LATTICE DEFECTS IN SILICON RAPIDLY SOLIDIFIED FROM THE MELT

为了研究硅在高温下的缺陷行为，进行了两种实验。(1)研制了红外线快速加热冷却装置，真空熔炼并淬火了FZ-Si小颗粒。通过透射电子显微镜（TEM）研究了淬火试样。(2)利用高分辨透射电子显微镜（HRTEM）对硅的熔化和凝固过程进行了原位观察，并采用了一种特殊设计的加热试样保持器。主要使用含氧量较低的FZ-Si试样，但在某些情况下也检查了广泛用于半导体器件技术的CZ-Si试样。结果表明：淬火态试样中存在多种晶格缺陷：{111}微孪晶、非本征型{111}层错、层错四面体、60度位错、间隙型位错环和未识别的细小缺陷团。 ...更多信息 HRTEM显示空缺集中。原位高温高分辨透射电镜观察表明，液固界面大部分变为{111}面，界面以一对原子台阶沿着界面横向运动的方式前后移动，温度变化不大。界面运动经常被几个微小的硅酸盐和杂质在试样表面扩散所打断。在液固界面附近，连续{111}晶面的剪切运动形成了{111}微孪晶。建议在固相和液相之间形成厚度约为1 nm的过渡层。在高温下观察到大量的{113}缺陷团簇，这些缺陷团簇可能与间隙原子团簇有关。实验结果表明，在硅熔化温度附近的高温下，一定会产生间隙原子和空位，它们与引入的杂质相关联，形成各种晶格缺陷。少

In order to study defect behaviors of silicon at high temperatures, two kinds of experiments have been performed. (1) A rapid heating and cooling apparatus with infrared rays was prepared, and small FZ-Si particles were vacuum-melted and quenched. The as-quenched specimens were investigated by transmission electron microscopy (TEM). (2) In situ high-resolution transmission electron microscopy (HRTEM) has been carried out to observe melting and solidification of silicon using a specially designed heating specimen holder. FZ-Si specimens with lower oxygen content have been mainly used, but CZ-Si specimens widely used in the semiconductor device technology were also examined in some cases. The results are summarized as follows.A variety of lattice defects were found to be formed in the as-quenched specimens ; {111} micro-twins, extrinsic type {111} stacking faults, stacking fault tetrahedra, 60 degree dislocations, interstitial type dislocation loops and unidentified fine defect clusters. … More HRTEM suggested clustering of vacancies. In situ high temperature HRTEM observations showed most liquid-solid interface planes became {111}, and the interface went forth or back by lateral motion of a pair of atomic steps along the interface with slight temperature change. The interface motion was frequently interrupted by several tiny silicate with impurities diffusing on the specimen surfaces. It was also shown that {111} micro-twins were formed by shear motion of successive {111} planes in the vicinity of liquid-solid interface. Formation of a transient layer with a thickness of about 1 nm is suggested to exist between solid and liquid phases. A number of {113} defect clusters possibly associated with interstitial atom clustering were observed at high temperatures. It is concluded from the present experiments that both interstitial atoms and vacancies are certainly produced at high temperatures near the melting temperature of silicon, and they are correlated with introduced impurities to form various lattice defects. Less