Stress and doping impact on intrinsic point defect behavior in growing single crystal silicon
Stress and doping impact on intrinsic point defect behavior in growing single crystal silicon
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DOI：
10.1002/pssb.201400022
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发表时间：
2014-11
期刊：
影响因子：
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通讯作者：
K. Sueoka;E. Kamiyama;J. Vanhellemont;K. Nakamura
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文献类型：
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作者：
K. Sueoka;E. Kamiyama;J. Vanhellemont;K. Nakamura
为了大规模生产直径为450 mm的无缺陷Si晶体，必须考虑热应力对熔体生长单晶过程中本征点缺陷性质和行为的影响。最近，首次发表的实验证据表明，熔体/固体界面附近的压缩热应力使直径为300 mm的直拉Si晶体更富空位。为了定量地解释这些实验结果，使用基于密度泛函理论（DFT）的计算来确定空位（V）和自填隙（I）的形成率对压缩平面应力的依赖性。发现与各向同性应力相比，压缩平面应力给出了所谓的“Voronkov准则”的更高的应力依赖性。计算的平面应力依赖性与已发表的实验值非常一致，在开发直径为450 mm的无缺陷Si晶体的提拉工艺时应考虑到这一点。此外，实验观察到的替代型掺杂剂的类型和浓度对本征点缺陷行为和生长缺陷形成的影响背后的机制得到澄清。在DFT计算结果的基础上，提出了一个合适的重掺杂Si本征点缺陷行为模型。(i)在熔点处掺入的总V和I浓度取决于掺杂剂的类型和浓度。(ii)大部分的总V和I浓度有助于Frenkel对复合在硅晶体生长过程中的温度比那些形成生长在本征点缺陷集群高得多。Voronkov模型在考虑到目前的改进的同时，清楚地解释了所有报道的关于重掺杂Si生长缺陷的实验结果。最重要的剩余问题方面的本征点缺陷的行为和性能在单晶生长过程中从熔体进行了讨论。
For the mass‐production of 450 mm‐diameter defect‐free Si crystals, one has to take into account the impact of thermal stress on intrinsic point defect properties and behavior during single crystal growth from a melt. Very recently, first experimental evidence was published that the compressive thermal stress near the melt/solid interface makes a growing 300 mm diameter Czochralski Si crystal more vacancy‐rich. In order to explain these experimental results quantitatively, the dependence of the formation enthalpies of the vacancy (V) and the self‐interstitial (I) on compressive plane stress was determined using density functional theory (DFT) based calculations. It is found that compressive plane stress gives a higher stress dependence of the so‐called “Voronkov criterion” compared to isotropic stress. The calculated plane stress dependence is in excellent agreement with the published experimental values and should be taken into account in the development of pulling processes for 450 mm diameter defect‐free Si crystals. Also, the mechanisms behind the experimentally observed impact of the type and concentration of substitutional dopants on intrinsic point defect behavior and formation of grown‐in defects are clarified. On the basis of the DFT calculated results, an appropriate model of intrinsic point defect behavior in heavily doped Si is proposed. (i) The incorporated total V and I concentrations at the melting point depend on the types and concentrations of dopants. (ii) Most of the total V and I concentrations contribute to Frenkel pair recombination during Si crystal growth at temperatures much higher than those to form grown‐in intrinsic point defect clusters. The Voronkov model, while taking into account the present improvements, clearly explains all reported experimental results on grown‐in defects for heavily doped Si. The most important remaining problems with respect to intrinsic point defect behavior and properties during single crystal growth from a melt are also discussed.