Position and Orientation Control of Si Thin-Film Crystal Grain Using Nano-Imprint Technology

本研究工作旨在开发一种能够控制非晶衬底上Si薄膜晶粒位置和晶向的创新技术。下文总结了这项工作。(1)我们已经开发了一种方法，以提高晶体的成核在所需的位置的非晶硅通过转移非常少量的金属形成的尖端阵列，这是通过各向异性蚀刻的单晶硅覆盖有金属膜，在非晶硅膜表面的纳米尺寸的区域制备。所涉及的化学是金属诱导的硅结晶。在低至450 ℃的结晶温度下观察到晶体增强的晶体成核。Ni被认为是这种现象的最有效的金属物种。使用电子背散射图案分析的晶体取向分析表明，如此制备的晶粒的晶体取向为（111）取向。(2)熔化和再结晶 关于我们 已经发现，通过照射受激准分子激光脉冲来照射如此制备的硅膜，由于由上述金属诱导结晶形成的晶核的晶粒生长，导致直径大至3微米的硅晶粒的生长。发现通过形成二氧化硅膜的抗反射涂层来减少激光的反射，从而增加晶粒尺寸。(3)通过在沉积非晶硅之前在非晶衬底的表面处形成凹坑阵列，发现硅膜在受激准分子激光退火的照射下开始再结晶。结果，形成直径约为2微米的硅颗粒阵列。(4)通过结合使用在衬底表面处的凹坑形成的晶粒定位和金属诱导的非晶硅横向结晶的优选取向，能够制备位置和取向被控制的硅晶粒。(5)在金属诱导横向晶化之前对非晶硅薄膜进行图形化处理，会出现横向晶向的过滤效应。发现这种效应对于进一步改善硅晶粒的结晶质量是有效的。少

This research work was carried out aiming at developing a innovative technology that can control the position and crystal orientation of Si thin-film grains on an amorphous substrate. The followings summarize this work.(1) We have developed a method to enhance crystal nucleation at desired position of amorphous silicon by transferring very small amount of metal form a tip array, which was prepared by anisotropic etching of single crystal silicon covered with a metal film, to nano-meter sized area at the surface of amorphous silicon film. The chemistry involved is the metal induced crystallization of silicon. The crystal enhanced crystal nucleation is observed at crystallization temperatures as low as 450 degree C. Ni was found to be most effective metal species for this phenomenon. Analysis of crystal orientation using electron backscattering pattern analysis has revealed that the crystal orientation of thus prepared crystal grains are (111) orientation.(2) Melting and recrystallizatio … More n of thus prepared silicon film by irradiating an excimer laser light pulse have been found to result in the growth of silicon grains whose diameter is as large as 3 micrometers owing to the grain growth from the crystal nucleus formed by the above mentioned metal induced crystallization. The grain size was found to be increased by reducing the reflection of the laser light by forming an antireflective coating of silicon dioxide film.(3) By forming an array of pit at the surface of the amorphous substrate before deposition of amorphous silicon, the silicon film was found to start recrysatallization upon irradiation of excimer laser annealing. As the result, an array of silicon grains having the diameter of about 2 micrometers are formed.(4) By combining the grain positioning using the pit formation at the substrate surface and the preferred orientation of the metal induced lateral crystallization of amorphous silicon, it is able to prepare silicon crystal grains whose position and orientation are controlled.(5) The filtering effect of lateral crystal orientation appears when the amorphous silicon film was patterned prior to the metal induced lateral crystallization. This effect was found to be effective to further improve the crystalline quality of silicon grains. Less