Crystallization behavior of semiconducting materrials from Undercooled Melts

在过去的几十年里，硅一直是最重要的工业材料之一。在此期间，电子工业一直在努力增加锭的尺寸，以降低芯片生产成本。然而，直径越大，用于处理基材的工厂和设备的投资额就越高。近年来，一个具有挑战性的降低成本的想法被提出，那就是将集成电路安装在小球形硅晶体的表面上。然而，需要开发生长这种球形单晶的技术。本研究采用控制过冷度下的无容器处理技术，从未冷却的硅液滴中进行结晶。测量的生长速率与过冷度被分为三个区域，IA，IB，II和III，分别从界面形态的点。一种界面由硼组成的薄板晶体， 关于我们 在过冷度小于40 K的IA区，观察到了锯齿状的第三小平面和波状边缘平面。在过冷度从40 K到100 K的IB区，薄板晶体分叉成多个板。在过冷度为100 ~ 200 K的区域II中，观察到规则排列的小面枝晶，而在过冷度超过200 K的区域III中，观察到不规则排列的枝晶。假设界面的形态变化为边缘平面的三维失稳，对于直径为5 mm的样品，从区域I到区域II的过渡的临界过冷度理论上估计为100 K。理论分析表明，模具临界过冷度与试样尺寸有关，试样尺寸越小，模具临界过冷度越大。在区域I中的温度下接种的样品是具有大晶粒的准单晶，除了观察到孪晶和开裂的小区域。结果表明，如果使用较小的样品，例如直径为2或3 mm，则可以生长单晶。少

Over the past several decades silicon has been one of the most important industrial materials. In this period, electronics industries have strived to increase the size of ingots in order to lower the cost of chip production. The larger the diameter, however, the higher the amount of investments in plants and equipment for processing the substrate has to be. Recently, a challenging idea that will reduce the cost has been proposed ; that is to mount integrated circuit on the surface of small spherical silicon crystal. However, the technique of growing such spherical single crystals needs to be developed. In the present study, the crystallization from the unedercooled drop of silicon was carried out by means of techniques of containerless processing under the controlled undercooling. The measured growth rate vs. undercooling was categorized into three regions, IA, IB, II and III, respectively, from the point of the interface morphology. A thin plate crystal whose interface consisted of bo … More th faceted (III) plane and wavy edge plane like saw-tooth was observed in the region IA where the undercooling is less than 40 K. The Thin plate crystal branched to several plates in the region IB where the undercooling from 40K to 100K. In the region II where the undercolling is from 100K to 200K, regularly arrayed faceted dendrite was observed, whereas irregularly arrayed dendrite was observed in the region III where the undercooling is beyond 200K. Assuming the morphological change of the interface as the three-dimensional destabilization of the edge plane, the critical undercooling for the transition from region I to region II was theoretically estimated as 100 K for the samples whose diameter is 5mm. The theoretical treatment predicts that the critical undercooling will depend on the sample size, that is, the smaller the sample size, the larger die critical undercooling. The sample seeded at temperatures in the region I is a quasisingle crystal with a large grain, except a small area where twinning and a cracking are observed. The result suggests that a single crystal could be grown, if a smaller sample, for instance, 2 or 3mm in diameter, were used. Less