Z-axis magnetic field sensor

Abstract

The utility model discloses a Z-axis magnetic field sensor. The Z-axis magnetic field sensor is provided with two magnetic field conversion areas which are spaced by a certain distance through a semiconductor on-chip process, each magnetic field conversion area is provided with a plurality of parallel soft magnetic strips, and a plurality of magnetic resistors are manufactured on the two sides of the bottom of each soft magnetic strip. All magnetic resistors in each magnetic field conversion area are set to be the same in sensitive direction, and the sensitive directions of the magnetic resistors in the two magnetic field conversion areas are opposite; and the magnetic resistance coefficients of the two magnetic field conversion areas meet specific constraint conditions. Magnetoresistors in the two magnetic field conversion areas are organically connected into a sensing half-bridge on the same wafer through a semiconductor on-chip process, so that the Z-axis magnetic field sensor has good anti-interference capability. The Z-axis magnetic field sensor provided by the utility model has good anti-interference capability, the annealing step of the magnetic resistor is simple, and the Z-axis magnetic field sensor is convenient to realize by adopting a semiconductor on-chip process.

Description

Technical Field

[0001] This utility model relates to the design and manufacturing of semiconductor magnetic field sensing devices, specifically to a Z-axis magnetic field sensor. Background Technology

[0002] Currently, magnetic field sensors are mainly classified into Hall effect-based magnetic field sensors and electron tunneling-based magnetoresistive sensors according to their sensing principles. Magnetoresistive sensors have received increasing attention and investment from the industry due to their low power consumption and ease of system integration using semiconductor processes. Among these, optimizing the magnetic circuit design and improving the anti-interference capability of magnetoresistive sensors are important areas of focus for improvement. To balance these two aspects of performance, the latest design for Z-axis magnetic field sensors uses nickel-iron alloys as the magnetic field conversion structure, shielding against interfering magnetic fields through an external shielding layer, or using sensing circuitry to cancel out interference between magnetoresistive sensing signals.

[0003] The method of canceling out interference between magnetoresistive sensing signals using a sensing circuit typically requires symmetrically placing magnetoresistors with different sensitivity directions on both sides of the nickel-iron substrate. This significantly increases the fabrication difficulty and process complexity of the Z-axis magnetic field sensor. This is because Z-axis magnetic field sensors usually require multiple nickel-iron substrates arranged together, and improving anti-interference capability necessitates symmetrically placing magnetoresistors with opposite sensitivity directions on both sides of the nickel-iron substrate's bottom. The sensitivity direction of the magnetoresistors depends on their annealing direction, which requires performing different annealing processes on very small wafer areas during fabrication. This undoubtedly increases the difficulty of annealing and the manufacturing cost of the Z-axis magnetic field sensor. Utility Model Content

[0004] In view of this, the present invention provides a Z-axis magnetic field sensor. The Z-axis magnetic field sensor includes at least a first magnetic field conversion region and a second magnetic field conversion region spaced apart by a certain distance. Each magnetic field conversion region includes a plurality of soft magnetic strips configured to convert the Z-axis magnetic field into a magnetic field in the XY plane, and the soft magnetic strips in the first magnetic field conversion region and the second magnetic field conversion region are arranged parallel to each other.

[0005] Each soft magnetic strip has magnetic reluctance on both the left and right sides of its bottom. The magnetic reluctance sensitivity directions are the same in each magnetic field conversion region, but opposite in the two magnetic field conversion regions. The sum of the sensitivity coefficients of the left side of the bottom of each soft magnetic strip in the first magnetic field conversion region and the vector sum of the XY plane sensitivity coefficients of the right side of the bottom of each soft magnetic strip in the second magnetic field conversion region equals 0; the sum of the sensitivity coefficients of the right side of the bottom of each soft magnetic strip in the first magnetic field conversion region and the vector sum of the XY plane sensitivity coefficients of the left side of the bottom of each soft magnetic strip in the second magnetic field conversion region also equals 0.

[0006] Preferably, in any of the magnetic field conversion regions, the sensitive direction of the magnetoresistive field is perpendicular to the extension direction of the soft magnetic strip in the XY plane within that magnetic field conversion region.

[0007] In the first magnetic field conversion region, the magnetoresistors on the bottom left side of each soft magnetic strip are connected in series to form a first branch. In the second magnetic field conversion region, the magnetoresistors on the bottom right side of each soft magnetic strip are connected in series to form a second branch. The first and second branches constitute one arm of the first sensing half-bridge. In the first magnetic field conversion region, the magnetoresistors on the bottom right side of each soft magnetic strip are connected in series to form a third branch. In the second magnetic field conversion region, the magnetoresistors on the bottom left side of each soft magnetic strip are connected in series to form a fourth branch. The third and fourth branches constitute the other arm of the first sensing half-bridge.

[0008] The Z-axis magnetic field sensor provided by this invention is fabricated on a single wafer using semiconductor on-chip technology. Clearly, through the above design, magnetoresistive components with opposite sensing directions, used to cancel out interference fields, are placed in different wafer regions. All magnetoresistive components within the same wafer region have the same sensing direction, thus facilitating the use of a uniform annealing process during manufacturing. The magnetic sensor is based on XMR, which includes AMR, TMR, and GMR.

[0009] Furthermore, the first branch and the second branch are connected in series or in parallel to form one arm of the first sensing half-bridge, and the third branch and the fourth branch are connected in series or in parallel to form the other arm of the first sensing half-bridge.

[0010] Furthermore, the dimensions of the soft magnetic strips in the first and / or second magnetic field conversion regions can be either not exactly the same or exactly the same, without affecting the anti-interference capability of the Z-axis sensor. This is because the sensitivity coefficients of all magnetoresistances belonging to the first and second magnetic field conversion regions on the same bridge arm are equal in magnitude and opposite in direction, and the same bridge arm itself can cancel out the influence of the horizontal interference field.

[0011] Preferably, the soft magnetic strips in the first and second magnetic field conversion regions are identical, and the soft magnetic strips in each magnetic field conversion region are uniformly arranged. Preferably, the soft magnetic strips are made of NiFe material.

[0012] Furthermore, the Z-axis magnetic field sensor has two first sensing half-bridges, and the two first sensing half-bridges constitute a sensing full-bridge.

[0013] Furthermore, the upper and / or lower ends of the first magnetic field conversion region and the second magnetic field conversion region are provided with shielding layers for shielding the magnetic field in the XY plane.

[0014] The Z-axis magnetic field sensor provided by this invention, combining the characteristics of the sensing circuit, rationally places magnetoresistive elements with the same sensitive direction on both sides of the bottom of the soft magnetic strip within the same magnetic field conversion region, so as to facilitate the use of a unified annealing process. The Z-axis magnetic field sensor structure provided by this invention is suitable for implementation using semiconductor on-chip technology. This structure has good anti-interference capabilities and simplifies the manufacturing process of existing Z-axis magnetic field sensors, effectively reducing manufacturing costs. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the Z-axis magnetic field sensor provided by this utility model in the first part of the embodiment. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0018] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0019] In the description of this utility model, the terms "inner", "outer", "upper", "lower", "vertical", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the utility model product is usually placed when in use. They are only used to facilitate the description of this utility model and simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0020] It should be noted that, where there is no conflict, the embodiments of this utility model and the features in the embodiments can be combined with each other.

[0021] like Figure 1 In some embodiments shown, the Z-axis magnetic field sensor provided by this invention includes at least a first magnetic field conversion region Q1 and a second magnetic field conversion region Q2 spaced apart by a certain distance. Each magnetic field conversion region includes several soft magnetic strips Z disposed for converting the Z-axis magnetic field into a magnetic field in the XY plane. The soft magnetic strips Z in the first magnetic field conversion region Q1 and the second magnetic field conversion region Q2 are arranged parallel to each other. The soft magnetic strips Z are used to convert the magnetic field in the Z-axis direction into a magnetic field in the XY plane for magnetoresistive sensing. Typically, the soft magnetic strips Z are made of NiFe material in a corresponding area on a wafer. Obviously, other soft magnetic materials are also acceptable if cost is not a consideration.

[0022] Each soft magnetic strip Z has magnetic resistance on both sides of its bottom. For example... Figure 1 As shown, in the first magnetic field conversion region Q1, all magnetoresistors r1 have the same sensitive direction; in the second magnetic field conversion region Q2, all magnetoresistors r2 have the same sensitive direction, but opposite to the sensitive direction of magnetoresistors r1. Figure 1 In order to simplify the manufacturing process, the sensitive directions of magnetoresistive r1 and magnetoresistive r2 are parallel to the arrangement direction of the soft magnetic strips Z. In fact, the anti-interference effect can be achieved as long as the following conditions are met: the sum of the sensitivity coefficients of the magnetoresistive r1 on the bottom left side of each soft magnetic strip Z in the first magnetic field conversion region Q1 and the vector sum of the sensitivity coefficients of the magnetoresistive r1 on the bottom right side of each soft magnetic strip Z in the second magnetic field conversion region Q2 equals 0; the sum of the sensitivity coefficients of the magnetoresistive r1 on the bottom right side of each soft magnetic strip Z in the first magnetic field conversion region Q1 and the vector sum of the sensitivity coefficients of the magnetoresistive r2 on the bottom left side of each soft magnetic strip Z in the second magnetic field conversion region Q2 equals 0.

[0023] Preferably, in any of the magnetic field conversion regions, the sensitive direction of the magnetoresistive field is perpendicular to the extension direction of the soft magnetic strip in the XY plane within that magnetic field conversion region.

[0024] exist Figure 1 In the first magnetic field conversion region Q1, the magnetoresistive r1 on the left side of the bottom of each soft magnetic strip Z is connected in series to form a first branch. In the second magnetic field conversion region Q2, the magnetoresistive r2 on the right side of the bottom of each soft magnetic strip Z is connected in series to form a second branch. The first and second branches are connected in series to form one arm of the first sensing half-bridge. In the first magnetic field conversion region Q1, the magnetoresistive r1 on the right side of the bottom of each soft magnetic strip Z is connected in series to form a third branch. In the second magnetic field conversion region Q2, the magnetoresistive r2 on the left side of the bottom of each soft magnetic strip Z is connected in series to form a fourth branch. The third and fourth branches are connected in series to form the other arm of the first sensing half-bridge.

[0025] It is worth noting that connecting the first and second branches in series or in parallel to form one arm of the first sensing half-bridge, and connecting the third and fourth branches in series or in parallel to form the other arm of the first sensing half-bridge, can both achieve the technical effect of anti-interference.

[0026] The Z-axis magnetic field sensor provided by this utility model is fabricated on a single wafer using semiconductor on-chip technology. For example... Figure 1 As shown, the magnetoresistors in the sensing half-bridge circuit, which are used to cancel out the influence of interference fields and have opposite sensitive directions, are respectively set in different wafer regions. All magnetoresistors within the same wafer region have the same sensitive direction, thus allowing for convenient uniform annealing during manufacturing. Because all magnetoresistors belonging to the first magnetic field conversion region Q1 and all magnetoresistors belonging to the second magnetic field conversion region Q2 on the same bridge arm have equal magnitudes and opposite directions in sensitivity coefficient, the same bridge arm itself can cancel out the influence of horizontal interference fields. Therefore, the Z-axis magnetic field sensor provided by this invention has good resistance to horizontal interference fields.

[0027] Furthermore, the dimensions of the soft magnetic strips Z in the first magnetic field conversion region Q1 and / or the second magnetic field conversion region Q2 may not be exactly the same, or they may be exactly the same. Preferably, the soft magnetic strips Z in the first magnetic field conversion region Q1 and the second magnetic field conversion region Q2 are exactly the same, and the soft magnetic strips Z in the magnetic field conversion regions Q1 and Q2 are uniformly arranged.

[0028] Furthermore, the Z-axis magnetic field sensor has two first sensing half-bridges, which together form a sensing full-bridge, with the magnetoresistive sensitivity directions on adjacent bridge arms being opposite. The full-bridge configuration of the Z-axis magnetic field sensor is a common sensing circuit form, resulting in a stronger output sensing signal. The magnetic sensor is based on XMR, which includes AMR, TMR, and GMR.

[0029] Furthermore, in order to minimize the influence of the horizontal interference field, the upper and / or lower ends of the first magnetic field conversion region Q1 and the second magnetic field conversion region Q2 are also provided with shielding layers for shielding the XY plane magnetic field.

[0030] The Z-axis magnetic field sensor structure provided by this utility model has good anti-interference ability. It is fabricated on the same wafer using semiconductor on-chip technology, which effectively simplifies the annealing process when fabricating magnetoresistive materials and effectively reduces the manufacturing cost.

[0031] Finally, it should be noted that the above description is only a preferred embodiment of this utility model and is not intended to limit this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A Z-axis magnetic field sensor, characterized in that, The Z-axis magnetic field sensor includes at least a first magnetic field conversion region and a second magnetic field conversion region spaced a certain distance apart. Each magnetic field conversion region includes several soft magnetic strips configured to convert the Z-axis magnetic field into a magnetic field in the XY plane. The soft magnetic strips in the first magnetic field conversion region and the second magnetic field conversion region are arranged parallel to each other. Each soft magnetic strip has magnetic reluctance on both the left and right sides of its bottom. The magnetic reluctance sensitivity direction is the same in each magnetic field conversion region, and the magnetic reluctance sensitivity direction is opposite in the two magnetic field conversion regions. The sum of the sensitivity coefficients of the left side of the bottom of each soft magnetic strip in the first magnetic field conversion region and the vector sum of the XY plane sensitivity coefficients of the right side of the bottom of each soft magnetic strip in the second magnetic field conversion region are equal to 0. The sum of the sensitivity coefficients of the right side of the bottom of each soft magnetic strip in the first magnetic field conversion region and the vector sum of the XY plane sensitivity coefficients of the left side of the bottom of each soft magnetic strip in the second magnetic field conversion region are also equal to 0. In the first magnetic field conversion region, the magnetoresistance on the left side of the bottom of each soft magnetic strip is connected in series to form a first branch, and in the second magnetic field conversion region, the magnetoresistance on the right side of the bottom of each soft magnetic strip is connected in series to form a second branch. The first branch and the second branch constitute one arm of the first sensing half-bridge. In the first magnetic field conversion region, the magnetoresistance on the right side of the bottom of each soft magnetic strip is connected in series to form a third branch, and in the second magnetic field conversion region, the magnetoresistance on the left side of the bottom of each soft magnetic strip is connected in series to form a fourth branch. The third branch and the fourth branch constitute the other arm of the first sensing half-bridge.

2. The Z-axis magnetic field sensor as described in claim 1, characterized in that, The first branch and the second branch are connected in series or in parallel to form one arm of the first sensing half-bridge, and the third branch and the fourth branch are connected in series or in parallel to form the other arm of the first sensing half-bridge.

3. The Z-axis magnetic field sensor as described in claim 2, characterized in that, In any of the magnetic field conversion regions, the sensitive direction of the magnetoresistive force is perpendicular to the extension direction of the soft magnetic strip in the XY plane within that magnetic field conversion region.

4. The Z-axis magnetic field sensor as described in any one of claims 1-3, characterized in that, The soft magnetic strips in the first magnetic field conversion region and / or the second magnetic field conversion region are not exactly the same size.

5. The Z-axis magnetic field sensor as described in any one of claims 1-3, characterized in that, The soft magnetic strips in the first and second magnetic field conversion regions are exactly the same size.

6. The Z-axis magnetic field sensor as described in any one of claims 1-3, characterized in that, The Z-axis magnetic field sensor has two first sensing half-bridges, and the two first sensing half-bridges constitute a sensing full-bridge.

7. The Z-axis magnetic field sensor as described in any one of claims 1-3, characterized in that, The soft magnetic strip is made of NiFe material.

8. The Z-axis magnetic field sensor according to claim 7, characterized in that, The magnetic sensor is based on XMR, which includes AMR, TMR, and GMR.

9. The Z-axis magnetic field sensor as described in claim 8, characterized in that, The Z-axis magnetic field sensor is fabricated on the same wafer using semiconductor on-chip technology.

10. The Z-axis magnetic field sensor as described in claim 9, characterized in that, The upper and / or lower ends of the first and second magnetic field conversion regions are provided with shielding layers for shielding the magnetic field in the XY plane.

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