Simulation method for irradiation displacement damage and influence of MOSFET gate oxide layer

Abstract

The invention discloses a method for simulating irradiation displacement damage and influence of an MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) gate oxide layer, which mainly solves the problems of incomplete description of irradiation defect evolution parameters and inaccurate simulation result in the prior art. Comprising the following steps: 1) obtaining the type and number of traps generated in a gate oxide layer after irradiation through molecular dynamics simulation; 2) utilizing first principle software to construct a gate oxide layer supercell and introducing a trap type; (3) acquiring the energy level position of a trap by applying a first principle to the supercell containing the defect, and calculating a capture cross section; 4) inputting the types, the number, the energy level positions and the capture cross sections of the traps into semiconductor device simulation software for performance simulation; and 5) obtaining the influence of trapped charges in the irradiated gate oxide layer on the electrical performance of the device. According to the method, the influence of irradiation displacement damage on the gate oxide layer can be comprehensively and accurately described, the influence of defects on the electrical performance of the device is determined, and a reliable basis is provided for further guiding and optimizing the performance of the semiconductor device.

Description

Technical Field

[0001] The present invention relates to the field of simulation technology, and in particular to a method for simulating radiation displacement damage and influence of a MOSFET gate oxide layer. Background Art

[0002] Space is filled with a large number of high-energy charged particles, such as heavy ions and protons. These particles can have various effects on aerospace electronic devices, causing equipment failure or even damage, and bringing huge economic losses to aerospace engineering. The radiation damage caused by the radiation environment to semiconductor devices or circuits is mainly manifested as ionization damage and displacement damage. Both types of damage will produce radiation-induced defects inside the device. The type, concentration, trap energy level, capture cross section and other parameters of the defects jointly determine their specific impact on the electrical properties of the device. Semiconductor devices are subject to various radiation effects in the space environment, among which the more typical one is displacement damage. This damage will produce a large number of defects in the oxide layer and substrate of the semiconductor device, seriously affecting the electrical performance of the device.

[0003] At present, the development of the prior art only focuses on the trap types and concentrations of defects generated in the substrate of the device after irradiation and their effects on the device, without considering the oxide layer defects, let alone the capture cross section and trap energy level of the gate oxide layer defects that are extremely important for the device characteristics. For example, in the patent document with the publication number CN 115186536 A, a simulation method and system for the evolution of irradiated defects in semiconductor devices are provided, which uses molecular dynamics to simulate the defect evolution of semiconductor materials, obtains the healing rate of defects and the stable defect concentration, and completes the device performance simulation on this basis. The method obtains the initial defect concentration of the semiconductor device and the defect concentration after the defect is healed, and inputs the defect concentration into TCAD, thereby obtaining the defect healing rate and the effect of the steady-state defect concentration on the performance of the semiconductor device. However, the scheme only considers the relationship between the healing rate of defects inside the substrate and the defect concentration in the steady state on the electrical performance of the device, and does not consider the trap energy level and capture cross section of defects in the gate oxide layer and their effects. In the patent document with publication number CN 115130306 A, a simulation method and system for the evolution of radiation defects in semiconductor devices are proposed. Based on molecular dynamics and dynamic Monte Carlo, the simulation calculation of the generation and evolution of radiation defects in semiconductor devices in time and space across scales is realized. The method can obtain information on different types of radiation-induced defects in semiconductor devices, such as the type, concentration, spatial position and other parameters of the defects. However, the trap energy level and capture cross section of the defects are not obtained, and parameter information such as the trap energy level and capture cross section of the defects in the gate oxide layer is not considered.

[0004] At present, most scholars focus on the evolutionary behavior of all defects in the entire device system, but not on the impact of gate oxide defects on the electrical performance of the device; or consider the type of defects generated in the device after irradiation and the corresponding concentration and spatial position parameters, but do not pay attention to the influence of the trap energy level position and capture cross section of the oxide defects. However, for the gate oxide defects of MOSFET, in addition to clarifying the impact of the type and concentration of irradiation displacement damage defects on the electrical performance of the device, it is also necessary to clarify the trap energy level and capture cross section and their impact. Therefore, there is an urgent need for a technical solution that can comprehensively describe the impact of gate oxide defect parameters on the electrical performance of the device after irradiation. Summary of the invention

[0005] The purpose of the present invention is to address the deficiencies of the above-mentioned prior art and propose a simulation method for MOSFET gate oxide layer radiation displacement damage and its influence, which is used to solve the problem that the prior art ignores the gate oxide layer defects induced by radiation and their influence on device performance, resulting in incomplete description of radiation defect evolution parameters and inaccurate simulation results. The present invention considers the theoretical calculation of stable defects, the number of defects, energy levels and capture cross sections induced by radiation in the gate oxide layer, and their influence on device performance. Starting from a microscopic perspective, molecular dynamics is used to simulate the types and numbers of stable defects generated by displacement damage in oxide films. The energy levels and capture cross sections of defects are calculated using first principles for different types of radiation-induced defects. The number, energy level and capture cross sections of various defects induced by radiation are used as input to carry out device simulation, and the influence of radiation displacement damage on the electrical characteristics of the device is obtained.

[0006] The present invention achieves the above-mentioned purpose by the following specific steps:

[0007] (1) Through molecular dynamics simulation, the types and numbers of traps generated in the gate oxide layer after irradiation are obtained:

[0008] (1.1) Construct a gate oxide supercell and use potential function to characterize the interaction force between atoms in the supercell;

[0009] (1.2) Using the isothermal and isobaric NPT ensemble as the initial system, the system temperature is balanced to room temperature T′, and the distance from the unit cell boundary is The range is set as the isothermal layer, the temperature of the isothermal layer is maintained at T′ by connecting the Nose-Hoova thermostat, and the inner region is set as the simulation region. The microcanonical NVE ensemble is used in the simulation process;

[0010] (1.3) The particle is incident along the normal direction of the unit cell surface and from the center just above the unit cell;

[0011] (1.4) An atom is randomly selected from the system as the primary collision atom. When the kinetic energy obtained by the primary collision atom is greater than its displacement threshold energy, a defect is generated off-site.

[0012] (1.5) Obtain the type and quantity of traps generated in the gate oxide layer after irradiation;

[0013] (2) Input the trap type into the first-principles software to obtain the energy level position and capture cross section of the trap:

[0014] (2.1) constructing a gate oxide supercell with an optimized structure and a number of atoms not exceeding 300 using first-principles software, and introducing any one or more trap types obtained in step (1) to obtain a supercell containing defects;

[0015] (2.2) Processing the supercell containing the defect using first-principles software to obtain the energy level position of the defect;

[0016] (2.3) Calculate the capture cross section σ:

[0017]

[0018] Where C represents the capture coefficient of the defect, is the carrier velocity;

[0019] (3) The type, number, energy level position and capture cross section of the traps are used as input parameters, and the performance of the semiconductor device is simulated using semiconductor device simulation software to obtain the effect of the trapped charge in the gate oxide layer after irradiation on the electrical performance of the device.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] First, since the present invention uses molecular dynamics to obtain the defect type and quantity of radiation displacement damage, it is possible to quickly obtain stable defect types and quantities;

[0022] Second, the present invention takes into account the difficulty of obtaining trap energy levels and capture cross sections by molecular dynamics. Therefore, for different types of defects, the first principles are introduced when calculating their energy levels and capture cross sections, so that the energy levels and capture cross sections of the defects can be obtained by calculation;

[0023] Second, the present invention combines molecular dynamics with first principles, obtains defects generated in the gate oxide layer after irradiation and its corresponding trap energy levels, capture cross sections and other parameters through linkage simulation, and inputs the obtained defect parameters into semiconductor process simulation and device simulation tools, thereby being able to more comprehensively and accurately describe the impact of irradiation displacement damage on the gate oxide layer, and further describe the impact of gate oxide layer defects generated after irradiation on the electrical properties of the device, providing a reliable basis for further guiding the optimization of semiconductor device performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the overall implementation flow chart of the method of the present invention;

[0025] Figure 2 It is a schematic diagram of the application process of the present invention;

[0026] Figure 3 is a defect evolution diagram generated after irradiation in an embodiment of the present invention;

[0027] Figure 4 is a total wave state density curve of the monoclinic tetracoordinate oxygen vacancy structure of hafnium oxide in an embodiment of the present invention;

[0028] Figure 5 is a curve diagram showing the variation of the capture cross section with temperature in an embodiment of the present invention;

[0029] Figure 6 Graph showing the effect of defects caused by displacement damage after irradiation on the electrical performance of the device in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings.

[0031] Embodiment 1: Refer to the attached Figure 1 and Figure 2 The present invention proposes a method for simulating the radiation displacement damage and influence of a MOSFET gate oxide layer, and the specific steps are as follows:

[0032] Step 1. Obtain the type and number of traps generated in the gate oxide layer after irradiation through molecular dynamics simulation:

[0033] (1.1) constructing a gate oxide layer supercell, and using a potential function to characterize the interaction force between atoms in the supercell, wherein the potential function includes a deep learning potential function and an empirical potential function; the number of atoms in the gate oxide layer supercell is determined by the following formula:

[0034]

[0035] Among them, E r is the energy of the primary impact atom, N is the number of atoms, k B is the Boltzmann constant, ΔT represents the temperature change, atoms is the number of atoms, and eV is electron volt, which is the unit of energy.

[0036] (1.2) Using the isothermal and isobaric NPT ensemble as the initial system, the system temperature is balanced to room temperature T′, and the distance from the unit cell boundary is The range is set as the isothermal layer, the temperature of the isothermal layer is maintained at T′ by connecting the Nose-Hoova thermostat, and the inner region is set as the simulation region. The microcanonical NVE ensemble is used in the simulation process;

[0037] (1.3) The particle is incident along the normal direction of the unit cell surface and from the center just above the unit cell;

[0038] (1.4) An atom is randomly selected from the system as the primary collision atom. When the kinetic energy obtained by the primary collision atom is greater than its displacement threshold energy, a defect is generated;

[0039] (1.5) Obtain the type and quantity of traps generated in the gate oxide layer after irradiation;

[0040] Step 2. Input the trap type into the first-principles software to obtain the energy level position and capture cross section of the trap:

[0041] (2.1) Use first-principles software to construct a gate oxide supercell with no more than 300 atoms and optimized structure, and introduce any one or more trap types obtained in step (1) to obtain a supercell containing defects. The structural optimization refers to adjusting relevant parameters in the first-principles software so that the atoms reach their respective equilibrium positions, obtain a stable unit cell structure, and achieve optimization; the relevant parameters include supercell optimization status, structural optimization accuracy, atomic motion trajectory, and autonomous optimization convergence energy standard, wherein the supercell optimization status includes supercell volume, shape, and atomic position. The first-principles software includes siesta, vasp, wien2k, PWSCF, Materials Studio, etc., and Vasp software is preferably used in this embodiment.

[0042] (2.2) The supercell containing the defect is processed by first-principles software to obtain the energy level position of the defect; the specific implementation steps are as follows:

[0043] (2.2.1) For a supercell containing defects, 1.2 times the maximum cutoff energy of all its elements is set as the plane wave cutoff energy;

[0044] (2.2.2) Set the Monkhorst-Pack K point;

[0045] (2.2.3) Optimize the structure of the supercell containing defects to obtain the structure file;

[0046] (2.2.4) Obtain defect state energy and charge distribution through static self-consistency;

[0047] (2.2.5) The density of states diagram is extracted through density of states calculation, and the position of the gap state energy level generated in the bandgap is obtained from it, which is the energy level position of the defect; this is achieved as follows: first, the structure file is converted into a static calculation file, and then a static self-consistent calculation is performed to adjust the electrons in the system to reach the lowest energy state of the system; at the same time, the K point is modified and a non-self-consistent calculation is performed to obtain an accurate density of states; finally, the density of states data is calculated and processed to obtain the density of states diagram.

[0048] (2.3) Calculate the capture cross section σ:

[0049]

[0050] Where C represents the capture coefficient of the defect, is the carrier rate; they are obtained according to the following formulas:

[0051]

[0052] where V is the volume of the periodic structure including the defect, is Planck's constant, π is the circumference of a circle, g is the degeneracy of the defect, w a represents the thermal occupancy of the excited state, represents the phonon-electron coupling matrix element, the δ function represents the energy conservation constraint before and after the transition, and E in With E jm is the total energy of the initial and final vibrational states;

[0053]

[0054] Where k is the Boltzmann constant, m is the effective mass, and T″ is the absolute temperature.

[0055] Step 3. The type, quantity, energy level position and capture cross section of the trap are used as input parameters, and the performance simulation of the semiconductor device is performed by semiconductor device simulation software, including Sentaurus TCAD, Silvaco TCAD, Ansys, COMSOL, etc. In this embodiment, Sentaurus TCAD (Technology Computer Aided Design) software is preferably used to simulate the performance of the semiconductor device to obtain the influence of the trapped charge in the gate oxide layer after irradiation on the electrical performance of the device; the implementation is as follows:

[0056] (3.1) Use semiconductor device simulation software to build device models;

[0057] (3.2) The defect-free transfer characteristic curve before irradiation is obtained by simulation using semiconductor device simulation software;

[0058] (3.3) Introducing defects in the gate oxide layer;

[0059] (3.4) Using Gaussian distribution to simulate the trap energy level distribution of defects;

[0060] (3.5) Simulating the transfer characteristic curve including defects after irradiation by semiconductor device simulation software;

[0061] (3.6) The transfer characteristic curves before and after irradiation are compared to obtain the influence of defects generated in the gate oxide layer after irradiation on the electrical performance of the device.

[0062] Example 2: Referring to 2-6, the overall implementation steps of the simulation method provided in this example are the same as those in Example 1. The present invention is not only applicable to monoclinic HfO 2 Gate materials, also applicable to other phases of HfO 2 Materials and other oxide materials; the gate oxide layer is currently HfO 2 Taking the example of the present invention, the specific implementation process of the method of the present invention is further described in detail:

[0063] Step A: Describe the type and quantity of traps generated in the oxide layer after irradiation by molecular dynamics; the specific implementation steps include the following:

[0064] a1) Constructing supercell: Select the energy of primary collision atom as 3KeV, based on the formula To obtain an energy of 3 KeV, at least 57,900 atoms are required for simulation, of which E r is the energy of the primary impact atom, N is the number of atoms, k B is the Boltzmann constant. So far, a HfO with 96000 (20×20×20) atoms has been constructed. 2 Supercell;

[0065] a2) Select potential function: Based on the construction of the supercell, select a suitable potential function to describe the interaction force between atoms. In this embodiment, a deep learning potential function is used to describe the interaction force between Hf and O atoms. The potential function can also be described by other forms of numerical potential functions such as empirical potential functions.

[0066] a3) Setting initial conditions: After the potential function is determined, it is necessary to set appropriate initial conditions and boundary conditions. The initial conditions and boundary conditions set in the present invention are: the initial system uses the NPT ensemble, the system temperature is balanced to 300K, and the distance from the unit cell boundary is The range is set as the isothermal layer. The temperature of the isothermal layer is always kept at 300K by connecting the Nose-Hoova thermostat to simulate the external environment temperature. The internal area is set as the simulation area. The NVE ensemble is used in the simulation process to avoid the influence of the force applied by the thermostat on the dynamics.

[0067] a4) Selecting the incident position and angle of the particle: After the initial conditions and boundary conditions are determined, the particle incident parameters are selected. The present invention selects the particle incident position as the center just above the unit cell, and the incident angle is incident along the normal direction of the unit cell surface.

[0068] a5) Selection of primary collision atoms: The present invention selects O atoms as primary collision atoms. When the kinetic energy obtained by the primary collision atoms is greater than their displacement threshold energy, defects will be generated off-site. Here, the initial kinetic energy of 3KeV is selected for the O atoms;

[0069] a6) Obtaining defect types and quantities: Through the above 5 steps, the displacement damage effect can be simulated, so that the types and quantities of traps induced by radiation can be obtained. The results are as follows: Figure 3 As shown. It can be seen that when the system temperature is 300K, 12 oxygen vacancies (dark blue) and 12 oxygen gaps (light blue) will be generated after the primary impact atom is a 3KeV particle incident. Since the impact of oxygen vacancies on the device is much greater than that of oxygen gaps, the impact of oxygen gaps is ignored in the present invention.

[0070] Step B. Describing the trap energy level positions and capture cross sections of different traps by first principles. In this embodiment, oxygen vacancy defects are taken as an example. The implementation steps include:

[0071] b1) Construction of supercell: First, a HfO supercell with optimized lattice constants is constructed using first-principles software. 2 Supercell (the number of atoms in a supercell generally does not exceed 300. Exceeding 300 will increase the amount of calculation and waste machine time). Therefore, this paper selects a supercell (2×2×2) of 96 atoms and introduces the defect type obtained in step A into the supercell.

[0072] b2) Obtain defect energy and charge distribution: First, set the calculated cutoff energy and K point. The selection of the cutoff energy is related to the elements in the primitive cell. Generally, 1.2 times the maximum cutoff energy of all elements is selected. The K point can be directly obtained using the VASPKIT script in the VASP software. Therefore, in this embodiment, the cutoff energy is set to 500eV (the cutoff energy of O is 400eV, and the cutoff energy of Hf is 220eV), and the K point is 0.04Angstrom -1 , then the supercell containing oxygen vacancy defects is structurally optimized and relaxed, and after relaxation, the defect state energy and charge distribution are obtained by electronic self-consistency.

[0073] b3) Obtain defect energy level: Finally, the state density calculation can be performed to extract the state density diagram. From the state density, the position of the gap state energy level generated in the band gap can be obtained. This position is the defect energy level introduced by the defect, such as Figure 4 The position of the trap level shown is 2.3 eV from the valence band top;

[0074] b4) Obtaining the capture cross section: The capture cross section is calculated mainly using the following three formulas: The capture coefficient of the defect can be obtained as follows: where V is the volume of the periodic structure containing the defect, g is the degeneracy of the defect, and w is a represents the thermal occupancy of the excited state, represents the phonon-electron coupling matrix element, the δ function represents the energy conservation constraint before and after the transition, and E in With E jm is the total energy of the initial and final vibrational states; and Where C is the capture coefficient, σ is the capture cross section, k is the Boltzmann constant, m is the effective mass, and T is the temperature. These three formulas can be used to calculate the change of the capture cross section with temperature, such as Figure 5 As shown. Since the temperature of the final system is 300K, we extract the capture cross section at 300K. Figure 5 It can be seen that when T = 300K, the capture cross section is 2.6e -18 cm 2 ;

[0075] b5) In summary, the position of the trap level of oxygen vacancies at a temperature of 300 K is 2.3 eV from the top of the valence band, and the capture cross section is 2.6 e -18 cm 2 .

[0076] Step C. Use Sentaurus TCAD to describe the effect of defects generated after irradiation on device performance, as follows:

[0077] c1) Model building: Build a MOSFET model in Sentaurus TCAD and obtain the transfer characteristic curve before irradiation;

[0078] c2) Add material parameters: In Sentaurus TCAD, the oxide layer has no carrier mobility, so even if you add a defect model, the defect will not capture / emit carriers. Therefore, you need to add a defect model in HfO 2 Add the electron / hole mobility to the material parameter file, where the electron / hole mobility is 20cm -2 / V·s、1e -5 cm -2 / V·s, let HfO 2 Defects in the ions can capture and emit carriers;

[0079] c3) From step A, we can see that the defects generated are mainly oxygen vacancies. However, there are no oxygen vacancy defects in Sentaurus TCAD. Considering that the role of oxygen vacancies is to emit electrons, we use donor-type defects to represent oxygen vacancies.

[0080] c4) Add defect parameters: From step B, it can be concluded that when the system temperature is 300°C, the trap energy level of the oxygen vacancy is at 2.3 eV at the top of the valence band, that is, near the center of the forbidden band, and the capture cross section is 2.6e -18 cm 2 In order to achieve the same effect as in the experiment, this embodiment preferably uses Gaussian distribution to describe the energy level distribution of oxygen vacancy traps. Of course, the energy level distribution of traps is not limited to Gaussian distribution, and exponential distribution, single energy level, etc. can also be used.

[0081] c5) Obtain the curve after irradiation: Use TCAD to simulate the transfer characteristic curve after irradiation to obtain the influence of oxygen vacancy defects generated after irradiation on the electrical properties of the device. The results are as follows: Figure 6 shown.

[0082] c6) Similarly, the effect of a certain defect or the coexistence of multiple defects on the electrical performance of the device can be obtained.

[0083] The present invention adopts molecular dynamics to simulate the types and quantities of stable defects generated by displacement damage in an oxide film, applies first principles to calculate the energy levels and capture cross sections of defects for different types of radiation-induced defects, takes the quantity, energy level and capture cross section of various radiation-induced defects as input to carry out device simulation, and obtains the influence of radiation displacement damage on the electrical characteristics of the device, thus solving the problem that the prior art does not consider the influence of the energy level and capture cross section of gate oxide layer defects and their influence on device performance.

[0084] Parts of the present invention that are not described in detail belong to common knowledge among those skilled in the art.

[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Obviously, for professionals in this field, after understanding the content and principles of the present invention, they may make various modifications and changes in form and details without departing from the principles and structures of the present invention. However, these modifications and changes based on the ideas of the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A method for simulating MOSFET gate oxide layer radiation displacement damage and its influence, characterized in that: The steps include: (1) Through molecular dynamics simulation, the types and numbers of traps generated in the gate oxide layer after irradiation are obtained: (1.1) Construct a gate oxide supercell and use potential function to characterize the interaction force between atoms in the supercell; (1.2) Using the isothermal and isobaric NPT ensemble as the initial system, the system temperature is balanced to room temperature T′, and the distance from the unit cell boundary is The range is set as the isothermal layer, the temperature of the isothermal layer is maintained at T′ by connecting the Nose-Hoova thermostat, and the inner region is set as the simulation region. The microcanonical NVE ensemble is used in the simulation process; (1.3) The particle is incident along the normal direction of the unit cell surface and from the center just above the unit cell; (1.4) An atom is randomly selected from the system as the primary collision atom. When the kinetic energy obtained by the primary collision atom is greater than its displacement threshold energy, a defect is generated; (1.5) Obtain the type and quantity of traps generated in the gate oxide layer after irradiation; (2) Input the trap type into the first-principles software to obtain the energy level position and capture cross section of the trap: (2.1) constructing a gate oxide supercell with an optimized structure and a number of atoms not exceeding 300 using first-principles software, and introducing any one or more trap types obtained in step (1) to obtain a supercell containing defects; (2.2) Processing the supercell containing the defect using first-principles software to obtain the energy level position of the defect; (2.3) Calculate the capture cross section σ: Where C represents the capture coefficient of the defect, is the carrier velocity; (3) The type, number, energy level position and capture cross section of the traps are used as input parameters, and the performance of the semiconductor device is simulated using semiconductor device simulation software to obtain the effect of the trapped charge in the gate oxide layer after irradiation on the electrical performance of the device.

2. The simulation method according to claim 1, characterized in that: In step (1.1), a gate oxide supercell is constructed. The number of atoms contained in the supercell is determined by the following formula: Among them, E r is the energy of the primary impact atom, N is the number of atoms, k B is the Boltzmann constant, ΔT represents the temperature change, atoms is the number of atoms, and eV is electron volt, which is the unit of energy.

3. The simulation method according to claim 1, characterized in that: The potential function described in step (1.1) includes a deep learning potential function and an empirical potential function.

4. The simulation method according to claim 1, characterized in that: In step (2.2), the supercell containing the defect is processed by first principle software to obtain the energy level position of the defect; the specific implementation steps are as follows: (2.2.1) For the supercell containing oxygen vacancy defects, 1.2 times the maximum cutoff energy of all its elements is set as the plane wave cutoff energy; (2.2.2) Set the K point and perform structural optimization on the supercell containing the defect to obtain the structure file; (2.2.3) Obtain defect state energy and charge distribution through static self-consistency; (2.2.4) The density of states diagram is extracted through state density calculation, and the position of the gap state energy level generated in the band gap is obtained from it. This position is the energy level position of the defect.

5. The simulation method according to claim 4, characterized in that: The structural optimization described in step (2.1) and step (2.2.2) refers to adjusting relevant parameters in the first-principles software to make the atoms reach their respective equilibrium positions, obtain a stable unit cell structure, and achieve optimization; the relevant parameters include supercell optimization status, structural optimization accuracy, atomic motion trajectory, and autonomous optimization convergence energy standard, wherein the supercell optimization status includes supercell volume, shape, and atomic position.

6. The simulation method according to claim 5, characterized in that: The first principles software includes siesta, vasp, wien2k, PWSCF, and Materials Studio.

7. The simulation method according to claim 4, characterized in that: In step (2.2.4), the state density diagram is extracted through state density calculation, which is implemented as follows: first, the structure file is converted into a static calculation file, and then a static self-consistent calculation is performed to adjust the electrons in the system to reach the lowest energy state of the system; at the same time, the K point is modified and a non-self-consistent calculation is performed to obtain an accurate state density; finally, the state density data is calculated and processed to obtain the state density diagram.

8. The simulation method according to claim 1, characterized in that: The capture coefficient C and carrier rate of the defect described in step (2.3) According to the following formulas: where V is the volume of the periodic structure including the defect, is Planck's constant, π is the circumference of a circle, g is the degeneracy of the defect, w a represents the thermal occupancy of the excited state, represents the phonon-electron coupling matrix element, the δ function represents the energy conservation constraint before and after the transition, and E in With E jm is the total energy of the initial and final vibrational states; Where k is the Boltzmann constant, m is the effective mass, and T″ is the absolute temperature.

9. The simulation method according to claim 1, characterized in that: The influence of the trapped charges in the gate oxide layer after irradiation on the electrical performance of the device in step (3) is obtained according to the following steps: (3.1) Use semiconductor device simulation software to build device models; (3.2) The defect-free transfer characteristic curve before irradiation is obtained by simulation using semiconductor device simulation software; (3.3) Introducing defects in the gate oxide layer; (3.4) Using Gaussian distribution to simulate the trap energy level distribution of defects; (3.5) Simulating the transfer characteristic curve including defects after irradiation by semiconductor device simulation software; (3.6) The transfer characteristic curves before and after irradiation are compared to obtain the influence of defects generated in the gate oxide layer after irradiation on the electrical performance of the device.

10. The simulation method according to claim 9, characterized in that: The semiconductor device simulation software includes Sentaurus TCAD, Silvaco TCAD, Ansys, and COMSOL.

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