Method for simulating silicon surface oxide growth based on ion implantation technology
By constructing a single-crystal silicon model and simulating the oxidation reaction, the difficult problem of the microscopic mechanism of defect formation in the oxygen injection process was solved, the accurate simulation of the oxide layer structure and the optimization of process parameters were achieved, and the performance and stability of the device were improved.
Patent Information
- Application Number
- CN202210762601.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-06-30
- Publication Date
- 2025-09-19
- Estimated Expiration
- 2042-06-30
AI Technical Summary
Existing technologies make it difficult to understand the microscopic mechanism of defect formation in the oxygen implantation process at the atomic level, which affects device performance and stability.
By constructing a single crystal silicon model, setting a vacuum layer on the surface, and using the reaction force field molecular dynamics method to simulate the oxidation reaction, the organizational morphological parameters of the oxide layer are obtained and evaluated, and the process parameters are adjusted until the preset requirements are met.
It achieves accurate simulation and control of the oxide layer's micromorphological parameters, provides low-cost and efficient process optimization guidance, and improves the device's operating stability and lifespan.
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Figure CN115186462B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of semiconductor material preparation, in particular to a method for simulating the growth of a silicon surface oxide layer based on ion implantation technology. Background Art
[0002] Typically, a buried oxide (SOI) layer, or silicon dioxide insulating layer, is placed between the top silicon layer and the silicon substrate of a semiconductor device. This layer acts as a mask for certain impurities and facilitates selective diffusion. Therefore, the combination of photolithography and diffusion processes led to the development of planar processing and very large-scale integrated circuits. To create a buried oxide layer on a silicon substrate, high-energy, high-current oxygen ions are implanted into the silicon substrate to form an oxygen-rich silicon layer. A high-temperature annealing process triggers a chemical reaction between the silicon and oxygen atoms, forming the silicon dioxide insulating layer. This process is known as oxygen implantation. Oxygen implantation offers many advantages, including the ability to perform oxygen implantation at relatively low temperatures, precise control of the oxygen concentration and implantation depth within the silicon substrate, uniform oxidation over large areas, good reproducibility, high oxide layer purity, minimal lateral diffusion, and easily controlled process conditions. However, experimental oxygen implantation inevitably introduces point defects in the SiO2 oxide layer, which can affect device performance and even compromise device stability and lifetime. The effects of process conditions on the type and concentration of generated defects can be optimized and analyzed experimentally, but it is difficult to understand the microscopic mechanism of defect formation at the atomic level.
[0003] Therefore, if a method that accurately simulates the actual oxygen injection process can be developed, by adjusting different process conditions, the defect types and concentrations in the oxide layer and transition layer after oxidation can be simulated, and in turn the actual process conditions can be optimized to make the defects meet the actual requirements, thereby providing reasonable optimization guidance for the oxidation process of the device, it will have important engineering value and scientific significance. Summary of the Invention
[0004] The problem solved by the present invention is how to guide and optimize process conditions so that the point defects generated by the oxygen injection process meet the requirements.
[0005] To solve the above problems, the present invention provides a method for simulating the growth of a silicon surface oxide layer based on ion implantation technology, comprising the following steps:
[0006] Step S1: constructing a model of single crystal silicon, setting a vacuum layer on the surface of the single crystal silicon in the model, and using a reaction force field molecular dynamics method to put the single crystal silicon into an initial equilibrium state;
[0007] Step S2: heating the single crystal silicon to a reaction temperature, and repeatedly emitting O atoms at random positions toward the surface of the single crystal silicon at intervals of a preset time, so that an oxidation reaction occurs on the surface of the single crystal silicon; after the oxidation reaction is completed and reaches an equilibrium state, annealing the mold to obtain an oxide layer;
[0008] Step S3: Acquire and evaluate the tissue morphology parameters of the oxide layer. If the tissue morphology parameters do not meet the preset requirements, repeat and optimize steps S1 and S2 until the tissue morphology parameters meet the preset requirements.
[0009] Furthermore, in step S1, the model of the single crystal silicon is a single crystal silicon square cell model having a diamond crystal structure.
[0010] Furthermore, in step S1, the initial equilibrium state of the single crystal silicon includes: optimizing the positions of the single crystal silicon atoms and relaxing them to a normal pressure state so that the force on the single crystal silicon atoms is zero.
[0011] Furthermore, in step S1, the thickness of the vacuum layer is in the range of 2-5 nm.
[0012] Furthermore, in step S2, the reaction temperature is in the range of 500-800K.
[0013] Furthermore, in step S2, the preset time range is 5-10 ps.
[0014] Furthermore, in step S2, the emission speed is in the range of 1500-3000 m / s, and the emission direction is along the reverse
[100] crystal orientation.
[0015] Furthermore, in step S2, the annealing temperature is in the range of 1000-1300K.
[0016] Furthermore, in step S3, the optimizing steps S1 and S2 include: optimizing the reaction temperature, the preset time, the emission mode and the annealing mode of step S2.
[0017] Furthermore, in step S3, the organizational morphology parameters of the oxide layer include at least density, silicon-oxygen ratio, defect type and defect concentration.
[0018] The advantages of the method for simulating the growth of an oxide layer on a silicon surface based on ion implantation technology described in the present invention over the prior art are that, by constructing a model of single crystal silicon, a vacuum layer is set on the surface of the single crystal silicon in the model, and the process of emitting O atoms onto the single crystal silicon surface at a reaction temperature and random positions is repeatedly simulated until an oxidation reaction occurs on the single crystal silicon surface, and an oxide layer is obtained after annealing; and the micromorphological parameters of the oxide layer are obtained and evaluated, thereby accurately simulating the actual process of forming an oxide layer by ion implantation on the single crystal silicon surface through simulation means, and controlling the micromorphological parameters of the product. The present invention simulates the microscopic details of bond formation and bond breaking and the dynamic process of atomic structure formation during the entire ion implantation reaction at the atomic level, which is conducive to analyzing the mechanism of microstructure formation and ultimately obtaining a systematic understanding of the micromorphological parameters of the oxide layer. The method for simulating the growth of an oxide layer on a silicon surface based on ion implantation technology is conducive to controlling the micromorphological parameters of the oxide layer and evaluating them. If the preset requirements are not met, the simulation is repeated and the process parameters involved in the experimental process are adjusted until the micromorphological parameters meet the preset requirements. The actual ion implantation technology is known through the obtained process parameters, achieving a low-cost and high-efficiency guidance role. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 This is a flow chart of a method for simulating the growth of an oxide layer on a silicon surface based on ion implantation technology in an embodiment of the present invention;
[0020] Figure 2 This is a configuration structure diagram of single crystal silicon before O atoms are injected to simulate the growth of silicon surface oxide layer based on ion implantation technology in an embodiment of the present invention;
[0021] Figure 3 This is a configuration structure diagram of single crystal silicon during the process of implanting O atoms to simulate the growth of a silicon surface oxide layer based on ion implantation technology in an embodiment of the present invention;
[0022] Figure 4 This is a configuration structure diagram of single crystal silicon after O atoms are implanted to simulate the growth of silicon surface oxide layer based on ion implantation technology in an embodiment of the present invention;
[0023] Figure 5 This is a defect concentration statistical diagram of the organizational morphology parameters of the oxide layer obtained by simulating the growth of the silicon surface oxide layer at a reaction temperature of 500K based on the ion implantation technology in an embodiment of the present invention;
[0024] Figure 6 This is a statistical analysis diagram of atomic bond angles of an oxide layer based on ion implantation in an embodiment of the present invention;
[0025] Figure 7 This is a statistical analysis diagram of the atomic bond lengths of the oxide layer based on ion implantation in an embodiment of the present invention. DETAILED DESCRIPTION
[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.
[0027] It should be noted that, in the description of the embodiments of this application, the term "some specific embodiments" means 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 representation of the above terms does not necessarily refer to the same implementation or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples.
[0028] Combine Figure 1 As shown, an embodiment of the present invention provides a method for simulating the growth of a silicon surface oxide layer based on ion implantation technology, comprising the following steps:
[0029] Step S1: constructing a single crystal silicon model, setting a vacuum layer on the surface of the single crystal silicon in the model, and using the reaction force field molecular dynamics method to put the single crystal silicon into an initial equilibrium state;
[0030] Step S2: heating the single crystal silicon to a reaction temperature, and repeatedly emitting O atoms at random positions onto the surface of the single crystal silicon at intervals of a preset time, so that an oxidation reaction occurs on the surface of the single crystal silicon; after the oxidation reaction is completed and reaches an equilibrium state, annealing the model to obtain an oxide layer;
[0031] Step S3: Acquire and evaluate the tissue morphology parameters of the oxide layer. If the tissue morphology parameters do not meet the preset requirements, repeat and optimize steps S1 and S2 until the tissue morphology parameters meet the preset requirements.
[0032] The advantages of the method for simulating the growth of an oxide layer on a silicon surface based on ion implantation technology described in an embodiment of the present invention over the prior art are that, by constructing a model of single crystal silicon, a vacuum layer is set on the surface of the single crystal silicon in the model, and the process of emitting O atoms onto the single crystal silicon surface at a reaction temperature and random positions is repeatedly simulated until an oxidation reaction occurs on the single crystal silicon surface, and an oxide layer is obtained after annealing; and the micromorphological parameters of the oxide layer are obtained and evaluated, so as to accurately simulate the actual process of ion implantation on the single crystal silicon surface to form an oxide layer through simulation means, and to control the micromorphological parameters of the product. The present invention simulates the microscopic details of bond formation and bond breaking and the dynamic process of atomic structure formation during the entire ion implantation reaction at the atomic level, which is conducive to analyzing the mechanism of microstructure formation and ultimately obtaining a systematic understanding of the micromorphological parameters of the oxide layer. The method for simulating the growth of an oxide layer on a silicon surface based on ion implantation technology is conducive to controlling the micromorphological parameters of the oxide layer and evaluating them. If the preset requirements are not met, the simulation is repeated and the process parameters involved in the experimental process are adjusted until the micromorphological parameters meet the preset requirements. The actual ion implantation technology is known through the obtained process parameters, achieving a low-cost and high-efficiency guidance role.
[0033] Specifically, in step S1, a model of single crystal silicon is established using analytical dynamics simulation software, such as LAMMPS, a vacuum layer is added to the surface of the single crystal silicon model, and then the molecular dynamics reaction force field is used to put the silicon atoms in an initial equilibrium state.
[0034] Specifically, in step S2, a reaction force field molecular dynamics method is used to simulate the entire process of O atoms being injected into the surface of a single crystal silicon at a relatively high speed within a vacuum layer. The simulation is carried out in an isothermal and isobaric thermodynamic ensemble. At a specific reaction temperature, such as 500K, O atoms are injected into the surface of a single crystal silicon at a speed of 1500m / s at random positions. The O atoms fully collide on the surface of the single crystal silicon, and a chemical reaction process of bond breaking, bond formation, and stability occurs. The above process is repeated to achieve the purpose of generating an oxide layer of a certain thickness. The entire system is subjected to molecular dynamics relaxation at a constant temperature to fully react and stabilize. Finally, the entire system is subjected to molecular dynamics annealing to cool it to room temperature and pressure, and finally the oxide layer after ion implantation can be obtained.
[0035] Specifically, in step S3, the organizational morphology parameters of the oxide layer are obtained, and the organizational morphology parameters of the oxide layer are compared with the preset requirements. If the requirements are met, the process parameters of the generation process are determined; if the preset requirements are not met, the simulation process of steps S1 and S2 is repeated, and the parameters involved in the simulation process are adjusted, such as reaction temperature and annealing time, until the preset requirements are met.
[0036] In some specific embodiments, in step S1 , the model of the single crystal silicon is a single crystal silicon square cell model having a diamond crystal structure.
[0037] Therefore, under finite boundary conditions, a single crystal silicon square cell model with a diamond crystal structure is constructed, which has a clear structure and is conducive to the extraction and application of tissue morphology parameters.
[0038] In some specific embodiments, in step S1, the initial equilibrium state of the single crystal silicon includes: optimizing the positions of the single crystal silicon atoms and relaxing them to a normal pressure state, so that the force on the single crystal silicon atoms is zero. Thus, the atoms of the single crystal silicon are in a state of equilibrium with zero force, which facilitates accurate control of O atoms and other conditions during the simulation process and improves the accuracy of various process parameters.
[0039] In some specific embodiments, in step S1, the vacuum layer thickness ranges from 2 to 5 nm, thereby providing sufficient space for the O atoms to react with the single crystal silicon surface, thereby preventing the movement path of the O atoms from being restricted, thereby affecting the accuracy of the simulated reaction.
[0040] In some specific embodiments, in step S2, the reaction temperature is in the range of 500-800 K. Thus, the O atoms are activated to form molecules, thereby increasing the probability of the reaction.
[0041] In some specific embodiments, in step S2, the preset time range is 5-10 ps, thereby providing sufficient reaction time and reducing the impact on other simulation processes.
[0042] In some specific embodiments, in step S2, the emission speed is in the range of 1500-3000 m / s, and the emission direction is along the reverse
[100] crystal orientation, thereby increasing the probability of the reaction occurring and ensuring the efficiency of the simulation process.
[0043] In some specific embodiments, in step S2 , the annealing temperature is in the range of 1000-1300 K. Thus, the oxide layer of a certain thickness generated after ion implantation is annealed to adjust the tissue morphology and eliminate tissue defects.
[0044] In some specific embodiments, in step S3, optimizing steps S1 and S2 includes optimizing the reaction temperature, preset time, emission method, and annealing method of step S2. Thus, by modifying these process parameters, the final microstructure parameters of the oxide layer are adjusted to meet preset requirements, which provides guidance for practical ion implantation technology.
[0045] In some specific embodiments, in step S3, the morphological parameters of the oxide layer include at least density, silicon-oxygen ratio, defect type, and defect concentration. This allows for control of the deep structure of the oxide layer and improves the depth of optimization of the actual ion implantation technology.
[0046] Example 1
[0047] In this embodiment, an oxide layer is obtained by simulating the growth of an oxide layer on the silicon surface using ion implantation technology. The specific steps are as follows:
[0048] Using the simulation method of the present invention, the interaction between atoms is described by the reaction force field, and a 3.3nm×3.3nm×4.4nm single crystal silicon model is constructed, which includes 1800 Si atoms and a 2nm thick vacuum layer is added. Figure 2 As shown. The direction of molecular incidence is along the direction of the reverse
[100] crystal orientation, that is, perpendicular to the silicon surface and moving downward, with an incidence speed of 1500m / s. A total of 3000 cycles were performed, with a preset time of 5ps for full reaction in each cycle. The reaction temperature was controlled at 500K. After all simulations were completed, the reaction temperature was maintained for 100ps to allow the structure after the reaction to relax to the equilibrium state. The model system was subjected to reaction force field molecular dynamics annealing, with an annealing temperature of 1000K and an annealing time of 200ps. After annealing to room temperature, it was cooled to 0K. Finally, the atomic position was optimized to obtain the final oxide layer, where Figure 3 This is the configuration structure diagram of single crystal silicon during the process of injecting O atoms. Figure 4 This is the configuration structure diagram after O atoms are injected.
[0049] Obtain the density, silicon-oxygen ratio, defect type and defect concentration of the oxide layer for evaluation. Figure 5 As shown in FIG, a statistical diagram of defect concentration of the oxide layer obtained at a reaction temperature of 500K is shown, in which the concentrations of overcoordination (OVER_CN) and ODC5 are the highest, indicating that the lattice disorder of the ion implantation is relatively high.
[0050] Figure 6 and Figure 7 These are statistical analysis diagrams of the atomic bond angle and atomic bond length of the oxide layer based on ion implantation obtained at 500K, where the bond length is mainly concentrated around 1.59A and the bond angle distribution is relatively discrete.
[0051] Example 2
[0052] In this embodiment, an oxide layer is obtained by simulating the growth of an oxide layer on the silicon surface using ion implantation technology. The specific steps are as follows:
[0053] Using the simulation method of the present invention, the interaction between atoms is described by a reaction force field. A 3.3nm×3.3nm×4.4nm single-crystal silicon model is constructed, which includes 1800 Si atoms and a 5nm thick vacuum layer. The direction of molecular incidence is along the direction of the reverse
[100] crystal orientation, that is, perpendicular to the silicon surface and moving downward, with an incidence speed of 3000m / s. A total of 3000 cycles are performed, and each cycle is given a preset time of 10ps for full reaction. The reaction temperature is controlled at 800K. After all simulations are completed, the reaction temperature is maintained for another 100ps to allow the structure after reaction to relax to an equilibrium state. The model system is subjected to reaction force field molecular dynamics annealing at an annealing temperature of 1300K and an annealing time of 200ps. After annealing to room temperature, it is cooled to 0K. Finally, the atomic positions are optimized to obtain the final oxide layer.
[0054] The density, silicon-oxygen ratio, defect type, and defect concentration of the oxide layer are obtained for evaluation.
[0055] Example 3
[0056] In this embodiment, an oxide layer is obtained by simulating the growth of an oxide layer on the silicon surface using ion implantation technology. The specific steps are as follows:
[0057] Using the simulation method of the present invention, the interaction between atoms is described by the reaction force field, and a 3.3nm×3.3nm×4.4nm single crystal silicon model is constructed, which includes 1800 Si atoms and a 4nm thick vacuum layer is added. Figure 2 As shown in the figure. The direction of the molecular incident is along the direction of the reverse
[100] crystal orientation, that is, perpendicular to the silicon surface and moving downward, with an incident speed of 2000 m / s. A total of 3000 cycles were performed, with a preset time of 7 ps for each cycle for full reaction. The reaction temperature was controlled at 680 K. After all simulations were completed, the reaction temperature was maintained for another 100 ps to allow the structure to relax to the equilibrium state after the reaction. The model system was subjected to reaction force field molecular dynamics annealing at a temperature of 1100 K and an annealing time of 200 ps. After annealing to room temperature, it was cooled to 0 K. Finally, the atomic positions were optimized to obtain the final oxide layer.
[0058] The density, silicon-oxygen ratio, defect type, and defect concentration of the oxide layer are obtained for evaluation.
[0059] Although the present invention is disclosed as above, the scope of protection disclosed by the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the scope of protection of the present invention.
Claims
1. A method for simulating the growth of a silicon surface oxide layer based on ion implantation technology, characterized in that: The steps include: Step S1: constructing a model of single crystal silicon, setting a vacuum layer on the surface of the single crystal silicon in the model, and using a reaction force field molecular dynamics method to put the single crystal silicon into an initial equilibrium state; Step S2: heating the single crystal silicon to a reaction temperature, and repeatedly emitting O atoms at random positions toward the surface of the single crystal silicon at intervals of a preset time, until an oxidation reaction occurs on the surface of the single crystal silicon; after the oxidation reaction is completed and reaches an equilibrium state, annealing the model to obtain an oxide layer; the emission speed ranges from 1500 to 3000 m / s, and the emission direction is along the reverse [100] crystal direction; Step S3: obtaining and evaluating the tissue morphology parameters of the oxide layer, if the tissue morphology parameters do not meet the preset requirements, repeating and optimizing steps S1 and S2 until the tissue morphology parameters meet the preset requirements; Wherein, in step S1, the initial equilibrium state of the single crystal silicon includes: optimizing the positions of the single crystal silicon atoms and relaxing them to a normal pressure state so that the force on the single crystal silicon atoms is zero; In step S3, the optimization steps S1 and S2 include: optimizing the reaction temperature, the preset time, the emission method and the annealing method of step S2; the organizational morphology parameters of the oxide layer include at least: density, silicon-oxygen ratio, defect type and defect concentration.
2. The method for simulating silicon surface oxide layer growth based on ion implantation technology according to claim 1, characterized in that: In step S1, the model of the single crystal silicon is a single crystal silicon square cell model having a diamond crystal structure.
3. The method for simulating silicon surface oxide layer growth based on ion implantation technology according to claim 1, characterized in that: In step S1, the thickness of the vacuum layer is in the range of 2-5 nm.
4. The method for simulating the growth of silicon surface oxide layer based on ion implantation technology according to claim 1, characterized in that: In step S2, the reaction temperature ranges from 500 to 800K.
5. The method for simulating silicon surface oxide layer growth based on ion implantation technology according to claim 1, characterized in that: In step S2, the preset time ranges from 5 to 10 ps.
6. The method for simulating silicon surface oxide layer growth based on ion implantation technology according to claim 1, characterized in that: In step S2, the annealing temperature ranges from 1000 to 1300K.