Screening method, device and equipment for etching gas

Abstract

The invention discloses a method, a device and equipment for screening etching gas, relates to the technical field of microelectronic manufacturing and etching, and aims to solve the problems of low efficiency and high cost when the etching gas is screened in the prior art. The method comprises the following steps: constructing a plurality of initial fluorine saturation cluster models; the method comprises the following steps: firstly, carrying out cluster model pre-screening on a plurality of initial fluorine saturation cluster models to obtain a plurality of target fluorine saturation cluster models and target reaction sites and target etching gases of the plurality of target fluorine saturation cluster models; then carrying out mechanical verification on the plurality of target fluorine-saturated cluster models to obtain the reaction strength degrees of the target etching gas and the silicon or germanium-silicon cluster in the plurality of target fluorine-saturated cluster models; and finally, based on the reaction strength of the target etching gas and the silicon or germanium-silicon cluster in the plurality of target fluorine saturation cluster models, determining the etching gas for the silicon and germanium-silicon laminated structure. The cost is reduced while the screening efficiency of the etching gas is improved.

Description

Technical Field

[0001] This invention relates to the field of etching technology in microelectronics manufacturing, and in particular to a method, apparatus and equipment for screening etching gases. Background Technology

[0002] In existing technologies, traditional plasma etching methods easily cause silicon layer loss when addressing the lateral etching problem of Si / SiGe stacked structures in GAA devices. While existing non-plasma etching methods rely on fluorine-containing etching gases with high SiGe / Si etching selectivity, the variety of etching gases currently available is limited, posing significant safety risks. There is an urgent need to introduce new etching gases. For potential etching gases, experimental methods are typically used to screen them. However, this experimental testing method is not only inefficient but also prohibitively expensive, hindering the verification of new etching gases and impeding the rapid development of GAA devices.

[0003] Therefore, there is an urgent need for a more advanced etching gas screening method to solve the problems of low efficiency and high cost in the existing technology for screening etching gases. Summary of the Invention

[0004] The purpose of this invention is to provide a method, apparatus, and equipment for screening etching gases. From the perspectives of static electronic structure, reaction kinetics, and reaction thermodynamics, the invention systematically analyzes the mechanism and ease of reaction of various etching gas molecules with Si / SiGe stacked structures in different chemical environments. This improves the efficiency of etching gas screening while reducing costs, and solves the problems of low efficiency and high cost in the prior art when screening etching gases.

[0005] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for screening etching gases, which may include: Multiple initial fluorine-saturated cluster models are constructed; the multiple initial fluorine-saturated cluster models are saturated cluster models that reflect the local structural features of the surface of silicon and germanium-silicon stacked materials in contact with fluorine-containing etching gas molecules; Cluster model pre-screening is performed on multiple initial fluorine-saturated cluster models to obtain multiple target fluorine-saturated cluster models and target reaction sites and target etching gases of the multiple target fluorine-saturated cluster models; the cluster model pre-screening includes at least the localization of potential active sites of the models, cluster model screening, analysis of the orbital interaction between the cluster structure and the etching gas molecules, and analysis of the steric hindrance effect; Based on the target reaction sites and target etching gases of multiple target fluorine-saturated cluster models, mechanical verification is performed on the multiple target fluorine-saturated cluster models to obtain the degree of reaction strength between the target etching gas and silicon or germanium-silicon clusters in the multiple target fluorine-saturated cluster models; the mechanical verification includes reaction thermodynamic verification and reaction kinetic verification. Based on the varying degrees of reaction strength between the target etching gas and silicon or germanium-silicon clusters in multiple target fluorine-saturated cluster models, the etching gas used for silicon and germanium-silicon stacked structures is determined.

[0006] Preferably, constructing multiple initial fluorine-saturated cluster models may include: Based on the orientation of the exposed surfaces of silicon and germanium-silicon layers during the etching process, multiple original fluorine-saturated cluster models were constructed. These models included multiple silicon cluster models saturated with fluorine atoms and having different numbers of silicon atoms, as well as multiple germanium-silicon cluster models saturated with fluorine atoms and having different total numbers of silicon and germanium atoms. Calculate the bond dissociation energy of various chemical bonds in multiple original fluorine-saturated cluster models, determine the minimum number of atoms at which bond dissociation does not change significantly with the increase of the number of atoms in the two clusters, and take the minimum number of atoms as the total number of silicon atoms in the silicon cluster model and the total number of germanium-silicon atoms in the germanium-silicon cluster model. A silicon cluster model saturated with fluorine atoms is constructed based on the orientation of the exposed surface of the silicon layer and the total number of silicon atoms, and a germanium-silicon cluster model saturated with fluorine atoms is constructed based on the orientation of the exposed surface of the germanium-silicon layer and the total number of germanium-silicon atoms, thereby obtaining multiple initial fluorine-saturated cluster models.

[0007] Preferably, the step of performing cluster model pre-screening on multiple initial fluorine-saturated cluster models to obtain multiple target fluorine-saturated cluster models and the target reaction sites and target etching gases of the multiple target fluorine-saturated cluster models may include: The electron population of multiple initial fluorine-saturated cluster models is analyzed to locate potential active sites of multiple initial fluorine-saturated cluster models. Models with atomic surface positive charge values ​​greater than preset values ​​are selected as target fluorine-saturated cluster models to obtain multiple target fluorine-saturated cluster models and potential active sites of multiple target fluorine-saturated cluster models. Orbital interaction analysis was performed on the cluster structure and etching gas molecules of multiple target fluorine-saturated cluster models to determine the orbitals that participate in the reaction at the potential active sites, and the etching gas that is more likely to react with germanium and silicon but less likely to react with silicon was selected as the target etching gas. Spatial steric hindrance effect analysis was performed on multiple target fluorine-saturated cluster models after orbital interaction analysis to eliminate potential active sites that could not react due to steric hindrance, thereby obtaining the target reaction sites.

[0008] Preferably, the step of performing a localization analysis on the electronic layout of the multiple initial fluorine-saturated cluster models to locate the potential active sites of the multiple initial fluorine-saturated cluster models, and selecting models among the multiple initial fluorine-saturated cluster models whose atomic surface positive charge values ​​are greater than a preset value as target fluorine-saturated cluster models, thereby obtaining multiple target fluorine-saturated cluster models and their potential active sites, may include: Geometric structure optimization was performed on multiple initial fluorine-saturated cluster models to obtain multiple intermediate fluorine-saturated cluster models; the structure of each model in the multiple intermediate fluorine-saturated cluster models was in a stable state and the charge energy was at its minimum value. Natural population analysis was performed on multiple intermediate fluorine-saturated cluster models to obtain the net charge data for each silicon and germanium atom in the multiple intermediate fluorine-saturated cluster models; The model with a positive charge value on the atomic surface of the intermediate fluorine-saturated cluster model that is greater than a preset value is used as the target fluorine-saturated cluster model to obtain multiple target fluorine-saturated cluster models. The silicon and germanium atoms with the highest positive charge density in the multiple target fluorine-saturated cluster models were selected as potential active sites.

[0009] Preferably, the step of performing orbital interaction analysis on the cluster structures of multiple target fluorine-saturated cluster models and etching gas molecules to determine the orbitals participating in the reaction at the potential active sites, and selecting etching gases that are more likely to react with germanium and silicon but less likely to react with silicon as target etching gases, may include: Natural bond orbital analysis was performed on multiple target fluorine-saturated cluster models to obtain the amount of lone pair electrons of fluorine atoms transferred to empty orbitals in silicon and germanium. The natural bond orbital analysis included analyzing the types of chemical bonds in the clusters, the interaction between electrons and empty orbitals, the bond order of each chemical bond, and the charge transfer path. Frontier molecular orbital analysis was performed on multiple target fluorine-saturated cluster models to obtain the highest occupied molecular orbital and the lowest unoccupied molecular orbital for the multiple target fluorine-saturated cluster models and etching gas molecules. Orbital overlap population analysis was performed on multiple target fluorine-saturated cluster models to determine the overlap integral of the highest occupied molecular orbital and the lowest unoccupied molecular orbital of the etching gas molecule when the etching gas molecule attacks the potential reaction site in the multiple target fluorine-saturated cluster models. Based on the overlap integral of the highest occupied molecular orbital and the lowest unoccupied molecular orbital of the etching gas molecules in multiple target fluorine-saturated cluster models, the etching gas that is more likely to react with germanium and silicon but less likely to react with silicon is determined, and the etching gas that is more likely to react with germanium and silicon but less likely to react with silicon is selected as the target etching gas.

[0010] Preferably, the step of performing steric hindrance effect analysis on multiple target fluorine-saturated cluster models after orbital interaction analysis, eliminating potential active sites that cannot react due to steric hindrance, and obtaining the target reaction sites, may include: Spatial steric hindrance parameters are calculated for multiple target fluorine-saturated cluster models; the spatial steric hindrance parameter calculation includes at least: calculating the minimum and maximum steric hindrance radii of the spatially hindering groups around the potential active sites; the minimum steric hindrance radius indicates that the more spacious the space around the site, the easier it is for etching gas molecules to approach; the maximum steric hindrance radius indicates that the more crowded the space around the site, the more difficult it is for etching gas molecules to approach. The van der Waals surfaces of multiple target fluorine-saturated cluster models are plotted using visualization software, and different colors are used to represent charge distribution. It is determined whether potential active sites are wrapped by the van der Waals surfaces of surrounding fluorine atoms. If the potential active sites are completely blocked, the potential active sites are taken as the target reaction sites.

[0011] Preferably, based on the target reaction sites and target etching gases of the multiple target fluorine-saturated cluster models, mechanical verification is performed on the multiple target fluorine-saturated cluster models to obtain the degree of reaction strength between the target etching gas and silicon or germanium-silicon clusters in the multiple target fluorine-saturated cluster models, which may include: Based on the target reaction sites and target etching gas of multiple target fluorine-saturated cluster models, reaction thermodynamic analysis is performed on multiple target fluorine-saturated cluster models to obtain the reaction enthalpy change and Gibbs free energy change of the target etching gas with multiple target fluorine-saturated cluster model groups; Based on the target reaction sites and target etching gases of multiple target fluorine-saturated cluster models, reaction kinetics analysis is performed on multiple target fluorine-saturated cluster models. The transition state search method is used to search for the transition state structure in the kinetic reaction process to obtain the reaction energy barrier between the target etching gas and multiple target fluorine-saturated cluster model groups. Based on the enthalpy change, Gibbs free energy change, and reaction energy barrier of the target etching gas and multiple target fluorine-saturated cluster model groups, the reaction strength between the target etching gas and silicon or germanium-silicon clusters in the multiple target fluorine-saturated cluster models is determined.

[0012] Preferably, determining the etching gas for the silicon and germanium-silicon stacked structure based on the relative strengths of the reaction between the target etching gas and silicon or germanium-silicon clusters in multiple target fluorine-saturated cluster models may include: By comparing the ease with which different etching gases react with germanium-silicon clusters, the etching gas that is more likely to react chemically with various germanium-silicon cluster structures was selected as the alternative etching gas. By comparing the differences in physical quantities when the candidate etching gases react with silicon clusters and germanium-silicon clusters, the etching gas with a difference in physical quantities greater than the target value for silicon clusters and germanium-silicon clusters is selected as the etching gas for the silicon and germanium-silicon stacked structure; the physical quantities include at least the energy barrier, enthalpy change and Gibbs free energy change.

[0013] Compared with existing technologies, the etching gas screening method provided by this invention constructs multiple initial fluorine-saturated cluster models. These initial fluorine-saturated cluster models are saturated cluster models that reflect the local structural features of the surface of silicon and germanium-silicon stacked materials in contact with fluorine-containing etching gas molecules. Then, cluster model pre-screening is performed on these initial fluorine-saturated cluster models to obtain multiple target fluorine-saturated cluster models, target reaction sites, and target etching gases for these target fluorine-saturated cluster models. The cluster model pre-screening includes at least the localization of potential active sites, cluster model screening, analysis of the orbital interactions between cluster structures and etching gas molecules, and analysis of steric hindrance effects. Finally, based on the target reaction sites and target etching gases of the multiple target fluorine-saturated cluster models, mechanical verification is performed on these multiple target fluorine-saturated cluster models to obtain the reaction sites between the target etching gas and silicon or germanium-silicon clusters in the multiple target fluorine-saturated cluster models. The method involves several steps: First, the intensity of the reaction between the target etching gas and silicon or germanium-silicon clusters is assessed. Second, mechanical verification includes both thermodynamic and kinetic verification. Finally, based on the varying reaction strengths of the target fluorine-saturated clusters in multiple target models, the etching gas used for silicon and germanium-silicon stacked structures is determined. Based on this, the present invention constructs a four-step effective etching gas screening method: fluorine-saturated cluster model → cluster model screening (localization of potential active sites, cluster model screening, orbital interaction analysis of cluster structure and etching gas molecules, and steric hindrance effect analysis) → cluster model mechanical verification (thermodynamic and kinetic verification) → comprehensive analysis. This method efficiently and cost-effectively screens etching gases with high SiGe / Si etching selectivity for non-plasma etching of Si / SiGe stacked structures in GAA devices, avoiding the high cost and low efficiency of experimental verification methods.

[0014] Secondly, the present invention provides a screening device for etching gases, which may include: A cluster model construction module is used to construct multiple initial fluorine-saturated cluster models; the multiple initial fluorine-saturated cluster models are saturated cluster models that reflect the local structural features of the surface of silicon and germanium-silicon stacked materials in contact with fluorine-containing etching gas molecules; The cluster model pre-screening module is used to pre-screen multiple initial fluorine-saturated cluster models to obtain multiple target fluorine-saturated cluster models and target reaction sites and target etching gases of the multiple target fluorine-saturated cluster models; the cluster model pre-screening includes at least the localization of potential active sites of models, cluster model screening, analysis of orbital interactions between cluster structure and etching gas molecules, and analysis of steric hindrance effects; The reaction strength determination module is used to perform mechanical verification on multiple target fluorine-saturated cluster models based on the target reaction sites and target etching gases of the multiple target fluorine-saturated cluster models, and to obtain the degree of reaction strength between the target etching gas and silicon or germanium-silicon clusters in the multiple target fluorine-saturated cluster models; the mechanical verification includes reaction thermodynamic verification and reaction kinetic verification. An etching gas determination module is used to determine the etching gas for silicon and germanium-silicon stacked structures based on the reaction strength between the target etching gas and silicon or germanium-silicon clusters in multiple target fluorine-saturated cluster models.

[0015] Compared with the prior art, the etching gas screening device provided by the present invention has the same beneficial effects as the etching gas screening method provided in the first aspect, which will not be elaborated here.

[0016] Thirdly, the present invention provides an electronic device, comprising: processor; Memory used to store the processor's executable instructions; The processor is configured to execute the etching gas screening method described in the first aspect by running instructions in the memory.

[0017] Compared with the prior art, the electronic device provided by the present invention has the same beneficial effects as the etching gas screening method provided in the first aspect, which will not be elaborated here. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic diagram of the main process of a method for screening etching gases provided by the present invention; Figure 2 A schematic diagram of the cluster model convergence test in the etching gas screening method provided by the present invention; Figure 3 A schematic diagram of the atomic structure of silicon or germanium, silicon clusters with a total number of silicon atoms of 5, and several germanium-silicon cluster models with different configurations in the etching gas screening method provided by the present invention. Figure 4 A schematic diagram of the natural population analysis results of the germanium-silicon cluster model in the etching gas screening method provided by the present invention; Figure 5 Molecular orbital (LUMO) analysis diagram of Si-Ge clusters in an etching gas screening method provided by the present invention; Figure 6 A schematic diagram of the IRC curve of the reaction between fluorine gas, a common etching gas, and Si-Ge clusters in the etching gas screening method provided by this invention; Figure 7 A schematic diagram of the bond critical point analysis of germanium-silicon clusters in an etching gas screening method provided by the present invention; Figure 8 A schematic diagram of the structure of an etching gas screening device provided by the present invention; Figure 9 This is a schematic diagram of the structure of an electronic device provided by the present invention. Detailed Implementation

[0019] To facilitate a clear description of the technical solutions in the embodiments of the present invention, the terms "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. For example, the first threshold and the second threshold are merely used to distinguish different thresholds and do not limit their order. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and the terms "first" and "second" are not necessarily different.

[0020] It should be noted that in this invention, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0021] In this invention, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding related objects have an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, a combination of a and b, a combination of a and c, a combination of b and c, or a, b, and c, where a, b, and c can be single or multiple.

[0022] Currently, for GAA devices The problem of lateral etching of stacked structures is addressed by existing non-plasma etching methods, which rely heavily on high-performance etching. The limited variety of fluorinated etching gases with high etching selectivity poses significant safety risks. Introducing potential etching gases requires extensive experimentation to repeatedly verify their effectiveness and safety in order to screen out suitable new etching gases. However, this method of verification using physical experiments is costly and inefficient. Therefore, a more advanced screening method is urgently needed to predict etching gases with high SiGe / Si etching selectivity to reduce costs and address the issues of low efficiency and high cost in existing etching gas screening technologies.

[0023] In view of this, the present invention provides a method, apparatus, and device for screening etching gases, which systematically analyzes various etching gas molecules and different chemical environments from the perspectives of static electronic structure, reaction kinetics, and reaction thermodynamics. The mechanism and ease of reaction of the multilayer structure are important considerations for its application in GAA devices. High-performance non-plasma etching of stacked structures The etching selectivity provides a scientific and effective theoretical guide for screening etching gases, which improves screening efficiency and reduces costs compared with traditional experimental methods; it solves the problems of low efficiency and high cost in the screening of etching gases in existing technologies.

[0024] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings: Please see Figure 1 , Figure 1 This is a schematic diagram of the main process of an etching gas screening method provided by the present invention. The main body executing the method is a server or terminal equipped with the etching gas screening method provided by the present invention, such as an online gas screening service platform or a mobile handheld terminal.

[0025] exist Figure 1In this context, the methods for screening etching gases may include: Step 110: Construct multiple initial fluorine-saturated cluster models; the multiple initial fluorine-saturated cluster models are saturated cluster models that reflect the local structural features of the surface of silicon and germanium-silicon stacked materials in contact with fluorine-containing etching gas molecules.

[0026] In step 110, various fluorine-saturated cluster models of silicon and germanium-silicon (hereinafter referred to as silicon and germanium-silicon cluster models) are established to reflect the local structural characteristics of the surface of the Si / SiGe stacked material in contact with fluorine-containing etching gas (hereinafter referred to as etching gas) molecules. A silicon cluster model saturated with fluorine atoms can be constructed based on the orientation of the exposed surfaces of the silicon and germanium-silicon layers and the number of atoms determined by cluster model convergence tests. Alternatively, germanium-silicon cluster models with different chemical environments (different germanium-to-silicon atom ratios or different atomic spatial symmetries for the same germanium-to-silicon atom ratio) can be constructed. Then, cluster model convergence tests can be performed. For example, based on the orientation of the exposed surfaces of the silicon and germanium-silicon layers in the actual etching process, silicon cluster models with different numbers of silicon atoms saturated with fluorine atoms and germanium-silicon cluster models with different total numbers of silicon and germanium atoms can be constructed. The ratio of germanium to silicon atoms in the germanium-silicon cluster models can be randomly selected and kept consistent. This yields multiple initial fluorine-saturated cluster models required by the present invention.

[0027] Step 120: Perform cluster model pre-screening on multiple initial fluorine-saturated cluster models to obtain multiple target fluorine-saturated cluster models and target reaction sites and target etching gases of the multiple target fluorine-saturated cluster models; the cluster model pre-screening includes at least the localization of potential active sites of the models, cluster model screening, analysis of the orbital interactions between cluster structures and etching gas molecules, and analysis of steric hindrance effects.

[0028] In step 120, when locating potential active sites in the model, the initial fluorine-saturated cluster model needs to be geometrically optimized to ensure that each structure is in a stable state and the energy reaches a minimum. Then, charge population analysis is performed to calculate the net charge of each silicon and germanium atom in each cluster model. The silicon and germanium atoms with the highest positive charge density are selected as the initially located potential active sites, excluding the possibility of reaction sites surrounding atoms with extremely low positive charge density. Further, orbital interaction analysis is performed on each cluster structure and etching gas molecules, and steric hindrance effect analysis is used to exclude potential active sites that cannot react due to steric hindrance. Finally, the orbitals participating in the reaction at the potential reaction sites are predicted, and from the perspective of electronic structure, it is predicted that they are more likely to react with germanium and silicon than with silicon. Etching gas with high etching selectivity.

[0029] Step 130: Based on the target reaction sites and target etching gases of the multiple target fluorine-saturated cluster models, perform mechanical verification on the multiple target fluorine-saturated cluster models to obtain the degree of reaction strength between the target etching gas and silicon or germanium-silicon clusters in the multiple target fluorine-saturated cluster models; the mechanical verification includes reaction thermodynamic verification and reaction kinetic verification.

[0030] Step 140: Based on the strength of the reaction between the target etching gas and silicon or germanium-silicon clusters in multiple target fluorine-saturated cluster models, determine the etching gas for silicon and germanium-silicon stacked structures.

[0031] In steps 130 to 140, reaction thermodynamics and kinetics analyses are performed based on the selected target reaction sites and target etching gas to verify the actual feasibility of the reaction. The ease or strength of the reaction between the etching gas and silicon / germanium-silicon clusters is quantified by calculating physical quantities such as the reaction enthalpy change and reaction barrier. For example, the reaction enthalpy change between the etching gas and the clusters can be calculated. ) and Gibbs free energy change ( ),like This indicates that the reaction proceeds thermodynamically spontaneously. The more negative the reaction, the stronger the thermodynamic driving force (the higher the reactivity); if Even if the previous electronic and steric hindrance conditions are met, the reaction is unlikely to occur spontaneously. Finally, a comprehensive analysis is conducted to compare the ease with which different etching gases react with germanium-silicon clusters. If, based on thermodynamic and kinetic criteria, the reaction is more likely to occur for multiple germanium-silicon cluster structures, the etching gas that meets the requirements is selected as a candidate. Then, the energy barriers, enthalpy changes, and Gibbs free energy changes of the etching gases in the candidate reactions with silicon and germanium-silicon clusters are compared. For silicon and germanium-silicon clusters, the etching gas with the largest difference in the compared physical quantities is selected as the fluorine-containing etching gas with a high SiGe / Si etching selectivity screened by the etching gas screening method provided in this invention.

[0032] Based on this, the present invention provides a method for screening etching gases. This method employs a four-step analysis approach: constructing a fluorine-saturated cluster model → cluster model screening → cluster model mechanical verification → comprehensive analysis. This approach performs a hierarchical screening of potential etching gases, providing scientific and effective theoretical guidance for the screening of potential etching gases. It achieves efficient and low-cost screening of high-fluorine-saturated etching gases. The etching gas with high etching selectivity is used in GAA devices. The multilayer structure enables non-plasma etching, effectively avoiding the loss of silicon layers; it also solves the problems of low efficiency and high cost in the screening of etching gases in existing technologies.

[0033] It should be noted that the etching gas screening method provided by this invention is preferably based on first-principles calculations to screen potential etching gases. Of course, molecular dynamics (MD) or Monte Carlo (MC) methods can also be used. First-principles calculation, also known as ab initio, is a calculation method based on fundamental principles of quantum mechanics (such as the Schrödinger equation). It only requires input of basic physical constants (such as electron mass, charge, etc.) and does not rely on experimental fitting parameters to predict the ground-state properties of materials, such as electronic structure, energy, band structure, and density of states. This method is highly accurate and is typically applicable to small systems with fewer than a few hundred atoms and static (or zero-temperature) structure optimization. Therefore, this invention preferably uses first-principles calculations to screen potential etching gases.

[0034] As an optional embodiment, in step 110, multiple initial fluorine-saturated cluster models are constructed, which can be constructed according to the technical solutions corresponding to S1 to S3.

[0035] S1: Based on the orientation of the exposed surfaces of silicon and germanium-silicon layers in the etching process, multiple original fluorine-saturated cluster models are constructed. These multiple original fluorine-saturated cluster models include multiple silicon cluster models saturated with fluorine atoms and having different numbers of silicon atoms, as well as multiple germanium-silicon cluster models saturated with fluorine atoms and having different total numbers of silicon and germanium atoms.

[0036] S2: Calculate the bond dissociation energy of various chemical bonds in multiple original fluorine-saturated cluster models, determine the minimum number of atoms at which bond dissociation does not change significantly with the increase of the number of atoms in the two clusters, and take the minimum number of atoms as the total number of silicon atoms in the silicon cluster model and the total number of germanium-silicon atoms in the germanium-silicon cluster model.

[0037] To study the chemical reaction between the germanium-silicon surface and etching gas molecules, the first step is to model both the germanium-silicon surface and the etching gas molecules. The etching gas molecules can be directly modeled based on their actual molecular structure. For the silicon and germanium-silicon surfaces, a cluster model can be used to model the reaction sites (reaction centers) between the surface and the etching gas. Then, the cluster model convergence is tested according to S1, yielding the following results: Figure 2 The test structure shown is as follows. Figure 2 This diagram illustrates the cluster model convergence test in the etching gas screening method provided by this invention. Figure 2 In this context, N represents the number of atoms, from... Figure 2 It can be found that the bond dissociation energy of Si-Ge bonds in germanium-silicon clusters is less than that of Si-Si bonds in silicon clusters.

[0038] Specifically, in S1 and S2, firstly, based on the orientation of the exposed surfaces of silicon and germanium-silicon layers in the actual etching process, silicon cluster models with different numbers of silicon atoms saturated with fluorine atoms and germanium-silicon cluster models with different total numbers of silicon and germanium atoms are constructed. The ratio of germanium to silicon atoms in the germanium-silicon cluster model can be randomly selected and kept consistent. Then, the bond dissociation energies of various types of chemical bonds in each cluster model are calculated, and curves showing how the bond dissociation energies of various types of chemical bonds change with the number of silicon atoms in the silicon cluster and the total number of silicon and germanium atoms in the germanium-silicon cluster increase. Finally, the smallest number of atoms at which bond dissociation begins not to change significantly with the increase of the number of atoms in either cluster is taken as the number of silicon atoms in the silicon cluster model and the total number of germanium and silicon atoms in the germanium-silicon cluster model. Furthermore, the number of germanium and silicon atoms in the cluster model can be determined based on the cluster model convergence test using the method corresponding to S3, and molecular structure modeling software can be used to construct models such as… Figure 3 The model shown is a silicon cluster model, and a germanium-silicon cluster model under different chemical environments (different germanium-silicon atomic ratios or different atomic spatial symmetries of the same germanium-silicon atomic ratio). Figure 3 The diagram shows the atomic structure of silicon or germanium, silicon clusters with a total silicon atom count of 5, and several germanium-silicon cluster models with different configurations in the etching gas screening method provided by this invention.

[0039] S3: Construct a silicon cluster model saturated with fluorine atoms based on the orientation of the exposed surface of the silicon layer and the total number of silicon atoms, and construct a germanium-silicon cluster model saturated with fluorine atoms based on the orientation of the exposed surface of the germanium-silicon layer and the total number of germanium-silicon atoms, thus obtaining multiple initial fluorine-saturated cluster models.

[0040] In S3, based on the orientation of the exposed surfaces of silicon and germanium-silicon layers and the number of atoms determined by the cluster model convergence test, a silicon cluster model saturated with fluorine atoms is constructed, resulting in multiple initial fluorine-saturated cluster models; germanium-silicon cluster models with different chemical environments are constructed, where the chemical environment includes different ratios of germanium and silicon atoms or different atomic spatial symmetries of the same ratio of germanium and silicon atoms.

[0041] Based on this, various fluorine-saturated cluster models of silicon and germanium-silicon were constructed to reflect the local structural characteristics of the surface of Si / SiGe stacked materials in contact with fluorine-containing etching gas molecules. Etching gases that can be calculated based on first-principles calculations for silicon and germanium-silicon cluster models were then screened.

[0042] As an optional embodiment, in step 120, multiple initial fluorine-saturated cluster models are pre-screened to obtain multiple target fluorine-saturated cluster models and target reaction sites and target etching gases of multiple target fluorine-saturated cluster models. The pre-screening of cluster models can be performed using the techniques in S4 to S6.

[0043] S4: Analyze the electron population of multiple initial fluorine-saturated cluster models, locate the potential active sites of multiple initial fluorine-saturated cluster models, and take the models with atomic surface positive charge values ​​greater than preset values ​​as target fluorine-saturated cluster models to obtain the potential active sites of multiple target fluorine-saturated cluster models.

[0044] Preferably, the electronic layout of multiple initial fluorine-saturated cluster models is analyzed to locate the potential active sites of the multiple initial fluorine-saturated cluster models. Models with atomic surface positive charge values ​​greater than a preset value are selected as target fluorine-saturated cluster models. This process yields multiple target fluorine-saturated cluster models and their potential active sites, which may include: Multiple initial fluorine-saturated cluster models were geometrically optimized to obtain multiple intermediate fluorine-saturated cluster models. The structures of each model in these intermediate fluorine-saturated cluster models were in a stable state, with the charge energy at its minimum. Natural population analysis was performed on these intermediate fluorine-saturated cluster models to obtain the net charge data for each silicon and germanium atom in each model. Models with surface positive charges greater than a preset value were selected as target fluorine-saturated cluster models, resulting in multiple target fluorine-saturated cluster models. The silicon and germanium atoms with the highest positive charge density in these target fluorine-saturated cluster models were identified as potential active sites.

[0045] Specifically, the computational chemistry software Gaussian can be used to optimize the geometric structure of constructed silicon cluster models and germanium-silicon cluster models in different chemical environments based on density functional theory (DFT), selecting appropriate functionals (such as B3LYP) and basis sets (G311) to achieve stable structures and minimize energy. For example, Gaussian can be used to perform natural population analysis (NPA) on the geometrically optimized cluster models to calculate the net charge of each silicon and germanium atom in each cluster model, thereby obtaining... Figure 4 The analysis results shown are as follows: Figure 4 This diagram illustrates the natural population analysis results of a germanium-silicon cluster model in the etching gas screening method provided by this invention. Silicon and germanium atoms with the highest positive charge density are selected as potential active sites for preliminary localization. Simultaneously, the possibility of regions surrounding atoms with extremely low positive charge density acting as reaction sites is excluded, reducing the system analysis burden. Figure 4In this diagram, q1 represents a charged non-central silicon atom, which is positively charged and is a potential reaction site; q2 represents a charged non-central germanium atom, which is positively charged and is a potential reaction site; q3 represents a charged central germanium atom, which is negatively charged and is unlikely to be a reaction site. If q1 > q2, then the non-central silicon atom is more likely to be a potential reaction site.

[0046] S5: Perform orbital interaction analysis on the cluster structure and etching gas molecules of multiple target fluorine-saturated cluster models to determine the orbitals that participate in the reaction at potential active sites, and select the etching gas that is more likely to react with germanium and silicon but less likely to react with silicon as the target etching gas.

[0047] Preferably, orbital interaction analysis is performed on the cluster structures of multiple target fluorine-saturated cluster models and the etching gas molecules to determine the orbitals participating in the reaction at potential active sites. The etching gas that reacts more readily with germanium and silicon but less readily with silicon is selected as the target etching gas. This may include: Natural bond orbital analysis was performed on multiple target fluorine-saturated cluster models to obtain the amount of lone pair electrons transferred from fluorine atoms to empty orbitals in silicon and germanium. Natural bond orbital analysis included analyzing the types of chemical bonds in the clusters, the interaction between electrons and empty orbitals, the bond order of each chemical bond, and the charge transfer path. Frontier molecular orbital analysis was performed on multiple target fluorine-saturated cluster models to obtain the highest occupied molecular orbitals and lowest unoccupied molecular orbitals for the multiple target fluorine-saturated cluster models and etching gas molecules. Orbital overlap population analysis was performed on multiple target fluorine-saturated cluster models to determine the overlap integral of the highest occupied molecular orbitals and lowest unoccupied molecular orbitals of etching gas molecules when they attack potential reaction sites. Based on the overlap integral of the highest occupied molecular orbitals and lowest unoccupied molecular orbitals of etching gas molecules in multiple target fluorine-saturated cluster models, etching gases that are more likely to react with germanium and silicon but less likely to react with silicon were identified, and these etching gases were selected as target etching gases.

[0048] Specifically, firstly, the computational chemistry software Gaussian is used to perform natural bond orbital (NBO) analysis to analyze the types of chemical bonds in the clusters, for example, analyzing... Bond, lone pair electron-empty orbital interaction ( Feedback keys, etc.; then calculate the clusters The lower the bond order, the easier it is for the chemical bond to break. The reaction involves the recoordination of F bonds, and the sites with lower bond orders are more prone to bond breakage. Finally, charge transfer path analysis is performed, and the amount of lone pair electrons of fluorine atoms in the etching gas molecules transferred to empty orbitals of silicon and germanium is calculated based on the second-order perturbation stabilization energy obtained from natural bond orbital analysis.

[0049] Furthermore, computational chemistry software can be used to perform tasks such as... Figure 5 The analysis of frontier molecular orbitals (FMOs) shown is as follows. Figure 5 This invention provides a molecular orbital (LUMO) analysis diagram of Si-Ge clusters in an etching gas screening method. First, by calculating the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of each cluster and etching gas molecule, it is confirmed that the electron cloud distribution of the LUMOs in the clusters is concentrated at the localized potential reaction sites; a higher LUMO density indicates higher local reactivity. Then, the energy difference between the LUMO of each cluster and the HOMO of the etching gas molecule is calculated. If the energy difference corresponding to a certain etching gas is smaller, it indicates that the etching gas is more likely to react with the cluster from an electron transfer perspective. Further, the orbital symmetry matching degree between the LUMO of each cluster and the HOMO of the etching gas molecule is analyzed. If the two are symmetrically matched, such as both the cluster LUMO and the etching gas molecule HOMO being σ-type, then the orbital overlap is considered to be higher, and electron transfer is more efficient. Finally, computational chemistry software was used to perform Ligand Overlap Based Analysis (LOBA) to construct the initial structure of the cluster-etching gas molecule complex. The orbital overlap integral of the HOMO of the etching gas and the LUMO of the cluster was calculated when the etching gas molecules attacked potential reaction sites. Based on the principle that the larger the overlap integral, the higher the spatial overlap between the two orbitals and the easier it is for electron transfer to occur, the ease of electron transfer at potential reaction sites was determined.

[0050] S6: Perform steric hindrance effect analysis on multiple target fluorine-saturated cluster models after orbital interaction analysis, eliminate potential active sites that cannot react due to steric hindrance, and obtain target reaction sites.

[0051] Preferably, steric hindrance effect analysis is performed on multiple target fluorine-saturated cluster models after orbital interaction analysis to eliminate potential active sites that cannot react due to steric hindrance, thereby obtaining target reaction sites. This may include: calculating steric hindrance parameters for multiple target fluorine-saturated cluster models; the calculation of steric hindrance parameters includes at least: calculating the minimum and maximum steric hindrance radii of the steric hindrance groups surrounding the potential active sites; the minimum steric hindrance radius indicates that the more spacious the space around the site, the easier it is for etching gas molecules to approach; the maximum steric hindrance radius indicates that the more crowded the space around the site, the more difficult it is for etching gas molecules to approach; using visualization software to draw the van der Waals surfaces of the clusters of multiple target fluorine-saturated cluster models, using different colors to represent charge distribution, and determining whether the potential active sites are wrapped by the van der Waals surfaces of the surrounding fluorine atoms; if the potential active sites are completely blocked, then the potential active sites are taken as target reaction sites.

[0052] Specifically, firstly, the steric hindrance parameters can be calculated using the computational chemistry software Gaussian. This involves calculating the minimum and maximum steric hindrance radii of the steric hindrance groups surrounding the potential reaction site. A larger maximum steric hindrance radius indicates a more crowded space around the site, making it harder for etching gas molecules to approach. The van der Waals surfaces of the clusters are then visualized using visualization software, with different colors representing charge distribution. It is observed whether the potential reaction site (positively charged region) is enveloped by the van der Waals surfaces of surrounding fluorine atoms. If the active site is completely obscured (no exposed positively charged region on the van der Waals surface), then steric hindrance dominates the reaction. Secondly, the geometric verification of the reactant approach path is performed. An initial complex structure is constructed to guide the etching gas molecules towards the cluster's active site, and the geometry of this complex is optimized. If, after optimization, the etching gas molecules can stably remain near the screened potential site (the complex energy is lower than the sum of the energies of the cluster and the etching gas molecules), it indicates that the steric hindrance at that site is relatively small, and therefore, this site can be used as a potential site for further analysis. Conversely, if the steric hindrance is too large, the site is actually inactive and should be excluded.

[0053] As an optional embodiment, in step 130, based on the target reaction sites and target etching gas of multiple target fluorine-saturated cluster models, mechanical verification is performed on multiple target fluorine-saturated cluster models to obtain the degree of reaction strength between the target etching gas and silicon or germanium-silicon clusters in the multiple target fluorine-saturated cluster models, which may include: Based on the target reaction sites and target etching gases of multiple target fluorine-saturated cluster models, reaction thermodynamic analysis was performed on the multiple target fluorine-saturated cluster models to obtain the enthalpy change and Gibbs free energy change of the target etching gas with the multiple target fluorine-saturated cluster model clusters. Based on the target reaction sites and target etching gases of the multiple target fluorine-saturated cluster models, reaction kinetic analysis was performed on the multiple target fluorine-saturated cluster models. The transition state search method was used to search for the transition state structure in the kinetic reaction process to obtain the reaction energy barrier of the target etching gas with the multiple target fluorine-saturated cluster model clusters. Based on the reaction enthalpy change, Gibbs free energy change and reaction energy barrier of the target etching gas with the multiple target fluorine-saturated cluster model clusters, the reaction strength between the target etching gas and silicon or germanium-silicon clusters in the multiple target fluorine-saturated cluster models was determined.

[0054] Specifically, in performing reaction thermodynamic analysis, the computational chemistry software Gaussian can be used to analyze the enthalpy change of the reaction between the optimized clusters and the etching gas molecules based on density functional theory and physicochemical theory. ) and Gibbs free energy change ( The calculation of ) if A value less than 0 indicates that the reaction proceeds thermodynamically spontaneously. The more negative the reaction, the stronger the thermodynamic driving force (the higher the reactivity). If the value is greater than 0, even if the previous electron and steric hindrance conditions are met, the reaction is unlikely to occur spontaneously.

[0055] Furthermore, in performing reaction kinetic analysis, computational chemistry software can be used to find the transition state structure of the reaction based on the potential sites obtained from previous analyses and transition state theory, through transition state search methods. This allows for the acquisition of results such as... Figure 6 The distribution curve shown is... Figure 6 A schematic diagram of the IRC curve of the reaction between fluorine gas and Si-Ge clusters, a common etching gas, in the etching gas screening method provided by this invention; Figure 6In the diagram, the horizontal axis represents the intrinsic reaction coordinates, and the vertical axis represents the total energy of the transition state relative to the reactants. Then, the reaction energy barrier is calculated; a lower energy barrier indicates a faster reaction rate. For example, reactions with energy barriers less than 10 kcal / mol are generally more likely to occur at room temperature, while reactions with energy barriers greater than 25 kcal / mol are less likely to occur. If there are multiple potential reaction sites in a cluster, the reaction energy barriers can be calculated separately for each site; the site with the lowest energy barrier is the site with the highest actual activity. Finally, electron density topological analysis is performed. The computational chemistry software Multiwfn, based on the Atomic Integral Charge (AIM) theory, can be used to calculate the electron density topological map of the reaction process (reactants → transition state → products). The calculated bond critical points (BCPs) are then analyzed. Figure 7 As shown, Figure 7 This is a schematic diagram of the bond critical point analysis of germanium-silicon clusters in a method for screening etching gases provided by the present invention; for example: Figure 7 The orange dots illustrate this using germanium-silicon clusters as an example. First, it's determined whether a new bond critical point forms between the potential reaction site and the attacking F atom. Simultaneously, the change in electron density ρ of the Si / Ge-F bond is tracked during the reaction. A decrease in ρ indicates bond weakening (breakage), while an increase in ρ indicates bond formation (new bond generation). This allows us to determine the reaction strength between the target etching gas and the silicon or germanium-silicon clusters in multiple target fluorine-saturated cluster models. It should be noted that the electron density ρ at the BCP is greater than 0.1. Laplace quantity A value less than 0 usually indicates a covalent bond. A value greater than 0 usually indicates an ionic bond.

[0056] As an optional embodiment, in step 140, determining the etching gas for the silicon and germanium-silicon stacked structure based on the relative strength of the reaction between the target etching gas and silicon or germanium-silicon clusters in multiple target fluorine-saturated cluster models may include: comparing the ease with which different etching gases react with germanium-silicon clusters, and selecting the etching gas that is more likely to react chemically with multiple germanium-silicon cluster structures as a candidate etching gas; comparing the differences in physical quantities when the candidate etching gas reacts with silicon clusters and germanium-silicon clusters, and selecting the etching gas whose difference in the physical quantities for silicon clusters and germanium-silicon clusters is greater than the target value as the etching gas for the silicon and germanium-silicon stacked structure; the physical quantities include at least the energy barrier, enthalpy change, and Gibbs free energy change.

[0057] Specifically, this step employs a comprehensive analysis method to screen for etching gases with high SiGe / Si etching selectivity, which can then be used for non-plasma etching of Si / SiGe stacked structures in GAA devices. First, the ease with which different etching gases react with germanium-silicon clusters needs to be compared. If, based on thermodynamic and kinetic criteria, the reaction is more likely to occur for various germanium-silicon cluster structures, then the etching gas meeting the requirements is selected as a candidate. Second, the energy barriers, enthalpy changes, and Gibbs free energy changes of the candidate etching gases when reacting with silicon and germanium-silicon clusters are compared. The etching gas with the greatest difference in comparative physical quantities for silicon and germanium-silicon clusters is selected as the fluorine-containing etching gas with high SiGe / Si etching selectivity.

[0058] Based on this, the present invention provides a method for screening etching gases. Through a four-step method of constructing a fluorine-saturated cluster model → cluster model screening → cluster model mechanical verification → comprehensive analysis, potential etching gases are screened in a graded manner. This method achieves efficient and low-cost screening of etching gases with high SiGe / Si etching selectivity, and solves the problems of low efficiency and high cost in the screening of etching gases in the prior art.

[0059] Secondly, the present invention provides a screening device for etching gases, please refer to [reference needed]. Figure 8 , Figure 8 This is a schematic diagram of the structure of an etching gas screening device provided by the present invention.

[0060] exist Figure 8 In this process, the screening device may include: The cluster model construction module 810 is used to construct multiple initial fluorine-saturated cluster models; the multiple initial fluorine-saturated cluster models are saturated cluster models that reflect the local structural features of the surface of silicon and germanium-silicon stacked materials in contact with fluorine-containing etching gas molecules.

[0061] The cluster model pre-screening module 820 is used to pre-screen multiple initial fluorine-saturated cluster models to obtain multiple target fluorine-saturated cluster models and target reaction sites and target etching gases of the multiple target fluorine-saturated cluster models; the cluster model pre-screening includes at least the localization of potential active sites of the models, cluster model screening, analysis of the orbital interaction between the cluster structure and the etching gas molecules, and analysis of the steric hindrance effect.

[0062] The reaction strength determination module 830 is used to perform mechanical verification on the multiple target fluorine-saturated cluster models based on the target reaction sites and target etching gases of the multiple target fluorine-saturated cluster models, and to obtain the degree of reaction strength between the target etching gas and silicon or germanium-silicon clusters in the multiple target fluorine-saturated cluster models; the mechanical verification includes reaction thermodynamic verification and reaction kinetic verification.

[0063] The etching gas determination module 840 is used to determine the etching gas for silicon and germanium-silicon stacked structures based on the degree of reaction between the target etching gas and silicon or germanium-silicon clusters in multiple target fluorine-saturated cluster models.

[0064] Compared with the prior art, the present invention provides an etching gas screening device, which sets up a cluster model construction module 810, a cluster model pre-screening module 820, a reaction strength determination module 830, and an etching gas determination module 840. The cluster model construction module 810 can construct multiple initial fluorine-saturated cluster models, and the cluster model pre-screening module 820 can perform cluster model pre-screening on these models to obtain multiple target fluorine-saturated cluster models, target reaction sites, and target etching gases. The reaction strength determination module 830 then uses these target fluorine-saturated cluster models to perform mechanical verification, obtaining the reaction strength between the target etching gas and silicon or germanium-silicon clusters. Finally, the etching gas determination module 840 uses the reaction strength between the target etching gas and silicon or germanium-silicon clusters to determine the etching gas used for silicon and germanium-silicon stacked structures. A four-step effective etching gas screening method based on fluorine-saturated cluster model → cluster model screening → cluster model mechanical verification → comprehensive analysis has been implemented. This method efficiently and cost-effectively screens etching gases with high SiGe / Si etching selectivity, avoiding the problem of excessive cost and low efficiency in screening through experimental verification.

[0065] Thirdly, the present invention provides an electronic device, please refer to [link to relevant documentation]. Figure 9 , Figure 9 This is a schematic diagram of the structure of an electronic device provided by the present invention.

[0066] exist Figure 9 The electronic device includes: a processor 910; and a memory 900 for storing executable instructions of the processor 910. The processor 910 is used to execute the etching gas screening processing method disclosed in any of the above embodiments by running the instructions in the memory 900.

[0067] The processor 910, memory 900, communication interface 920, input device 930, and output device 940 are interconnected via a bus. Among them: A bus can include a pathway for transmitting information between various components of a computer system.

[0068] The processor 910 can be a general-purpose processor, such as a general-purpose central processing unit (CPU), a microprocessor, etc., or an application-specific integrated circuit (ASIC), or one or more integrated circuits used to control the execution of the program of the present invention. It can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), an off-the-shelf programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0069] The processor 910 may include a main processor, as well as a baseband chip, modem, etc.

[0070] The memory 900 stores a program that executes the technical solution of this invention, and may also store an operating system and other key business functions. Specifically, the program may include program code, which includes computer operation instructions. More specifically, the memory 900 may include read-only memory (ROM), other types of static storage devices capable of storing static information and instructions, random access memory (RAM), other types of dynamic storage devices capable of storing information and instructions, disk storage, flash memory, etc.

[0071] Input device 930 may include a device for receiving user input data and information, such as a keyboard, mouse, camera, scanner, touch screen, etc.

[0072] Output device 940 may include devices that allow information to be output to a user, such as a display screen, printer, speaker, etc.

[0073] The communication interface 920 may include a device that uses any transceiver to communicate with other devices or communication networks, such as Ethernet, Radio Access Network (RAN), Wireless Local Area Network (WLAN), etc.

[0074] The processor 910 executes the program stored in the memory 900 and calls other devices, and can be used to implement each step of any of the etching gas screening methods provided in the above embodiments of this application.

[0075] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings, the disclosure, and the appended claims in carrying out the claimed invention. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results.

[0076] Although the invention has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made therein without departing from the spirit and scope of the invention. Accordingly, this specification and drawings are merely exemplary descriptions of the invention as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if such modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include such modifications and modifications.

Claims

1. A method for screening etching gases, characterized in that, include: Multiple initial fluorine-saturated cluster models are constructed; the multiple initial fluorine-saturated cluster models are saturated cluster models that reflect the local structural features of the surface of silicon and germanium-silicon stacked materials in contact with fluorine-containing etching gas molecules; Cluster model pre-screening is performed on multiple initial fluorine-saturated cluster models to obtain multiple target fluorine-saturated cluster models and target reaction sites and target etching gases of the multiple target fluorine-saturated cluster models; the cluster model pre-screening includes at least the localization of potential active sites of the models, cluster model screening, analysis of the orbital interaction between the cluster structure and the etching gas molecules, and analysis of the steric hindrance effect; Based on the target reaction sites and target etching gases of multiple target fluorine-saturated cluster models, mechanical verification is performed on the multiple target fluorine-saturated cluster models to obtain the degree of reaction strength between the target etching gas and silicon or germanium-silicon clusters in the multiple target fluorine-saturated cluster models; the mechanical verification includes reaction thermodynamic verification and reaction kinetic verification. Based on the varying degrees of reaction strength between the target etching gas and silicon or germanium-silicon clusters in multiple target fluorine-saturated cluster models, the etching gas used for silicon and germanium-silicon stacked structures is determined.

2. The method for screening etching gases as described in claim 1, characterized in that, The construction of multiple initial fluorine-saturated cluster models includes: Based on the orientation of the exposed surfaces of silicon and germanium-silicon layers during the etching process, multiple original fluorine-saturated cluster models were constructed. These models included multiple silicon cluster models saturated with fluorine atoms and having different numbers of silicon atoms, as well as multiple germanium-silicon cluster models saturated with fluorine atoms and having different total numbers of silicon and germanium atoms. Calculate the bond dissociation energy of various chemical bonds in multiple original fluorine-saturated cluster models, determine the minimum number of atoms at which bond dissociation does not change significantly with the increase of the number of atoms in the two clusters, and take the minimum number of atoms as the total number of silicon atoms in the silicon cluster model and the total number of germanium-silicon atoms in the germanium-silicon cluster model. A silicon cluster model saturated with fluorine atoms is constructed based on the orientation of the exposed surface of the silicon layer and the total number of silicon atoms, and a germanium-silicon cluster model saturated with fluorine atoms is constructed based on the orientation of the exposed surface of the germanium-silicon layer and the total number of germanium-silicon atoms, thereby obtaining multiple initial fluorine-saturated cluster models.

3. The method for screening etching gases as described in claim 1, characterized in that, The pre-screening of multiple initial fluorine-saturated cluster models yields multiple target fluorine-saturated cluster models, along with their target reaction sites and target etching gases, including: The electron population of multiple initial fluorine-saturated cluster models is analyzed to locate potential active sites of multiple initial fluorine-saturated cluster models. Models with atomic surface positive charge values ​​greater than preset values ​​are selected as target fluorine-saturated cluster models to obtain multiple target fluorine-saturated cluster models and potential active sites of multiple target fluorine-saturated cluster models. Orbital interaction analysis was performed on the cluster structure and etching gas molecules of multiple target fluorine-saturated cluster models to determine the orbitals that participate in the reaction at the potential active sites, and the etching gas that is more likely to react with germanium and silicon but less likely to react with silicon was selected as the target etching gas. Spatial steric hindrance effect analysis was performed on multiple target fluorine-saturated cluster models after orbital interaction analysis to eliminate potential active sites that could not react due to steric hindrance, thereby obtaining the target reaction sites.

4. The method for screening etching gases as described in claim 3, characterized in that, The step involves performing a localization analysis on the electronic layout of multiple initial fluorine-saturated cluster models to locate potential active sites within these models. Models with atomic surface positive charge values ​​exceeding a preset value are selected as target fluorine-saturated cluster models. This process yields multiple target fluorine-saturated cluster models and their potential active sites, including: Geometric structure optimization was performed on multiple initial fluorine-saturated cluster models to obtain multiple intermediate fluorine-saturated cluster models; the structure of each model in the multiple intermediate fluorine-saturated cluster models was in a stable state and the charge energy was at its minimum value. Natural population analysis was performed on multiple intermediate fluorine-saturated cluster models to obtain the net charge data for each silicon and germanium atom in the multiple intermediate fluorine-saturated cluster models; The model with a positive charge value on the atomic surface of the intermediate fluorine-saturated cluster model that is greater than a preset value is used as the target fluorine-saturated cluster model to obtain multiple target fluorine-saturated cluster models. The silicon and germanium atoms with the highest positive charge density in the multiple target fluorine-saturated cluster models were selected as potential active sites.

5. The method for screening etching gases as described in claim 3, characterized in that, The method involves performing orbital interaction analysis on the cluster structures and etching gas molecules of multiple target fluorine-saturated cluster models to determine the orbitals participating in the reaction at the potential active sites. Etching gases that react more readily with germanium and silicon but less readily with silicon are selected as target etching gases, including: Natural bond orbital analysis was performed on multiple target fluorine-saturated cluster models to obtain the amount of lone pair electrons of fluorine atoms transferred to empty orbitals in silicon and germanium. The natural bond orbital analysis included analyzing the types of chemical bonds in the clusters, the interaction between electrons and empty orbitals, the bond order of each chemical bond, and the charge transfer path. Frontier molecular orbital analysis was performed on multiple target fluorine-saturated cluster models to obtain the highest occupied molecular orbital and the lowest unoccupied molecular orbital for the multiple target fluorine-saturated cluster models and etching gas molecules. Orbital overlap population analysis was performed on multiple target fluorine-saturated cluster models to determine the overlap integral of the highest occupied molecular orbital and the lowest unoccupied molecular orbital of the etching gas molecule when the etching gas molecule attacks the potential reaction site in the multiple target fluorine-saturated cluster models. Based on the overlap integral of the highest occupied molecular orbital and the lowest unoccupied molecular orbital of the etching gas molecules in multiple target fluorine-saturated cluster models, the etching gas that is more likely to react with germanium and silicon but less likely to react with silicon is determined, and the etching gas that is more likely to react with germanium and silicon but less likely to react with silicon is selected as the target etching gas.

6. The method for screening etching gases as described in claim 3, characterized in that, The spatial steric hindrance effect analysis is performed on multiple target fluorine-saturated cluster models after orbital interaction analysis to eliminate potential active sites that cannot react due to steric hindrance, thereby obtaining the target reaction sites, including: Spatial steric hindrance parameters are calculated for multiple target fluorine-saturated cluster models; the spatial steric hindrance parameter calculation includes at least: calculating the minimum and maximum steric hindrance radii of the spatially hindering groups around the potential active sites; the minimum steric hindrance radius indicates that the more spacious the space around the site, the easier it is for etching gas molecules to approach; the maximum steric hindrance radius indicates that the more crowded the space around the site, the more difficult it is for etching gas molecules to approach. The van der Waals surfaces of multiple target fluorine-saturated cluster models are plotted using visualization software, and different colors are used to represent charge distribution. It is determined whether potential active sites are wrapped by the van der Waals surfaces of surrounding fluorine atoms. If the potential active sites are completely blocked, the potential active sites are taken as the target reaction sites.

7. The method for screening etching gases as described in claim 1, characterized in that, Based on the target reaction sites and target etching gases of multiple target fluorine-saturated cluster models, mechanical verification was performed on the multiple target fluorine-saturated cluster models to obtain the degree of reaction strength between the target etching gas and silicon or germanium-silicon clusters in the multiple target fluorine-saturated cluster models, including: Based on the target reaction sites and target etching gas of multiple target fluorine-saturated cluster models, reaction thermodynamic analysis is performed on multiple target fluorine-saturated cluster models to obtain the reaction enthalpy change and Gibbs free energy change of the target etching gas with multiple target fluorine-saturated cluster model groups; Based on the target reaction sites and target etching gases of multiple target fluorine-saturated cluster models, reaction kinetics analysis is performed on multiple target fluorine-saturated cluster models. The transition state search method is used to search for the transition state structure in the kinetic reaction process to obtain the reaction energy barrier between the target etching gas and multiple target fluorine-saturated cluster model groups. Based on the enthalpy change, Gibbs free energy change, and reaction energy barrier of the target etching gas and multiple target fluorine-saturated cluster model groups, the reaction strength between the target etching gas and silicon or germanium-silicon clusters in the multiple target fluorine-saturated cluster models is determined.

8. The method for screening etching gases as described in claim 1, characterized in that, The determination of the etching gas for silicon and germanium-silicon stacked structures based on the varying degrees of reaction strength between the target etching gas and silicon or germanium-silicon clusters in multiple target fluorine-saturated cluster models includes: By comparing the ease with which different etching gases react with germanium-silicon clusters, the etching gas that is more likely to react chemically with various germanium-silicon cluster structures was selected as the alternative etching gas. By comparing the differences in physical quantities when the candidate etching gases react with silicon clusters and germanium-silicon clusters, the etching gas with a difference in physical quantities greater than the target value for silicon clusters and germanium-silicon clusters is selected as the etching gas for the silicon and germanium-silicon stacked structure; the physical quantities include at least the energy barrier, enthalpy change and Gibbs free energy change.

9. A screening device for etching gases, characterized in that, include: A cluster model construction module is used to construct multiple initial fluorine-saturated cluster models; the multiple initial fluorine-saturated cluster models are saturated cluster models that reflect the local structural features of the surface of silicon and germanium-silicon stacked materials in contact with fluorine-containing etching gas molecules; A cluster model pre-screening module is used to pre-screen multiple initial fluorine-saturated cluster models to obtain multiple target fluorine-saturated cluster models and target reaction sites and target etching gases of the multiple target fluorine-saturated cluster models. The cluster model pre-screening includes at least the localization of potential active sites in the model, cluster model screening, analysis of the orbital interactions between the cluster structure and the etching gas molecules, and analysis of the steric hindrance effect. The reaction strength determination module is used to perform mechanical verification on multiple target fluorine-saturated cluster models based on the target reaction sites and target etching gases of the multiple target fluorine-saturated cluster models, and to obtain the degree of reaction strength between the target etching gas and silicon or germanium-silicon clusters in the multiple target fluorine-saturated cluster models; the mechanical verification includes reaction thermodynamic verification and reaction kinetic verification. An etching gas determination module is used to determine the etching gas for silicon and germanium-silicon stacked structures based on the reaction strength between the target etching gas and silicon or germanium-silicon clusters in multiple target fluorine-saturated cluster models.

10. An electronic device, characterized in that, include: processor; Memory used to store the processor's executable instructions; The processor is configured to execute the etching gas screening method according to any one of claims 1 to 8 by running instructions in the memory.

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