拉晶工艺参数对N型单晶硅氧含量的影响研究

Research on the Influence of Czochralski Process Parameters on Oxygen Content of N-Type Monocrystalline Silicon

TOPCon电池基板是以N型硅片为主,N型硅片的氧含量在一定程度上影响着TOPCon电池的转换效率。本文采用直拉法进行单晶硅的拉制,通过调整埚转、氩气流量和炉压来研究拉晶工艺参数对N型单晶硅氧含量的影响。数值模拟分析和实验结果表明:坩埚转速的增加会抑制浮力-热毛细漩涡,减少熔体界面处SiO的挥发,提高硅熔体内部和单晶硅棒氧含量;增大氩气流量和降低炉压可增大熔体界面处SiO的质量流量,有效促进SiO挥发,减少固液界面处氧含量,从而降低单晶硅棒氧含量。根据单晶硅氧含量测试和EL检测结果可知,坩埚转速5 r/min、氩气流量100 L/min和炉压1 200 Pa时拉制的N型单晶硅氧含量最低,电池端同心圆比例也是最低的。本文研究结果可为N型单晶硅棒降氧提供一定思路。

TOPCon cell substrates are dominated by N-type silicon wafers,and the oxygen content of N-type silicon wafers affects the conversion efficiency of TOPCon cells to a certain extent.In this paper,the Czochralski method was used to grow monocrystalline silicon,and the influence of crystal growth process parameters on the oxygen content of N-type monocrystalline silicon were studied by adjusting the crucible rotation rates,argon flow rates and furnace pressure.The numerical simulation analysis and experimental results show that:the accretion of crucible rotation rates can suppress buoyancy-thermal capillary vortices,reduce the volatilization of SiO at the melt interface,and increase the oxygen content in the silicon melt and in the monocrystalline silicon rods;increasing the argon flow rates and decreasing the furnace pressure can enlarge the mass flow rates of SiO at the melt interface,effectively promote SiO volatilization,reduce the oxygen content at the solid-liquid interface,and thus lessen the oxygen content in the monocrystalline silicon rods.The monocrystalline silicon oxygen content test and EL detection results show that,with the 5 r/min of crucible rotation rate,100 L/min of argon flow rate,and 1200 Pa of furnace pressure,the oxygen content in N-type monocrystalline silicon is the lowest,and the concentric circle ratio is also the lowest in the production of photovoltaic cells.The research in this paper can provide some ideas for reducing oxygen content in N-type monocrystalline silicon rods.