Magnetic field sensor chip and manufacturing method thereof

Abstract

The invention discloses a magnetic field sensor chip, and relates to the field of magnetic field sensors, and the magnetic field sensor chip comprises a plastic package floor layer. The magnetic conductive structure layer is arranged on the upper side of the plastic package floor layer; the magnetic sensitive thin film device is arranged on the upper side of the magnetic conductive structure layer, and the magnetic sensitive thin film device comprises a substrate, a bottom electrode layer, a TMR functional layer, a top electrode layer, a passivation layer, a seed layer and a sputtering magnetic conductive layer from bottom to top; and the packaging shell layer is arranged on the upper side of the magnetic conductive structure layer, and a protection object is filled between the packaging shell layer and the magnetic conductive structure layer. The wide-range magnetic sensitive film structure is adopted, the linear interval of the device is further widened under the action of the double magnetic conductive layers, the magnetic linear measurement interval superior to 0.5% within the linearity degree of 2000 Gs and the magnetic test precision superior to 0.1 Gs are achieved, the measurement range of the tunneling magnetoresistance TMR magnetic sensitive device is greatly widened, and the measurement precision of the device is improved. And the magnetic field measurement precision of similar products in the same interval is improved by utilizing the characteristic of high precision.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic field sensors, and in particular to a magnetic field sensor chip and a manufacturing method thereof. Background Art

[0002] In recent years, with the rapid development of smart grids and new energy vehicles, the requirements for the detection accuracy of electrical and magnetic quantities have been continuously improved. How to develop and apply low-power, wide-range magnetic field sensor technology to achieve fast and accurate measurement of electrical and non-electrical quantities is facing huge challenges. For example, the current detection demand in the field of new energy vehicles has exceeded 1000A. In the power system, the accurate coverage of mA to kA current can further improve the measurement safety.

[0003] Traditional current measurement technology mainly relies on current transformers, but the current transformers have problems such as low bandwidth, easy saturation of the core, and large size, which lead to slow response speed, high measurement cost, and cumbersome testing in the actual current measurement process. In recent years, sensors based on the tunnel magnetoresistance effect have the characteristics of small size, low power consumption, and high sensitivity, especially in terms of power consumption and volume.

[0004] The biggest advantages of TMR magnetic sensitive elements are low power consumption, small size and high test accuracy. However, due to the limitation of the saturation field of the magnetic material itself, the linear range of TMR magnetic sensitive elements is mostly between 10 and 50 Gs when magnetic conductive materials are not used. The magnetic shielding factor is defined as the ratio of the magnetic field in the air to the magnetic field around the magnetic sensitive element. The magnetic shielding efficiency is the magnetic field around the magnetic sensitive element. The wide range of more than 2000 Gs is desired. However, the linear range of existing commercial TMR sensors mostly does not exceed 1000 Gs. In order to better meet the above-mentioned kA-level application requirements and to use the high sensitivity of TMR sensors to broaden their measurement limits, it is urgent to study new TMR magnetic field sensor chips with wide range characteristics to meet the testing requirements of wide range and high sensitivity. Summary of the invention

[0005] The present invention is proposed in view of the above problems existing in the magnetic field sensor chip.

[0006] Therefore, the problem to be solved by the present invention is how to achieve a high magnetic shielding factor without increasing the volume of the magnetic conductive structure as much as possible.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: a magnetic field sensor chip, comprising a plastic sealing floor layer; a magnetic conductive structure layer, arranged on the upper side of the plastic sealing floor layer; a magnetically sensitive thin film device, arranged on the upper side of the magnetic conductive structure layer, the magnetically sensitive thin film device comprising from bottom to top a substrate, a bottom electrode layer, a functional layer, a top electrode layer, a passivation layer, a seed layer and a sputtered magnetic conductive layer; a packaging shell layer, arranged on the upper side of the magnetic conductive structure layer and filled with a protective material; the sputtered magnetic conductive layer and the magnetic conductive structure layer are bonded together by bonding or auxiliary bonding to minimize the distance between the TMR functional layer and the magnetic conductive structure layer.

[0008] As a preferred solution of the magnetic field sensor chip described in the present invention, the TMR functional layer adopts a high-linearity magnetic sensitive structure, including a thicker soft magnetic layer NiFe and a superparamagnetic free layer structure. Optionally, the TMR functional layer is PtMn(20)\CoFe(2)\Ru(1)\CoFeB(2)\MgO(1)\CoFeB(1.5)\NiFe(20)\IrMn(16) from bottom to top.

[0009] As a preferred solution of the magnetic field sensor chip of the present invention, the sputtered magnetic conductive layer and the magnetic conductive alloy layer of the magnetic sensitive thin film device are tightly attached to each other through a bonding or auxiliary bonding process.

[0010] As a preferred solution of the magnetic field sensor chip of the present invention, the magnetic conductive structure layer adopts a three-dimensional structure, a hollow magnetic conductive alloy structure is arranged on the magnetic conductive alloy layer, and the magnetic sensitive thin film device is arranged in the hollow magnetic conductive alloy structure.

[0011] As a preferred solution of the magnetic field sensor chip of the present invention, the magnetic linear range of the chip is adjusted by adjusting the thickness of the magnetic conductive alloy layer or the thickness of the hollow magnetic conductive alloy structure.

[0012] As a preferred solution of the magnetic field sensor chip of the present invention, the total thickness of the passivation layer and the seed layer is regulated to adjust the magnetic linear range of the chip. The thicker the total thickness of the passivation layer and the seed layer, the larger the linear range of the chip and the lower the sensitivity.

[0013] In order to solve the above technical problems, the present invention also provides the following technical solutions: a method for manufacturing a magnetic field sensor chip, the steps of which are as follows: preparing a magnetically sensitive functional device layer; preparing a magnetically conductive structure layer; bonding the magnetically conductive structure layer to the magnetically sensitive functional device layer by bonding, auxiliary bonding or adhesion; and encapsulating the above structure in a tube shell.

[0014] As a preferred solution of the manufacturing method of the magnetic field sensor chip of the present invention, wherein: a TMR magnetic sensitive film stack structure is grown on a substrate, including a bottom electrode and a TMR functional layer; the magnetic sensitive film stack is patterned by a standard photolithography process, an extraction electrode is prepared, and a top electrode is prepared by overlaying; the extraction electrode part is protected by photoresist on the above structure, and a passivation layer, a seed layer and a magnetic conductive layer are sputtered on the film stack; the photoresist is washed off to expose the extraction electrode part of the chip.

[0015] As a preferred solution of the manufacturing method of the magnetic field sensor chip of the present invention, wherein: the magnetic conductive alloy structure is processed by wire cutting, and optionally, a Permalloy magnetic conductive structure can be prepared; or a magnetic conductive structure layer containing a high magnetic permeability alloy carrier is prepared by 3D printing; a passivation layer is patterned on the surface of the magnetic conductive structure layer, and an electrode structure corresponding to the magnetic sensitive functional device layer is patterned on the passivation layer, and then the electrode is led out by bonding.

[0016] The beneficial effects of the present invention are as follows: the present invention adopts a wide-range magnetic sensitive film structure to achieve a magnetic linear measurement range better than 0.5% within a linearity of 2000Gs and a magnetic test accuracy better than 0.1Gs, which greatly improves the measurement range of the tunneling magnetoresistance TMR magnetic sensitive device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 Schematic diagram of the structure of the magnetic field sensor chip.

[0019] Figure 2 Schematic diagram of the structure of the magnetic sensitive thin film device of the magnetic field sensor chip.

[0020] Figure 3 Another structural schematic diagram of a magnetic field sensor chip.

[0021] Figure 4 Schematic diagram of the bonding structure between the magnetically sensitive thin film device and the magnetically conductive junction layer of the magnetic field sensor chip.

[0022] Figure 5 This is the relationship curve between the output of the magnetic field sensor chip and the external magnetic field.

[0023] Figure 6 This is the curve of magnetic field shielding efficiency versus thickness of magnetic conductive material layer obtained by simulation in magnetic field sensor chip.

[0024] Figure 7 This is the curve of the magnetic field shielding efficiency obtained by simulation in the magnetic field sensor chip as the magnetic permeability of the magnetic material changes.

[0025] Figure 8 Schematic diagram of the composition structure of the magnetic sensitive film.

[0026] Fig. 9 The manufacturing flow chart of the magnetic field sensor chip.

[0027] Fig.10 Schematic diagram of the magnetic conductive structure layer used in Example 3.

[0028] Fig.11 The magnetic field distribution change diagram of the magnetic conductive structure layer used in Example 3 under the external magnetic field

[0029] Fig.12 The magnetic field shielding efficiency of the magnetic conductive structure layer used in Example 3 varies with the magnetic conductive thickness. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0031] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0032] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it an embodiment that is mutually exclusive with other embodiments, either individually or selectively.

[0033] Example 1

[0034] Reference Figure 1 to Figure 7 , which is the first embodiment of the present invention, provides a magnetic field sensor chip, which includes a plastic package floor layer 100, a magnetic conductive structure layer 200, a magnetic sensitive thin film device 300 and a packaging shell layer 400.

[0035] Specifically, the magnetic field sensor chip includes a plastic sealing floor layer 100, a magnetic conductive structure layer 200, a magnetically sensitive thin film device 300 and a packaging shell layer 400 from bottom to top. The magnetically sensitive thin film device 300 includes a substrate 301, a bottom electrode layer 302, a TMR functional layer 303, a top electrode layer 304, a passivation layer 305, a seed layer 306 and a sputtered magnetic conductive layer 307 from bottom to top according to the growth process; the packaging shell layer 400 is arranged on the upper side of the magnetic conductive structure layer 200 and is filled with a protective material 500; the sputtered magnetic conductive layer 301 and the magnetic conductive structure layer 200 are bonded to each other by bonding or auxiliary bonding to minimize the distance between the TMR functional layer 303 and the magnetic conductive structure layer 200.

[0036] Furthermore, the magnetic sensitive thin film device 300 is a multilayer thin film device prepared on a silicon substrate by sputtering and photolithography processes, wherein a bottom electrode layer 302 is disposed on a substrate 301, and a TMR functional layer 303 is disposed on the bottom electrode layer 302, wherein the TMR functional layer 303 includes an antiferromagnetic pinning layer, a reference layer, a tunneling layer, a free layer, a soft magnetic layer, etc. A top electrode layer 304 is disposed on the TMR functional layer, a passivation layer 305 is disposed on the top electrode layer 304, a seed layer 306 is disposed on the passivation layer 305 to improve the adhesion of the growth of the magnetic conductive material, and a sputtered magnetic conductive layer 307 is disposed on the seed layer 306.

[0037] The sputtered magnetic conductive layer 307 and the magnetic conductive structure layer 200 are of the same structure and can be connected by thermocompression bonding. After the magnetic sensitive thin film device 300 is prepared, its front surface is thermocompressed and bonded to the magnetic conductive structure layer 200 to form a Figure 1 In order to ensure the electrode leads of the chip, it is necessary to expose the electrode 308 in the magnetic sensitive thin film device 300, and at the same time, prepare the passivation layer 305 and the electrode 309 on the magnetic conductive structure through a mask. The electrode 309 and the electrode 308 are also made of the same material, and the conductive connection is achieved through the bonding process. After that, the lead can be bonded on the electrode 309 to connect the pins.

[0038] like Figure 5 , showing the test results of the magnetic sensor chip implemented by the scheme in Example 1. The test condition is 1V voltage. Within the range of 2000Gs magnetic field, the linearity is better than 1%, showing a wide range characteristic.

[0039] like Figure 6As shown in the figure, in order to ensure that the range after adding the shielding layer meets the design requirements, comsolmultiphysics is used to simulate the magnetic field shielding efficiency. The method is to create an air domain, compare the magnetic field size of the air domain and the TMR sensor site, calculate the magnetic field shielding efficiency, consider the thickness of the seed layer 306 and the insulating protection layer, and the surface spacing between the free layer and the Permalloy layer is 1.6um. When the thickness of the sputtered magnetic conductive layer 307 is 30um, the shielding efficiency can reach about 3%, that is, the shielding factor is 33, which can achieve a large range improvement effect.

[0040] On the basis of the above, a magnetic conductive structure layer 200 is added below the inner shielding layer, such as Figure 1 As shown. This magnetic conductive structure layer is fixed at 2.5mm*2.5mm*40μm, slightly smaller than the package size. The distance from the chip is d = 1.5mm, Figure 7 The variation of magnetic shielding factor with the thickness of sputtered magnetic conductive layer with and without modified magnetic conductive structure layer is compared. It can be seen that the outer shielding layer can further increase the magnetic shielding factor and further increase the range of the sensor.

[0041] Example 2

[0042] Reference Figure 8 and Fig. 9 , which is the third embodiment of the present invention, and is based on the first two embodiments.

[0043] Specifically, in order to achieve wide-range magnetic sensitive chip characteristics, the PtMn(20)\CoFe(2)\Ru(1)\CoFeB(2)\MgO(1)\CoFeB(1.5)\NiFe(20)\IrMn(16) structure is used on the magnetic sensitive film stack material, where PtMn(20) is the bottom antiferromagnetic pinning layer, CoFe(2)\Ru(1)\CoFeB(2) is an artificial antiferromagnetic structure to achieve more stable pinning. CoFeB(1.5)\NiFe(20) is a free layer soft magnetic layer combination to increase the range, and the IrMn(16) pinning layer is used for orthogonal pinning to improve the stability and linearity of the film.

[0044] When manufacturing the magnetic field sensor chip, the first step is to form the magnetically sensitive functional device layer, including growing a TMR magnetically sensitive film stack structure on a substrate, patterning the magnetically sensitive film stack through a standard photolithography process, preparing an extraction electrode and overlaying to prepare a top electrode, protecting the extraction electrode portion on the above structure with a photoresist, sputtering a passivation layer 305, a seed layer 306 and a magnetic conductive layer on the film stack, and washing off the photoresist to expose the extraction electrode portion of the chip.

[0045] Next is the magnetic conductive structure layer 200, which includes a magnetic conductive alloy layer 201 processed by wire cutting. Optionally, a Permalloy magnetic conductive structure can be prepared; or a magnetic conductive structure layer 200 containing a high magnetic permeability alloy carrier is prepared by 3D printing; a passivation layer 305 is patterned on the surface of the magnetic conductive structure layer 200, and an electrode structure corresponding to the magnetic sensitive functional device 300 is patterned on the passivation layer 305, and then the electrode is led out by bonding.

[0046] Finally, the magnetic conductive layer is joined to the magnetically sensitive thin film device 300 by bonding, auxiliary bonding or adhesion, and the above structure is packaged in a tube shell.

[0047] Example 3

[0048] Reference Figure 3 and Figure 10 to Figure 12 , which is the second embodiment of the present invention, and this embodiment is based on the previous embodiment.

[0049] Specifically, when the magnetic conductive structure layer 200 is at the um to mm level, a three-dimensional structure may be adopted, including a magnetic conductive alloy layer 201 and a hollow magnetic conductive alloy structure 202, wherein the magnetic conductive alloy layer 201 is disposed on the upper side of the plastic package bottom plate layer 100. The hollow magnetic conductive alloy structure 202 is disposed on the upper side of the magnetic conductive alloy layer 201, the magnetic sensitive thin film device 300 is disposed in the middle of the hollow magnetic conductive alloy structure 202, and the outer layer 400 of the packaging shell is disposed on the upper side of the hollow magnetic conductive alloy structure 202. This structure can achieve a greater magnetic shielding multiple due to the addition of the hollow magnetic conductive alloy structure 202 on the basis of the planar structure.

[0050] It should be noted that the hollow magnetically conductive alloy structure 202 is rectangular.

[0051] In such Figure 4 The scheme in the paper adds a hollow magnetic alloy, but there is no sputtered magnetic layer, and the magnetic lines of force are distributed as follows: Fig.11 As the thickness of the hollow magnetic alloy increases, its magnetic shielding efficiency can reach about 2.5%, that is, the shielding factor is 40, which can achieve a greater range improvement effect.

[0052] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A magnetic field sensor chip, characterized in that: include, Plastic sealing floor layer (100); A magnetic conductive structure layer (200) is arranged on the upper side of the plastic-sealed floor layer (100); A magnetically sensitive thin film device (300) is arranged on the upper side of the magnetic conductive structure layer (200), wherein the magnetically sensitive thin film device (300) comprises, from bottom to top, a substrate (301), a bottom electrode layer (302), a TMR functional layer (303), a top electrode layer (304), a passivation layer (305), a seed layer (306) and a sputtered magnetic conductive layer (307); A packaging shell layer (400) is arranged on the upper side of the magnetic conductive structure layer (200) and a protective material (500) is filled between the two; The sputtered magnetic conductive layer (307) and the magnetic conductive structural layer (200) are bonded together by bonding or auxiliary bonding to reduce the distance between the TMR functional layer (303) and the magnetic conductive structural layer (200).

2. The magnetic field sensor chip according to claim 1, characterized in that: The TMR functional layer (303) is PtMn (20)\CoFe (2)\Ru (1)\CoFeB (2)\MgO (1)\CoFeB (1.5)\NiFe (20)\IrMn (16) from bottom to top.

3. The magnetic field sensor chip according to claim 2, characterized in that: The sputtered magnetic conductive layer (307) of the magnetically sensitive thin film device (300) is tightly attached to the magnetic conductive alloy layer (201) through a bonding or auxiliary bonding process.

4. The magnetic field sensor chip according to claim 3, characterized in that: The magnetic conductive structure layer (200) adopts a three-dimensional structure, a hollow magnetic conductive alloy structure (202) is arranged on the magnetic conductive alloy layer (201), and the magnetic sensitive thin film device (300) is arranged in the hollow magnetic conductive alloy structure (202).

5. The magnetic field sensor chip according to claim 4, characterized in that: The magnetic linear range of the chip is adjusted by adjusting the thickness of the magnetic conductive alloy layer (201) or the thickness of the hollow magnetic conductive alloy structure (202).

6. The magnetic field sensor chip according to claim 5, characterized in that: The total thickness of the passivation layer (305) and the seed layer (306) is regulated to adjust the magnetic linear range of the chip. The thicker the total thickness of the passivation layer (305) and the seed layer (306), the larger the linear range of the chip and the lower the sensitivity.

7. A method for manufacturing a magnetic field sensor chip, characterized in that: Applicable to the magnetic field sensor chip as claimed in claims 1 to 6, the steps are as follows: preparing a magnetically sensitive functional device layer; preparing a magnetic conductive structural layer; The magnetic conductive structure layer is joined to the magnetic sensitive functional device layer by bonding, auxiliary bonding or adhesion; The above structure is packaged in a tube shell.

8. The method for manufacturing a magnetic field sensor chip according to claim 7, characterized in that: The specific manufacturing method of the magnetic sensitive functional device layer is as follows: Growing a TMR magnetically sensitive film stack structure on the substrate, including a bottom electrode and a TMR functional layer; The magnetic sensitive film stack is patterned by a standard photolithography process to prepare the lead-out electrode and the top electrode by overlaying; A photoresist is used to protect the lead-out electrode portion on the above structure, and a passivation layer, a seed layer and a magnetic conductive layer are sputtered and grown on the film stack; The photoresist is washed away to expose the lead electrode part of the chip.

9. The method for manufacturing a magnetic field sensor chip according to claim 8, characterized in that: The specific manufacturing method of the magnetic conductive structure layer is as follows: By wire cutting, the magnetic conductive alloy structure can be processed, and optionally, the Permalloy magnetic conductive structure can be prepared; Or use 3D printing to prepare a magnetic conductive structure layer containing a high magnetic permeability alloy carrier; A passivation layer is patterned on the surface of the magnetic conductive structure layer, and an electrode structure corresponding to the magnetic sensitive functional device layer is patterned on the passivation layer, and then the electrode is led out by bonding.

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