超大口径电子级单晶硅的研发是为适应我国发展超大规模集成电路的重大需求，坩埚内部硅熔体流动的不稳定特性是影响大尺寸单晶硅生长的关键因素之一。本项目研究提拉法制备450 mm口径单晶硅过程中坩埚内部硅熔体流动的不稳定特性，及其对结晶界面形态的影响机制。根据单晶硅生长动力学关于结晶界面过冷度与生长速率之间的关系，建立不稳定熔体流动与波动结晶界面的耦合数值模型，研究单晶硅生长过程中坩埚旋转和外磁场等关键物理量对不稳定熔体流动中熔体温度和速度的脉动及其频谱特性的影响规律，获得结晶界面过冷度的脉动特征，进而阐明熔体不稳定性对结晶界面形状、生长速率和界面处温度梯度等界面形态参数的影响机理，提出改善熔体流动稳定性和结晶界面形态的初步技术方案，为提拉法制备高质量大尺寸单晶硅技术提供科学理论依据。

The research and development (R&D) of large-diameter electronic grade monocrystalline silicon is to meet the strategic requirement of the development of very large-scale integrated circuit (VLSI) in our country. The instability of the silicon melt flow in the crucible is one of the key factors influencing the growth of large-diameter monocrystallline silicon. In this project we study the characteristics of unstable melt flow in the crucible during the Czochralski (CZ) crystal growth of silicon of 450 mm in diameter, and investigate the influence mechanism of flow instability on the interface morphology of crystal growth. A numerical model, coupling the unstable melt flow and the fluctuant crystal growth interface, is established by considering the relationship between the kinetic undercooling and the growth rate. With this model, we study the influence mechanisms of the key parameters, such as the rotation rates of crystal and crucible, and the size and position of cusp-shaped magnetic field, on the fluctuations and spectral characteristics of temperature and velocity in the unstable melt flow. The fluctuation of undercooling at the growth interface is obtained to reveal the influence of flow instability on the interface morphology parameters, such as the interface shape, the growth rate and the temperature gradient at the growth interface. Some preliminary technical solutions are proposed to improve the stability of melt flow and morphology of the growth interface, which provides a theoretical basis to the manufacture of large-diameter monocrystalline silicon with high quality.