjacent induction coils 10; for the second type of magnetoresistive element 101, all the magnetoresistive elements 101 at the periphery of one induction coil 10 are sequentially connected in series by using connecting leads 102 to form a U-shaped magnetoresistive element link 22, and two ends of the U-shaped magnetoresistive element link 22 are respectively connected with one contact resistor 106.
An optional outermost one of the magnetoresistive element links 22 is provided with a redundant sense coil 107 on an outer side thereof facing away from the sense coil 10. In fig. 1, the 3 sensing coils 10 include a redundant sensing coil 107, which is configured to enable two sides of each magnetoresistive element 101 in the magnetoresistive element link 22 to correspond to the sensing coil, so that the environments of the two sides of each magnetoresistive element 101 in the magnetoresistive element link 22 can be ensured to be consistent, and the detection accuracy of the contact resistor 106 can be improved.
The Z-axis gradient magnetic field generates an induced current in the induction coil 10. Fig. 3 is a schematic diagram of the induced current of the magnetoresistive element and two flank segments on two sides of the magnetoresistive element. The currents 201 are induced in the side sections 105 of the induction coil, optionally on both sides of the magneto-resistive element 101, in opposite directions.
The direction of the current in the land segment 103 of the induction coil 10 is parallel to the sensitivity direction 202 of the magnetoresistive element 101. The direction of the induced current 201 in the tooth side section 105 of the induction coil 10 is perpendicular to the plane of the wafer substrate 109, and the magnetic field generated by the induced current 201 in the perpendicular direction is parallel to the direction of the wafer substrate 109 and the arrangement direction of the magnetic sensing elements 101 at the magnetic resistance elements 101, so that the induced current 201 in the tooth side section 105 of the induction coil 10 generates a planar magnetic field in the horizontal plane, that is, the Z-axis direction gradient magnetic field passes through the induction coil 10 and is converted into a horizontal gradient magnetic field consistent with the sensitivity direction 202 of the magnetic sensing elements 101. The magnetoresistive element 101 between the two opposite side segments 105 thus converts the horizontal planar gradient magnetic field into a change in the magnetoresistive value. Therefore, high-precision detection of the gradient magnetic field in the Z-axis direction is realized.
Referring to fig. 4, a schematic diagram of a Z-axis gradient magnetic field sensor chip according to an embodiment of the present invention is shown.
The Z-axis gradient magnetic field sensor chip provided by the embodiment includes: a wafer substrate 109, the wafer substrate 109 being located in a horizontal plane X-Y, the Z-axis being perpendicular to the horizontal plane; at least one induction coil 10, wherein the induction coil 10 is a closed coil, the longitudinal section of the induction coil 10 is a concave-convex tooth-shaped structure comprising a tooth bottom section 103, a tooth top section 104 and a side section 105, and a support structure 108 is filled between at least the tooth top section 104 of the induction coil 10 and the wafer substrate 109; the magnetoresistive element 101, the magnetoresistive element 101 is connected through connecting the lead wire 102 and forms the magnetoresistive element link, the magnetoresistive element link is connected with contact electrode 106, the orthographic projection of the contact electrode 106 on the horizontal plane is located on the periphery of the induction coil 10; the induction coil 10, the magnetoresistive element 101, the connecting lead 102 and the contact electrode 106 are all located on the same surface of the wafer substrate 109, and the bottom land section 103 and the top land section 104 of the induction coil 10 are all parallel to the surface of the wafer substrate 109; the land sections 103 of the induction coil 10 are located above both sides of the magnetoresistive element 101, wherein the direction of the current in the land sections 103 of the induction coil 10 is perpendicular to the sensitivity direction of the magnetoresistive element 101; the induction coil 10 senses a change in the magnetic field in the Z-axis direction to generate an induction current, and the magnetoresistive element 101 converts a planar magnetic field generated in a horizontal plane by the induction current of the induction coil 10 into a change in the magnetoresistive value. The horizontal plane is the X-Y plane. Fig. 4 illustrates that 3 induction coils 10 are included in the Z-axis gradient magnetic field sensor chip, and in other embodiments, other numbers of induction coils may be included in the Z-axis gradient magnetic field sensor chip, which is not limited to this.
In this embodiment, the land sections 103 of the optional induction coil 10 are located above both sides of the magnetoresistive element 101, and based on this, the magnetoresistive elements in the Z-axis gradient magnetic field sensor chip are classified into two types.
When the surface of the wafer substrate 109 is orthographically projected, the first type of magnetoresistive element 101 is located in a closed region defined by the induction coil 10, one magnetoresistive element 101 is arranged between two opposite tooth bottom sections 103 in the induction coil 10, and the orthographically projected area of the magnetoresistive element 101 on the surface of the wafer substrate 109 is located between the two opposite tooth bottom sections 103 of the corresponding induction coil 10; for the first type of magnetoresistive element 101, all the magnetoresistive elements 101 in two adjacent induction coils 10 are connected in series in sequence by using the connecting leads 102 to form a U-shaped magnetoresistive element link 21, and two ends of the U-shaped magnetoresistive element link 21 are respectively connected with a contact resistor 106.
When the front surface of the wafer substrate 109 is orthographically projected, the second type of magnetoresistive element 101 is located in a gap region between two adjacent induction coils 10, one magnetoresistive element 101 is arranged between two opposite tooth bottom sections 103 of the two adjacent induction coils 10, and the orthographically projected of the magnetoresistive element 101 on the front surface of the wafer substrate 109 is located between two opposite tooth bottom sections 103 of the two corresponding adjacent induction coils 10; for the second type of magnetoresistive element 101, all the magnetoresistive elements 101 at the periphery of one induction coil 10 are sequentially connected in series by using connecting leads 102 to form a U-shaped magnetoresistive element link 22, and two ends of the U-shaped magnetoresistive element link 22 are respectively connected with one contact resistor 106.
An optional outermost one of the magnetoresistive element links 22 is provided with a redundant sense coil 107 on an outer side thereof facing away from the sense coil 10. In fig. 4, the 3 sensing coils 10 include a redundant sensing coil 107, which is configured to enable two sides of each magnetoresistive element 101 in the magnetoresistive element link 22 to correspond to the sensing coil, so that the environments of the two sides of each magnetoresistive element 101 in the magnetoresistive element link 22 can be ensured to be consistent, and the detection accuracy of the contact resistor 106 can be improved.
The Z-axis gradient magnetic field generates an induced current in the induction coil 10. Fig. 5 is a schematic diagram illustrating the induced current of the magnetoresistive element and two land segments on two sides of the magnetoresistive element. The induced currents 201 in the land sections 103 of the induction coils, optionally located on both sides of the magneto-resistive element 101, are opposite in direction.
The direction of current flow 201 in the land segment 103 of the induction coil 10 is perpendicular to the sensitivity direction 202 of the magnetoresistive element 101. The induced current direction 201 in the tooth bottom section 103 of the induction coil 10 is parallel to the wafer substrate 109, and the magnetic field generated by the induced current 201 in the horizontal direction is parallel to the direction of the wafer substrate 109 at the magnetoresistive element 101 and perpendicular to the arrangement direction of the magnetoresistive element 101, so that the induced current 201 in the tooth bottom section 103 of the induction coil 10 generates a planar magnetic field in the horizontal plane, that is, the gradient magnetic field in the Z-axis direction is converted into a horizontal gradient magnetic field which is consistent with the sensitivity direction 202 of the magnetoresistive element 101 through the induction coil 10. The magnetoresistive element 101 between two opposing land segments 103 thus converts the horizontal planar gradient magnetic field into a change in the magnetoresistive value. Therefore, high-precision detection of the gradient magnetic field in the Z-axis direction is realized.
The difference between the Z-axis gradient magnetic field sensor chip shown in fig. 6 and fig. 4 is that the sensing coil bottom land segment 103 is located right above the magnetoresistive element 101, i.e. the orthographic projection of the sensing coil bottom land segment 103 on the wafer substrate 109 covers the magnetoresistive element 101, and it is not necessary to provide a redundant sensing coil, and the detection principle is the same, and is not described herein again. Fig. 7 is a schematic diagram illustrating the induced current of the magnetoresistive element and the segment of the bottom land directly above the magnetoresistive element. The direction of the induced current 201 in the land section 103 of the induction coil, which may optionally be located directly above the magneto-resistive element 101, is perpendicular to the sensitivity direction 202 of the magneto-resistive element 101. Wherein, the induced current 201 in the bottom land segment 103 of the induction coil is parallel to the plane of the wafer substrate and perpendicular to the sensitivity direction 202 of the magneto-resistive element 101, and the magnetic field generated by the current 201 is the same as the sensitivity direction 202 of the magneto-resistive element 101 at the magneto-resistive element 101.
For any of the above embodiments, the contact electrode 106, the connecting lead 102, the induction coil 10 and the magnetoresistive element 101 are all disposed on the same surface of the wafer substrate 109 as shown in fig. 8. The magnetoresistive element 101 and the connecting leads 102 may be directly disposed on the surface of the wafer substrate 109. The supporting structure 108 is filled between the optional induction coil 10 and the wafer substrate 109, so that the distance between the induction coil 10 and the surface of the wafer substrate 109 can be increased, and the bottom land segment 103 of the induction coil is located right above or above both sides of the magnetoresistive element 101. The height of the optional induction coil tooth flank section 105 is greater than or equal to the height of the magnetoresistive element 101.
In other embodiments, the bottom surface section of the sensing coil is located directly above the magnetoresistive element or above both sides of the magnetoresistive element, and optionally, a support structure is filled below the magnetoresistive element and the connecting leads, and the support structure is filled between the sensing coil and the wafer substrate, so as to raise the distance between the sensing coil and the surface of the wafer substrate.
Fig. 9 is a cross-sectional schematic view of the chip of fig. 4, with optional sense coil land sections 103 located over both sides of the magnetoresistive element 101, wherein support structures 108 are provided on both sides of the magnetoresistive element 101, and sense coil land sections 103 are provided on the upper surface of the support structures 108, enabling the sense coil to be located over both sides of the magnetoresistive element 101.
Fig. 10 is a cross-sectional view of the chip shown in fig. 6, wherein a land section 103 of the optional induction coil is located directly above the magnetoresistive element 101, and an insulating material is filled between the magnetoresistive element 101 and the induction coil. The optional insulating material is the same as the material of the support structure 108, which reduces manufacturing processes and reduces costs. The manufacturing process includes covering the magnetoresistive element 101 with a supporting structure 108, and providing the supporting structure 108 with an induction coil tooth bottom section 103 and other structures, so that the induction coil is located right above the magnetoresistive element 101.
For the Z-axis gradient magnetic field sensor chip described in any of the above embodiments, the optional induction coil is annular. The optional induction coil is constructed of a non-magnetic metal. The orthographic projection of the induction coil on the plane of the wafer substrate can be in a ring shape or a runway ring shape, and the induction coil is a closed coil. The optional magnetoresistive element is an anisotropic magnetoresistive, a giant magnetoresistive, or a tunnel junction magnetoresistive. Not limited thereto.
The magnetoresistive element 101 of the optional Z-axis gradient magnetic field sensor chip shown in fig. 11 is covered with an insulating material 110 between and above the induction coil to protect the performance of the Z-axis gradient magnetic field sensor chip.
For the Z-axis gradient magnetic field sensor chip described in any of the above embodiments, the output signal of the Z-axis gradient magnetic field sensor chip may be output in a single-ended output or differential output manner.
The output of the alternative Z-axis gradient magnetic field sensor chip shown in fig. 12 is output in a single-ended half-bridge manner. Wherein R1 is a magneto-resistive resistor, R0 is a reference resistor, and the resistance value of the reference resistor does not change along with an external magnetic field.
The output of the alternative Z-axis gradient magnetic field sensor chip shown in fig. 13 is output in a single-ended half-bridge manner. Wherein, R1 and R2 are both magnetoresistive resistors and have opposite sensitivity directions.
The output of the optional Z-axis gradient magnetic field sensor chip shown in fig. 14 is output in a differential full-bridge manner. Wherein, R1 and R3 are magnetoresistive resistors, R0 is a reference resistor, and the resistance value of the reference resistor does not change along with an external magnetic field.
The output of the optional Z-axis gradient magnetic field sensor chip shown in fig. 15 is output in a differential full-bridge manner. Wherein, R1, R2, R3 and R4 are all magnetoresistive resistors, the sensitivity directions of R1 and R3 are consistent, the sensitivity directions of R2 and R4 are consistent, and the sensitivity directions of R1 and R2 are opposite.
As shown in fig. 16, the non-magnetic package 301 covers the chip 302 of the alternative Z-axis gradient magnetic field sensor, which facilitates electrical connection of the chip 302 and improves stability and reliability of the chip 302. The non-magnetic packaging shell 301 cannot interfere with the Z-axis magnetic field, and the accuracy of the magnetic field detection result is guaranteed.
The Z-axis gradient magnetic field sensor chip provided by the embodiment of the invention adopts the closed induction coil with the longitudinal section being in a tooth-shaped structure, converts the Z-axis magnetic field change in the vertical direction into the current change in the induction coil, further converts the current change in the induction coil into the horizontal direction magnetic field change through the trend of the induction coil, utilizes the vertical direction coil to cause the magnetic field change near the magnetic resistance element, takes the magnetic resistance chip as a sensitive element, converts the Z-direction magnetic field change into the magnetic resistance value change through the induction coil, and then converts the magnetic resistance value into an electric signal through the contact resistor. The accurate and high-sensitivity detection of the magnetic field gradient in the Z direction is realized by utilizing the characteristics of high sensitivity and low power consumption of the magnetic resistance element and the characteristics of low loss and no hysteresis of geometric conversion sensitivity of the coil.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious modifications, rearrangements, combinations and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (10)
1. A Z-axis gradient magnetic field sensor chip, comprising:
the wafer substrate is positioned in a horizontal plane, and the Z axis is vertical to the horizontal plane;
the vertical section of the induction coil is a concave-convex tooth-shaped structure comprising a tooth bottom surface section, a tooth top surface section and a side surface section, and a support structure is filled between at least the tooth top surface section of the induction coil and the wafer substrate;
the magnetoresistive elements are connected through connecting leads to form a magnetoresistive element link, the magnetoresistive element link is connected with a contact electrode, and the orthographic projection of the contact electrode on the horizontal plane is positioned on the periphery of the induction coil;
the induction coil, the magnetoresistive element, the connecting lead and the contact electrode are all positioned on the same surface of the wafer substrate, and a tooth bottom surface section and a tooth top surface section of the induction coil are all parallel to the surface of the wafer substrate;
the tooth bottom surface section of the induction coil is positioned right above or above two sides of the magnetic resistance element, wherein the current direction in the tooth bottom surface section of the induction coil is vertical to the sensitivity direction of the magnetic resistance element; or, the side section of the induction coil is positioned on the side of the magnetic resistance element, and the current direction in the tooth bottom section of the induction coil is parallel to the sensitivity direction of the magnetic resistance element;
the induction coil senses the change of the magnetic field in the Z-axis direction to generate induction current, and the magnetic resistance element converts the plane magnetic field generated in the horizontal plane by the induction current of the induction coil into the change of the magnetic resistance value.
2. The Z-axis gradient magnetic field sensor chip of claim 1, wherein the bottom land section of the sensing coil is located above both sides of the magnetoresistive element, or the side section of the sensing coil is located on the side of the magnetoresistive element, and a redundant sensing coil is disposed on the outer side of the outermost one of the magnetoresistive element links away from the sensing coil.
3. The Z-axis gradient magnetic field sensor chip of claim 1, wherein the side sections of the induction coil on either side of the magnetoresistive element induce opposite directions of current flow; or the directions of the induced currents in the tooth bottom surface sections of the induction coils positioned at the two sides of the magnetic resistance element are opposite.
4. The Z-axis gradient magnetic field sensor chip of claim 1, wherein the bottom land section of the induction coil is located directly above the magnetoresistive element, and an insulating material is filled between the magnetoresistive element and the induction coil.
5. The Z-axis gradient magnetic field sensor chip of claim 1, wherein the induction coil is annular.
6. The Z-axis gradient magnetic field sensor chip of claim 1, wherein the induction coil is composed of a non-magnetic metal.
7. The Z-axis gradient magnetic field sensor chip of claim 1, wherein a side segment height of the induction coil is greater than or equal to a height of the magnetoresistive element.
8. The Z-axis gradient magnetic field sensor chip of claim 1, wherein the magneto-resistive element is an anisotropic magneto-resistance, a giant magneto-resistance, or a tunnel junction magneto-resistance.
9. The Z-axis gradient magnetic field sensor chip of claim 1, wherein the Z-axis gradient magnetic field sensor chip is externally covered with a package housing of nonmagnetic material.
10. The Z-axis gradient magnetic field sensor chip according to claim 1, wherein the output signal of the Z-axis gradient magnetic field sensor chip is output in a single-ended output or differential output manner.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117054936A (en) * | 2023-10-12 | 2023-11-14 | 江苏多维科技有限公司 | Gradient sensor |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117054936A (en) * | 2023-10-12 | 2023-11-14 | 江苏多维科技有限公司 | Gradient sensor |
| CN117054936B (en) * | 2023-10-12 | 2024-01-12 | 江苏多维科技有限公司 | Gradient sensor |
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