碳化硅晶体生长炉辐射换热特性的数值模拟

Numerical Simulation of Radiation Heat Transfer in SiC Crystal Growth Furnace

采用C语言建立了碳化硅（SiC）晶体生长炉三维温度场数值模拟平台,基于柱坐标系构建生长炉物理模型,采用有限体积法离散数学模型,利用S2S（Surface to Surface）辐射模型考察了生长室内的辐射换热特性,提出判断辐射面可视性的最短距离法.模拟了电流强度1250 A、电流频率16 k Hz条件下的生长炉温度场,定量揭示了生长室内的辐射换热强度;采用标准偏差法研究了线圈结构对晶体内部温度及温度梯度均匀性的影响.结果表明,螺旋电磁加热线圈容易导致生长炉内部温度场呈非轴对称分布;辐射热流较导热热流大102-103倍,辐射换热促使生长室内温度分布均匀;螺旋线圈的布置方式使晶体截面温度呈非轴对称分布,造成温度梯度的均匀性变差,晶体生长过程中容易产生热应力,影响晶体质量.

Three dimensional numerical simulation platform for SiC crystal growth furnace was established based on C programmg language, where physical model of the furnace was built based on cylindrical coordinate, governing equations for electromagnetic and temperature fields were discretized by finite volume method, and radiation characteristic was studied with the help of S2S （Surface to Surface） radiation model. The least distance method was developed, which was used to check whether radiation surfaces were visible with each other or not efficiently. And then the radiation heat transfer in SiC growth chamber and temperature field of SiC growth furnace were studied quantificationally when the current intensity is 1250 A and the current frequency is 16 kHz. The effects of coil structures on crystal temperature field and its gradient distributions were studied by standard deviation method. The results showed that spiral electromagnetic coil generated asymmetrical temperature field easily. The radiation heat flux was 10^2-10^3 more than conduction heat flux. The radiation was helpful to increase temperature evenness. The spiral temperature field on the SiC crystal cross-section reduced the poor homogeneity of temperature gradient, which made the crystal to generate large thermal stress.