阅读说明：本技术 一种测试灵敏方向可调的gmr磁场传感器及制备方法 (GMR magnetic field sensor with adjustable testing sensitivity direction and preparation method thereof ) 是由 刘明 王志广 胡忠强 苏玮 于 2020-03-19 设计创作，主要内容包括：一种测试灵敏方向可调的GMR磁场传感器及制备方法,包括第一导电材料、第二导电材料、第三导电材料、基底和磁阻条；四个第一导电材料成四宫格状分布在基底表面；若干磁阻条平行等间距设置,相邻的两个磁阻条之间的端部通过第二导电材料连接,使若干磁阻条形成S型串联结构；相邻的第一导电材料之间均设置有S型串联结构,形成惠斯通电桥,S型串联结构端部的磁阻条与第一导电材料连接。本发明通过磁电耦合效应实现了一种灵敏方向可调的新型GMR磁场传感器,利用在压电基底上施加不同的电压改变自由层的磁化方向,最大可以实现探测方向90°调控。保证了在更多工程场景下的应用,可以提高传感器的性能表现,提高传感器的工作效率和应用范围。(A GMR magnetic field sensor with adjustable test sensitivity direction and a preparation method thereof comprise a first conductive material, a second conductive material, a third conductive material, a substrate and a magnetoresistive strip; the four first conductive materials are distributed on the surface of the substrate in a four-grid shape; the plurality of magnetic resistance strips are arranged in parallel at equal intervals, and the end parts between two adjacent magnetic resistance strips are connected through a second conductive material, so that the plurality of magnetic resistance strips form an S-shaped series structure; and an S-shaped series connection structure is arranged between every two adjacent first conductive materials to form a Wheatstone bridge, and the magnetoresistive strips at the end parts of the S-shaped series connection structures are connected with the first conductive materials. The invention realizes a novel GMR magnetic field sensor with adjustable sensitivity direction through magnetoelectric coupling effect, and the magnetization direction of the free layer is changed by applying different voltages on the piezoelectric substrate, so that the detection direction can be adjusted and controlled at 90 degrees to the maximum extent. The method ensures the application in more engineering scenes, can improve the performance of the sensor, and improves the working efficiency and the application range of the sensor.)

1. A GMR magnetic field sensor with adjustable test sensitivity direction is characterized by comprising a first conductive material (2), a second conductive material (3), a third conductive material (4), a substrate (1) and a magnetoresistive strip (5); the four first conductive materials (2) are distributed on the surface of the substrate (1) in a four-grid shape; the plurality of magnetic resistance strips (5) are arranged in parallel at equal intervals, and the end parts between two adjacent magnetic resistance strips (5) are connected through a second conductive material (3), so that the plurality of magnetic resistance strips (5) form an S-shaped series structure; an S-shaped series connection structure is arranged between every two adjacent first conductive materials (2) to form a Wheatstone bridge, and the magnetoresistive strips (5) at the ends of the S-shaped series connection structures are connected with the first conductive materials (2).

2. The GMR magnetic field sensor with adjustable test sensitivity direction according to claim 1, wherein the magnetoresistive strips (5) are of a sandwich structure and comprise a bottom buffer layer, a middle layer and an upper protection layer; the bottom buffer layer is made of Ta with the thickness of 5nm, and the upper protective layer is made of Ta with the thickness of 5 nm.

3. A GMR magnetic field sensor with adjustable test sensitivity according to claim 2, wherein the intermediate layer comprises a free layer, a pinned layer and a nonmagnetic metal material layer, the free layer is Ru/NiFe/CoFe and has a thickness of 3nm-20 nm; the pinning layer is CoFe/Ru/CoFe/IrMn, and the thickness is 3nm-50 nm; the non-magnetic metal material is Cu with the thickness of 1-10 nm.

4. A GMR magnetic field sensor with adjustable test sensitivity according to claim 1, wherein the first (2), the second (3) and the third (4) conductive materials are all conductive metals; the substrate (1) is a PMN-PT piezoelectric substrate.

5. A method for preparing a GMR magnetic field sensor with adjustable testing sensitivity direction, which is based on any one of claims 1 to 4, and comprises the following steps:

step 1, providing a PMN-PT piezoelectric substrate and preprocessing the PMN-PT substrate;

step 2, spin-coating photoresist on the PMN-PT piezoelectric substrate to enable the photoresist to cover the PMN-PT substrate;

step 3, putting the PMN-PT piezoelectric substrate coated with the photoresist in a drying oven to completely cure the photoresist;

step 4, carrying out ultraviolet exposure and development on the first photoresist layer through a mask plate with a first predefined pattern, removing redundant photoresist, and leaving the first predefined pattern on the PMN-PT piezoelectric substrate;

step 5, growing a magnetic resistance material layer on the processed substrate by utilizing a magnetron sputtering film growth technology, and then removing the first layer of photoresist;

step 6, removing the first layer of photoresist, and after dropwise adding the photoresist on the PMN-PT piezoelectric substrate on which the magnetoresistive material grows, covering the photoresist;

step 7, putting the PMN-PT piezoelectric substrate coated with the photoresist in a drying oven to completely cure the photoresist;

step 8, carrying out ultraviolet exposure and development on the second photoresist layer through a mask plate with a second predefined pattern, removing redundant photoresist, and leaving the second predefined pattern on the PMN-PT piezoelectric substrate;

step 9, growing a first conductive material and a second conductive material on the processed substrate by utilizing a magnetron sputtering film growth technology, wherein the thicknesses of the film layers of the first conductive material and the second conductive material are 50-100nm, and the first conductive material and the second conductive material are Ta or Au; then removing the second layer of photoresist;

and step 10, growing a third conductive material on the processed substrate by utilizing a magnetron sputtering film growth technology, wherein the thickness of the film layer of the third conductive material is 50-100nm, and the third conductive material comprises Ta or Au.

6. The method for preparing a GMR magnetic field sensor with adjustable test sensitivity and direction according to claim 5, wherein the preprocessing in the step 1 comprises the following steps: respectively ultrasonically cleaning the mixture for 5min by using acetone, alcohol and deionized water in sequence, then drying the mixture by using N2, and keeping the temperature in an oven at 115 ℃ for 20 min.

7. The method for preparing a GMR magnetic field sensor with adjustable test sensitivity and direction as claimed in claim 5, wherein in step 2 and step 6, the type of the photoresist is APR-3510T, after the photoresist is dripped on the PMN-PT piezoelectric substrate, the photoresist is rotated on a spin coater at a rotation speed of 600 for 10s to cover the PMN-PT piezoelectric plate, and then the photoresist is rotated at a rotation speed of 4000 for 40s to make the photoresist thickness uniform.

8. The method for preparing the GMR magnetic field sensor with the adjustable test sensitivity direction according to the claim 5, characterized in that in the step 3 and the step 7, the inside of the oven is heated for 20min at 115 ℃.

9. The method for preparing a GMR magnetic field sensor with adjustable test sensitivity direction according to claim 5, characterized in that in the step 5, an external bias magnetic field is added to the PMN-PT piezoelectric substrate in the film growth process, the included angle between the bias magnetic field direction and the magnetoresistive strips is 0 degree and 180 degrees when the free layer grows, and the bias magnetic field direction is horizontal and transverse; when the pinning layer grows, the included angle between the bias magnetic field direction and the magnetoresistive strips is 90 degrees, and the bias magnetic field direction is vertical.

Technical Field

The invention belongs to the technical field of sensors, and particularly relates to a GMR magnetic field sensor with adjustable testing sensitivity direction and a preparation method thereof.

Background

In the design and manufacture of the conventional GMR sensor, the conventional GMR sensor has a single sensitive test direction due to the design of the pinned layer and the free layer. In practical use, in order to characterize the spatial distribution of a three-dimensional spatial magnetic field, simultaneous measurements by three mutually orthogonal sensors are required. However, because the distance between three independent sensor elements of the three-axis magnetometer is large, the GMR sensor adopting the design cannot accurately measure the magnetic field information of a certain position and can only be used for measuring the size of a uniform magnetic field in a large space. In addition, the conventional GMR sensor employs three independent sensing units, which increases the size and cost of the sensor. In many engineering applications, small-volume, high-precision magnetic field sensors are required.

Disclosure of Invention

The invention aims to provide a GMR magnetic field sensor with adjustable testing sensitivity direction and a preparation method thereof, so as to solve the problems.

In order to achieve the purpose, the invention adopts the following technical scheme:

a GMR magnetic field sensor with adjustable test sensitivity direction comprises a first conductive material, a second conductive material, a third conductive material, a substrate and a magnetoresistive strip; the four first conductive materials are distributed on the surface of the substrate in a four-grid shape; the plurality of magnetic resistance strips are arranged in parallel at equal intervals, and the end parts between two adjacent magnetic resistance strips are connected through a second conductive material, so that the plurality of magnetic resistance strips form an S-shaped series structure; and an S-shaped series connection structure is arranged between every two adjacent first conductive materials to form a Wheatstone bridge, and the magnetoresistive strips at the end parts of the S-shaped series connection structures are connected with the first conductive materials.

Furthermore, the magnetic resistance strip is of a sandwich structure and comprises a bottom buffer layer, a middle layer and an upper protective layer; the bottom buffer layer is made of Ta with the thickness of 5nm, and the upper protective layer is made of Ta with the thickness of 5 nm.

Furthermore, the middle layer comprises a free layer, a pinning layer and a nonmagnetic metal material layer, wherein the free layer is Ru/NiFe/CoFe, and the thickness is 3nm-20 nm; the pinning layer is CoFe/Ru/CoFe/IrMn, and the thickness is 3nm-50 nm; the non-magnetic metal material is Cu with the thickness of 1-10 nm.

Further, the first conductive material, the second conductive material and the third conductive material are all conductive metals; the substrate is a PMN-PT piezoelectric substrate.

Further, a method for preparing a GMR magnetic field sensor with adjustable test sensitivity direction comprises the following steps:

step 1, providing a PMN-PT piezoelectric substrate and preprocessing the PMN-PT substrate;

step 2, spin-coating photoresist on the PMN-PT piezoelectric substrate to enable the photoresist to cover the PMN-PT substrate;

step 3, putting the PMN-PT piezoelectric substrate coated with the photoresist in a drying oven to completely cure the photoresist;

step 4, carrying out ultraviolet exposure and development on the first photoresist layer through a mask plate with a first predefined pattern, removing redundant photoresist, and leaving the first predefined pattern on the PMN-PT piezoelectric substrate;

step 5, growing a magnetic resistance material layer on the processed substrate by utilizing a magnetron sputtering film growth technology, and then removing the first layer of photoresist;

step 6, removing the first layer of photoresist, and after dropwise adding the photoresist on the PMN-PT piezoelectric substrate on which the magnetoresistive material grows, covering the photoresist;

step 7, putting the PMN-PT piezoelectric substrate coated with the photoresist in a drying oven to completely cure the photoresist;

step 8, carrying out ultraviolet exposure and development on the second photoresist layer through a mask plate with a second predefined pattern, removing redundant photoresist, and leaving the second predefined pattern on the PMN-PT piezoelectric substrate;

step 9, growing a first conductive material and a second conductive material on the processed substrate by utilizing a magnetron sputtering film growth technology, wherein the thicknesses of the film layers of the first conductive material and the second conductive material are 50-100nm, and the first conductive material and the second conductive material are Ta or Au; then removing the second layer of photoresist;

and step 10, growing a third conductive material on the processed substrate by utilizing a magnetron sputtering film growth technology, wherein the thickness of the film layer of the third conductive material is 50-100nm, and the third conductive material comprises Ta or Au.

Further, the pretreatment in step 1 comprises: respectively ultrasonically cleaning the mixture for 5min by using acetone, alcohol and deionized water in sequence, then drying the mixture by using N2, and keeping the temperature in an oven at 115 ℃ for 20 min.

Further, in the step 2 and the step 6, the photoresist is APR-3510T, after the photoresist is dripped on the PMN-PT piezoelectric substrate, the photoresist is rotated on a spin coater at the rotation speed of 600 for 10s to cover the PMN-PT piezoelectric plate, and then the photoresist is rotated at the rotation speed of 4000 for 40s to make the photoresist uniform in thickness.

Further, in step 3 and step 7, the inside of the oven was heated at 115 ℃ for 20 min.

Further, in the step 5, in the film growth process, an external bias magnetic field is added to the PMN-PT piezoelectric substrate, the included angles between the direction of the bias magnetic field and the magnetoresistive strips are 0 degree and 180 degrees when the free layer grows, and the direction of the bias magnetic field is horizontal and transverse; when the pinning layer grows, the included angle between the bias magnetic field direction and the magnetic resistance strip is 90 degrees, and the bias magnetic field direction is vertical.

Compared with the prior art, the invention has the following technical effects:

the invention realizes a novel GMR magnetic field sensor with adjustable sensitivity direction through magnetoelectric coupling effect, and the magnetization direction of the free layer is changed by applying different voltages on the piezoelectric substrate, so that the detection direction can be adjusted and controlled at 90 degrees to the maximum extent. The method ensures the application in more engineering scenes, can improve the performance of the sensor, and improves the working efficiency and the application range of the sensor.

The problem that the traditional GMR sensor only has a single sensitive direction is solved through a magnetoelectric coupling mode. Compared with the traditional GMR sensor, the performance of the sensor can be effectively improved by utilizing a magnetoelectric coupling method, the regulation and control of the sensitivity direction at 90 degrees can be realized to the maximum extent, and the application range of the GMR sensor is enlarged.

Drawings

Fig. 1 illustrates the overall structure of a GMR sensor.

Fig. 2 illustrates the design structure of the sensor in a GMR sensor.

Fig. 3 illustrates a manufacturing flow of a GMR sensor.

In the figure: 1-piezoelectric substrate material, 2-first conductive material, 3-second conductive material, 4-third conductive material, 5-magnetoresistive strip, 6-magnetic field direction.

Detailed Description

The invention is further described below with reference to the accompanying drawings:

referring to fig. 1 to 3, a GMR magnetic field sensor with adjustable test sensitivity direction includes a first conductive material 2, a second conductive material 3, a third conductive material 4 and a magnetoresistive strip 5; the four first conductive materials 2 are distributed in a four-grid shape, the plurality of magnetic resistance strips 5 are arranged in parallel at equal intervals, and the end parts between two adjacent magnetic resistance strips 5 are connected through the second conductive material 3, so that the plurality of magnetic resistance strips 5 form an S-shaped series connection structure; an S-shaped series connection structure is arranged between every two adjacent first conductive materials 2 to form a Wheatstone bridge, and the magnetoresistive strips 5 at the end parts of the S-shaped series connection structures are connected with the first conductive materials 2; the first conductive material 2, the second conductive material 3, and the third conductive material 4 are all conductive metals.

The magnetic resistance strip 5 is of a sandwich structure and comprises a bottom buffer layer, a middle layer and an upper protective layer; the buffer layer at the bottom layer is made of Ta with the thickness of 5nm, the protective layer at the upper layer is made of Ta with the thickness of 5nm, the middle layer comprises a free layer, a pinning layer and a nonmagnetic metal material layer, the free layer is Ru/NiFe/CoFe with the thickness of 3nm-20 nm; the pinning layer is CoFe/Ru/CoFe/IrMn, and the thickness is 3nm-50 nm; the non-magnetic metal material is Cu with the thickness of 1-10 nm.

A novel GMR magnetic field sensor with adjustable sensitivity direction based on magnetoelectric coupling comprises the following steps:

step 1, providing a PMN-PT piezoelectric substrate and preprocessing the PMN-PT substrate;

step 2, after dropwise adding photoresist on the PMN-PT piezoelectric substrate, enabling the photoresist to cover the PMN-PT substrate;

step 3, putting the PMN-PT piezoelectric substrate coated with the photoresist in a drying oven to completely cure the photoresist;

step 4, carrying out ultraviolet exposure and development on the first photoresist layer through a mask plate with a first predefined pattern, removing redundant photoresist, and leaving the first predefined pattern on the PMN-PT piezoelectric substrate;

and 5, growing a magnetic resistance material layer on the processed substrate by utilizing a magnetron sputtering film growth technology, and then removing the first layer of photoresist.

Step 6, removing the first layer of photoresist, and after dropwise adding the photoresist on the PMN-PT piezoelectric substrate on which the magnetoresistive material grows, covering the photoresist;

step 7, putting the PMN-PT piezoelectric substrate coated with the photoresist in a drying oven to completely cure the photoresist;

step 8, carrying out ultraviolet exposure and development on the second photoresist layer through a mask plate with a second predefined pattern, removing redundant photoresist, and leaving the second predefined pattern on the PMN-PT piezoelectric substrate;

step 9, growing a first conductive material and a second conductive material on the processed substrate by utilizing a magnetron sputtering film growth technology, wherein the thicknesses of the first conductive material film layer and the second conductive material film layer are 50-100nm, and the first conductive material and the second conductive material comprise Ta or Au; then removing the second layer of photoresist;

and step 10, growing a third conductive material on the processed substrate by utilizing a magnetron sputtering film growth technology, wherein the thickness of the film layer of the third conductive material is 50-100nm, and the third conductive material comprises Ta or Au.

The pretreatment in step 1 comprises: respectively ultrasonically cleaning the mixture for 5min by using acetone, alcohol and deionized water in sequence, then drying the mixture by using N2, and keeping the temperature in an oven at 115 ℃ for 20 min.

In the step 2 and the step 6, the type of the photoresist is APR-3510T, after the photoresist is dripped on the PMN-PT piezoelectric substrate, the photoresist is rotated on a spin coater at the rotation speed of 600 for 10s to enable the photoresist to cover the PMN-PT piezoelectric plate, and then the photoresist is rotated at the rotation speed of 4000 for 40s to enable the thickness of the photoresist to be uniform.

In step 3 and step 7, the inside of the oven was heated at 115 ℃ for 20 min.

Step 5, in the film growth process, adding an external bias magnetic field to the PMN-PT piezoelectric substrate, wherein the included angles between the direction of the bias magnetic field and the magnetoresistive strips are 0 degree and 180 degrees when the free layer grows, and the direction of the bias magnetic field is horizontal and transverse; when the pinning layer grows, the included angle between the bias magnetic field direction and the magnetoresistive strips is 90 degrees, and the bias magnetic field direction is vertical.

In the process of film growth, an external bias magnetic field 6 is added to the PMN-PT substrate, and the included angles between the direction of the bias magnetic field 6 and the magnetoresistive strips 5 are 0 degree, 90 degrees and 180 degrees, as shown in FIG. 1, the direction of the bias magnetic field 6 is horizontal and transverse. The free layer film thickness can be changed, other magnetic materials can be used, the pinning layer material film thickness can be changed, other antiferromagnetic materials can be used, and the number and the size of the magnetoresistive strips 5 can be changed. The conductive metals 2, 3 and the magnetoresistive strips 5 form a wheatstone bridge.

The test result shows that the magnetization curve of the pinning layer can be changed by applying voltage to the PMN-PT, so that the hard and easy axis of the pinning layer realizes the regulation and control effect of 90 degrees.