Simulation Method of Radiation Displacement Damage and Impact on MOSFET Gate Oxide

Abstract

This invention discloses a simulation method for irradiation displacement damage and its effects on the gate oxide layer of a MOSFET, primarily addressing the problems of incomplete description of irradiation defect evolution parameters and inaccurate simulation results in existing technologies. The method includes: 1) obtaining the type and number of traps generated in the gate oxide layer after irradiation through molecular dynamics simulation; 2) constructing a gate oxide layer supercell using first-principles calculation software and introducing trap types; 3) using first-principles calculations to obtain the energy level positions of the traps and calculate the trapping cross-section for the defect-containing supercell; 4) inputting the trap type, number, energy level positions, and trapping cross-section into semiconductor device simulation software for performance simulation; and 5) obtaining the influence of trap charges in the irradiated gate oxide layer on the device's electrical performance. This invention can comprehensively and accurately describe the impact of irradiation displacement damage on the gate oxide layer, clarifying the influence of defects on the device's electrical performance, and providing a reliable basis for further guiding the optimization of semiconductor device performance.

Description

Technical Field

[0001] This invention relates to the field of simulation technology, and more specifically, to a method for simulating the damage and effects of irradiation displacement on the gate oxide layer of a MOSFET. Background Technology

[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, leading to equipment failure or even damage, resulting in huge economic losses for aerospace engineering. Radiation damage to semiconductor devices or circuits caused by the radiation environment mainly manifests as ionization damage and displacement damage. Both types of damage generate radiation-induced defects within the device. The type, concentration, trap energy level, and trapping cross-section of these defects collectively determine their specific impact on the device's electrical performance. Semiconductor devices are subjected to various radiation effects in the space environment, among which displacement damage is particularly typical. This damage generates numerous defects in the oxide layer and substrate of the semiconductor device, severely affecting its electrical performance.

[0003] Currently, existing technologies only focus on the trap types and concentrations of defects generated in the substrate after irradiation and their impact on the device, without considering oxide layer defects, let alone the trapping cross-sections and trap energy levels of gate oxide defects, which are extremely important for device characteristics. For example, patent document CN 115186536 A provides a simulation method and system for simulating the evolution of irradiation defects in semiconductor devices. It uses molecular dynamics to simulate the defect evolution of semiconductor materials, obtaining the defect healing rate and stable defect concentration, and then performs device performance simulation based on this. This method obtains the initial defect concentration and the defect concentration after defect healing in the semiconductor device, and inputs the defect concentration into TCAD to obtain the impact of defect healing rate and steady-state defect concentration on semiconductor device performance. However, this scheme only considers the relationship between the healing rate of defects inside the substrate and the steady-state defect concentration on the electrical performance of the device, without considering the trapping energy levels and trapping cross-sections of defects in the gate oxide layer and their impact. The patent document with publication number CN 115130306 A proposes a simulation method and system for the evolution of irradiation defects in semiconductor devices. Based on molecular dynamics and dynamic Monte Carlo, it realizes the spatiotemporal cross-scale simulation calculation of the entire process of the generation and evolution of irradiation defects in semiconductor devices. This method can obtain information on different types of irradiation-induced defects in semiconductor devices, such as the type, concentration, and spatial location of defects. However, it does not obtain the trap energy level and trapping cross section of defects, nor does it consider the trap energy level and trapping cross section of defects in the gate oxide layer.

[0004] Currently, most scholars focus on the evolution of all defects in the entire device system, neglecting the impact of gate oxide defects on the device's electrical performance; or they consider the types, concentrations, and spatial location parameters of defects generated after irradiation, without considering the influence of the trap level positions and trapping cross-sections of oxide defects. However, for MOSFET gate oxide defects, in addition to clarifying the impact of irradiation displacement damage defect types and concentrations on device electrical performance, it is also necessary to clarify the trap levels and trapping cross-sections and their effects. Therefore, a technical solution that can comprehensively describe the impact of gate oxide defect parameters after irradiation on device electrical performance is urgently needed. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a simulation method for irradiation displacement damage and its effects on MOSFET gate oxide layers. This method solves the problem that existing technologies neglect irradiation-induced gate oxide defects and their impact on device performance, leading to incomplete descriptions of irradiation defect evolution parameters and inaccurate simulation results. This invention considers theoretical calculations of stable defects induced by irradiation in the gate oxide layer, including their number, energy levels, and trapping cross-sections, and their impact on device performance. From a microscopic perspective, it uses molecular dynamics simulations to determine the types and numbers of stable defects generated by displacement damage in the oxide film. For different types of irradiation-induced defects, first-principles calculations are applied to determine the defect energy levels and trapping cross-sections. Using the number, energy levels, and trapping cross-sections of various irradiation-induced defects as inputs, device simulations are conducted to obtain the impact of irradiation displacement damage on the device's electrical characteristics.

[0006] The specific steps of this invention to achieve the above objectives are as follows:

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

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

[0009] (1.2) Using the isothermal and isobaric NPT ensemble as the initial system, the system temperature is equilibrated to room temperature T′, at a distance from the unit cell boundary. The range is set as a constant temperature layer, and the temperature of the constant temperature layer is maintained at T′ by connecting a Nose-Hoova thermostat. The internal region is set as the simulation region, and the simulation process uses a micro-canonical NVE ensemble.

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

[0011] (1.4) Randomly select an atom from the system as the primary impact atom. When the kinetic energy acquired by the primary impact atom is greater than its displacement threshold energy, a defect is generated in place.

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

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

[0014] (2.1) Construct a gate oxide supercell with no more than 300 atoms and optimized structure using first-principles software, and introduce any one or more trap types obtained in step (1) to obtain a supercell containing defects;

[0015] (2.2) The energy level positions of the defects are obtained by processing the supercell containing the defects using first-principles software;

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

[0017]

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

[0019] (3) The type, number, energy level position and trapping cross section of the traps are used as input parameters. The performance of the semiconductor device is simulated by semiconductor device simulation software to obtain the effect of the trap 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, because this invention uses molecular dynamics to obtain the defect type and quantity of irradiation displacement damage, it is able to quickly obtain a stable defect type and quantity.

[0022] Secondly, considering that molecular dynamics makes it difficult to obtain trap energy levels and trapping cross sections, this invention introduces first principles when calculating the energy levels and trapping cross sections for different types of defects, thereby enabling the energy levels and trapping cross sections of defects to be calculated.

[0023] Secondly, this invention combines molecular dynamics with first-principles calculations to obtain the defects generated in the gate oxide layer after irradiation and their corresponding trap energy levels, trapping cross sections, and other parameters through linked simulation. The obtained defect parameters are then input into semiconductor process simulation and device simulation tools, thereby enabling a more comprehensive and accurate description of the impact of irradiation displacement damage on the gate oxide layer. This, in turn, describes the impact of irradiated gate oxide layer defects on the electrical performance of the device, providing a reliable basis for further guiding the optimization of semiconductor device performance. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating the overall implementation of the method of the present invention;

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

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

[0027] Figure 4 This is a graph showing the total wave state density of the hafnium oxide monoclinic four-coordinate oxygen vacancy structure in an embodiment of the present invention.

[0028] Figure 5 This is a graph showing the change of the capture cross section with temperature in an embodiment of the present invention;

[0029] Figure 6 This diagram illustrates the impact of irradiation-induced displacement damage defects on the electrical performance of the device in an embodiment of the present invention. Detailed Implementation

[0030] The present invention will now be further described with reference to the accompanying drawings.

[0031] Example 1: Refer to Appendix Figure 1 and Figure 2 The present invention proposes a simulation method for irradiation displacement damage and its effects on MOSFET gate oxide layer, the specific steps of which 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) Construct a gate oxide supercell and use a potential function to characterize the interaction forces between atoms in the supercell. The potential function includes a deep learning potential function and an empirical potential function. The number of atoms in the gate oxide supercell is determined by the following formula:

[0034]

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

[0036] (1.2) Using the isothermal and isobaric NPT ensemble as the initial system, the system temperature is equilibrated to room temperature T′, at a distance from the unit cell boundary. The range is set as a constant temperature layer, and the temperature of the constant temperature layer is maintained at T′ by connecting a Nose-Hoova thermostat. The internal region is set as the simulation region, and the simulation process uses a micro-canonical NVE ensemble.

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

[0038] (1.4) Randomly select an atom from the system as the primary impact atom. When the kinetic energy acquired by the primary impact atom is greater than its displacement threshold energy, a defect is generated in place.

[0039] (1.5) Obtain the type and number 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 trap's energy level position and trapping cross-section:

[0041] (2.1) Construct a gate oxide supercell with no more than 300 atoms and optimized structure using first-principles software, 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 to allow atoms to reach their respective equilibrium positions, thereby obtaining a stable cell structure and achieving optimization. The relevant parameters include supercell optimization status, structural optimization accuracy, atomic motion trajectories, and autonomous optimization convergence energy standard, where the supercell optimization status includes supercell volume, shape, and atomic positions. First-principles software includes Siesta, VASP, Wien2k, PWSCF, Materials Studio, etc., and VASP software is preferred in this embodiment.

[0042] (2.2) The energy level positions of the defects are obtained by processing the supercell containing the defects using first-principles software; the specific implementation steps are as follows:

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

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

[0045] (2.2.3) Perform structural optimization on the supercell containing defects to obtain the structural file;

[0046] (2.2.4) The energy and charge distribution of the defect state are obtained through static self-consistency;

[0047] (2.2.5) Extract the density of states map through density of states calculation and obtain the energy level position of the gap state generated in the band gap. This position is the energy level position of the defect. The implementation is as follows: First, convert the structure file into a static calculation file, and then perform static self-consistent calculation to adjust the electrons in the system to reach the lowest energy state of the system. At the same time, modify the K point and perform non-self-consistent calculation to obtain the accurate density of states. Finally, calculate and process the density of states data to obtain the density of states map.

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

[0049]

[0050] Where C represents the defect capture coefficient, The carrier velocity is obtained from the following formulas:

[0051]

[0052] Where V is the volume of the periodic structure containing the defects. Let π be Planck's constant, π be pi, g be the degeneracy of the defect, and w be... a Indicates the thermal occupancy rate of the excited state, The phonon-electron coupling matrix element is represented by the δ function, which represents the energy conservation constraint before and after the transition. in With E jm 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″ represents the absolute temperature.

[0055] Step 3. Using the type, number, energy level location, and trapping cross-section of the traps as input parameters, and employing semiconductor device simulation software, including Sentaurus TCAD, Silvaco TCAD, Ansys, COMSOL, etc., this embodiment preferably uses Sentaurus TCAD (Technology Computer Aided Design) software to simulate the performance of the semiconductor device, obtaining the influence of the trap charge in the gate oxide layer on the electrical performance of the device after irradiation; the implementation is as follows:

[0056] (3.1) Construct device models using semiconductor device simulation software;

[0057] (3.2) The transfer characteristic curves without defects before irradiation were obtained by simulation using semiconductor device simulation software;

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

[0059] (3.4) The trap energy level distribution of the defect is simulated using a Gaussian distribution;

[0060] (3.5) Simulate the transfer characteristic curves containing defects after irradiation using semiconductor device simulation software;

[0061] (3.6) By comparing the transfer characteristic curves before and after irradiation, the influence of defects generated in the gate oxide layer after irradiation on the electrical performance of the device can be obtained.

[0062] Example 2: Referring to 2-6, the simulation method provided in this example is implemented in the same way as in Example 1. This invention is not only applicable to monoclinic HfO2 gate materials, but also to HfO2 materials of other phases and other oxide materials. Now, taking HfO2 as the gate oxide layer as an example, the specific implementation process of the method of this invention will be described in further detail:

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

[0064] a1) Constructing a supercell: The energy of the primary impacting atoms is chosen to be 3 keV, based on the formula... To achieve an energy of 3 keV, a minimum of 57,900 atoms are needed for simulation, where E r Where N is the energy of the primary colliding atom, N is the number of atoms, and k is the energy of the primary colliding atom. B is the Boltzmann constant. Thus, an HfO2 supercell with 96,000 (20 × 20 × 20) atoms was constructed;

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

[0066] a3) Setting initial conditions: After the potential function is determined, appropriate initial and boundary conditions need to be set. The initial and boundary conditions set in this invention are as follows: 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 a constant temperature layer. The temperature of the constant temperature layer is always kept at 300K by connecting a Nose-Hoova thermostat to simulate the external ambient temperature. The internal area is set as a simulation area. The simulation process uses the NVE ensemble to avoid the force applied by the temperature controller from affecting the dynamics.

[0067] a4) Selecting the incident position and angle of the particle: After determining the initial and boundary conditions, select the particle incident parameters. In this invention, the incident position of the particle is the center directly above the unit cell, and the incident angle is the incident direction along the normal direction of the unit cell surface.

[0068] a5) Selection of primary impact atom: In this invention, O atom is selected as the primary impact atom. When the kinetic energy acquired by the primary impact atom is greater than its displacement threshold energy, it will displace and generate a defect. Here, 3 KeV of initial kinetic energy is given to O atom.

[0069] a6) Obtaining Defect Types and Quantities: The above five steps simulate displacement damage effects, thus revealing the types and quantities of irradiation-induced traps. The results are as follows: Figure 3 As shown, at a system temperature of 300K, a 3keV primary impact particle will generate 12 oxygen vacancies (dark blue) and 12 oxygen gaps (light blue) upon incident. Since the impact of oxygen vacancies on the device is far greater than that of oxygen gaps, the influence of oxygen gaps is ignored in this invention.

[0070] Step B. Describe the trap energy level positions and trapping cross sections of different traps using first-principles calculations. This embodiment takes oxygen vacancy defects as an example, and the steps include:

[0071] b1) Constructing a supercell: First, a lattice constant optimized HfO2 supercell is constructed using first-principles software (the number of atoms in the supercell is generally no more than 300, as more than 300 atoms will increase the computational load and waste machine time). Therefore, this paper selects a supercell with 96 atoms (2×2×2) and introduces the defect type obtained in step A into the supercell.

[0072] b2) Obtaining Defect Energy and Charge Distribution: First, set the calculated cutoff energy and K-point. The cutoff energy is related to the elements in the unit cell, generally chosen to be 1.2 times the maximum cutoff energy among all elements. The K-point can be obtained directly using the VASPKIT script in the VASP software. Therefore, in this embodiment, the cutoff energy is set to 500 eV (400 eV for O and 220 eV for Hf), and the K-point is set to 0.04 Angstrom. -1 Then, the structure of the supercell containing oxygen vacancy defects is optimized and relaxed. After relaxation, electronic self-consistency is performed to obtain the energy and charge distribution of the defect states.

[0073] b3) Obtaining Defect Energy Levels: Finally, the density of states can be calculated to extract the density of states map. From the density of states, the positions of the interstitial state energy levels generated in the band gap can be obtained. These positions are the defect energy levels introduced by the defect. Figure 4 The location of the trap level shown is 2.3 eV from the top of the valence band;

[0074] b4) Obtaining the capture section: The following three formulas are mainly used to calculate the capture section: The defect trapping coefficient can be obtained, where V is the volume of the periodic structure containing the defect, g is the degeneracy of the defect, and w a Indicates the thermal occupancy rate of the excited state, The phonon-electron coupling matrix element is represented by the δ function, which represents the energy conservation constraint before and after the transition. in With E jm 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. The change of the capture cross-section with temperature can be calculated using these three formulas, such as... Figure 5 As shown. Since the final system temperature 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 location of the oxygen vacancy trap level at 300 K is 2.3 eV from the valence band top, with a trapping cross-section of 2.6 eV. -18 cm 2 .

[0076] Step C. Describe the impact of irradiation-induced defects on device performance using Sentaurus TCAD, as follows:

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

[0078] c2) Adding material parameters: In Sentaurus TCAD, the oxide layer has no carrier mobility, so even if a defect model is added, the defects will not capture / emit carriers. Therefore, electron / hole mobility needs to be added to the HfO2 material parameter file, with electron / hole mobility of 20 cm⁻¹. -2 / V·s、1e -5 cm -2 / V·s, allowing defects in HfO2 to capture and emit charge carriers;

[0079] c3) As can be seen from step A, the generated defects 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) Adding defect parameters: From step B, it can be concluded that when the system temperature is 300℃, the trapping energy level of the oxygen vacancy is at the top of the valence band at 2.3 eV, that is, near the center of the band gap, with a trapping cross-section of 2.6 eV. -18 cm 2 To achieve the same effect as in experiments, this embodiment preferably uses a Gaussian distribution to describe the oxygen vacancy trap energy level distribution. Of course, the trap energy level distribution is not limited to a Gaussian distribution; it can also use an exponential distribution, a single energy level, etc.

[0081] c5) Obtaining the irradiated curve: By simulating the transfer characteristic curve after irradiation using TCAD, the influence of oxygen vacancy defects generated after irradiation on the electrical performance of the device can be obtained. The results are as follows: Figure 6 As shown.

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

[0083] This invention employs molecular dynamics to simulate the stable defect types and quantities generated by displacement damage in oxide thin films. For different types of irradiation-induced defects, first-principles calculations are used to determine the defect energy levels and trapping cross sections. The quantity, energy levels, and trapping cross sections of various irradiation-induced defects are used as inputs to conduct device simulations, thereby obtaining the impact of irradiation displacement damage on the electrical characteristics of the device. This solves the problem that existing technologies do not consider the influence of gate oxide defect energy levels and trapping cross sections and their impact on device performance.

[0084] The parts of this invention not described in detail are common knowledge to those skilled in the art.

[0085] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Obviously, those skilled in the art, after understanding the content and principle of the present invention, may make various modifications and changes in form and detail without departing from the principle and structure of the present invention. However, these modifications and changes based on the concept of the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A method for simulating the damage and effects of irradiation displacement on the gate oxide layer of a MOSFET, characterized in that, Includes the following steps: (1) The types and numbers of traps generated in the gate oxide layer after irradiation were obtained through molecular dynamics simulation: (1.1) Construct a gate oxide supercell and use a potential function to characterize the interaction forces between atoms in the supercell; (1.2) Using the isothermal and isobaric NPT ensemble as the initial system, the system temperature is equilibrated to room temperature T′, at a distance from the unit cell boundary. The range is set as a constant temperature layer, and the temperature of the constant temperature layer is maintained at T′ by connecting a Nose-Hoova thermostat. The internal region is set as the simulation region, and the simulation process uses a micro-canonical NVE ensemble. (1.3) The particle is incident along the normal direction of the cell surface and from the center directly above the cell. (1.4) Randomly select an atom from the system as the primary impact atom. When the kinetic energy acquired by the primary impact atom is greater than its displacement threshold energy, a defect is generated in place. (1.5) Obtain the type and number of traps generated in the gate oxide layer after irradiation; (2) Input the trap type into the first-principles software to obtain the trap's energy level position and trapping cross section: (2.1) Construct a gate oxide supercell with no more than 300 atoms and optimized structure using first-principles software, and introduce any one or more trap types obtained in step (1) to obtain a supercell containing defects; (2.2) The energy level positions of the defects are obtained by processing the supercell containing the defects using first-principles software; (2.3) Calculate the capture section σ: Where C represents the defect capture coefficient, The carrier velocity; (3) The type, number, energy level position and trapping cross section of the traps are used as input parameters. The performance of the semiconductor device is simulated by semiconductor device simulation software to obtain the effect of the trap 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), the gate oxide supercell is constructed. The number of atoms contained in the supercell is determined by the following formula: Among them, E r The energy of the primary colliding atom, N is the number of atoms, and k is the energy of the primary colliding atom. B ΔT is the Boltzmann constant, ΔT represents the temperature change, atoms is the number of atoms, and eV is the electron volt, which is a unit of energy.

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

4. The simulation method according to claim 1, characterized in that: Step (2.2) involves processing the defect-containing supercell using first-principles software to obtain the energy level positions of the defects; the specific implementation steps are as follows: (2.2.1) For a supercell containing oxygen vacancy defects, the plane wave cutoff energy is set to 1.2 times the maximum cutoff energy of all its elements. (2.2.2) Set the K point and perform structural optimization on the supercell containing defects to obtain the structural file; (2.2.3) The energy and charge distribution of the defect state are obtained through static self-consistency; (2.2.4) Extract the density of states map by calculating the density of states, and obtain the position of the interstitial state energy level generated in the band gap 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 mentioned in steps (2.1) and (2.2.2) refers to adjusting relevant parameters in the first-principles software to make the atoms reach their respective equilibrium positions, thereby obtaining a stable unit cell structure and achieving 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 principle 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 density of states diagram is extracted through density of states calculation 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 the accurate density of states; finally, the density of states data is calculated and processed to obtain the density of states diagram.

8. The simulation method according to claim 1, characterized in that: The trapping coefficient C and carrier velocity of the defect described in step (2.3) We obtain them respectively from the following formulas: Where V is the volume of the periodic structure containing the defects. Let π be Planck's constant, π be pi, g be the degeneracy of the defect, and w be... a Indicates the thermal occupancy rate of the excited state, The phonon-electron coupling matrix element is represented by the δ function, which represents the energy conservation constraint before and after the transition. in With E jm The total energy of the initial and final vibrational states; Where k is the Boltzmann constant, m is the effective mass, and T″ represents the absolute temperature.

9. The simulation method according to claim 1, characterized in that: The effect of trapped charges in the irradiated gate oxide layer on the electrical performance of the device, as described in step (3), is obtained according to the following steps: (3.1) Construct device models using semiconductor device simulation software; (3.2) The transfer characteristic curves without defects before irradiation were obtained by simulation using semiconductor device simulation software; (3.3) Introduce defects in the gate oxide layer; (3.4) The trap energy level distribution of the defect is simulated using a Gaussian distribution; (3.5) Simulate the transfer characteristic curves containing defects after irradiation using semiconductor device simulation software; (3.6) By comparing the transfer characteristic curves before and after irradiation, the influence of defects generated in the gate oxide layer after irradiation on the electrical performance of the device can be obtained.

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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