热屏结构对300 mm半导体级单晶硅生长过程温度分布影响的数值模拟  

Numerical Simulation of the Effect of Heat Shield Structure on Temperature Distribution in Growing 300 mm Semiconductor Grade Monocrystalline Silicon

作　　者：倪浩然 陈亚 王黎光 芮阳 赵泽慧 马成 刘洁 张兴茂 赵延祥 杨少林[2] NI Haoran;CHEN Ya;WANG Liguang;RUI Yang;ZHAO Zehui;MA Cheng;LIU Jie;ZHANG Xingmao;ZHAO Yanxiang;YANG Shaolin(Ningxia Research Center of Semiconductor-grade Silicon Wafer Materials Engineering Technology,Ferrotec(Ningxia)Semiconductor Co.,Ltd.,Yinchuan 750021,China;Ningxia Research Center of Silicon Target and Silicon-Carbon Negative Materials Engineering Technology,School of Materials Science and Engineering,North Minzu University,Yinchuan 750021,China)

机构地区：[1]宁夏中欣晶圆半导体科技有限公司,宁夏半导体级硅晶圆材料工程技术研究中心,银川750021 [2]北方民族大学材料科学与工程学院,宁夏硅靶及硅碳负极材料工程技术研究中心,银川750021

出　　处：《人工晶体学报》2024年第7期1196-1211,共16页Journal of Synthetic Crystals

基　　金：2022年银川市校企联合创新专项重大重点项目(2022XQZD007);2022年宁夏回族自治区重点研发计划项目(2022BFE02007)。

摘　　要：半导体级单晶硅是芯片的基础核心材料,不仅要求控制杂质浓度,还对晶体的缺陷有很高的要求。原生点缺陷浓度作为衡量晶体品质的重要指标之一,需要通过热场的优化、晶体生长温度场的调整、晶体生长过程中晶棒温度分布的控制,以及V/G值(拉速与晶棒内轴向温度梯度比值)的优化来调控。本文采用ANSYS软件中流体计算模块Fluent的有限体积分析法,研究了不同热屏结构对300 mm半导体级直拉单晶硅温度分布的影响。针对二段式热屏,模拟了不同热屏角度下拉晶初期(400 mm)、中期(800和1400 mm)和末期(2000 mm)三个等径阶段的温度分布、固液界面轴向温度梯度和V/G值。通过分析各阶段V/G值的变化,在相对较大的温度梯度下,寻找到了一种V/G值更接近临界值ζ且径向均一性更优的热屏结构,为控制缺陷的浓度提供更好的条件。通过对晶棒热历史的讨论,优化热屏结构以缩短降温周期,为控制缺陷的尺寸提供更好的条件。模拟计算结果表明,热屏夹角为110°、热屏下段厚度为70 mm、热屏内壁与晶棒间距为30 mm时,其结构设计能够提供低缺陷单晶硅生产的温度分布条件。Monocrystalline silicon is the fundamental material for chip manufacturing,and its quality depends not only on the control of impurity concentration but also on minimizing crystal defects.The density of native point defects in the crystal is one of the critical indicators for assessing the quality of the crystal,which requires optimization of the thermal field,adjustment of the temperature distribution during the crystal growth process,and precise control of the V/G ratio(the ratio of the pulling speed to the axial temperature gradient within the crystal).This study employs the finite volume method in ANSYS Fluent software to analyze the effect of different heat shield structures on the temperature distribution during the growth of 300 mm semiconductor-grade monocrystalline silicon by the Czochralski(Cz)process.Specifically,we investigated a two-piece heat shield design,altering the structure at different angles,and simulated the temperature distribution,axial temperature gradient at the solid-liquid interface,and V/G ratio at various stages of the pulling process(the initial stage at 400 mm,mid-stages at 800 and 1400 mm,and the final stage at 2000 mm).By analyzing the changes in V/G values across these stages,a heat shield structure with V/G values closer to the critical valueζand better radial uniformity was found under relatively large temperature gradients,providing better conditions for reducing defect density.Additionally,by discussing the thermal history of the crystal rod,optimizing the heat shield structure to shorten the cooling cycle and providing better conditions for controlling the size of defects.The simulation results indicate that a heat shield structure with an included angle of 110°,a bottom thickness of 70 mm,and a gap of 30 mm between the inner wall of the heat shield and the crystal rod provides suitable temperature distribution conditions for the production of low-defect monocrystalline silicon.

关 键 词：半导体级单晶硅 有限体积分析 热屏结构 温度场 流场 V/G值 缺陷 

分 类 号：TQ127.2[化学工程—无机化工] O782.5[理学—晶体学]