Method for constructing microscopic reaction model of polysilicon efficient deposition process

Abstract

The present invention discloses a method for constructing a microscopic reaction model of a polysilicon efficient deposition process, wherein the steps include: a. constructing the microscopic distribution state of gas and the microscopic distribution state of atoms on the surface of silicon rods; b. constructing a simulation box, introducing gas into the simulation box, and obtaining a preliminary chemical reaction model; c. optimizing the chemical reaction model; d. fixing all atoms in the cell layer at the bottom of the Si substrate in the chemical reaction model to complete the construction of the chemical reaction model. The present invention effectively solves the problem that the Si substrate cannot maintain a stable configuration at high temperature and is prone to agglomeration by fixing the Si cell layer; constructing a Si substrate (Si supercell) by periodically repeating the Si cell, and realizing the simulation of the continuous and uninterrupted Si rod surface. The chemical reaction model construction method of the present invention is applicable to the chemical vapor deposition process of polysilicon, and is also applicable to the gas-solid two-phase modeling process of other chemical vapor deposition processes.

Description

Technical Field

[0001] The invention belongs to the field of molecular dynamics simulation calculation, and in particular relates to a method for constructing a microscopic reaction model of a polysilicon efficient deposition process. Background Art

[0002] Polysilicon is an important industrial raw material for the information industry and solar photovoltaic power generation industry. It is a strategic frontier material that the country encourages to develop. It is also an important industrial raw material that is indispensable for supercomputers, aerospace, and cutting-edge weapons. With the rapid development of my country's electronics industry and the widespread application of polysilicon in high-tech fields, the market demand for high-quality electronic-grade polysilicon has grown rapidly. Accelerating the localization of strategic basic raw materials such as high-purity electronic-grade polysilicon for integrated circuit chips is related to the national economy, society and national defense security. The efficient deposition process of polysilicon plays an important role in the production process of high-quality polysilicon. It is the basis and key to achieving large-scale production of electronic-grade polysilicon. The current mainstream technology for producing polysilicon is the trichlorosilane-hydrogen reduction method. Its core equipment, the polysilicon reduction furnace, is actually a gas chemical vapor deposition chamber. Trichlorosilane (TCS) undergoes thermal decomposition and reduction reaction in a hydrogen atmosphere to generate single-element silicon and deposit on the surface of the heated original silicon core, which promotes the continuous growth of silicon rods and finally grows into silicon rods with a diameter of about 25 cm, which is the final polysilicon product. However, at present, there are problems such as uneven distribution of flow field and thermal field in the polysilicon reduction furnace, a large number of reaction types (as many as dozens of reactions are involved), and a large number of by-products that need to be solved urgently.

[0003] The efficient deposition process of polysilicon involves a multi-component complex heat and mass transfer process, which has the characteristics of high reaction temperature, many side reactions, low single-pass conversion rate, reversible main reaction, extremely fast reaction rate, extremely short intermediate state life, and extremely small reaction interface scale. It is extremely challenging to obtain the dynamic evolution law of the gas-solid interface. In order to develop a new generation of high-efficiency deposition technology for high-quality polysilicon, it is necessary to study the reaction intermediates, elementary reactions, reaction control steps, etc. involved, that is, it is necessary to obtain a complete chemical reaction mechanism. However, the current experimental means lack in-situ detection technology, and it is difficult to directly characterize the dynamic evolution law of the product at a high temperature of 1100°C; macroscopic simulation methods cannot simulate the gas phase and gas-solid surface chemical reaction process at the molecular scale. The molecular dynamics (MD) method is a powerful computer simulation method that connects the microscopic world and the macroscopic world. It simulates the structure and behavior of molecules with molecular models, and obtains the dynamic changes of the microscopic state of each atom and molecule in the system over time by solving Newton's equations of motion, thereby obtaining various physical and chemical properties of the molecular system statistics, and can intuitively describe the process at the molecular level. For example, quantum chemical methods in MD simulation can study the chemical reactions of the system at the electronic level and have been widely used.

[0004] The reaction molecular dynamics method is a type of MD method that combines chemical reaction force field and molecular dynamics. When applied to molecular systems, it can continuously describe the breaking and formation of chemical bonds. Its calculation accuracy is close to quantum chemical methods such as density functional theory (DFT) and greatly reduces the complexity of the calculation. It has the advantages of being able to simply describe chemical reactions and can simulate and calculate larger molecular systems. Therefore, the reaction molecular dynamics method has shown great advantages in studying the chemical reaction mechanism of the efficient deposition process of polysilicon at the molecular level. In order to realize the simulation study of reaction molecular dynamics, the first and key issue is how to construct a reasonable, accurate and easy-to-operate microscopic chemical reaction model for the surface and interface behavior of the polysilicon chemical vapor deposition process. However, there is currently no report on a model construction method suitable for describing the microscopic process of polysilicon chemical vapor deposition at ultra-high temperatures. Summary of the invention

[0005] The present invention is based on the inventor's discovery and understanding of the following facts and problems: 1. Quantum chemical methods require solving the Schrödinger equation, so the calculation cost is high and the scale of the system that can be simulated and calculated is relatively small; 2. When constructing a reaction model based on quantum chemical methods, it is necessary to pre-set active sites and reaction paths, which not only increases the difficulty of model construction, but also depends on the pre-set active sites and cannot fully obtain chemical reaction information; 3. When the reaction molecular dynamics method is applied to a molecular system, it can continuously describe the breaking and generation of chemical bonds. Its calculation accuracy is close to that of quantum chemical methods such as density functional theory (DFT) and greatly reduces the complexity of calculation. It has the advantage of being able to simply describe chemical reactions and can simulate and calculate larger molecular systems. However, there is currently no model construction method suitable for describing the microscopic process of polysilicon chemical vapor deposition at ultra-high temperatures; 4. In the past, cluster models were generally used to study the hydrochlorination reaction on the surface of Si rods, but these cluster models cannot simulate continuous surfaces and cannot capture the long-range effects of crystal structures.

[0006] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0007] To this end, the embodiment of the present invention proposes a method for constructing a microscopic reaction model of a polysilicon efficient deposition process, describes the polysilicon chemical vapor deposition process at the microscopic molecular level, and constructs a chemical reaction model suitable for reaction molecular dynamics simulation calculation. 1. The scale of the system that can be simulated by the reaction model constructed by the present invention is greatly increased, and can reach the order of 10,000 atoms; 2. The present invention does not need to pre-set active sites and reaction paths, which not only reduces the difficulty of the model construction process and increases the ease of operation, but also helps to obtain chemical reaction process information that is closer to the intrinsic; 3. The present invention alleviates the unevenness of force distribution by fixing the Si unit cell layer, effectively solves the problem that the Si substrate cannot maintain a stable configuration at high temperature and is prone to agglomeration, and is suitable for simulating and studying the reaction process at ultra-high temperature; 4. The present invention constructs the Si substrate by periodically repeating the Si unit cell, realizing the simulation of the continuous and uninterrupted Si rod surface; 5. The chemical reaction model construction method of the present invention is suitable for the chemical vapor deposition process of polysilicon, and is also suitable for the gas-solid two-phase modeling process of other chemical vapor deposition processes.

[0008] The method for constructing a microscopic reaction model of a polysilicon efficient deposition process according to an embodiment of the present invention comprises the following steps:

[0009] a. Construct a single SiHCl3 and H2 molecule and optimize its molecular structure to construct a mixed gas uniformly mixed with multiple SiHCl3 and H2 molecules;

[0010] b. Using a single Si unit cell to construct a Si supercell composed of multiple Si units to complete the construction of the Si substrate;

[0011] c. Modify the size of the Si supercell in the z direction in step b to construct a simulation box that can contain the mixed gas;

[0012] d. introducing the mixed gas in step a onto the Si substrate of the simulation box in step c to obtain a preliminary chemical reaction model;

[0013] e. Setting a convergence value, the chemical reaction model in step d is calculated by energy minimization to obtain an optimized chemical reaction model;

[0014] f. Fix all atoms in the unit cell layer at the bottom of the Si substrate of the chemical reaction model in step e to complete the construction of the chemical reaction model.

[0015] The advantages and technical effects brought by the embodiments of the present invention are as follows: 1. Large model scale: the number of atoms contained in the model can reach the order of 10,000, which is much larger than the scale of the model constructed based on quantum chemical methods (about 100 atoms); 2. Easy model operation: the present invention does not require pre-setting of active sites and reaction paths, which not only reduces the difficulty of the model construction process and increases the ease of operation, but also helps to obtain chemical reaction process information that is closer to the intrinsic nature; 3. The model is resistant to high temperatures: under high temperature simulation, the reaction model can still maintain the stable configuration of the Si substrate, which is suitable for reaction simulation in ultra-high temperature environment; 4. High model accuracy: in order to simulate the continuous and uninterrupted Si rod surface, the Si substrate of the model is constructed by periodically repeating the Si unit cell; 5. High modeling efficiency: through By applying specific methods to perform energy minimization calculations, the time cost consumed in the modeling process can be effectively reduced; 6. Flexible model parameters: The setting of model parameters in the modeling process is very flexible, and the model parameters, such as gas density, gas quantity, etc., can be changed according to the characteristics of the simulation system, which is conducive to examining the impact of various actual working conditions on the simulation results; 7. Wide range of applications: The model construction method is suitable for describing chemical vapor deposition processes, including but not limited to polysilicon, and only needs to replace the substrate material according to the corresponding simulation system; 8. Wide range of model uses: This model can not only be used to study the elementary reactions occurring in the chemical vapor deposition process of polysilicon, but can also be used to study the surface and interface dynamic behavior of molecules during the deposition process, such as the diffusion process, adsorption process and desorption process of gas molecules on the surface of the Si substrate.

[0016] According to the method for constructing a microscopic reaction model of a polysilicon efficient deposition process according to an embodiment of the present invention, in the step a, the optimized SiHCl3 and H2 molecules are mixed according to a set ratio, and the optimized SiHCl3 and H2 molecules are mixed according to a set density.

[0017] According to the method for constructing a microscopic reaction model of a polysilicon efficient deposition process according to an embodiment of the present invention, wherein in the step a, the set ratio of the mixed SiHCl3 and H2 molecules is less than 1:3; the set density of the mixed gas should be less than 0.01 g / cm 3 .

[0018] According to the method for constructing a microscopic reaction model of a polysilicon efficient deposition process according to an embodiment of the present invention, wherein in the step b, the size of the Si substrate in the x and y directions is larger than the size of the mixed gas in the corresponding x and y directions.

[0019] According to the method for constructing a microscopic reaction model of a polysilicon efficient deposition process according to an embodiment of the present invention, wherein, in the step b, the number of layers of Si crystal cells included in the Si substrate in the z direction is at least 2.

[0020] According to the method for constructing a microscopic reaction model of a polysilicon efficient deposition process according to an embodiment of the present invention, in the step e, the atoms in the chemical reaction model are distributed according to the principle of minimizing the total energy of the system through energy minimization calculation.

[0021] According to the method for constructing a microscopic reaction model of a polysilicon efficient deposition process according to an embodiment of the present invention, in the step e, the convergence value is ≤10 -10 .

[0022] According to the method for constructing a microscopic reaction model of a polysilicon efficient deposition process according to an embodiment of the present invention, in the step f, the unit cell layer at the bottom is the unit cell layer away from the gas end.

[0023] According to the method for constructing a microscopic reaction model of a polysilicon efficient deposition process according to an embodiment of the present invention, in the step f, the fixing method is to set the speed and force of all atoms in the unit cell layer at the bottom of the Si substrate to zero. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a flow chart of the construction process of the chemical reaction model of an embodiment of the present invention;

[0025] Figure 2 It is a schematic diagram of the process of constructing a 3D chemical reaction model according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0027] like Figure 1 As shown, a method for constructing a microscopic reaction model of a polysilicon efficient deposition process according to an embodiment of the present invention includes the following steps:

[0028] a. Construct a single SiHCl3 and H2 molecule and optimize its molecular structure to construct a mixed gas uniformly mixed with multiple SiHCl3 and H2 molecules;

[0029] b. Using a single Si unit cell to construct a Si supercell composed of multiple Si units to complete the construction of the Si substrate;

[0030] c. Modify the size of the Si supercell in the z direction in step b to construct a simulation box that can contain the mixed gas;

[0031] d. introducing the mixed gas in step a onto the Si substrate of the simulation box in step c to obtain a preliminary chemical reaction model;

[0032] e. Setting a convergence value, the chemical reaction model in step d is calculated by energy minimization to obtain an optimized chemical reaction model;

[0033] f. Fix all atoms in the unit cell layer at the bottom of the Si substrate of the chemical reaction model in step e to complete the construction of the chemical reaction model.

[0034] The advantages and technical effects brought by the embodiments of the present invention are as follows: 1. Large model scale: the number of atoms contained in the model can reach the order of 10,000, which is much larger than the scale of the model constructed based on quantum chemical methods (about 100 atoms); 2. Easy model operation: the present invention does not require pre-setting of active sites and reaction paths, which not only reduces the difficulty of the model construction process and increases the ease of operation, but also helps to obtain chemical reaction process information that is closer to the intrinsic nature; 3. The model is resistant to high temperatures: under high temperature simulation, the reaction model can still maintain the stable configuration of the Si substrate, which is suitable for reaction simulation in ultra-high temperature environment; 4. High model accuracy: in order to simulate the continuous and uninterrupted Si rod surface, the Si substrate of the model is constructed by periodically repeating the Si unit cell; 5. High modeling efficiency: through By applying specific methods to perform energy minimization calculations, the time cost consumed in the modeling process can be effectively reduced; 6. Flexible model parameters: The setting of model parameters in the modeling process is very flexible, and the model parameters, such as gas density, gas quantity, etc., can be changed according to the characteristics of the simulation system, which is conducive to examining the impact of various actual working conditions on the simulation system; 7. Wide range of applications: The model construction method is suitable for describing chemical vapor deposition processes, including but not limited to polycrystalline silicon, and only needs to replace the substrate material according to the corresponding simulation system; 8. The model has a wide range of uses: This model can not only be used to study the elementary reactions occurring in the chemical vapor deposition process of polycrystalline silicon, but can also be used to study the surface and interface dynamic behavior of molecules during the deposition process, such as the diffusion process, adsorption process and desorption process of gas molecules on the surface of the Si substrate.

[0035] According to the method for constructing a microscopic reaction model of the polysilicon efficient deposition process of an embodiment of the present invention, wherein, in the step a, the optimized SiHCl3 and H2 molecules are mixed according to a set ratio and a set density; in general, the set ratio and the set density are based on actual simulation requirements and simulation strategies. According to industrial test results, in order to promote the reaction, an excess of H2 should be maintained in the mixed gas, and the ratio of the mixed SiHCl3 and H2 molecules is less than 1:3. In order to save the actual physical calculation time, preferably, the ratio of the mixed SiHCl3 and H2 molecules is 1:10; the density of the mixed gas also needs to be determined according to the specific simulation system. In order to maintain the aggregation state of the gas phase, the density of the mixed gas should be less than 0.01g / cm 3; The number of SiHCl3 and H2 molecules contained in the mixed gas can be determined based on the actual computing power and the acceptable physical computing time. The number of SiHCl3 molecules includes 10 to 40 in the embodiment of the present invention, but is not limited thereto; similarly, the number of H2 molecules includes 100 to 400 in the embodiment of the present invention, but is not limited thereto.

[0036] According to the method for constructing a microscopic reaction model of a polysilicon efficient deposition process according to an embodiment of the present invention, wherein, in the step b, the size of the Si substrate in the x and y directions is larger than the size of the mixed gas in the corresponding x and y directions. In the construction method of the embodiment of the present invention, the size of the mixed gas in the x and y directions is rounded upward to obtain an integer of the size of the mixed gas. When setting the size of the Si substrate in the x and y directions, the Si substrate size number needs to be greater than or equal to the integer of the mixed gas size, and then the number of Si crystal cells of the Si substrate is obtained according to the Si substrate size number; in the construction method of the embodiment of the present invention, the number of layers of Si crystal cells in the z direction is determined based on the actual computing power and the acceptable physical computing time, and the number of layers of Si crystal cells contained in the z direction of the Si substrate is at least 2 layers. Furthermore, the number of Si crystal cell layers fixed in the z direction of the Si substrate needs to satisfy the condition: 1≤fixed number of Si crystal cell layers≤(total number of Si crystal cell layers-1).

[0037] In the construction method of the embodiment of the present invention, in order to compare and study the reactivity of different crystal planes of the Si substrate, the constructed Si substrate can also be subjected to a crystal cutting operation, including but not limited to the (100) plane, (110) plane, and (111) plane.

[0038] In the construction method of the embodiment of the present invention, considering the size of the mixed gas in the z direction, the thickness of the vacuum layer between the reserved gas and the Si substrate and between the gas and the simulation box, the size of the Si supercell in the z direction is modified accordingly to construct a simulation box that can contain the mixed gas.

[0039] In the construction method of an embodiment of the present invention, for the xy surface where the Si substrate contacts the mixed gas, the surface atomic charge can be saturated by adding H atoms to the Si atoms, so that part of the active sites on the surface of the Si substrate are passivated, so as to study the influence of a layer of H atoms adsorbed on the surface of the Si substrate on the chemical reaction occurring during the deposition process.

[0040] In the construction method of the embodiment of the present invention, the thickness of the vacuum layer reserved between the mixed gas and the Si substrate, and between the Si substrate and the simulation box includes but is not limited to Generally set to

[0041] According to the method for constructing a microscopic reaction model of a polysilicon efficient deposition process according to an embodiment of the present invention, in the step e, a convergence value is set, a molecular force field is selected, and the geometric structure of the chemical reaction model is optimized so that each atom in the chemical reaction model is distributed according to the principle of minimizing the total energy of the system. When performing energy minimization calculations, the convergence value in the in command file cannot be set too large, and the convergence value is ≤10 -10 .

[0042] According to the method for constructing a microscopic reaction model of a polysilicon efficient deposition process according to an embodiment of the present invention, in the step f, the unit cell layer at the bottom is the unit cell layer away from the gas end. In the construction method of the embodiment of the present invention, with respect to the microscopic existence state of the silicon rod bulk phase atoms, all atoms in the unit cell layer at the bottom of the Si substrate are fixed by setting the speed and force of all atoms in the unit cell layer to zero, thereby completing the construction of the chemical reaction model.

[0043] The present invention is described in detail below with reference to embodiments.

[0044] Example 1

[0045] Using MS software, first construct single SiHCl3 and H2 molecules; after the two molecules are optimized by the Universal force field, use the Modules→Amorphous Cell→Calculation operation steps to optimize the geometric structure of SiHCl3 and H2 molecules according to the gas density of 0.001g / cm 3 Mixing, where the number of SiHCl3 and H2 molecules are 10 and 100 respectively, obtains the gas phase mixed gas model Import a single Si cell into MS through the menu bar File→Import→Structures→ceramics→Si.msi operation steps 26 Si cells are periodically generated in the x and y directions, and 2 Si cells are periodically generated in the z direction to construct a Si supercell containing 26×26×2 Si cells; the length of the Si supercell in the z direction is modified to Simulation box for building chemical reaction models The mixed gas was introduced above the center of the xy plane of the Si substrate to obtain the initial structure of the chemical reaction model, in which the vacuum layer between the Si substrate and the mixed gas and the vacuum layer between the mixed gas and the simulation box in the z direction were The initial structure of the chemical reaction model was optimized based on the energy minimization principle through calculations using the Minimize module of the LAMMPS software. The chemical reaction model was fixed in one layer of unit cells in the z direction away from one end of the mixed gas by writing commands in the in file and setting the speed and force of the relevant atoms to zero, thus obtaining the final chemical reaction model. The total number of atoms contained in the model is 11066. The simulation results show that the chemical reaction model can maintain a stable Si substrate configuration when performing reaction molecular dynamics simulation calculations at 2000K and 2500K.

[0046] Example 2

[0047] Using MS software, first construct single SiHCl3 and H2 molecules; after the two molecules are optimized by the Universal force field, use the Modules→Amorphous Cell→Calculation operation steps to optimize the geometric structure of SiHCl3 and H2 molecules according to the gas density of 0.001g / cm 3 Mixing, where the number of SiHCl3 and H2 molecules are 20 and 200 respectively, obtains the gas phase mixed gas model Import a single Si cell into MS through the menu bar File→Import→Structures→ceramics→Si.msi operation steps 32 Si cells are periodically generated in the x and y directions, and 2 Si cells are periodically generated in the z direction to construct a Si supercell containing 32×32×2 Si cells; the length of the Si supercell in the z direction is modified to Simulation box for building chemical reaction models The mixed gas was introduced above the center of the xy plane of the Si substrate to obtain the initial structure of the chemical reaction model, in which the vacuum layer between the Si substrate and the mixed gas and the vacuum layer between the mixed gas and the simulation box in the z direction were The initial structure of the chemical reaction model was optimized based on the energy minimization principle by calculation of the Minimize module of the LAMMPS software; by writing commands in the in file and setting the speed and force of the relevant atoms to zero, the chemical reaction model was fixed in one layer of unit cells away from the mixed gas end in the z direction to obtain the final chemical reaction model; the total number of atoms contained in the model is 16884; the simulation results show that when performing reaction molecular dynamics simulation calculations at 2000K and 2500K, the chemical reaction model can maintain a stable Si substrate configuration.

[0048] Example 3

[0049] Using MS software, first construct single SiHCl3 and H2 molecules; after the two molecules are optimized by the Universal force field, use the Modules→Amorphous Cell→Calculation operation steps to convert SiHCl3 and H2 molecules into a gas with a density of 0.005 g / cm 3 Mixing, where the number of SiHCl3 and H2 molecules are 30 and 300 respectively, obtains the gas phase mixed gas model Import a single Si cell into MS through the menu bar File→Import→Structures→ceramics→Si.msi operation steps 22 Si cells are periodically generated in the x and y directions, and 2 Si cells are periodically generated in the z direction to construct a Si supercell containing 22×22×2 Si cells; the length of the Si supercell in the z direction is modified to Simulation box for building chemical reaction models The mixed gas was introduced above the center of the xy plane of the Si substrate to obtain the initial structure of the chemical reaction model, in which the vacuum layer between the Si substrate and the mixed gas and the vacuum layer between the mixed gas and the simulation box in the z direction were The initial structure of the chemical reaction model was optimized based on the energy minimization principle by calculation of the Minimize module of the LAMMPS software. The chemical reaction model was fixed in one layer of unit cells away from the mixed gas end in the z direction by writing commands in the in file and setting the speed and force of the relevant atoms to zero, thus obtaining the final chemical reaction model. The total number of atoms contained in the model is 8494. The simulation results show that the chemical reaction model can maintain a stable Si substrate configuration when performing reaction molecular dynamics simulation calculations at 2000K and 2500K.

[0050] Example 4

[0051] Using MS software, first construct single SiHCl3 and H2 molecules; after the two molecules are optimized by the Universal force field, use the Modules→Amorphous Cell→Calculation operation steps to convert SiHCl3 and H2 molecules into a gas with a density of 0.005 g / cm 3 Mixing, where the number of SiHCl3 and H2 molecules are 40 and 400 respectively, obtains the gas phase mixed gas model Import a single Si cell into MS through the menu bar File→Import→Structures→ceramics→Si.msi operation steps 24 Si cells are periodically generated in the x and y directions, and 2 Si cells are periodically generated in the z direction to construct a Si supercell containing 24×24×2 Si cells; the length of the Si supercell in the z direction is modified to Simulation box for building chemical reaction models The mixed gas was introduced above the center of the xy plane of the Si substrate to obtain the initial structure of the chemical reaction model, in which the vacuum layer between the Si substrate and the mixed gas and the vacuum layer between the mixed gas and the simulation box in the z direction were The initial structure of the chemical reaction model was optimized based on the energy minimization principle after calculation by the Minimize module of LAMMPS. The speed and force of the relevant atoms were set to zero by writing commands in the in file, and the chemical reaction model was fixed in one layer of unit cells away from the mixed gas end in the z direction to obtain the final chemical reaction model. The total number of atoms contained in the model is 10216. The simulation results show that when performing reaction molecular dynamics simulation calculations at 2000K and 2500K, the chemical reaction model can maintain a stable Si substrate configuration.

[0052] Comparative Example 1

[0053] The method is basically the same as that of Example 1, except that after the construction of the Si substrate is completed, the chemical bonds of the Si atoms suspended in the bottom atomic layer of the Si substrate are saturated by adding H atoms. Cl atoms are placed in the outermost layer to form a Si(100)-2×1-Cl structure.

[0054] The model constructed in Comparative Example 1 realizes the simulation study of the structure and energy changes of a single Si atom when it is adsorbed on the Si(100)-2×1-Cl surface. However, this model constructed based on the quantitative calculation method is only suitable for simulating the deposition behavior of a single Si atom on the surface of a Si substrate, and cannot be used to study the regular deposition behavior and the bonding and breaking state of chemical bonds exhibited when more Si atoms are deposited on the surface of a Si substrate at the same time.

[0055] Comparative Example 2

[0056] The method is basically the same as that in Example 1, except that Si atomic clusters are used to simulate the silicon substrate (Si base).

[0057] The reaction model constructed in Comparative Example 2, on the one hand, uses a cluster model containing very few atoms, cannot simulate the continuous Si rod surface, and cannot capture the long-range effect of the crystal structure. The present invention constructs a Si substrate by periodically repeating Si unit cells, thereby realizing the simulation of a continuous and uninterrupted Si rod surface. On the other hand, the model requires presetting of active sites and reaction paths, and then determines the main reaction channel of the reaction through calculations of transition states and other aspects. The chemical reaction information obtained by simulation calculation depends on the preset active sites and reaction paths, and it is impossible to obtain complete chemical reaction information.

[0058] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0059] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for constructing a microscopic reaction model of a polysilicon efficient deposition process, characterized in that: The following steps are involved: a. Construct a single SiHCl3 and H2 molecule and optimize its molecular structure to construct a mixed gas uniformly mixed with multiple SiHCl3 and H2 molecules; b. Using a single Si unit cell to construct a Si supercell composed of multiple Si units to complete the construction of the Si substrate; c. Modify the size of the Si supercell in the z direction in step b to construct a simulation box that can contain the mixed gas; d. introducing the mixed gas in step a onto the Si substrate of the simulation box in step c to obtain a preliminary chemical reaction model; e. Setting a convergence value, the chemical reaction model in step d is calculated by energy minimization to obtain an optimized chemical reaction model; f. For the Si substrate of the chemical reaction model in step e, the speed and force of all atoms in the unit cell layer at the bottom are set to zero for fixation, thereby completing the construction of the chemical reaction model.

2. The method for constructing a microscopic reaction model of a polysilicon efficient deposition process according to claim 1, characterized in that: In the step a, the optimized SiHCl3 and H2 molecules are mixed according to a set ratio, and / or the optimized SiHCl3 and H2 molecules are mixed according to a set density.

3. The method for constructing a microscopic reaction model of a polysilicon efficient deposition process according to claim 2, characterized in that: In step a, the set ratio of the mixed SiHCl3 and H2 molecules is less than 1:3; the set density of the mixed gas is less than 0.01 g / cm 3 .

4. The method for constructing a microscopic reaction model of a polysilicon efficient deposition process according to claim 1, characterized in that: In the step b, the dimensions of the Si substrate in the x and y directions are larger than the dimensions of the mixed gas in the corresponding x and y directions.

5. The method for constructing a microscopic reaction model of a polysilicon efficient deposition process according to claim 1, characterized in that: In the step b, the number of Si unit cell layers included in the Si substrate in the z direction is ≥2.

6. The method for constructing a microscopic reaction model of a polysilicon efficient deposition process according to claim 1, characterized in that: The step e comprises: Through energy minimization calculations, the atoms in the chemical reaction model are distributed according to the principle of minimizing the total energy of the system.

7. The method for constructing a microscopic reaction model of a polysilicon efficient deposition process according to claim 1, characterized in that: In the step e, the convergence value is ≤10 -10 .

8. The method for constructing a microscopic reaction model of a polysilicon efficient deposition process according to claim 1, characterized in that: In the step f, the unit cell layer at the bottom is the unit cell layer at the end away from the gas.

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