PVT法碳化硅晶体生长热应力分析  

Thermal stress analysis of SiC crystal growth by PVT method

作　　者：孟大磊[1] 李璐杰[1] 张政[1] MENG Dalei;LI Lujie;ZHANG Zheng(The 46th Research Institute,CETC,Tianjin 300220,China)

机构地区：[1]中国电子科技集团公司第四十六研究所,天津300220

出　　处：《材料研究与应用》2020年第3期179-183,189,共6页Materials Research and Application

摘　　要：基于有限元数值计算方法,对物理气相传输(PVT)法生长碳化硅(SiC)晶体过程中籽晶托、坩埚侧壁、轴向温度梯度三个因素导致的热应力进行分析.研究结果表明:籽晶托与晶体之间的热失配所引起的热应力最大区域位于二者连接部位且靠近晶锭侧边缘,且与籽晶托厚度成正相关;坩埚壁与晶体之间热失配产生的热应力集中区域位于晶锭侧面,也与坩埚壁厚度成正相关;轴向温度梯度产生的热应力取值与轴向温度梯度取值正相关,存在一温度梯度取值,使得切应力分量低于位错形成的临界剪切应力限σ_(crs).根据研究结果,优化籽晶托及坩埚结构和热场,抑制了晶体开裂现象,并大幅降低了所制备SiC晶体的位错密度.Based on the finite element numerical calculation method,the thermal stress of SiC bulk crystal induced by the three factors of the seed crystal holder,the thickness of the sidewall of the crucible,and the axial temperature gradient during the growth of silicon carbide(SiC)crystal by the physical vapor transport(PVT)method is analyzed.The results show that the maximum thermal stress caused by the thermal mismatch between the seed crystal holder and the crystal is the main reason and induced the maximum thermal stress,and the crystal is located at the connecting part of the two parts and close to the side edge of the ingot,which is positively correlated with the thickness of the seed crystal holder.The thermal mismatch between the sidewall of crucible and the crystal was the secondary cause.The value of thermal stress generated by the axial temperature gradient is positively related to the value of the axial temperature gradient.The stress component is lower than the critical shear stress limitσcrs for dislocation formation.Based on the results,the structure and thermal field of the seed crystal holder and the crucible were optimized to suppress the crystal cracking phenomenon and greatly reduce the dislocation density of the prepared SiC crystal.

关 键 词：物理气相传输 碳化硅单晶 热应力 有限元 

分 类 号：TQ127.1[化学工程—无机化工]