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小角晶界是重掺硼直拉<111>单晶硅生产制造过程中出现的严重缺陷,生产中需要避免。主要研究掺杂浓度对小角晶界的影响,通过实验发现当前工艺下小角晶界产生的临界掺杂浓度为9.05×1019cm-3。分析研究小角晶界的宏观分布及形态特征,其宏观分布与晶体各项异性具有一致性,并随掺杂浓度变化而规律性变化。利用位错模型计算小角晶界两侧晶向差为0.6″~12.76″,其晶向差随掺杂浓度增加而逐步变大。根据位错模型计算并分析自由能与掺杂浓度的关系,得到样品中宏观长度下小角晶界自由能为5.037×10-10~7 200.421×10-10J,并随着掺杂浓度增加而逐步变大。此外结合生长工艺和晶格补偿原理,提出高掺杂浓度下避免小角晶界的方法,并得到无小角晶界的重掺硼单晶硅,对实际生产有重要意义。
Small angle grain boundaries are heavy defects in the production process of heavy boron-doped Czochralski <111> monocrystalline silicon and need to be avoided in production. The effect of doping concentration on the small-angle grain boundaries is mainly studied. The critical doping concentration in the small-angle grain boundaries is 9.05 × 10 19 cm -3. The macro-distribution and morphological characteristics of the small-angle grain boundaries are analyzed and studied. The macroscopic distribution is consistent with the anisotropy of the crystals and varies regularly with the doping concentration. The dislocation model is used to calculate the crystal orientation difference of 0.6 “~ 12.76” on both sides of the small-angle grain boundary. The crystal orientation difference increases with the increase of the doping concentration. The relationship between free energy and doping concentration was calculated and analyzed according to the dislocation model. The free energy of the small-angle grain boundary in macro-length was 5.037 × 10-10 ~ 7 200.421 × 10-10J, and gradually increased with the doping concentration Bigger. In addition, combined with the growth process and the principle of lattice compensation, the method of avoiding small-angle boundaries at high doping concentration is proposed, and the heavily boron-doped single-crystal silicon without small angle boundaries is obtained, which is of great significance for practical production.