Z-axis magnetic field sensor

Abstract

The utility model provides a Z-axis magnetic field sensor which is characterized in that the sensing direction of a magnetic resistance unit on one side above or below a Z-axis magnetic field conversion part is an X-axis direction or a Y-axis direction, and a soft magnetic layer is arranged on the outer surface of at least one of an upper end electrode and a lower end electrode to shield an interference magnetic field in an XY plane direction. And meanwhile, the to-be-measured magnetic field converted by the Z-axis magnetic field conversion part is attenuated. According to the Z-axis magnetic field sensor provided by the invention, the anti-interference and anti-saturation capabilities are effectively improved through the combined arrangement of the magnetic resistance position structure, the position and the sensing direction, and the Z-axis magnetic field sensor can be applied to a high-intensity magnetic field including a camera module and a complex interference electromagnetic signal environment to measure a Z-axis magnetic field.

Description

Technical Field

[0001] This application relates to the field of structural design of magnetic field measuring devices, specifically to a Z-axis magnetic field sensor with strong anti-interference and anti-saturation capabilities. Background Technology

[0002] Magnetoresistive sensors are a crucial physical component for measuring magnetic field strength. Magnetoresistive sensors offer advantages such as fast response, low power consumption, and small size, making them widely used in mobile phones, computers, automobiles, aviation, aerospace, and other equipment for measuring related physical quantities. They are also core components in various magnetic shaft buttons.

[0003] Currently, the development of magnetoresistive sensors mainly focuses on designing magnetic sensor structures that meet the requirements of various application scenarios. Among these, the anti-interference capability is a core indicator that is most frequently considered in magnetoresistive sensor design, while another important core indicator is the anti-saturation capability. Due to the physical characteristics of magnetoresistive sensors, they have a certain effective range when measuring magnetic fields. When the strength of the magnetic field to be measured is relatively large, the magnetoresistive response will fail or become distorted, i.e., saturation will occur.

[0004] Z-axis magnetic field sensors typically employ a magnetic field conversion structure (usually made of soft magnetic material, such as nickel-iron) to convert the Z-axis magnetic field into an XY-plane magnetic field, which is then measured using magnetoresistive sensing with the X or Y axis as the sensing direction. However, existing Z-axis magnetoresistive sensors struggle to meet measurement requirements in strong magnetic fields and complex electromagnetic environments. This is because magnetoresistive sensors are prone to saturation in strong electromagnetic fields, and the magnetic field conversion structure itself has a magnetizing effect, further exacerbating the risk of magnetoresistive saturation. Furthermore, the anti-interference capability of Z-axis magnetic field sensors is also a crucial factor to consider in complex electromagnetic environments. For example, in the image stabilization function of mobile phone cameras, where related physical quantities are measured, existing Z-axis magnetic field sensors will saturate under strictly limited installation space, thus failing to perform normal measurements. Summary of the Invention

[0005] To address the issue that existing Z-axis magnetic field sensors cannot perform measurements in strong magnetic fields and complex electromagnetic environments, this application provides a Z-axis magnetic field sensor with strong anti-interference and anti-saturation capabilities. This Z-axis magnetic field sensor utilizes an additional soft magnetic shielding layer to simultaneously shield interference fields in the XY plane and attenuate the effective magnetic field after conversion by the magnetic field conversion structure. This balances the anti-interference and anti-saturation capabilities of the Z-axis magnetic field sensor, enabling its direct application in the confined space within a mobile phone camera module for measuring relevant physical quantities.

[0006] The Z-axis magnetic field sensor provided in this application includes: a Z-axis magnetic field conversion unit for converting a Z-axis magnetic field into an XY plane magnetic field, and at least one magnetoresistive unit disposed on one side above or below the Z-axis magnetic field conversion unit. The sensing direction of the magnetoresistive unit is the X-axis direction or the Y-axis direction, and at least one of the upper and lower electrodes of the magnetoresistive unit is covered with a soft magnetic material layer; the component of the magnetic field converted by the Z-axis magnetic field conversion unit at the magnetoresistive unit, corresponding to the sensing direction of the magnetoresistive unit, is not zero.

[0007] Furthermore, the Z-axis magnetic field sensor provided in this application includes two magnetoresistive units symmetrically arranged on either side above or below the Z-axis magnetic field conversion unit. The sensing direction of both magnetoresistive units is either the X-axis or the Y-axis, and at least one electrode on the same side of the two magnetoresistive units is covered with a soft magnetic material layer. Taking the line connecting the locations of the two magnetoresistive units as the X-axis, the X-axis component of the magnetic field converted by the Z-axis magnetic field conversion unit at the locations of the two magnetoresistive units is not zero.

[0008] Clearly, in this Z-axis magnetic field sensor, the soft magnetic material layer not only shields against interfering magnetic fields in the XY plane, but also attenuates the magnetic field to be measured converted from the Z-axis magnetic field conversion unit. A small portion of the magnetic field to be measured leaks to the location of the magnetoresistive unit and is detected. Therefore, the magnetic field sensed by the magnetoresistive unit itself is relatively weak and not easily saturated.

[0009] To prevent interference from the XY plane magnetic field leaking into the functional layer of the magnetoresistive unit, the interference can be canceled out by the following arrangement of the two magnetoresistive units: the two magnetoresistive units have the same sensing direction and the same sensing coefficient, and are connected in series to form a sensing half-bridge, or connected in parallel to form two upper arms of a full bridge; or the two magnetoresistive units have opposite sensing directions and the same sensing coefficient, and are a pair of arms of a full bridge.

[0010] Furthermore, the soft magnetic material layer is disposed on the upper or lower surface of the magnetoresistive unit. Preferably, the soft magnetic material layer is disposed on the side of the two magnetoresistive units away from the Z-axis magnet conversion section.

[0011] Furthermore, the electrodes on the same side of the two magnetoresistive units are single-layer soft magnetic materials or composite layers containing soft magnetic material layers. That is, the soft magnetic material layer itself serves as an electrode of the magnetoresistive unit, or it covers the outer surface of the metal electrode of the magnetoresistive unit. When the soft magnetic shielding layer covers the metal electrode of the magnetoresistive unit, the thickness of the metal electrode will affect the magnitude of the magnetic field sensed by the magnetoresistive functional layer. Preferably, the thickness of the metal electrode covered by the soft magnetic material layer is greater than or equal to 0.1 μm.

[0012] Furthermore, the magnetoresistive unit is an XMR magnetoresistive unit, and the XMR includes GMR, TMR, and AMR.

[0013] The Z-axis magnetic field sensor provided in this application is designed for measuring relevant physical parameters in a confined space within a camera module under conditions of strong magnetic fields and complex electromagnetic environments (with image stabilization). The Z-axis magnetic field sensor is based on the coordinated arrangement of a soft magnetic shielding layer, the position of the magnetoresistive element, and their interconnections. This ensures that the soft magnetic shielding layer not only shields against interference fields but also effectively attenuates the magnetic field being measured. This guarantees that the magnetoresistive element will not saturate under strong magnetic fields and complex electromagnetic environments, thus accurately measuring the Z-axis magnetic field. Attached Figure Description

[0014] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0015] Figure 1 A schematic diagram of the Z-axis magnetic field sensor provided in this application in the first embodiment.

[0016] Figure 2 A schematic diagram of the Z-axis magnetic field sensor provided in this application in a second embodiment.

[0017] Figure 3 A schematic diagram of the Z-axis magnetic field sensor provided in this application in the third embodiment.

[0018] Figure 4 for Figures 1-3 Experimental curves of the Z-axis magnetic field sensor's resistance to X-axis interference field in the embodiment.

[0019] Figure 5 for Figures 1-3 The transformation curve of the magnetic field in the Z direction of the Z-axis magnetic field sensor in the embodiment. Detailed Implementation

[0020] 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, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0021] In this application, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0023] The present invention will now be described in further detail with reference to the accompanying drawings.

[0024] The Z-axis magnetic field sensor provided in this application includes: a Z-axis magnetic field conversion unit for converting a Z-axis magnetic field into an XY-plane magnetic field, and at least one magnetoresistive unit disposed on one side above or below the Z-axis magnetic field conversion unit. The sensing direction of the magnetoresistive unit is either the X-axis direction or the Y-axis direction, and at least one of the upper and lower electrodes of the magnetoresistive unit is covered with a soft magnetic material layer; the magnetic field component of the Z-axis magnetic field converted by the Z-axis magnetic field conversion unit at the magnetoresistive unit, corresponding to the sensing direction of the magnetoresistive unit, is not zero. By additionally disposing of a soft magnetic material layer on one side of the magnetoresistive unit, the influence of interfering magnetic fields in the XY plane is shielded, while the intensity of the effective measured magnetic field is attenuated to prevent magnetoresistive saturation.

[0025] like Figure 1 As shown, in the first embodiment, the Z-axis magnetic field sensor provided by this application includes: a Z-axis magnetic field conversion structure TR (which is made of soft magnetic material, such as NiFe), and two magnetoresistive units R1 and R2.

[0026] Magnetoresistive units R1 and R2 are symmetrically arranged above or below the Z-axis magnetic field conversion unit TR. Figure 1 The diagram only illustrates the case where magnetoresistive units R1 and R2 are located below the Z-axis magnetic field conversion section TR. The line connecting the locations of the two magnetoresistive units is taken as the X-axis, and the sensing directions of both magnetoresistive units R1 and R2 are along the X-axis. Figure 1 As shown, the upper electrode of the two magnetoresistive units R1 and R2 is an aluminum material layer, and the lower electrode is a copper (Cu) metal layer. A soft-touch material layer is deposited on the outer surface of the copper metal layer of magnetoresistive units R1 and R2. Figure 1(NiFe layer in the middle). The X-axis component of the magnetic field after the Z-axis magnetic field is converted by the Z-axis magnetic field conversion unit TR is not zero at the positions of the two magnetoresistive units R1 and R2. The positions of the magnetoresistive units R1 and R2 can be selected according to the experimental results and the actual required sensitivity of the Z-axis magnetic field sensor.

[0027] The additional soft magnetic material layer not only shields the interfering magnetic field in the XY plane, but also attenuates the magnetic field to be measured converted from the Z-axis magnetic field converter TR. A small portion of the magnetic field to be measured leaks to the location of the magnetoresistive units R1 and R2 and is detected. The magnetic field sensed by the magnetoresistive units R1 and R2 is greatly reduced, and the magnetoresistive units themselves are less likely to saturate; while the interfering magnetic field in the XY direction is shielded by the soft magnetic material layer.

[0028] To avoid interference from a small amount of leaked magnetic field in the XY plane, the effect can be eliminated by the following configuration of the two magnetoresistive units R1 and R2: the two magnetoresistive units R1 and R2 are configured to have the same sensing direction and the same sensing coefficient, and are connected in series to form a sensing half-bridge, or connected in parallel to form two upper arms of a full bridge; or the two magnetoresistive units are configured to have opposite sensing directions and the same sensing coefficient, and are configured as a pair of arms of a full bridge.

[0029] Obviously, the soft magnetic material layer can be disposed not only on the lower surface of the magnetoresistive units R1 and R2, but also on the upper surface of the magnetoresistive units R1 and R2, or on both the upper and lower surfaces.

[0030] like Figure 2 As shown, in the second embodiment, the Z-axis magnetic field sensor also includes a Z-axis magnetic field conversion structure TR (made of a soft magnetic material, such as NiFe), and two magnetoresistive units R1 and R2. Unlike the first embodiment, the soft sensing material layer ( Figure 2 The NiFe layer is disposed on the upper surface of the magnetoresistive units R1 and R2, i.e., the outer surface of the aluminum layer. Meanwhile... Figure 3 In the third embodiment shown, the soft test material layer ( Figure 3 The NiFe layer is simultaneously placed on the upper surface (i.e., the outer surface of the aluminum layer) and the lower surface (the outer surface of the copper layer) of the magnetoresistive units R1 and R2.

[0031] Furthermore, in the Z-axis magnetic field sensor provided in this application, the electrodes on the same side of the two magnetoresistive units are a single layer of soft magnetic material or a composite layer containing a soft magnetic material layer. That is, the soft magnetic material layer can cover the outer surface of the metal electrode of the magnetoresistive unit, thereby forming a composite layer containing a soft magnetic material layer; alternatively, the metal electrode can be omitted, and the soft magnetic material layer itself can serve as the electrode of the magnetoresistive unit. Setting the electrodes on the same side of the two magnetoresistive units as a soft magnetic material layer can further reduce the volume of the magnetoresistive unit, which is beneficial for the Z-axis magnetic field sensor to better adapt to narrow installation spaces.

[0032] Furthermore, when the soft magnetic shielding layer covers the metal electrode of the magnetoresistive unit, the thickness of the metal electrode will affect the magnitude of the magnetic field to be measured by the magnetoresistive sensing. Preferably, the thickness of the metal electrode covered by the soft magnetic material layer is greater than or equal to 0.1 μm.

[0033] Furthermore, the magnetoresistive unit is an XMR magnetoresistive unit, which includes GMR, TMR, and AMR. Preferably, the sensitivity of the magnetoresistive unit can be adjusted by the principle of free-layer magnetic exchange bias, or by shape anisotropy when there is no biased free layer.

[0034] Figure 4 The Z-axis magnetic field sensor provided in this application has magnetic field strength curves obtained by applying a 3000oe interference magnetic field on the X-axis when the magnetoresistive unit has no shielding layer, the upper surface is covered with NiFe, the lower surface is covered with NiFe, and both the upper and lower surfaces are covered with NiFe.

[0035] Figure 5 The Z-axis magnetic field sensor provided in this application shows the intensity curves of the magnetic field to be measured after applying a 3000oe magnetic field to the Z-axis when the magnetoresistive unit has no shielding layer, the upper surface is covered with NiFe, the lower surface is covered with NiFe, and both the upper and lower surfaces are covered with NiFe.

[0036] For Figure 4 , Figure 5 The structural dimensions of the experimental Z-axis magnetic field sensor are as follows: the dimensions of the upper NiFe surface of the magnetoresistive unit are: length * width * height = 11.5 μm * 4.5 μm * 0.3 μm; the dimensions of the lower NiFe surface are: length * width * height = 12 μm * 5 μm * 0.2 μm; the dimensions of the Z-axis magnetic field conversion structure are: length * width * height = 140 μm * 8 μm * 3 μm. The distance between the upper and lower NiFe surfaces of the magnetoresistive unit is 0.5 μm, and the vertical distance (i.e., height difference) from the bottom of the Z-axis magnetic field conversion part (also made of NiFe) to the two upper NiFe surfaces of the magnetoresistive unit is 1.1 μm. The permeability of all NiFe is 6000.

[0037] Depend on Figure 4 , Figure 5 It can be seen that, with the left and right edges of the Z-axis magnetic field conversion section (shaded areas) as the centers, and the left and right edges of the NiFe on the upper surface of the two magnetoresistive units as the ranges (i.e., regions 1 and 2), the shielding effect of the XY plane interference magnetic field is good. If only the shielding effect of the XY plane interference magnetic field is considered, it is obviously optimal to set NiFe shielding layers on both the upper and lower surfaces of the magnetoresistive unit. However, combined with... Figure 5 It can be seen that, for the Z-axis magnetic field conversion efficiency, there are non-zero regions in both regions 1 and 2. In order to obtain a sufficiently flat non-zero conversion region and a high conversion rate, it is preferable to cover only the lower surface of the magnetoresistive unit with NiFe (corresponding to...). Figure 2 The preferred embodiment is described below.

[0038] The above description is merely an embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A Z-axis magnetic field sensor, comprising: A Z-axis magnetic field conversion unit for converting a Z-axis magnetic field into an XY plane magnetic field, and at least one magnetoresistive unit disposed on one side above or below the Z-axis magnetic field conversion unit; characterized in that the sensing direction of the magnetoresistive unit is the X-axis direction or the Y-axis direction, and at least one of the upper and lower electrodes of the magnetoresistive unit is covered with a soft magnetic material layer; the magnetic field after the Z-axis magnetic field is converted by the Z-axis magnetic field conversion unit has a component at the magnetoresistive unit corresponding to the sensing direction of the magnetoresistive unit that is not zero.

2. The Z-axis magnetic field sensor as described in claim 1, characterized in that, The Z-axis magnetic field sensor includes two magnetoresistive units symmetrically arranged on both sides above or below the Z-axis magnetic field conversion unit; the sensing direction of the two magnetoresistive units is either the X-axis direction or the Y-axis direction, and at least one electrode on the same side of the two magnetoresistive units is covered with a soft magnetic material layer. Taking the line connecting the locations of the two magnetoresistive units as the X-axis, the X-axis component of the magnetic field after the Z-axis magnetic field is converted by the Z-axis magnetic field conversion unit at the locations of the two magnetoresistive units is not zero.

3. The Z-axis magnetic field sensor as described in claim 2, characterized in that, The two magnetoresistive units have the same sensing direction and the same sensing coefficient, and are connected in series to form a sensing half-bridge, or connected in parallel to form two upper arms of a full bridge; or the two magnetoresistive units have opposite sensing directions and the same sensing coefficient, and are a pair of arms of a full bridge.

4. The Z-axis magnetic field sensor as described in claim 2 or 3, characterized in that, The soft magnetic material layer is disposed on the upper or lower surface of the two magnetoresistive units.

5. The Z-axis magnetic field sensor as described in claim 4, characterized in that, The electrode on the same side is a single layer of soft magnetic material or a composite layer containing a soft magnetic material layer.

6. The Z-axis magnetic field sensor as described in claim 5, characterized in that, The electrode on the same side is a composite layer containing a soft magnetic material layer, and the surface of the soft magnetic material layer closest to the magnetoresistive unit has a minimum distance greater than or equal to 0.1 μm from the magnetoresistive end face.

7. The Z-axis magnetic field sensor as described in claim 6, characterized in that, The magnetoresistive unit is an XMR magnetoresistive unit, and XMR includes GMR, TMR, and AMR.

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