Manufacturing method of magnetoresistive film stack and magnetoresistive sensor

Abstract

The invention relates to the field of magnetic storage, in particular to a manufacturing method of a magnetoresistive film stack and a magnetoresistive sensor, a reference layer is arranged, and a barrier layer is arranged on the surface of the reference layer; a free layer with an inclined magnetic moment thickness is arranged on the surface of the barrier layer, and the magnetization direction of the free layer under the inclined magnetic moment is not in the plane of the free layer; and performing shape anisotropy processing on the free layer to reduce the included angle between the magnetization direction of the free layer and the plane of the free layer to be within a first threshold value, thereby obtaining the magnetoresistive film stack. The thickness of the free layer is controlled, the magnetization direction of the free layer is changed to be inclined, the anisotropic field of the free layer under the inclined magnetic moment is greatly reduced, the sensitivity of the free layer is greatly improved, and meanwhile, on the basis of the magnetoresistive film stack with the free layer with the inclined magnetic moment, the sensitivity of the free layer is greatly improved. By means of shape anisotropy, the magnetization direction of the free layer is arranged along an in-plane long axis, and linear output is achieved.

Description

Technical Field

[0001] The present invention relates to the field of magnetic storage, and in particular to a method for manufacturing a magnetoresistive film stack and a magnetoresistive sensor. Background Art

[0002] Magnetoresistive sensors (mainly giant magnetoresistive sensors and tunnel magnetoresistive sensors) are a new type of sensor that is widely used in consumer electronics, industrial electronics and other fields. The sensor uses the fact that the resistance of a magnetic multilayer film changes with the size and angle of the magnetic field to detect the magnetic field. It has the advantages of high sensitivity, small size and low power consumption.

[0003] Among them, one application scenario of magnetoresistive sensors is to detect the z-axis magnetic field, which becomes an alternative to Hall sensors. In order to achieve linear output, the magnetization direction of the reference layer needs to be fixed in the out-of-plane direction (z-axis) and the magnetization orientation of the free layer in the in-plane direction (xy plane). However, in the actual implementation process, a thicker free layer is usually prepared so that its magnetic moment remains in the in-plane direction when prepared. Although this cross structure has z-axis sensitivity, the free layer with an in-plane magnetization direction has a large anisotropy field, and a large out-of-plane magnetic field (greater than 200mT) is required to pull it to rotate in the out-of-plane direction, so it cannot maintain high sensitivity.

[0004] Therefore, how to find a method to improve the sensitivity of the magnetoresistive sensor while maintaining linear output is an urgent problem to be solved by those skilled in the art. Summary of the invention

[0005] The object of the present invention is to provide a method for manufacturing a magnetoresistive film stack and a magnetoresistive sensor, so as to solve the problem in the prior art that the sensitivity of the magnetoresistive sensor cannot be improved while maintaining linear output.

[0006] In order to solve the above technical problems, the present invention provides a method for manufacturing a magnetoresistive film stack, comprising:

[0007] Setting a reference layer, and setting a barrier layer on the surface of the reference layer;

[0008] A free layer with a tilted magnetic moment thickness is arranged on the surface of the barrier layer, wherein the magnetization direction of the free layer under the tilted magnetic moment is not within the plane of the free layer;

[0009] The free layer is subjected to shape anisotropy treatment so that the angle between the magnetization direction of the free layer and the plane of the free layer is reduced to within a first threshold, thereby obtaining the magnetoresistive film stack.

[0010] Optionally, in the manufacturing method of the magnetoresistive film stack, the free layer includes a first free sublayer, a ferromagnetic coupling layer and a second free sublayer; and the free layer with an inclined magnetic moment thickness arranged on the surface of the barrier layer includes:

[0011] Disposing the first free sub-layer on the surface of the barrier layer;

[0012] Disposing the ferromagnetic coupling layer on the surface of the first free sub-layer;

[0013] The second free sub-layer is disposed on the surface of the ferromagnetic coupling layer.

[0014] Optionally, in the method for manufacturing the magnetoresistive film stack, the ferromagnetic coupling layer includes at least one of a metal tantalum layer, a metal ruthenium layer, a metal tungsten layer and a metal molybdenum layer.

[0015] Optionally, in the method for manufacturing the magnetoresistive film stack, the step of performing shape anisotropy treatment on the free layer comprises:

[0016] The combination layer of the free layer and the reference layer, or the combination layer of the free layer, the reference layer and the barrier layer is processed by a single shape anisotropy process.

[0017] A magnetoresistive sensor device comprises a substrate, a seed layer, a pinning layer and a magnetoresistive film stack arranged in layers;

[0018] The seed layer is disposed on the surface of the substrate;

[0019] The pinning layer is used to pin the magnetization direction of the reference layer;

[0020] The magnetoresistive film stack is a stack obtained by any one of the above-mentioned methods for manufacturing a magnetoresistive film stack.

[0021] Optionally, in the magnetoresistive sensor device, the free layer in the magnetoresistive film stack is a strip-shaped free layer.

[0022] Optionally, in the magnetoresistive sensor device, the strip-shaped free layer is at least one of a rectangular free layer, an elliptical free layer and a long hexagonal free layer.

[0023] Optionally, in the magnetoresistive sensor device, the thickness of the free layer ranges from 1.2 nanometers to 1.8 nanometers, including endpoint values.

[0024] Optionally, in the magnetoresistive sensor device, the seed layer includes at least one of a metal tantalum layer, a metal ruthenium layer, a metal platinum layer and a metal palladium layer.

[0025] Optionally, in the magnetoresistive sensor device, the pinning layer includes at least one of a cobalt / platinum multilayer film, a cobalt / palladium multilayer film, a cobalt / nickel multilayer film, an iron / platinum multilayer film and an iron / palladium multilayer film.

[0026] The manufacturing method of the magnetoresistive film stack provided by the present invention is as follows: a reference layer is set, and a barrier layer is set on the surface of the reference layer; a free layer with a tilted magnetic moment thickness is set on the surface of the barrier layer, and the magnetization direction of the free layer under the tilted magnetic moment is not in the plane of the free layer; the free layer is subjected to shape anisotropy treatment, so that the angle between the magnetization direction of the free layer and the plane of the free layer is reduced to within a first threshold value, thereby obtaining the magnetoresistive film stack. In the present application, by controlling the thickness of the free layer, the magnetization direction of the free layer is first changed to a tilted setting, and the anisotropy field of the free layer under the tilted magnetic moment is greatly reduced, so that the sensitivity of the free layer is greatly improved. At the same time, based on the magnetoresistive film stack with the free layer having a tilted magnetic moment, the magnetization direction of the free layer is arranged along the long axis in the plane by means of shape anisotropy, and a cross structure is formed with the magnetization direction of the reference layer, thereby realizing linear output. The present invention also provides a magnetoresistive sensor having the above-mentioned beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 paying creative work.

[0028] Figure 1 A schematic flow chart of a specific implementation of a method for manufacturing a magnetoresistive film stack provided by the present invention;

[0029] Figures 2 to 4 A schematic structural diagram of a specific implementation of the magnetoresistive sensor provided by the present invention;

[0030] Figures 5 to 7 A top view of the free layer of a specific implementation manner of the magnetoresistive sensor provided by the present invention.

[0031] In the figure, it includes: 100-substrate, 200-seed layer, 300-pinned layer, 410-reference layer, 420-barrier layer, 430-free layer, 431-first free sublayer, 432-second free sublayer, 433-ferromagnetic coupling layer. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0033] The core of the present invention is to provide a method for manufacturing a magnetoresistive film stack, a flow chart of a specific implementation method thereof is shown as follows: Figure 1 As shown, it is called specific implementation mode 1, including:

[0034] S101: providing a reference layer, and providing a barrier layer on a surface of the reference layer.

[0035] The reference layer can be a single-layer film or a composite film layer, and can be made of cobalt iron boron material. When a single-layer film is used as the reference layer, the thickness of the reference layer can range from 0.7 nanometers to 1.8 nanometers, including endpoint values, such as any one of 0.70 nanometers, 1.02 nanometers or 1.80 nanometers.

[0036] The barrier layer may be a magnesium oxide layer. Of course, it may also be made of other materials, which is not limited in the present invention.

[0037] S102: Disposing a free layer with a tilted magnetic moment thickness on the surface of the barrier layer, wherein the magnetization direction of the free layer under the tilted magnetic moment is not within the plane of the free layer.

[0038] Taking a single layer of CoFeB as the free layer, the corresponding canted magnetic moment thickness ranges from 1.2 nanometers to 1.8 nanometers, including endpoint values, such as any one of 1.20 nanometers, 1.60 nanometers or 1.80 nanometers.

[0039] As a preferred implementation, the free layer includes a first free sub-layer, a ferromagnetic coupling layer and a second free sub-layer; and this step includes:

[0040] A1: The first free sub-layer is disposed on the surface of the barrier layer.

[0041] The thickness of the first free sub-layer ranges from 1.0 nanometers to 1.5 nanometers, including endpoint values, such as any one of 1.00 nanometers, 1.30 nanometers, or 1.50 nanometers.

[0042] A2: The ferromagnetic coupling layer is disposed on the surface of the first free sub-layer.

[0043] The ferromagnetic coupling layer is used to enable two free sub-layers to be ferromagnetically coupled.

[0044] The thickness of the ferromagnetic coupling layer ranges from 0.1 nanometers to 0.5 nanometers, including endpoint values, such as any one of 0.10 nanometers, 0.36 nanometers, or 0.50 nanometers.

[0045] The ferromagnetic coupling layer can be a metal titanium layer, a metal tungsten layer, a metal ruthenium layer, a metal iridium layer, a metal molybdenum layer, or a composite layer or a mixed layer of the above metal layers. The above metal layers have mature processes, low costs, and good ferromagnetic coupling effects, and the present invention is not limited here.

[0046] A3: Disposing the second free sublayer on the surface of the ferromagnetic coupling layer.

[0047] The second free layer has a thickness ranging from 2.6 nanometers to 2.8 nanometers, including endpoint values, such as any one of 2.60 nanometers, 2.75 nanometers, or 2.80 nanometers.

[0048] Preferably, the first free sub-layer and the second free sub-layer are made of the same material, which may be a cobalt iron boron layer. For a specific structural diagram, please refer to Figure 4 .

[0049] S103: performing shape anisotropy processing on the free layer to reduce the angle between the magnetization direction of the free layer and the plane of the free layer to within a first threshold, thereby obtaining the magnetoresistive film stack.

[0050] The shape anisotropy treatment refers to processing the shape of the free layer. Since the free layer is always a layered structure, this step mainly changes the shape of the layer, and "anisotropy" means that the free layer presents different properties in various directions when viewed from above, in other words, there is a major axis and a minor axis. In order to pull the magnetization direction of the free layer as close to the plane of the free layer as possible, the ratio of the major axis to the minor axis of the free layer should be as large as possible.

[0051] The first threshold is an angle value, and its corresponding value range can be 0 degrees to 5 degrees, including endpoint values. Of course, it can also be selected according to actual conditions.

[0052] Furthermore, the performing shape anisotropy processing on the free layer includes:

[0053] The combination layer of the free layer and the reference layer, or the combination layer of the free layer, the reference layer and the barrier layer is processed by a single shape anisotropy process.

[0054] In the preferred embodiment, in order to realize the shape anisotropy of the free layer, not only the free layer is processed for shape anisotropy, but also the reference layer and the barrier layer are processed. To realize the technical effect of the shape anisotropy, etching technology can be used. In the preferred embodiment, not only the free layer is etched to realize the shape change, but also other layers in the magnetoresistive film stack are etched, which reduces the process difficulty of processing shape anisotropy, thereby improving production efficiency and reducing production costs.

[0055] The manufacturing method of the magnetoresistive film stack provided by the present invention comprises the following steps: setting a reference layer, and setting a barrier layer on the surface of the reference layer; setting a free layer with a tilted magnetic moment thickness on the surface of the barrier layer, wherein the magnetization direction of the free layer under the tilted magnetic moment is not in the plane of the free layer; and performing shape anisotropy treatment on the free layer to reduce the angle between the magnetization direction of the free layer and the plane of the free layer to within a first threshold value, thereby obtaining the magnetoresistive film stack. In the present application, by controlling the thickness of the free layer, the magnetization direction of the free layer is first changed to a tilted setting, and the anisotropy field of the free layer under the tilted magnetic moment is greatly reduced, so that the sensitivity of the free layer is greatly improved. At the same time, based on the magnetoresistive film stack of the free layer with a tilted magnetic moment, the magnetization direction of the free layer is arranged along the long axis in the plane by means of shape anisotropy, and a cross structure is formed with the magnetization direction of the reference layer, thereby realizing linear output.

[0056] The present invention also provides a magnetoresistive sensor device, a structural schematic diagram of a specific implementation method thereof is shown as follows: Figures 2 to 7 As shown, it is called the second specific embodiment, which includes a stacked substrate 100, a seed layer 200, a pinning layer 300 and a magnetoresistive film stack;

[0057] The seed layer 200 is disposed on the surface of the substrate 100;

[0058] The pinning layer 300 is used to pin the magnetization direction of the reference layer 410;

[0059] The magnetoresistive film stack is a stack obtained by any one of the above-mentioned methods for manufacturing a magnetoresistive film stack.

[0060] Preferably, the free layer 430 in the magnetoresistive film stack is a strip-shaped free layer 430. The strip-shaped free layer 430 has a shape with obvious long axis and short axis, and the long axis and short axis are perpendicular to each other. As can be seen from the above, the larger the ratio of the long axis to the short axis, the closer the magnetization direction of the free layer 430 is to the plane of the free layer 430.

[0061] Specifically, the strip-shaped free layer 430 is at least one of a rectangular free layer 430, an elliptical free layer 430 and a long hexagonal free layer 430, which can be referred to Figure 5 , Figure 6 and Figure 7 , top views corresponding to the rectangular free layer 430 , the elliptical free layer 430 and the long hexagonal free layer 430 are respectively given.

[0062] In addition, the thickness of the free layer 430 in this specific embodiment corresponds to the canted magnetic moment thickness mentioned above, ranging from 1.2 nanometers to 1.8 nanometers, including endpoint values, such as any one of 1.20 nanometers, 1.66 nanometers or 1.80 nanometers.

[0063] The pinning layer 300 includes at least one of a cobalt / platinum multilayer film, a cobalt / palladium multilayer film, a cobalt / nickel multilayer film, an iron / platinum multilayer film, and an iron / palladium multilayer film.

[0064] When the pinning layer 300 adopts a cobalt / platinum multilayer film, the thickness of the cobalt film ranges from 0.2 nanometers to 0.6 nanometers, including endpoint values, such as any one of 0.20 nanometers, 0.33 nanometers or 0.60 nanometers, and the thickness of the platinum film ranges from 0.2 nanometers to 1.0 nanometers, including endpoint values, such as any one of 0.20 nanometers, 0.33 nanometers or 1.00 nanometers.

[0065] Of course, other antiferromagnetic materials can also be used to achieve the effect of the pinning layer 300, such as any one of IrMn (manganese iridium compound), PtMn (manganese platinum compound), PdMn (manganese palladium compound), and NiMn (manganese nickel compound). When the above antiferromagnetic compound is used as the pinning layer 300, the thickness of the pinning layer 300 ranges from 3 nanometers to 7 nanometers, including end values, such as any one of 3.0 nanometers, 5.3 nanometers, or 7.0 nanometers.

[0066] In addition, the seed layer 200 includes at least one of a metal tantalum layer, a metal ruthenium layer, a metal platinum layer and a metal palladium layer. The above layers have good interface contact performance with the pinning layer 300 and the substrate 100, and have low cost and mature technology. Of course, other materials can also be selected according to different actual needs, and the present invention is not limited here.

[0067] Of course, the free layer 430 can be stacked on a side closer to the seed layer 200 than the reference layer 410, or can be arranged on a side farther away from the seed layer 200. Figure 2 and Figure 3In the specific implementation manner corresponding to the accompanying drawings of the present invention, the reference layer 410 and the free layer 430 use cobalt iron boron (CoFeB) material, the barrier layer 420 uses magnesium oxide (MgO) material, the substrate 100 is a silicon substrate 100 (Si / SiO2), the seed layer 200 uses Seed layer in the figure, and the pinned layer 300 uses a composite film layer of cobalt and platinum. The m and n in the figure are the number of film layers, which can be selected according to actual conditions. The film layers are coupled with ruthenium (Ru), and are coupled with the reference layer 410 with metal titanium (Ta). The structural schematic diagram of the specific implementation manner including the first free sublayer 431, the ferromagnetic coupling layer 433 and the second free sublayer 432 described above is shown as follows: Figure 4 shown.

[0068] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0069] It should be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0070] The above is a detailed introduction to the manufacturing method of the magnetoresistive film stack and the magnetoresistive sensor provided by the present invention. This article uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core ideas of the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for manufacturing a magnetoresistive film stack, characterized in that: include: Setting a reference layer, and setting a barrier layer on the surface of the reference layer; A free layer with a tilted magnetic moment thickness is arranged on the surface of the barrier layer, wherein the magnetization direction of the free layer under the tilted magnetic moment is not within the plane of the free layer; The free layer is subjected to shape anisotropy treatment so that the angle between the magnetization direction of the free layer and the plane of the free layer is reduced to within a first threshold, thereby obtaining the magnetoresistive film stack.

2. The method for manufacturing a magnetoresistive film stack according to claim 1, wherein: The free layer includes a first free sub-layer, a ferromagnetic coupling layer and a second free sub-layer; The free layer having a tilted magnetic moment thickness arranged on the surface of the barrier layer comprises: Disposing the first free sub-layer on the surface of the barrier layer; Disposing the ferromagnetic coupling layer on the surface of the first free sub-layer; The second free sub-layer is disposed on the surface of the ferromagnetic coupling layer.

3. The method for manufacturing a magnetoresistive film stack according to claim 2, wherein: The ferromagnetic coupling layer includes at least one of a metal tantalum layer, a metal ruthenium layer, a metal tungsten layer and a metal molybdenum layer.

4. The method for manufacturing a magnetoresistive film stack according to claim 1, wherein: The performing shape anisotropy processing on the free layer comprises: The combination layer of the free layer and the reference layer, or the combination layer of the free layer, the reference layer and the barrier layer is processed by a single shape anisotropy process.

5. A magnetoresistive sensor device, characterized in that: It includes a substrate, a seed layer, a pinning layer and a magnetoresistive film stack which are stacked; The seed layer is disposed on the surface of the substrate; The pinning layer is used to pin the magnetization direction of the reference layer; The magnetoresistive film stack is a stack obtained by the method for manufacturing a magnetoresistive film stack according to any one of claims 1 to 4.

6. The magnetoresistive sensor device according to claim 5, characterized in that: The free layer in the magnetoresistive film stack is a strip-shaped free layer.

7. The magnetoresistive sensor device according to claim 6, characterized in that: The strip-shaped free layer is at least one of a rectangular free layer, an elliptical free layer and a long hexagonal free layer.

8. The magnetoresistive sensor device according to claim 5, characterized in that: The thickness of the free layer ranges from 1.2 nanometers to 1.8 nanometers, both inclusive.

9. The magnetoresistive sensor device according to claim 5, characterized in that: The seed layer includes at least one of a metal tantalum layer, a metal ruthenium layer, a metal platinum layer and a metal palladium layer.

10. The magnetoresistive sensor device according to claim 5, characterized in that: The pinning layer includes at least one of a cobalt / platinum multilayer film, a cobalt / palladium multilayer film, a cobalt / nickel multilayer film, an iron / platinum multilayer film and an iron / palladium multilayer film.

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