Graphoepitaxial Growth of Semiconductor Thin Film on the Textured Natural Crystalline Surface Relief Duplicated on a Foreign Substrate

根据外延生长机理，只要在非晶态衬底表面写入具有一定晶体周期和对称性的微扰，并且晶体生长受到周期性图案的影响，就可以在任何不同晶体结构的衬底上生长出单晶薄膜。这项技术通常被称为“石墨炉外延”。这项工作的目的是建立一种利用这种梯度外延生长现象来制备大面积单晶半导体薄膜的技术，并评估其应用于需要很大面积的半导体器件(如太阳能电池和显示器件)的可能性。1990年，新引入了红外光退火仪，获得了Ge薄膜再结晶的基本技术数据。还追求了从共晶合金中进行的与在Ge GraPhoepi…中所看到的相同类型的梯度外延生长在我们之前的工作中有更多的出租车。然而，硅既与合金金属发生反应，又与衬底发生反应，很难获得大尺寸的单晶硅薄膜。根据这一结果，决定了修正的主要目的是建立一种从硅颗粒外延生产大面积Ge的技术。1991年，人们提出了一种新的梯度外延衬底结构，并建立了相应的制备工艺。本工作中的衬底浮雕具有金字塔的形状，这种形状是通过对Si(100)晶片的选择性腐蚀而制成的。我们之前的底物在整个底物区域都有这个金字塔形的浮雕。生长的微晶的晶体取向受每个生长部位的表面起伏所控制。然而，很小的取向失配会产生许多晶界，得到的晶粒度最大可达0.01 mm左右。新结构是一种部分纹理的结构。织构部分的尺寸被确定为与我们以前的工作中的晶粒度相同的量级，在此基础上我们可以得到单晶。在剩余的区域上，可以利用织构部分上的梯度外延生长的单颗粒作为种子横向生长半导体薄膜。使用Si(100)晶片收集了有关衬底制作的系统技术数据。为了防止外延生长，对部分织构的硅片进行了氧化处理，并连续沉积了W、Al和Ge。然后用红外光退火仪对Ge薄膜进行再结晶处理。在平坦的衬底上，退火后的Ge薄膜具有(111)织构，这是梯度外延所必需的条件。然而，我们在金字塔浮雕部分看不到图形外延现象。对生长的Ge薄膜的仔细表征表明，与用Ar激光进行的退火相比，退火温度不够高。更快更高温的600ﾟC以上的退火是必要的。较少

According to the epitaxial growth mechanism, it can be expected that single crystalline thin film could be grown on any substrates of quite different crystalline structure if certain perturbation with some crystallographic period and symmetry were written on the amorphous substrate surface and the crystal growth were affected by the periodic pattern. This technology is generally called "Graphoepitaxy". The purpose of this work is the establishment of a technology to produce a large area single crystalline semiconductor thin film utilizing this graphoepitaxial growth phenomenon and assessment of the probability of the application to a semiconductor devices which requires a very large area such as solar cells and display devices.In 1990, an infrared light annealing apparatus was newly introduced and got basic technical data on the recrystallization of Ge film. It is also pursued that the same kind of graphoepitaxial growth from eutectic alloy would be occurred as was seen in Ge graphoepi … More taxy in our previous work. However, Si reacts with alloy metal aswell as the substrate and it is very difficult to obtain large single crystalline Si thin film. It was decided from this results, to revise, the main purpose to establish a technique to produce large area growth of Ge from Si graphoepitaxy. In 1991, a new structure of the graphoepitaxial growth substrate was proposed and the fabrication technique was established. The substrate relief in this work has the shape of pyramid fabricated by a selective etching of Si(100)wafer. Our previous substrate had this pyramidal relief on whole area of substrate. Crystallographic orientation of grown crystallite was controlled by the surface relief of each growing sites. However, very small orientation mismatch create many grain boundaries and obtained grain size is around 0.01mm at most. New structure is partially textured one. The size of the textured part is determined to be the same order of the grain size in our previous work on which we can made single grain crystal. On the remained area, semiconductor film could be grown laterally utilizing the graphoepitaxially grown single grain on the textured part as a seed. Systematic technical data on the substrate fabrication were collected using Si(100)wafers. The partially textured Si wafer was oxided to prevent epitaxial growth, and W, Al and Ge were deposited successively. After that, Ge film was recrystallized by infrared light annealing apparatus. Annealed Ge film on the flat substrate had(111)texture which is essentially required condition in graphoepitaxy. However we cannot see graphoepitaxy phenomenon on the pyramidal relief part. Careful characterization of grown Ge film implied that annealing temperature is not sufficient as compared with the annealing by Ar laser. More rapid and higher temperature annealing of more than 600ﾟC is found to be necessary. Less