拉速对12英寸单晶硅点缺陷分布影响的动态模拟仿真研究

Pulling Rate on Point-Defect Distribution in 12-Inch Silicon Single Crystal by Dynamical Simulations

半导体单晶生长过程中伴随大量的空穴性和间隙性本征点缺陷,这些本征缺陷在单晶生长过程中随着晶体温度的降低不断复合或湮灭形成纳米级空洞型或位错、层错等缺陷,会对硅片质量及后续的器件性能产生严重影响。利用计算机模拟仿真技术对12英寸半导体直拉单晶硅生长过程的传热及点缺陷进行了动态模拟仿真计算。动态仿真计算过程中分别采用了恒定及连续变化的拉速,以研究单晶直拉速度对点缺陷分布的影响。研究结果表明,生长速度较快时,晶体内部主要以空穴性点缺陷为主;当生长速度逐步降低,晶体内部空穴性缺陷区域逐渐缩小;通过合适的拉速控制及V/G理论,使用点缺陷动态模拟仿真计算可为生长特定点缺陷分布甚至无点缺陷硅单晶工艺提供有效依据。

During Czochralski silicon single crystal growth,a large amount of native point defects precipitated at melt/crystal interface due to defect supersaturation. With the decrease of crystal temperature,nanoscale micro-void and dislocation would grow through recombination or annihilation. All these defects had a serious impact on wafer quality and subsequent device performance. Global modeling and dynamical simulations of heat transfer and point defects for Czochralski 12-inch silicon single crystal growth were performed.The numerical simulation results showed that the core of growing crystal was dominated by vacancies when the growth rate was high,and the diameter of vacancy-dominated core decreased when the growth rate was gradually reduced. At enough low growth rate the whole core of growing crystal became interstitial-dominated. Point-defect dynamical simulations could provide an efficient way to grow silicon single crystals with specific point-defect distribution or even defect-free crystals through appropriate control of pulling rate.