Method and system for testing and analyzing magneto-optical parameters of magnetic multilayer film

Abstract

The invention discloses a method and system for testing and analyzing magneto-optical parameters of a magnetic multilayer film, and belongs to the technical field of photoelectron data analysis, and the method comprises the following steps: carrying out an ellipsometry test on a to-be-tested magnetic multilayer film sample to obtain ellipsometry parameters of the sample; constructing an optical model according to the structure of the magnetic multilayer film sample to be tested, and performing fitting calculation by combining an optical theory and the ellipsometric parameters obtained by testing to obtain optical property parameters of each layer of film in the sample; the method comprises the following steps: carrying out a magneto-optical ellipsometry test on a to-be-tested magnetic multilayer film sample to obtain a reflection coefficient of the sample in an unmagnetized state and a magneto-reflection coefficient caused by a Kerr effect, deriving a total propagation matrix of light in the magnetic multilayer film sample, and calculating to obtain a Jones matrix of the sample; and calculating the magneto-optical coupling coefficient of each layer of film according to the Jones matrix, the reflection coefficient, the magneto-reflection coefficient and the optical property parameter of each layer of film. According to the invention, accurate characterization of magneto-optical parameters of magnetic multilayer films with various thicknesses, various materials and various layer numbers can be realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optoelectronic data analysis, and particularly relates to a method and system for testing and analyzing magneto-optical parameters of a magnetic multilayer film. BACKGROUND

[0002] The statements in this section merely provide background information related to the application and do not necessarily constitute prior art.

[0003] In order to optimize magnetic performance, reduce size effect, and improve thermal stability, magnetic thin films are often designed as multilayer film structures. With the discovery of giant magnetoresistance effect (GMR) and tunneling magnetoresistance effect (TMR), the performance of materials can be improved by adjusting the interlayer coupling, so the research on magnetic multilayer films has further increased. Researchers design multilayer films to meet specific magnetic performance requirements, achieve new physical effects, and adapt to different application scenarios. By precisely controlling the material and thickness of each layer, the overall performance of the thin film can be optimized to meet the growing technical needs. For example, in materials with strong spin-orbit coupling (SOC), the flow of electric charge can induce a pure spin current perpendicular to the current direction. This spin current can effectively manipulate the magnetic moment of the adjacent magnetic layer, which is called spin-orbit torque (SOT). By designing a multilayer film structure, the SOT effect can be optimized and enhanced, thereby improving the efficiency and speed of magnetic moment manipulation, which is crucial for the development of high-performance spintronic devices. Alternatively, by designing an ultrathin oxide insulating barrier layer, the write current only needs to pass through the bottom electrode of the magnetic tunnel junction without passing through the ultrathin oxide insulating barrier layer, which helps to protect the barrier layer from breakdown, thereby prolonging the service life of the SOT device and reducing power consumption.

[0004] Magneto-optical effect refers to the change in the absorption, transmission, or reflection characteristics of a material under the action of a magnetic field. These characteristics can be used to detect and manipulate the magnetic state of the material. When linearly polarized light is incident on the surface of a magnetized medium and reflected, the polarization plane rotates, which is called the magneto-optical Kerr effect. The magneto-optical Kerr effect has important applications in magneto-optical storage technology, especially the polar Kerr effect. Magneto-optical ellipsometry is a new advanced technology that combines magneto-optical Kerr effect and ellipsometry. It is commonly used to detect the magneto-optical properties of materials and has the advantages of non-destructive, high precision, etc. More importantly, magneto-optical ellipsometry can analyze each layer of material in a multilayer film, including thickness, refractive index, and magneto-optical properties, which is very important for understanding and controlling the interface effects and interlayer coupling in multilayer films. Through magneto-optical ellipsometry testing, the composition and structure of multilayer film materials can be optimized, providing a theoretical and experimental basis for the design of magneto-optical devices, and promoting the development of new magneto-optical materials.

[0005] Magnetooptical ellipsometry is an indirect measurement method, and the magnetooptical ellipsometry measures parameters related to the optical properties of the material, rather than directly measuring the thickness or refractive index of the material, so a complex inversion and fitting of the measurement results is required to obtain the relevant parameters of the material. For example, the existing patent CN203396695U proposes a magnetooptical ellipsometry testing device using a tunable wavelength laser, which tests a single-layer magnetic thin film through magnetooptical ellipsometry, obtains the light intensity change rate under different polarizer angles, and then calculates the relevant magnetic parameters of the material through inversion and fitting. However, it should be noted that the above traditional magnetooptical ellipsometry is proposed for a single-layer magnetic thin film (such as a three-medium single-layer film system composed of a substrate, a magnetic thin film, and air). Since the total number of unknown quantities such as the refractive index , thickness , and magnetooptical coupling coefficient of a multi-layer film is too large, and there is also an optical interference phenomenon between the multi-layer films, the traditional magnetooptical ellipsometry analysis method cannot be directly applied to the analysis of multi-layer films. The solving process of all unknown quantities is complex and the solving method is not mature, and the accurate magnetooptical parameters of the multi-layer film cannot be obtained. SUMMARY

[0006] To solve the above problems of the prior art, the present application provides a test analysis method and system for magnetooptical parameters of a magnetic multi-layer film. According to the structure and optical property parameters of the magnetic multi-layer film, joint inversion is performed in combination with the magnetooptical ellipsometry test data to obtain the magnetooptical parameters of each layer in the multi-layer film structure. This solves the problem of magnetooptical ellipsometry data analysis of multi-layer films, accurately characterizes the magnetooptical parameters of magnetic multi-layer films of various thicknesses, various materials, and various layers, and improves the efficiency and accuracy of data analysis.

[0007] In a first aspect, the present application provides a test analysis method for magnetooptical parameters of a magnetic multi-layer film.

[0008] A test analysis method for magnetooptical parameters of a magnetic multi-layer film includes: Performing ellipsometry test on a magnetic multi-layer film sample to be tested to obtain ellipsometry parameters of the sample; Constructing an optical model according to the structure of the magnetic multi-layer film sample to be tested, and performing fitting calculation in combination with the optical theory and the obtained ellipsometry parameters to obtain the optical property parameters of each film in the sample; Performing magnetooptical ellipsometry test on the magnetic multi-layer film sample to be tested to obtain the reflection coefficient of the sample in the unmagnetized state and the magnetically induced reflection coefficient caused by the Kerr effect, deriving the total propagation matrix of light in the magnetic multi-layer film sample, and then calculating the Jones matrix of the multi-layer film sample according to the relationship between the total propagation matrix and the Jones matrix; According to the Jones matrix, the reflection coefficient, the magnetic reflection coefficient and the optical property parameters of each layer of the film in the sample, the magneto-optical coupling coefficient of each layer of the film is calculated.

[0009] In a second aspect, the present application provides a system for testing and analyzing magneto-optical parameters of a magnetic multilayer film.

[0010] A system for testing and analyzing magneto-optical parameters of a magnetic multilayer film comprises: An ellipsometric parameter testing module is configured to perform ellipsometric testing on a sample of the magnetic multilayer film to be tested, and obtain ellipsometric parameters of the sample. An optical property parameter characterization module is configured to construct an optical model according to a structure of the sample of the magnetic multilayer film to be tested, and perform fitting calculation in combination with the ellipsometric parameters obtained by testing and optical theory, to obtain optical property parameters of each layer of the film in the sample. A magneto-optical ellipsometric testing and analyzing module is configured to perform magneto-optical ellipsometric testing on the sample of the magnetic multilayer film to be tested, to obtain a reflection coefficient of the sample in an un-magnetized state and a magnetic reflection coefficient caused by a Kerr effect, to derive a total propagation matrix of light in the sample of the magnetic multilayer film, and to calculate a Jones matrix of the sample of the magnetic multilayer film according to a relationship between the total propagation matrix and the Jones matrix. A magneto-optical parameter characterization module is configured to calculate a magneto-optical coupling coefficient of each layer of the film according to the Jones matrix, the reflection coefficient, the magnetic reflection coefficient and the optical property parameters of each layer of the film in the sample.

[0011] In a third aspect, the present application further provides an electronic device, comprising a memory configured to store executable instructions, and a processor configured to execute the executable instructions stored in the memory to implement the method for testing and analyzing magneto-optical parameters of a magnetic multilayer film.

[0012] In a fourth aspect, the present application further provides a computer-readable storage medium storing executable instructions configured to cause a processor to execute the executable instructions to implement the method for testing and analyzing magneto-optical parameters of a magnetic multilayer film.

[0013] In a fifth aspect, the present application further provides a computer program product comprising executable instructions stored in a computer-readable storage medium, wherein a processor of an electronic device reads the executable instructions from the computer-readable storage medium and executes the executable instructions to implement the method for testing and analyzing magneto-optical parameters of a magnetic multilayer film.

[0014] The above one or more technical solutions have the following beneficial effects: 1. The application provides a method and system for testing and analyzing magneto-optical parameters of a magnetic multilayer film, which are used for magneto-optical ellipsometry of the magnetic multilayer film; the method is used for analyzing data obtained by magneto-optical ellipsometry of the multilayer film, that is, first, an optical structure model of the multilayer film is constructed by ellipsometry fitting, and parameters describing the structure and optical properties are solved, so as to reduce the number of unknown quantities in the multilayer film system; then, the reflection coefficient and the magneto-optical reflection coefficient are fitted by combining the magneto-optical ellipsometry results and jointly inverting, so as to simplify the solving process and enhance the accuracy and feasibility of the fitting results; finally, all the unknown data are obtained according to the calculation mode of the Jones matrix expression, so as to solve the magneto-optical parameters of each layer in the multilayer film structure and solve the problem of magneto-optical ellipsometry data analysis of the multilayer film.

[0015] 2. The method of the application can make up for the limitation that the traditional magneto-optical ellipsometry cannot be directly applied to the multilayer film system, enhance the applicability, realize accurate characterization of magneto-optical parameters of magnetic multilayer films with various thicknesses, various materials and various layers, and improve the efficiency and accuracy of data analysis.

[0016] The advantages of the additional aspects of the application will be partially given in the following description, partially become obvious from the following description, or be known by the practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings, which form a part of the specification, are included to provide a further understanding of the application and are incorporated herein for explanation by illustrating a preferred embodiment of the application.

[0018] Figure 1 A flowchart of the method for testing and analyzing magneto-optical parameters of a magnetic multilayer film according to an embodiment of the application; Figure 2 A schematic diagram of reflection and refraction of light on the surface of a bulk material according to an embodiment of the application; Figure 3 A schematic diagram of reflection and refraction of light in a multilayer film according to an embodiment of the application; Figure 4 A schematic diagram of a magneto-optical ellipsometry system according to an embodiment of the application. DETAILED DESCRIPTION

[0019] It should be noted that the following detailed description is exemplary only and is intended to provide further description of the present application in order to provide further explanation of the exemplary embodiments according to the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application pertains. Furthermore, it is to be understood that the use of the terms "including", "comprising", "having" and the like are meant to be inclusive, and are intended to mean that there are additions to the claimed elements or components.

[0020] To solve the problem that the magneto-optical ellipsometric data of the multi-layer film cannot be effectively analyzed in the prior art, the present application provides a testing and analyzing method and system for magneto-optical parameters of a magnetic multi-layer film. The method is used to analyze the data of the magneto-optical ellipsometric test of the multi-layer film, that is, first, an optical structure model of the multi-layer film is constructed by ellipsometric test fitting, and parameters describing the structure and optical properties are solved, then the reflection coefficient and the magneto-optical reflection coefficient are obtained by combining the magneto-optical ellipsometric test result fitting, and finally, all unknown data are obtained according to the calculation mode of the expression of the Jones matrix, so as to realize the acquisition of the magneto-optical parameters of each layer in the multi-layer film structure, and effectively improve the efficiency and accuracy of data analysis.

[0021] Embodiment one The present embodiment provides a testing and analyzing method for magneto-optical parameters of a magnetic multi-layer film, which realizes accurate characterization of magneto-optical parameters of magnetic thin films of various thicknesses, various materials and various layers. The magneto-optical parameters include the radiation refractive index and other optical property parameters, the thickness and other structure parameters of each thin film, and the magneto-optical coupling coefficient and the like of each magnetic thin film. As shown in the figure, Figure 1 the method proposed in the present embodiment specifically includes the following steps: Step S1, performing ellipsometric test on the magnetic multi-layer film sample to be tested to obtain the ellipsometric parameters of the sample.

[0022] Specifically, the magnetic multi-layer film sample to be tested is placed in an ellipsometer, the plane composed of the incident light and the reflected light of the ellipsometer is perpendicular to the plane of the sample, and the ellipsometric test is performed in this way. The ellipsometric parameters of the sample are obtained by the test, and the ellipsometric parameters include the amplitude ratio Psi (Ψ) and the phase difference Delta (Δ).

[0023] In this embodiment, a typical SOT material Ta / Pt / Co / HM (HM=Pt, Ta) magnetic heterojunction is taken as an example to be introduced as a magnetic multilayer film sample to be measured. The specific structure of the sample is Ta(2) / Pt(5) / Co(1) / Pt(2) and Ta(2) / Pt(5) / Co(1) / Ta(2), and the nominal layer thickness calculated by the growth time is in the bracket, and the unit is nm. The substrate of the sample is Si, and the Si is covered with a SiO2 oxide layer.

[0024] Further, the manufacturing process of the above sample is as follows: before the thin film starts to grow, the bare silicon substrate needs to be cleaned with acetone and alcohol in sequence, so as to avoid the influence of surface impurities on the interface; after the cleaning is completed, the thickness of the SiO2 (silicon dioxide) oxide layer on the substrate is measured by a spectroscopic ellipsometer, then Ta (tantalum) is sputtered as a seed layer, which serves to increase the adhesion between the sample and the substrate and ensure the flatness of the sample, so as to avoid sample falling off in the subsequent experiment, then Pt / Co / HM (platinum / cobalt / heavy metal) layers are sputtered respectively, and the covering layers of Pt and HM (Heavy Metal) can prevent the oxidation of the Co layer to a certain extent, so that no additional protective layer is needed.

[0025] For the above sample, the structure and optical properties of the Co-based magnetic heterojunction with different HM covering layers are characterized by a spectroscopic ellipsometer (SE-VM). First, the process of reflection and refraction of light on the surface of a bulk material is as shown in FIG. 1, wherein, Figure 2 φ 0 , φ 1 is the incident angle and the refraction angle, x, y and z are the spatial three-dimensional coordinate system, the plane composed of x and y is the plane of the thin film sample, and the z direction is the stacking direction of the multilayer thin film sample, E ip , E is represent the p-plane electric field component and the s-plane electric field component of the incident light respectively, E rp , E rs represent the p-plane electric field component and the s-plane electric field component of the reflected light after the incident light is reflected by the bulk material, E tp , E ts represent the p-plane electric field component and the s-plane electric field component of the transmitted light after the incident light is transmitted to the bulk material, m is the magnetization vector of the sample, and a is the included angle between m and the y coordinate axis direction, and b is the included angle between m and the z coordinate axis direction. As can be seen from the above, since any known polarized light will be decomposed into two components: s component (perpendicular to the incident plane) and p component (parallel to the incident plane) when it is reflected and refracted on the surface of a material, and the spectroscopic ellipsometer actually measures the ratio of the complex reflectivity of s light to p light, which is defined as: ; wherein, r ​p and r s These are the normalized p-ray and s-ray complex reflectivities, respectively. tan Ψ The amplitude ratio of the reflected p-ray to the s-ray is given. Δ The phase difference between the reflected p-ray and s-ray is denoted as . Indicates the phase of the p-beam after reflection. Indicates the phase of the reflected s-ray. i It is the imaginary unit of complex numbers.

[0026] In fact, the above equation is the elliptic equation. Through elliptic measurement, the two physical quantities, amplitude ratio Ψ and phase difference Δ, can be directly measured.

[0027] Furthermore, for bulk materials that light cannot penetrate, optical parameters such as refractive index can be directly calculated. However, for thin film materials, subsequent model analysis and inversion fitting are required to obtain the optical properties of the sample. That is, in step S2, based on the structure of the magnetic multilayer film sample to be tested, multiple reflections and refractions of light at the surface of the multilayer film sample, the interface between thin films, and the interface between the thin film and the substrate are considered to construct an optical model of the magnetic multilayer film sample to be tested.

[0028] Specifically, a suitable optical model needs to be established for the sample. When the research object is a multilayer thin film material, it is necessary to consider not only the reflection and refraction of light on the sample surface, but also the multiple reflections and refractions occurring at the interfaces between thin films and between the thin film and the substrate. For example... Figure 3 As shown, N0, N1, N i N m N sub They are air, the first thin film, and the second thin film, respectively. i Thin film, mth The refractive indices of the first thin film layer (i.e., the first thin film layer on the substrate) and the substrate; d1, d i d m These represent the thicknesses of the 1st, 1st, and 1st thin films, respectively; φ0 and φ... i Let be the incident angle of light and the refraction angle when light enters the i-th layer, z be the growth direction of the multilayer thin film sample, and y be the plane direction of the multilayer thin film sample. Based on the actual reflection and refraction of the multilayer film under test, a corresponding optical model is constructed.

[0029] Step S3: Based on the optical model, and combining optical theory with the ellipticity parameters obtained from testing, the optical property parameters of each thin film layer in the sample are calculated through fitting. These parameters include the refractive index N. i and thickness d i wait.

[0030] Specifically, based on the ellipsoidal parameters of the sample obtained through step S1, and according to the theoretical optical model constructed in step S2, which includes the refractive index and thickness of the substrate and each thin film layer, the theoretical ellipsoidal parameters corresponding to different parameters in the model are calculated using optical theory (such as the Fresnel equation). Then, the parameters in the model are iteratively adjusted using optimization algorithms (such as the least squares method) to minimize the difference between the theoretical and experimentally measured ellipsoidal parameters, thereby determining the optimal fitting parameters. Based on these optimal fitting parameters, the optical properties of the sample, such as the thickness and refractive index of the thin film, can be determined. Preferably, the accuracy of the model can also be evaluated by calculating the fitting residuals.

[0031] In this embodiment, an eight-layer structure model was constructed based on the growth conditions: air / roughening layer / HM capping layer / Co thin film layer / Pt thin film layer / Ta seed layer / SiO2 layer / Si substrate layer. Different dispersion models were established for different layers based on material properties. Through inversion fitting, the dispersion model parameters, dielectric function spectrum, and thickness of each layer were obtained. Furthermore, by comparing the nominal thickness and the fitted thickness of each layer, the errors were all within the sub-nanometer range, further demonstrating the rationality of the constructed model.

[0032] Step S4: Perform magneto-optical ellipsometric testing on the magnetic multilayer film sample to be tested.

[0033] In this embodiment, a self-built magneto-optical ellipsometric testing system (hereinafter referred to as the magneto-optical ellipsometric system) is used to test the Ta / Pt / Co / HM (HM=Pt, Ta) magnetic heterojunction material used as the sample. The magneto-optical ellipsometric system is as follows: Figure 4 As shown, the system includes, in sequence, a light source, a collimating lens, an adjustable aperture, a polarizer, an electromagnet and sample stage, an adjustable aperture, an analyzer, a chopper, a photodetector, a lock-in amplifier, and a computer. During testing, the sample to be tested is placed in the magneto-optical ellipsometric testing system. The light source emits natural light, which is first converted into linearly polarized light by the polarizer. Observing along the light propagation direction, the polarizer is set to rotate counterclockwise by an angle θ1 relative to the perpendicular polarization direction. Subsequently, the linearly polarized light propagates to the sample surface and is reflected into elliptically polarized light, with an incident angle φ0 during the reflection process. The reflected light is converted back into linearly polarized light by the analyzer and received by the detector. Observing along the light propagation direction, the analyzer is set to rotate counterclockwise by an angle θ2 relative to the perpendicular polarization direction. The detector section includes a chopper and a silicon photodiode. The AC signal received by the silicon photodiode after modulation by the chopper is amplified by the lock-in amplifier and then stored by the computer.

[0034] Wherein, in order to adapt to the multiple requirements of the sample to be tested, the magneto-optic ellipsometry testing system has multiple light sources for selection, for example, when the spectral characteristics of the magneto-optic properties of the sample are not concerned, a solid-state laser with fixed wavelength can be selected to achieve the best monochromaticity and light intensity stability; when the spectral characteristics need to be considered, a multi-wavelength tunable fiber laser can be selected for multi-wavelength testing, or a white light xenon lamp source or a super-continuous white light laser can be selected to realize continuous spectral testing within a certain range of wavelength by cooperating with a monochromator.

[0035] In the magneto-optic ellipsometry testing system proposed in the embodiment, in order to avoid the influence of stray light as much as possible and at the same time realize the adjustment of the size of the test light spot, an adjustable diaphragm is arranged in front of the polarizer and the analyzer along the light propagation direction; the core optical element in the system is the polarizer and the analyzer, and the extinction ratio thereof directly determines the Kerr deflection angle resolution capability of the system. In the embodiment, a double-Glan-Taylor calcite polarizer is selected for the polarizer and the analyzer; according to the magneto-optic ellipsometry testing principle, the electromagnet can provide a polar magnetic field sufficient to make the sample reach the saturation magnetization strength, and the magnetic pole size is suitable for fixing the sample; when the incident angle is large or small, the electromagnet coil does not affect the light path; in order to improve the signal-to-noise ratio, a chopper is arranged behind the analyzer for converting the direct-current light signal into an alternating-current light signal; a photodetector is used to collect the light intensity value after the analyzer, and in the example, in order to enhance the spectral response range, a Si photodetector is selected; the alternating-current signal detected by the detector is amplified by a lock-in amplifier, and then collected and stored by a computer; the lock-in amplifier receives the modulation frequency signal of the chopper as a reference signal, and amplifies the effective signal collected by the detector with the same frequency as the modulation frequency of the chopper, so as to greatly improve the signal-to-noise ratio. Through the above settings, environmental noise can be basically eliminated, and the precision of the detected Kerr signal can reach the micro-radian level.

[0036] Step S5, through the magneto-optic ellipsometry test of step S4, the reflection coefficient of the sample in the un-magnetized state and the magnetic reflection coefficient caused by the Kerr effect are obtained, the total propagation matrix of the light in the magnetic multi-layer film sample is derived, and then the Jones matrix of the multi-layer film sample is calculated according to the relationship between the total propagation matrix and the Jones matrix.

[0037] Step S5.1, the reflection coefficient and the magnetic reflection coefficient are obtained. Specifically, the reflection coefficient and the magnetic reflection coefficient are defined as follows: 、 、 respectively represent the magnetic reflection coefficients caused by the transverse, longitudinal and polar Kerr effects, is the reflection coefficient of the material in the un-magnetized state.

[0038] The expressions of the above four reflection coefficients are as follows: ; ; ; ; wherein Q is the magneto-optical coupling coefficient; m is the magnetization intensity vector suffered by the sample, defining m1, m2, m3 as the components of the magnetization intensity along the x, y, z axes, then A, B, C represent the normalization conditions wherein m1, m2, m3 are the components of the magnetization intensity in the x, y, z directions, A = sinαsinβ, B = cosαsinβ, C = cosβ, α is the angle between m and the y coordinate axis, and β is the angle between m and the z coordinate axis; φ 0 , φ 1 is the light incidence angle and the refraction angle when entering the first layer.

[0039] Step S5.2, according to the electromagnetic field theory and the boundary conditions between films, the boundary matrix when the light is incident on the upper boundary of each magnetic thin film, the boundary matrix when the light is emitted from the lower boundary, and the in-film transmission matrix are defined, and the total propagation matrix M of the light in the magnetic multi-layer film sample is derived.

[0040] Specifically, the present embodiment considers the interference phenomenon of the light between the multi-layer films, and defines the boundary matrix when the light is incident on the upper boundary of the first i layer magnetic thin film as A i , the boundary matrix when the light is emitted from the lower boundary as , and the in-film transmission matrix as D i , and the expression thereof is: ; ; wherein, in order to simplify the expression of the defined parameters, the following definitions are made: ; ; ; ; wherein φ i is the refraction angle when the light enters the first i layer.

[0041] According to the above conclusion, the total propagation matrix M of the light in the magnetic thin film sample can be directly derived, and the calculation formula thereof is: ; In the above formula, A0 is the boundary matrix when the light is emitted from the air to the surface of the first layer sample, A sub is the boundary matrix when the light is incident on the substrate.

[0042] By the above manner, the total propagation matrix M of the magnetic thin film under the condition of satisfying the ultra-thin film approximation is calculated.

[0043] Step S5.3, the Jones matrix of the multi-layer film sample is calculated according to the relationship between the total propagation matrix and the Jones matrix.

[0044] Specifically, to obtain the Jones matrix of the sample, first, the total propagation matrix M is blocked according to the description of the parameters in the matrix to the transmission and reflection, which is: ; Among them, H, J are the blocks describing the transmission, which do not need to be concerned here; G, I are the blocks describing the reflection.

[0045] Secondly, the relationship between the block sub-matrix describing the reflection in the total propagation matrix M and the Jones matrix is established, and the relationship formula is: ; Finally, the Jones matrix of the multi-layer structure is directly calculated by computer by the following formula, which includes the reflection coefficients of the incident P light and the reflected S light 、 , and the reflection coefficients of the incident S light to the reflected P light and the reflected S light 、 , and the calculation formula is: ; ; ; .

[0046] Step S7, according to the Jones matrix, the reflection coefficient, the magneto-optical reflection coefficient and the optical property parameters (i.e. the complex refractive index N i and the thickness d i ) of each layer of thin film in the sample, the magneto-optical coupling coefficient of each layer of thin film is calculated.

[0047] Specifically, when only considering the polar Kerr effect, and only one layer of magnetic layer in the multi-layer film, B=0, C=1, for non-magnetic layer Q=0, for magnetic layer, the above calculated Jones matrix, reflection coefficient, magneto-optical reflection coefficient can be solved, combined with the radiation refractive index and the thickness of the layer of thin film, the magneto-optical coupling coefficient of the layer of thin film is calculated, and the calculation formula is: ; Wherein, λ represents the wavelength, N0, N i , N sub are the air, the firsti refractive index of the layer film and the substrate; d i is the thickness of the i-th layer film; φ0and φ i is the light incidence angle and the refraction angle when entering the i-th layer, represents the magneto-optical reflection coefficient caused by the polar Kerr effect, is the reflection coefficient of the material in the un-magnetized state, is the reflection coefficient from the incident S light to the reflected S light.

[0048] Similarly, if there are multiple magnetic layers in the multi-layer film, the Jones matrix, the reflection coefficient, and the magneto-optical reflection coefficient obtained by the above calculation are combined with the corresponding layer film radiation refractive index and thickness to calculate the magneto-optical coupling coefficient of each magnetic film, respectively.

[0049] Embodiment Two The embodiment provides a test and analysis system for magneto-optical parameters of a magnetic multi-layer film, comprising: an ellipsometric parameter test module configured to perform ellipsometric test on a to-be-tested magnetic multi-layer film sample to obtain ellipsometric parameters of the sample; an optical property parameter characterization module configured to construct an optical model according to the structure of the to-be-tested magnetic multi-layer film sample, perform fitting calculation by combining the optical theory and the ellipsometric parameters obtained by test, and obtain optical property parameters of each layer film in the sample; a magneto-optical ellipsometric test and analysis module configured to perform magneto-optical ellipsometric test on the to-be-tested magnetic multi-layer film sample, obtain the reflection coefficient of the sample in the un-magnetized state and the magneto-optical reflection coefficient caused by the Kerr effect, derive a total propagation matrix of light in the magnetic multi-layer film sample, and calculate a Jones matrix of the multi-layer film sample according to the relationship between the total propagation matrix and the Jones matrix; a magneto-optical parameter characterization module configured to calculate a magneto-optical coupling coefficient of each layer film according to the Jones matrix, the reflection coefficient, the magneto-optical reflection coefficient, and the optical property parameters of each layer film in the sample.

[0050] Embodiment Three The embodiment provides an electronic device, comprising a memory configured to store executable instructions, and a processor configured to execute the executable instructions stored in the memory to implement the method provided in the embodiment.

[0051] Embodiment Four The embodiment also provides a computer readable storage medium storing executable instructions, which, when executed by a processor, causes the processor to execute the method provided in the embodiment.

[0052] Embodiment Five The embodiment provides a computer program product, which comprises executable instructions, the executable instructions being computer instructions; the executable instructions are stored in a computer readable storage medium. When a processor of an electronic device reads the executable instructions from the computer readable storage medium, the processor executes the executable instructions, so that the electronic device executes the above method provided by the embodiment.

[0053] The steps and the method of the above embodiments two to five correspond to the method embodiment one, and the specific embodiments can be referred to the related description part of the embodiment one. The term "computer readable storage medium" should be understood as including a single medium or multiple media of one or more instruction sets; it should also be understood as including any medium capable of storing, encoding or carrying the instruction set for execution by the processor and causing the processor to execute any method in the present application.

[0054] Those skilled in the art should understand that each module or each step of the present application can be realized by a general computer device, alternatively, they can be realized by program codes executable by a computing device, so that they can be stored in a storage device for execution by the computing device, or they can be respectively manufactured into each integrated circuit module, or a plurality of modules or steps among them can be manufactured into a single integrated circuit module to realize. The present application is not limited to any specific combination of hardware and software.

[0055] The above only describes the preferred embodiments of the present application, and the specific embodiments of the present application are described in combination with the drawings, but the present application is not limited to the scope of protection, and those skilled in the art should understand that various modifications or changes made on the basis of the technical solutions of the present application without creative labor are still within the protection scope of the present application.

Claims

1. A method for testing and analyzing the magneto-optical parameters of a magnetic multilayer film, characterized in that, include: Ellipsity testing was performed on the magnetic multilayer film sample to obtain the ellipsity parameters of the sample. An optical model is constructed based on the structure of the magnetic multilayer film sample to be tested. The optical properties of each thin film layer in the sample are obtained by fitting and calculating the model using optical theory and the ellipticity parameters obtained from the test. Magneto-optical ellipsometric analysis was performed on the magnetic multilayer film sample to obtain the reflection coefficient of the sample in the unmagnetized state and the magneto-reflective coefficient caused by the Kerr effect. The total propagation matrix of light in the magnetic multilayer film sample was derived. Then, based on the relationship between the total propagation matrix and the Jones matrix, the Jones matrix of the multilayer film sample was calculated. The magneto-optical coupling coefficient of each thin film layer was calculated based on the Jones matrix, reflection coefficient, magneto-reflective coefficient, and optical property parameters of each thin film layer in the sample.

2. The method for testing and analyzing magneto-optical parameters of a magnetic multilayer film as described in claim 1, characterized in that, The ellipticity parameters include the amplitude ratio and phase difference between the p-ray and s-ray after the incident light is reflected by the sample under test; Based on the structure of the magnetic multilayer film sample under test, and considering multiple reflections and refractions of light at the sample surface, film-to-film interfaces, and film-to-substrate interfaces, an optical model of the sample is constructed. Based on this model and according to optical theory, the amplitude ratio and phase difference obtained from the test are fitted to obtain the optical property parameters of each film layer in the multilayer film sample. These optical property parameters include the refractive index of each film layer. and thickness .

3. The method for testing and analyzing magneto-optical parameters of a magnetic multilayer film as described in claim 1, characterized in that, definition , , Let represent the magnetostrictive reflection coefficients caused by the transverse, longitudinal, and poloidal Kerr effects, respectively. The reflection coefficient of the material in its unmagnetized state is expressed as: ； ； ； ； in, For the first A thin film, where Q is the magneto-optical coupling coefficient, m is the magnetization vector experienced by the sample, and A, B, and C represent the normalization conditions. The components of the lower magnetization intensity m in the x, y, and z directions are A=sinαsinβ, B=cosαsinβ, and C=cosβ, where α is the angle between m and the y-axis and β is the angle between m and the z-axis. , The angles of incidence and refraction when light enters the first layer are the angle of incidence and the angle of refraction.

4. The method for testing and analyzing magneto-optical parameters of a magnetic multilayer film as described in claim 1, characterized in that, Based on electromagnetic field theory and inter-film boundary conditions, the boundary matrix at the upper boundary of each magnetic thin film incident, the boundary matrix at the lower boundary exiting, and the intra-mode transmission matrix are defined, and the total propagation matrix of light in the magnetic multilayer film sample is derived. Based on the relationship between the total propagation matrix and the Jones matrix, the Jones matrix of the multilayer film sample is calculated, including dividing the total propagation matrix into blocks according to the description of transmission and reflection of the parameters in the matrix. Establish the relationship between the block submatrices describing reflections in the total propagation matrix and the Jones matrix; calculate the multi-layered Jones matrix based on the relationship.

5. The method for testing and analyzing magneto-optical parameters of a magnetic multilayer film as described in claim 1, characterized in that, The Jones matrix includes the reflectance coefficients of the incident P-ray and the reflected S-ray. , And the reflection coefficients of the incident S-ray to the reflected P-ray and the reflected S-ray. , The calculation formula is: ； ； ； ； In the above formula, N0, N1, N i N m N sub They are air, the first thin film, and the second thin film, respectively. i Thin film, m The refractive indices of the thin film and the substrate; d1, d i d m Let represent the thicknesses of the first, i-th, and m-th thin films, respectively; φ0 and φ i Let be the incident angle of light and the refraction angle when light enters the i-th layer.

6. The method for testing and analyzing magneto-optical parameters of a magnetic multilayer film as described in claim 1, characterized in that, Considering only the poloidal Kerr effect, for multilayer films containing multiple magnetic layers, the Jones matrix, reflection coefficient, and magnetostrictive reflection coefficient obtained by simultaneous calculation are combined with the corresponding thin film emissivity. and thickness The magneto-optical coupling coefficient of each magnetic thin film layer was calculated. ; When there is only one magnetic layer in the multilayer film, B=0, C=1, Q=0 for non-magnetic layers, and magneto-optical coupling coefficient for magnetic layers can be calculated. The calculation formula is: ； In the above formula, λ represents the wavelength, N0, N i N sub They are air, the first i The refractive index of the thin film and the substrate; d i Let be the thickness of the i-th thin film; φ0 and φ i Let be the angle of incidence of light and the angle of refraction when light enters the i-th layer. This represents the magnetostrictive reflection coefficient caused by the poloidal Kerr effect. The reflection coefficient of the material in its unmagnetized state. denoted as the reflection coefficient from the incident S-ray to the reflected S-ray.

7. A testing and analysis system for magneto-optical parameters of magnetic multilayer films, characterized in that, include: The elliptic parameter testing module is used to perform ellipticity testing on the magnetic multilayer film sample under test and obtain the ellipticity parameters of the sample. The optical property parameter characterization module is used to construct an optical model based on the structure of the magnetic multilayer film sample to be tested, and to perform fitting calculations by combining optical theory and ellipticity parameters obtained from testing to obtain the optical property parameters of each thin film layer in the sample. The magneto-optical ellipsometric test and analysis module is used to perform magneto-optical ellipsometric tests on the magnetic multilayer film sample under test, obtain the reflection coefficient of the sample in the unmagnetized state and the magneto-induced reflection coefficient caused by the Kerr effect, derive the total propagation matrix of light in the magnetic multilayer film sample, and then calculate the Jones matrix of the multilayer film sample based on the relationship between the total propagation matrix and the Jones matrix. The magneto-optical parameter characterization module is used to calculate the magneto-optical coupling coefficient of each thin film based on the Jones matrix, reflection coefficient, magnetostrictive reflection coefficient, and optical property parameters of each thin film in the sample.

8. An electronic device, characterized in that, include: Memory, used to store executable instructions; The processor, when executing executable instructions stored in the memory, implements the method for testing and analyzing the magneto-optical parameters of the magnetic multilayer film as described in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, The device stores executable instructions for inducing a processor to execute the executable instructions to implement the method for testing and analyzing the magneto-optical parameters of the magnetic multilayer film as described in any one of claims 1-6.

10. A computer program product, characterized in that, The computer program product includes executable instructions stored in a computer-readable storage medium; When the processor of the electronic device reads the executable instructions from the computer-readable storage medium and executes the executable instructions, it implements the method for testing and analyzing the magneto-optical parameters of the magnetic multilayer film as described in any one of claims 1-6.

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