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小角晶界是Si单晶中的严重缺陷,生产中需要极力避免。对于重掺B直拉<111>Si单晶,当掺杂浓度接近固溶度时就容易产生小角晶界。对直拉Si单晶中小角晶界产生的原因进行梳理及深入分析,在理论上提出减少过冷度来减少小角晶界缺陷的方法。分别采用增加加热器功率减小过冷度及降低埚位减少过冷度的两种工艺方法,成功实现生长无小角晶界重掺B<111>Si单晶。通过生产中实际晶体生长情况对比分析发现,低埚位生长无小角晶界的重掺B直拉<111>Si单晶工艺更具备生产优势。
Small-angle grain boundaries are serious defects in Si single crystals that are strongly avoided in production. For heavily doped B Czochralski <111> Si single crystal, small angle grain boundaries easily occur when the doping concentration is close to the solid solubility. The reasons for the small-angle grain boundaries in Czochralski Si were combed and analyzed in depth, and a method to reduce the degree of undercooling and reduce the defects at the grain boundaries was put forward theoretically. Two kinds of processes, including increasing heater power to reduce supercooling degree and decreasing crucible temperature to reduce supercooling degree respectively, were successfully adopted to grow B <111> Si single crystals with no small-angle grain boundaries. Through the comparison of the actual crystal growth in the production, it is found that the production of low-alloyed B heavy-pull <111> Si single crystal without small-angle grain boundaries is more advantageous for production.