Unseeded Crystal Growth of (100)-Oriented Grain-Boundary-Free Si Thin-Film by a Single Scan of the CW-Laser Lateral Crystallization of a-Si on Insulator
Unseeded Crystal Growth of (100)-Oriented Grain-Boundary-Free Si Thin-Film by a Single Scan of the CW-Laser Lateral Crystallization of a-Si on Insulator
复制标题
通过绝缘体上非晶硅连续激光横向结晶的单次扫描实现 (100) 取向无晶界硅薄膜的无晶种晶体生长
作者：
N. Sasaki;M. Arif;Y. Uraoka;J. Gotoh;S. Sugimoto
在绝缘衬底上激光晶化a-Si薄膜是制作三维集成(3D IC)、平板显示器(FPD)或柔性电子器件的一种很有前途的技术，因为这种晶化可以在室温的衬底上进行，从而避免了对底层器件或支撑面的损害。为了提高场效应管(FET)的电学特性的均匀性，需要制备无晶界取向的薄膜。本文描述了一种新发现的简单方法，即在空气中用波长为532 nm的高顶平线光束对a-Si进行连续激光横向晶化的单次扫描，在室温下稳定地获得{100}取向的无晶界硅薄膜。在人工调制固液界面晶化的无晶界薄膜中，晶体取向难以控制，任何其他试图通过多次辐照获得择优表面取向的尝试都会导致晶界。在满足以下条件的条件下，实现了{100}取向的无晶界薄膜的自组织生长：(1)高度均匀的顶平线光束，(2)SiO_2帽，(3)在横向生长阈值附近的低激光功率密度，(4)单扫描结晶。较高的扫描速度使{100}取向的无晶界薄膜的工艺窗口变宽。这种结晶非常简单，因为它是通过一次非种子扫描与线束在室温空气中衬底进行的。
Laser crystallization of a-Si film on insulating substrate is a promising technology to fabricate three-dimensional integrations (3D ICs), flat panel displays (FPDs), or flexible electronics, because the crystallization can be performed on room temperature substrate to avoid damage to the underlying devices or supporting plane. Orientation-controlled grain-boundary-free films are required to improve the uniformity in electrical characteristics of field-effect-transistors (FETs)fabricated in those films. This paper describes the recently found simple method to obtain {100}-oriented grain-boundary-free Si thin-films stably, by using a single scan of continuous-wave (CW)-laser lateral crystallization of a-Si with a highly top-flat line beam with 532 nm wavelength at room temperature in air. It was difficult to control crystal orientations in the grain-boundary-free film crystallized by the artificial modulation of solid-liquid interface, and any other trial to obtain preferential surface orientation with multiple irradiations resulted in grain boundaries. The self-organized growth of the {100}-oriented grain-boundary-free films were realized by satisfying the following conditions: (1) highly uniform top-flat line beam, (2) SiO2 cap, (3) low laser power density in the vicinity of the lateral growth threshold, and (4) single scan crystallization. Higher scan velocity makes the process window wide for the {100}-oriented grain-boundary-free film. This crystallization is very simple, because it is performed by a single unseeded scan with a line beam at room temperature substrate in air.