基于光脉冲辅助的金属诱导横向晶化多晶硅薄膜的研究

【作者】 王玉林；

【导师】 祁康成；

【作者基本信息】 电子科技大学 ， 光学工程， 2005， 硕士

【摘要】 本文首先对显示技术的发展和多晶硅薄膜的制备方法以及应用前景进行了综述,同时对Ni金属诱导非晶硅横向晶化制备多晶硅的研究现状以及诱导机理与应用等进行了系统概述。 多晶硅薄膜晶体管(p-Si TFT)液晶显示器可以实现高分辨率、高集成度、同时有效降低显示器的功耗,因而成为目前平板显示领域主要研究方向;而以横向晶化多晶硅为有源层的TFT由于在导电方向有更少的晶界、更低的金属杂质污染、更高的载流子迁移率而成为目前有源矩阵液晶显示领域、投影显示、OLED显示等领域研究的热点。本论文系统的研究了基于光脉冲辐射的Ni金属横向诱导晶化低温p-Si材料的制备及TFT器件设计和制作工艺。 本研究中,采用PECVD淀积法在玻璃基底上淀积SiNx/a-Si/SiNx复合薄膜,在最上层SiNx上刻蚀窗口并以之为掩模用真空热蒸发方法蒸发镍,使窗口中Ni和a-Si接触,采用金属横向诱导(MILC)和快速退火(RTA)相结合的方法制备了高质量的横向多晶硅带,采用SEM、TEM、波谱分析等分析手段,研究了薄膜的成分和结构以及电气特性。 a-Si薄膜在Ni诱导下,横向晶化温度降低到400℃以下。在环境温度490℃,光脉冲通断时间12s/1.8min的条件下横向生长速率达到40um/h。对退火温度、非晶硅薄膜厚度,RTA光脉冲宽度等参数对Ni金属诱导横向晶化的影响及晶化机理进行了深入的研究。经高分辨率透射电镜对镍条覆盖区的横向表面的高分辩像研究,发现成垂直Ni分界线方向的柱状晶粒,以柱状晶粒层为TFT的沟道,得到大的迁移率。 对晶化机理的研究表明,a-Si在Ni诱导下低温晶化是由于Ni扩散进a-Si:H,使Si-Si键从共价键变成类似于金属键形成了Ni的硅化物,降低了Si-Si键的键强,当薄膜在退火过程中,Ni-Si键断裂重组,而形成Si晶核,同时Ni原子从晶态硅中析出,继续向前面的a-Si:H中扩散,并形成Si-Ni混合层而继续诱导a-Si:H晶化。 开创性地研究了在卤钨灯管照射下形成的快速退火和Ni金属诱导横向生长相结合的薄膜晶化,观察到晶粒沿着垂直Ni条方向的择优快速生长,此创新成果,对玻璃基板上大面积低温TFT工艺有重要意义。更多还原

【Abstract】 The development of display technology and the fabrication method and application of Poly-silicon film are reviewed. The research progress of metal induced lateral crystallization (MILC) of amorphous silicon, the induced mechanism and the application of Ni-induced lateral crystallization of amorphous silicon are summarized in detail in this thesis.Poly-crystallization silicon thin film transistor (p-Si TFT) addressing liquid crystal display has been currently the research and development focus in the field of flat panel displays, as it is most feasible approach to high resolution, high integration and low power consumption as a result of its high aperture ration. There are less number interface of the crystal grain, lower metal impurity and higher mobility in the electric current director, the MILC p-Si TFT has been the research focus in the fields of AMLCD, projection display, OLED etc. In this thesis, the p-Si films have been made in the method of MILC assisted by RTA at low temperature, the TFT’s frame and facture technics has been designed.In this work, SiNx/a-Si:H/SiNx tri-layer thin films were deposited on the glass by Plasma Enhanced Chemical Vapor Deposition (PECVD). Ni metal was deposited by thermal evaporation deposition on the a-Si window formed by etching the topside SiNx, and then in the specially designed anneal stove anneal the a-Si film by the method of both MILC and RTA. The formation and the composition of crystalline silicon and the mechanism of Ni-induced lateral crystallization of hydrogenated amorphous silicon (a-Si:H) at low temperature were studied through the techniques of SEM, TEM and WDS etc. The electric characteristic of the film has been studied.The temperature fell to 400 ℃, anneal time reduced to 2 hours in the method of MILC assisted by RTA. The horizontal growth speed reaches 40um/hour when the environment temperature is 490℃, the on/off time of the light pulse is 12s/1.8min. The effects of some parameters were studied such as annealing temperature, the film thickness, the XRT light pulse width etc. Ni MILC mechanism was also studied. The study to the sample by high-resolution transmission electric mirror indicated that the crystalline grain is in the vertical direction of the Ni boundary. The mobility更多还原