CN112836421B - Multi-scale correlation analysis method for micro-discharge inhibition of device - Google Patents
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Abstract
The invention discloses a multi-scale correlation analysis method for micro-discharge inhibition of a device, which relates to three scales of atom to nanometer scale, micrometer scale and millimeter to centimeter scale, and mainly comprises parameter calculation on each scale and correlation logic between scales. The atomic to nano scale is the level of the chemical components and the atomic geometrical structure of the material, the level of the surface microstructure belongs to the micron scale, and the level of the microwave device belongs to the millimeter to centimeter scale. The method is a correlation analysis and design method from materials to surfaces to devices. The correlation analysis method is low in cost, short in period and high in efficiency, and saves a large amount of time and invalid trial and error cost for developing micro discharge experiments.
Description
Technical Field
The invention belongs to the physical field of electronic science and technology high-power microwave engineering, particularly relates to a multi-scale correlation analysis method for micro discharge inhibition of a microwave device, and relates to the fields of electron emission, material performance measurement and numerical simulation calculation.
Background
The suppression technology of the micro-discharge of the device relates to physical mechanisms and engineering problems of multiple scales, and the root of the micro-discharge is the secondary electron emission on the surface of the material and the resonance action of secondary electrons and a microwave field. It follows that the key approach to suppressing microdischarges is to obtain materials and surface microstructures with low secondary electron emission levels and to design the structure of microwave devices. On the material level, the existing research and method mainly comprises the steps of theoretically exploring the influence of the surface state on secondary electron emission through concepts such as work function, affinity and the like, and experimentally adopting a novel material coating film, and the first principle calculation can also be used for calculating microscopic concept parameters such as the work function, the electron affinity and the like of the material. On the surface microstructure level, the existing method is to change the surface roughness and microstructure by forming surface periodic structure and irregular structure, so as to reduce the suppressed secondary electron emission, and the simulation calculation of the level includes the simulation calculation based on semi-empirical formula and the Monte Carlo simulation calculation of the secondary electron emission of the surface of a single material. On the device level, the traditional method is the simulation of the micro-discharge threshold of the device structure based on particle simulation and the experimental measurement of the micro-discharge threshold in experimental engineering.
However, the existing theory and technology only research a single factor influencing the generation of micro-discharge on a certain level, and there is no report of multi-scale comprehensive research on the association of three levels from the practical application point of view, and there is no research report of applying the first principle method to the material selection of the low secondary electron emission coefficient material. The existing method lacks a mature theory for organically linking the surface, the surface state, the secondary electron emission characteristic and the device structure, and a practical comprehensive analysis method for solving the micro-discharge problem of the device for guiding material selection, surface treatment process design and microwave device structure design does not exist.
Disclosure of Invention
The invention provides a multi-scale correlation analysis method for inhibiting micro-discharge of a device, aiming at theoretically guiding the selection of device materials, the process design of surface treatment and the structure design of a microwave device and forming a system for effectively inhibiting the generation of the micro-discharge of the device from the mechanism. The method relates to three scales of atom-nanometer scale, micrometer scale and millimeter-centimeter scale, and mainly comprises parameter calculation on each scale and correlation logic between the scales. The atom to nanometer scale is the level of the chemical components and the atom geometrical structure of the material, the level of the surface microstructure belongs to the micrometer scale, and the level of the microwave device belongs to the millimeter to centimeter scale. The method is a correlation analysis and design method from materials to surfaces to devices.
In order to achieve the purpose, the invention adopts the following technical scheme:
a multi-scale correlation analysis method for micro-discharge inhibition of devices is used for analyzing and predicting the micro-discharge inhibition effect of common devices, can carry out multi-scale correlation analysis on microwave devices with simple structures, and comprises the following specific steps:
(1) On the atom to nanometer scale, establishing a metal unit cell structure model according to parameters such as a lattice constant, a bond angle, a space group and the like of the metal material, and cutting the unit cell to obtain a crystal face of the required material;
(2) Performing relaxation calculation on the structural model based on a first principle method, performing non-self-consistent calculation to obtain a vacuum energy level and a Fermi energy level of the material, and calculating to obtain a work function and an optical energy loss spectrum;
(3) Adopting a secondary electron emission multi-generation model self-research program based on a Monte Carlo method, inputting a flat surface condition as surface appearance input, inputting a corresponding material type, and inputting the work function of the material obtained by calculation to the work function of the material to obtain a secondary electron emission coefficient simulation value of the surface of the material on a micrometer scale; the measured value of the secondary electron emission coefficient of the surface of the actual smooth material sample can be compared and verified;
(4) On the scale from millimeter to centimeter, inputting the secondary electron emission coefficient analog value of the material surface into an electron emission module of particle simulation software for micro-discharge threshold simulation calculation aiming at a simple flat plate structure device; or fitting the secondary electron emission coefficient analog value of the material surface according to a statistical theory, and calculating a threshold value according to the obtained group of parameters;
(5) Drawing a micro-discharge sensitive area curve of the device structure;
the whole process of the multi-scale correlation analysis of the device substrate material is realized, and then the multi-scale correlation analysis aiming at the micro-discharge inhibition of the device is carried out on the composite material structure treated by the surface coating process:
(6) Establishing respective unit cell structure models according to parameters such as lattice constants, bond angles, space groups and the like of the metal and the coating material; cutting a crystal cell of a metal material to obtain a required crystal face, carrying out lattice adaptation on a coating material and a substrate material, and establishing a crystal cell model of a composite structure;
(7) Adopting first principle calculation software to relax the composite structure model, carrying out non-self-consistent calculation to obtain a vacuum energy level and a Fermi energy level, and calculating to obtain a work function and an optical energy loss spectrum;
(8) Inputting the work function of the composite material obtained by calculation into the work function of the surface film in the program by adopting a double-layer material secondary electron emission multi-generation model program based on a Monte Carlo method, taking the surface roughness condition as the surface morphology input and taking a substrate material and a surface film material as the input material types to obtain a secondary electron emission coefficient simulation value of the surface; the measured value of the secondary electron emission coefficient of the surface sample wafer of the actual coating process can be compared and verified;
(9) Inputting the secondary electron emission coefficient analog value of the surface into an electron emission module of particle simulation software to perform micro-discharge threshold simulation calculation aiming at a simple flat plate structure device; or fitting the micro-discharge inhibition statistical model according to a micro-discharge inhibition statistical theory, and calculating a threshold value according to the obtained group of parameters;
(10) And drawing a micro-discharge sensitive area curve of the device structure.
The specific steps of the calculation method are explained as follows:
(1) When a unit cell structure model of a single material is established, firstly, a standard unit cell file is downloaded from a material database, and then an ASE module in VASP software is called to cut a metal crystal face to obtain a specific metal crystal face unit cell structure;
(2) Performing first principle calculation on atom to nanometer scale, and calculating by VASP commercial software to obtain work function and optical energy loss spectrum;
(3) The Monte Carlo simulation of the secondary electron emission coefficient on the micrometer scale adopts an autonomously developed complex surface secondary electron emission multi-generation model program;
(4) On the scale from millimeter to centimeter, calculating the micro-discharge threshold value by adopting a micro-discharge inhibition statistical theory or a particle simulation method according to the structural complexity, for example, aiming at a simple flat plate structure and a coaxial structure, adopting the micro-discharge inhibition statistical theory, firstly, carrying out Vaughan model piecewise function parameter fitting to calculate a micro-discharge sensitive area curve according to the statistical theory, and then analyzing the inhibition condition of the micro-discharge threshold value through the curve; if aiming at a device with a complex structure, three-dimensional particle simulation software is adopted to establish the device structure, the Monte Carlo simulation value of the secondary electron emission coefficient on the micrometer scale is set as the parameter of an electron emission model, and particle simulation is carried out to obtain the final threshold analysis;
(5) When a composite structure unit cell model for inhibiting process treatment is established, a lattice adaptation method for compounding two material unit cells is involved, and the problem of adaptation of the composite structure unit cell is treated in the multi-scale correlation analysis method.
The method for processing the composite structure unit cell adaptation problem in the multi-scale correlation analysis method in the step (5) is as follows: calculating the least common multiple according to each lattice constant, properly expanding the supercell according to the proportional relation between each lattice constant and the least common multiple, and carrying out cell averaging adaptation on the tiny errors to ensure that the structure can be smoothly relaxed.
The specific calculation method of the work function is as follows: after relaxation, setting a work function calculation label in an INCAR input file, carrying out non-self-consistent calculation to obtain vacuum potential distribution, and reading the vacuum energy level E of the material vacuum And Fermi level E fermi The value of the work function calculated is equal to the difference between the vacuum level minus the Fermi level, i.e. E w ＝E vacuum -E fermi 。
The analysis method for judging whether the inhibition effect exists and the reverse material selection guidance method comprise the following steps:
(1) Comparing the Monte Carr analog values of the secondary electron emission coefficients of the single metal and the composite film structure on a micrometer scale, if the analog value of the latter is smaller, the treatment process of the composite film structure has an inhibition effect on the surface secondary electron emission; otherwise, there is no inhibition effect;
(2) And comparing the threshold simulation results of the single metal and the composite film layer structure on the millimeter-centimeter scale, namely the device level, to directly obtain the conclusion whether the micro-discharge inhibition effect of the device exists.
The comparison includes two ways: if the micro-discharge threshold is calculated by adopting particle simulation, the micro-discharge threshold of the device corresponding to the single metal and the surface of the composite film layer is directly compared, and if the micro-discharge threshold is smaller, the micro-discharge of the device is inhibited by the treatment process of the composite film layer; if the micro-discharge sensitive area of the composite film layer structure is smaller, the first threshold value is larger, and the second threshold value is smaller, the composite film layer processing technology enables the device not to generate micro-discharge easily, namely the micro-discharge of the device has an inhibition effect; otherwise, no suppression effect is obtained.
The invention has the technical effects that: on the atomic scale, a unit cell model calculated by a first principle of a copper simple substance is established, VASP software is adopted to calculate to obtain a work function of 4.60eV, and QE and Yambo software are adopted to calculate to obtain an optical energy loss spectrum and an inelastic scattering cross section of the copper simple substance. Based on the results calculated by the first principle, the secondary electron emission Monte Carlo simulation of copper is carried out on the surface scale by adopting a complex surface multi-generation model program, and the maximum value of the secondary electron emission coefficient (SEY) simulation result is 1.5.
Further, multi-scale correlation analysis is carried out on the micro-discharge inhibition effect of the device after the copper surface is plated with the nickel film and is covered with the single-layer graphene. On the atomic scale, the work function of the coating composite structure is calculated to be 2.90eV; the secondary electron emission monte carlo simulation on the surface scale resulted in 1.24. On the basis, the device is subjected to micro-discharge sensitive area analysis, and micro-discharge sensitive area curves and threshold voltages of the device before and after processing are calculated according to a statistical theoretical model of micro-discharge. The sensitivity curve shows that the micro-discharge threshold of the flat-plate structure device is increased by the process of plating a nickel film on the surface of the device and covering single-layer graphene, namely, the micro-discharge of the device is inhibited to a certain degree.
The invention provides a brand new theoretical thought and method for researching the micro-discharge inhibition technology of the microwave device. The method not only provides complete theoretical guidance for material selection, processing technology and structural design of devices, but also has the advantages of low cost, short period and high efficiency, and saves a large amount of time and invalid trial and error cost for developing micro-discharge experiments.
Drawings
FIG. 1 is a technical roadmap of a multiscale correlation analysis method for device microdischarge suppression,
FIG. 2 is a flow chart of atom-to-nano scale calculation in a multi-scale correlation analysis method for device micro-discharge suppression.
FIG. 3 is a flow chart of Monte Carlo simulation of secondary electron emission coefficients on the micrometer scale in a multiscale correlation analysis method of device microdischarge suppression.
Fig. 4 is a flow chart of statistical theoretical analysis of millimeter-centimeter scale microdischarges in a multi-scale correlation analysis method for device microdischarge suppression.
FIG. 5 is a graph of unit cell model and slab vacuum layer potential distribution in first principles calculations from elemental copper atoms to nanoscale.
Fig. 6 is an optical energy loss spectrum in the first principle calculation from copper simple substance atoms to nano-scale, and the calculation of an optical loss function is required in the intermediate process of calculating a scattering cross section.
Fig. 7 is a surface secondary electron emission coefficient obtained on the micrometer scale of copper simple substance based on multi-scale analysis. The energy loss function was further obtained from the optical loss spectrum in fig. 6, and the inelastic scattering cross section of the electron was calculated. The total electron scattering cross section can be obtained by adding the obtained inelastic scattering cross section and a mature elastic scattering cross section (Mott scattering model), and the SEY curve of FIG. 7 can be obtained by carrying out the Monte Carlo simulation process of the secondary electron emission coefficient of copper according to FIG. 3, wherein the maximum SEY is about 1.5.
Fig. 8 is a unit cell model of a nickel-plated film-coated single-layer graphene composite structure in a first principle calculation on an atomic scale. Taking the surface after copper coating as an example, performing multi-scale correlation analysis of micro-discharge inhibition, and performing first principle calculation on the composite structure in the first step. And (3) adapting the unit cell structures of the single-layer graphene and the nickel, and establishing a unit cell model of the composite material.
Fig. 9 shows the results of a monte carlo simulation of the secondary electron emission coefficient after the copper surface is coated on a micron scale, with a maximum SEY of about 1.24. Compared with the Monte Carlo simulation result of the secondary electron emission coefficient of the copper surface without coating treatment, the coating treatment reduces the secondary electron emission coefficient.
Fig. 10 is a simulation result of a micro-discharge statistical theory sensitive area before and after a surface coating process for a copper-based device with a simple flat plate structure on a millimeter-centimeter scale. In the figure, the micro-discharge sensitive area is obviously reduced after the coating treatment, and the micro-discharge threshold is improved, which shows that the coating treatment can theoretically generate the effect of inhibiting micro-discharge, thereby achieving the final purpose of multi-scale correlation analysis.
Detailed Description
Referring to fig. 1, three-scale analysis is performed sequentially from atomic to nano-scale, micro-scale to millimeter to centimeter scale. On the level from atom to nano scale, namely material, the first principle micro parameter calculation is carried out through material composition and geometric structure modeling; using the result in the next micrometer scale, and carrying out the Monte Carlo simulation of the secondary electron emission on the surface of the material by combining the surface roughness; the simulation result of the surface secondary electron emission coefficient is used for simulating the micro-discharge threshold of the device in a millimeter-centimeter scale, and a particle simulation or statistical theory method can be adopted according to different device structures. And reversely designing a device structure according to the final micro-discharge threshold simulation result, and further providing guidance for the research of a material surface treatment process on a surface scale and the selection of a substrate on a material layer.
Referring to fig. 2, a crystal structure model is established and structure relaxation is performed according to material composition and atomic geometry; and then carrying out non-self-consistent calculation by adopting VASP or open source software to obtain data, further drawing to obtain a work function, state density and energy band structure, and carrying out calculation of a scattering cross section by adopting QE and Yambo software.
Referring to fig. 3, initial electrons enter the interior of the material from the surface and are scattered in the material, and the scattering cross section is provided by atomic-to-nanoscale first principle calculations. Judging the position every updating step, judging whether the electron beam is emitted from the surface, if not, changing the motion state of the electron beam and continuing scattering; if yes, the next judgment is carried out: whether or not to reenter the surface. If the electron does not enter the surface due to the actual surface topography condition, the secondary electron is emitted finally, and the process is ended; if the surface is re-entered, the material is re-entered after kinetic processing and a scattering cycle is performed. The work function used when the light source is emitted from the surface is also provided by the calculation of the atomic-to-nanoscale first principle, and the actual surface micro-topography when judging whether the light source enters the surface again is provided by a mathematical model or an input topography roughness matrix.
Referring to fig. 4, for a simple coaxial or flat-plate structure device, a micro-discharge sensitivity curve can be simulated faster by using a micro-discharge statistical theory, and the specific method is that a monte carlo simulation value of a secondary electron emission coefficient on a micrometer scale is used as data, and a modified Vaughan model piecewise function is used for parameter fitting to obtain a corresponding group of model parameters; and then modeling by adopting a micro-discharge statistical theory, and calculating to obtain a sensitive area curve corresponding to the device structure.
Referring to fig. 5, the first step of performing multi-scale correlation analysis using a copper material as an example is first-principle calculation modeling. And taking the built unit cell model file as a position coordinate input file of VASP software, setting calculation parameters, and relaxing to obtain a stable system structure. And then, changing calculation parameters to perform non-self-consistent calculation, drawing a vacuum potential distribution diagram, reading a vacuum energy level and a Fermi energy level, and calculating to obtain the work function.
Referring to fig. 6, the base state energy and wave function of the cell are first calculated using the software Quantum Espresso, and then the optical loss function is calculated using the Yambo software.
Referring to fig. 7, the energy loss function is further obtained from the optical loss spectrum in fig. 6, and the inelastic scattering cross section of the electron is calculated. The total electron scattering cross section can be obtained by adding the obtained inelastic scattering cross section and a mature elastic scattering cross section (Mott scattering model), and the SEY curve of FIG. 7 can be obtained by carrying out the Monte Carlo simulation process of the secondary electron emission coefficient of copper according to FIG. 3, wherein the maximum SEY is about 1.5.
Referring to fig. 8, a multi-scale correlation analysis of micro-discharge suppression is performed by taking the surface after copper plating as an example, and the first step is to perform first principle calculation on the composite structure. And (3) adapting the unit cell structures of the single-layer graphene and the nickel, and establishing a unit cell model of the composite material.
Referring to fig. 9, the maximum SEY is about 1.24. Compared with the Monte Carlo simulation result of the secondary electron emission coefficient of the copper surface without coating treatment, the coating treatment reduces the secondary electron emission coefficient.
Referring to fig. 10, after the coating treatment, the micro-discharge sensitive area is obviously reduced, and the micro-discharge threshold is increased, which indicates that the coating treatment theoretically generates the effect of inhibiting micro-discharge, and the final purpose of multi-scale correlation analysis is achieved.
In the multi-scale correlation analysis method for inhibiting micro-discharge, the multi-scale mainly comprises three scales: atomic to nano-scale, micro-scale and millimeter to centimeter scale. On the atom-nanometer scale, microscopic conceptual parameters and processes of the material chemical components and the atom geometric structure, such as work function, optical energy loss spectrum, electron affinity, electron state density, energy band structure, surface oxidation state, etc., which influence the secondary electron emission coefficient, are mainly researched. On the surface of the material, namely on the micrometer scale, incident initial electrons enter the material, and after the scattering process and the surface potential barrier trapping effect, emergent secondary electrons are generated on the surface of the material, and the value of the secondary electrons to the surface of the material is the secondary electron emission coefficient. On the scale, the influence of the surface micro-topography of a micro-discharge sensitive area of the device on the secondary electron emission coefficient is mainly researched, monte Carlo modeling of complex surface secondary electron emission is carried out on the micrometer scale based on the nanometer scale calculation and analysis, and the secondary electron emission coefficient under the corresponding surface material and surface treatment conditions is obtained through simulation. On the scale from millimeter to centimeter, the design of device level structure and simulation model are mainly studied, and the pre-estimation simulation calculation is carried out on the micro-discharge threshold of the microwave device on the basis of the existing surface secondary electron emission coefficient result on the micrometer scale. Through three-dimension correlation, micro-discharge inhibition schemes from material selection, surface treatment process and device structure design are explored.
The analysis method on each scale and the relevance among the analysis methods in the multi-scale association are explained as follows:
the analysis from atoms to nano-scale mainly takes the atomic structure of a device material as a core, and first-nature principle calculation at the material level is carried out by adopting mature commercial or open-source software based on a density functional theory. The microscopic concepts obtainable by the first principles calculations include work function, electron affinity, electron density of states, surface oxidation states, etc., which parameters have varying degrees of influence on the surface potential barrier across which the electrons exit. When the Monte Carlo simulation of the secondary electron emission coefficient is carried out on a micrometer scale, the surface potential barrier and the internal electron scattering process are key factors influencing the simulation value of the secondary electron emission coefficient. Therefore, the calculation result of the first principle from the atom to the nanometer scale can be used as the input variable parameter of the next micrometer scale to be applied to the material selection for inhibiting the secondary electron emission coefficient.
Monte Carlo simulation of secondary electron emission coefficients on a micrometer scale can approach the collision rule of electron scattering motion to the maximum extent, and has obvious advantages compared with a semi-empirical formula or a pure theoretical formula. Meanwhile, the requirements for setting a calculation model algorithm and analyzing and expressing the complex surface morphology are higher. Therefore, the secondary electron emission coefficient simulation value obtained by Monte Carlo simulation under the surface topography condition can be used for estimating the experimental result, and can also be corrected by the parameters of specific experimental conditions according to the experimental results of a large number of samples. The secondary electron emission coefficient result of the surface layer can be further applied to device simulation of next-scale analysis and used as an electron emission model parameter in device micro-discharge threshold and sensitive curve analysis on a millimeter-centimeter scale.
Finally, the simulation of the micro-discharge threshold of the device can be completed by particle simulation software or micro-discharge statistical theory through device-level simulation on the millimeter-centimeter scale. In particle simulation software, a simulation result of a secondary electron emission coefficient in a micron scale can be used as an input parameter of an electron emission model; if the micro-discharge statistical theory is adopted to analyze the micro-discharge threshold of the device, the secondary electron emission coefficient simulation result of the micrometer scale needs to be fitted into a group of piecewise function parameters corresponding to the statistical theory, and the piecewise function parameters are converted into a mathematical problem to be analyzed and calculated. Which of the two methods is adopted depends on the realizability of the device structure, and at present, the statistical theory method can only realize the micro-discharge sensitive area analysis and the threshold calculation of the device with a simple coaxial and flat structure.
Claims (9)
1. A multi-scale correlation analysis method for micro-discharge inhibition of devices is characterized in that the method is used for analyzing and predicting the micro-discharge inhibition effect of common devices, can perform multi-scale correlation analysis on microwave devices with simple structures, and comprises the following specific steps:
(1) On the atom-nanometer scale, establishing a metal unit cell structure model according to the lattice constant, the bond angle and the space group parameters of the metal material, and cutting the unit cell to obtain a crystal face of the required material;
(2) Performing relaxation calculation on the structural model based on a first principle method, performing non-self-consistent calculation to obtain a vacuum energy level and a Fermi energy level of the material, and calculating to obtain a work function and an optical energy loss spectrum;
(3) Adopting a secondary electron emission multi-generation model self-research program based on a Monte Carlo method, inputting the surface topography by taking the flat surface condition as the surface topography input, inputting the corresponding material type, inputting the material work function obtained by calculation to the work function of the material, and obtaining the secondary electron emission coefficient simulation value of the material surface on the micrometer scale; the measured value of the secondary electron emission coefficient of the surface of the actual smooth material sample can be compared and verified;
(4) On the scale from millimeter to centimeter, inputting the secondary electron emission coefficient analog value of the material surface into an electron emission module of particle simulation software for micro-discharge threshold simulation calculation aiming at a simple flat plate structure device; or fitting the secondary electron emission coefficient analog value of the material surface according to a statistical theory, and calculating a threshold value according to the obtained group of parameters;
(5) Drawing a micro-discharge sensitive area curve of the device structure;
the whole process of the multi-scale correlation analysis of the device substrate material is realized, and then the multi-scale correlation analysis aiming at the micro-discharge inhibition of the device is carried out on the composite material structure treated by the surface coating process:
(6) Establishing respective unit cell structure models according to the lattice constant, the bond angle and the space group parameters of the metal and the coating material; cutting a crystal cell of a metal material to obtain a required crystal face, carrying out crystal cell adaptation on a coating material and a substrate material, and establishing a crystal cell model of a composite structure;
(7) Adopting first principle calculation software to relax the unit cell model of the composite structure, carrying out non-self-consistent calculation to obtain a vacuum energy level and a Fermi energy level, and calculating to obtain a work function and an optical energy loss spectrum;
(8) Inputting the work function of the composite material obtained by calculation into the work function of the surface film in the program by adopting a double-layer material secondary electron emission multi-generation model program based on a Monte Carlo method, taking the surface roughness condition as the surface morphology input and taking a substrate material and a surface film material as the input material types to obtain a secondary electron emission coefficient simulation value of the surface; the measured value of the secondary electron emission coefficient of the sample wafer on the surface of the actual coating process can be compared and verified;
(9) Inputting the secondary electron emission coefficient analog value of the surface into an electron emission module of particle simulation software to perform micro-discharge threshold simulation calculation aiming at a simple flat plate structure device; or fitting the micro discharge suppression statistical model according to the micro discharge suppression statistical theory, and calculating a threshold value according to the obtained group of parameters;
(10) And drawing a micro-discharge sensitive area curve of the device structure.
2. The method for multi-scale correlation analysis of device micro-discharge suppression according to claim 1, wherein the specific method for establishing the unit cell structure model in step (1) is as follows: when a unit cell structure model of a single metal material is established, firstly, downloading a standard unit cell and cif files from a material database, opening the files by using VESTA software and storing the structure coordinates of the unit cell as POSCAR files; and then calling an ASE module in VASP software to cut the metal crystal face to obtain the metal crystal face unit cell structure.
3. The multi-scale correlation analysis method for device micro-discharge inhibition according to claim 1, wherein the first principle calculation method involved in the multi-scale correlation analysis method in steps (2) and (7) is specifically described as follows: performing first principle calculation on atom to nanometer scale, and calculating by adopting VASP software to obtain work function and optical energy loss spectrum; the specific calculation method of the work function is as follows: after relaxation, setting a work function calculation label in an INCAR input file, carrying out non-self-consistent calculation to obtain vacuum potential distribution, and reading the vacuum level E of the material vacuum And Fermi level E fermi The calculated work function value is equal to the difference between the vacuum level minus the Fermi level, i.e. E w ＝E vacuum -E fermi 。
4. The multi-scale correlation analysis method for device micro-discharge suppression according to claim 1, wherein the Monte Carlo simulation of secondary electron emission coefficient on the micrometer scale in the step (3) adopts a complex surface secondary electron emission multi-generation model program.
5. The multi-scale correlation analysis method for device micro-discharge suppression according to claim 1, wherein the micro-discharge threshold calculation method in the millimeter to centimeter scale in step (4) is as follows: adopting a micro-discharge inhibition statistical theory or a particle simulation method according to the structural complexity, adopting the micro-discharge inhibition statistical theory aiming at a simple flat plate structure and a coaxial structure, firstly carrying out Vaughan model piecewise function parameter fitting to calculate a micro-discharge sensitive area curve according to the statistical theory, and then analyzing the inhibition condition of a micro-discharge threshold value through the curve; aiming at a device with a complex structure, three-dimensional particle simulation software is adopted to establish the device structure, the Monte Carlo simulation value of the secondary electron emission coefficient on the micrometer scale is set as the parameter of an electron emission model, and particle simulation is carried out to obtain the final threshold analysis.
6. The multi-scale correlation analysis method for device micro-discharge suppression according to claim 1, wherein in the multi-scale correlation analysis method in step (6), a lattice adaptation method involving the combination of two material unit cells is used in establishing a composite structure unit cell model processed by a suppression process, and the processing method for the composite structure unit cell adaptation problem is as follows: calculating the least common multiple according to each lattice constant, properly expanding the supercell according to the proportional relation between each lattice constant and the least common multiple, and carrying out crystal cell coordinate averaging adaptation on small errors of the proportional relation to ensure that the structure can be smoothly relaxed.
7. The method for multi-scale correlation analysis of device micro-discharge suppression according to claim 1, wherein the procedure adopted in the monte carlo simulation of the surface secondary electron emission coefficient on the micron scale of the composite material in the step (8) is a multi-generation model procedure of the secondary electron emission of the complex surface of the multilayer material.
8. The multi-scale correlation analysis method for device micro-discharge inhibition according to claim 1, wherein the analysis method for determining whether inhibition effect exists and the reverse material selection guidance method comprise the following steps:
(1) Comparing the Monte Carr analog values of the secondary electron emission coefficients of the single metal and the composite film structure on a micrometer scale, if the analog value of the latter is smaller, the treatment process of the composite film structure has an inhibition effect on the surface secondary electron emission; otherwise, there is no inhibition effect;
(2) And comparing threshold simulation results of the single metal and the composite film layer structure on the millimeter to centimeter scale, namely the device level, so as to directly obtain the conclusion whether the micro-discharge inhibition effect of the device exists.
9. The method for multi-scale correlation analysis of device micro-discharge inhibition according to claim 8, wherein the comparing micro-discharge inhibition effect in step (2) comprises two ways: if the micro-discharge threshold is calculated by adopting particle simulation, the micro-discharge threshold of the device corresponding to the single metal and the surface of the composite film layer is directly compared, and if the micro-discharge threshold is smaller, the micro-discharge of the device is inhibited by the treatment process of the composite film layer; if the micro-discharge sensitive area of the composite film layer structure is smaller, the first threshold value is larger, and the second threshold value is smaller, the processing technology of the composite film layer ensures that the micro-discharge of the device is not easy to occur, namely the micro-discharge of the device has an inhibition effect; otherwise, no suppression effect is obtained.
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