Abstract:

This paper focuses on conducting microscopic-level reaction molecular dynamics simulations of the thermal decomposition and reduction system of trichlorosilane in a hydrogen atmosphere involved in the chemical vapor deposition process of polysilicon production. It qualitatively and quantitatively investigates the influence of the quantity ratio of reactants H₂ and hydrogen radicals H·on the microscopic action mechanism of the reaction process. Additionally, it comparatively analyzes the dynamic evolution and main transformation paths of reactants SiHCl₃, H₂, and H·, as well as intermediates HCl, SiH₂Cl₂, and SiH₄ in different reaction systems, providing fundamental theoretical support for the process improvement of the chemical vapor deposition process of polysilicon. The simulation results indicate that the reactivity of H· in the reaction system is significantly higher than that of H₂. The introduction of H· can noticeably accelerate the thermal decomposition and reduction processes of SiHCl₃ molecules in a hydrogen atmosphere. Specifically, the larger the quantity ratio of H· to H₂ added to the initial reaction system, the greater the number of SiHCl₃ molecules that are transformed when reaching reaction equilibrium. The production amount of intermediate HCl molecules is positively correlated with the quantity of H· added to the initial reaction system. An appropriate amount of H· can prompt SiHCl₃ molecules to form monohydrogenated species, while excessive H· promotes the formation of polyhydrogenated species. When the reaction temperature of the actual reaction system is set at 1000K and the quantity ratio of SiHCl₃ to H₂ is set at 1∶1, it is conducive to the formation of the byproduct SiH₂Cl₂. To obtain the intermediate SiH₄ at a relatively lower reaction temperature (1000K), the quantity ratio of SiHCl₃ to H₂ needs to be at least greater than 1∶1. Increasing the content of H₂ in the reaction system is beneficial for enhancing the yield of the intermediate SiH₄.

Key words: trichlorosilane, thermal decomposition and reduction system in gas, hydrogen radicals, reaction molecular dynamics simulations, dynamic evolution

摘要：

针对多晶硅生产工艺中的化学气相沉积过程涉及的三氯氢硅在氢气氛中的热分解及还原体系开展微观层面的反应分子动力学模拟，定性和定量地探究了反应物H₂与氢自由基（H·）的数量配比对反应过程的微观作用机制的影响，并比较分析了不同的反应体系中反应物SiHCl₃与H₂及H·、中间产物HCl与SiH₂Cl₂及SiH₄的动态演化情况及其主要的转化路径，为多晶硅化学气相沉积过程的工艺改进提供了基础的理论支撑。模拟结果表明，反应体系中H·的活泼性明显大于H₂，H·的引入可以明显加快SiHCl₃分子在氢气氛中的热分解与还原过程，具体表现为加入初始反应体系的H·与H₂数量比越大，达到反应平衡时被转化的SiHCl₃分子越多；中间产物HCl分子的生成量与加入初始反应体系的H·的数量正相关；适量的H·可以促使SiHCl₃分子形成一氢代物，而过量的H·促使SiHCl₃分子形成多氢取代物，当实际反应体系的反应温度设置为1000K且SiHCl₃与H₂数量配比设置为1∶1时，有利于副产物SiH₂Cl₂的形成；为了在相对较低的反应温度（1000K）下得到中间产物SiH₄，SiHCl₃与H₂的数量配比至少需要大于1∶1，增加反应体系中H₂的含量，有利于提高中间产物SiH₄的产量。

关键词: 三氯氢硅, 气相热分解与还原, 氢自由基, 反应分子动力学模拟, 动态演化