Laser-effected Ultra-large Grain Growth and Device Fabrication in Silicon Thin Films

该工作集中于在薄半导体膜中的激光驱动晶体生长，用于制造在包括高清晰度平板显示器的大面积电子器件中使用的薄膜晶体管（TFT）。其目标是通过一步制造工艺实现器件质量多晶材料的生产，并对单晶生长位置、取向和尺寸进行上级控制。在微观尺度上研究了快速变化的温度场的时空分布和固/液界面传播。本论文的主要工作如下：1）采用新型的双激光再结晶技术，一步制备出足够大的单晶区域，用于制备TFT。将开发一种新的基于激光的加工工具，并安装仪器，以实现先进的工艺控制和提高产量。将测试涉及图案化区域的处理以及空间修改的光束轮廓的方案。2）在所产生的多晶硅膜上制造和表征TFT，以检查多晶硅的质量，从而评估受控激光再结晶和横向晶体生长过程的有效性。研究结果将用于确定激光束参数和图案结构的最佳组合。3）设计并实现了一种基于热发射的时间和空间分辨的微尺度温度测量技术。测量的温度分布结合直接原位成像将提供关于微观结构演变的信息，包括淬火速率、过冷度、成核温度和固/液界面速度。实验结果将使复杂的相变过程的验证和准确的计算模型的建设。然后这些模型将用于改进工艺顺序。

0118366GrigoropoulosThe work is focused on laser-driven crystal growth in thin semiconductor films for fabricating thin film transistors (TFTs) utilized in large area electronics including high-definition flat panel displays. The goal is to achieve production of device-quality polycrystalline material through one-step manufacturing process with superior control of the single crystal growth location, orientation and size. The temporal and spatial distribution of the rapidly changing temperature field and solid/liquid interface propagation will be investigated at the microscale level. The following tasks will be carried out:1) One-step production of single crystal regions that are sufficiently large for fabricating TFTs via the novel double laser recrystallization technique. A new laser-based processing tool will be developed and instrumented for advanced process control and enhanced throughput. Schemes involving processing of patterned regions in conjunction with spatially modified beam profiles will be tested.2) Fabrication and characterization of TFTs on the produced poly-Si films in order to examine the quality of the poly-Si and hence evaluate the effectiveness of the controlled laser recrystallization and lateral crystal growth process. The results will be utilized to identify optimal combinations of the laser beam parameters and pattern configurations.3) Design and implementation of a new temporally and spatially resolved microscale temperature measurement technique based on thermal emission. The measured temperature distribution in conjunction with direct in-situ imaging will provide information on the microstructural evolution including the quenching rate, the degree of supercooling, the nucleation temperature and the solid/liquid interface velocity. The experimental findings will enable construction of validated and accurate computational models of the complex phase transformation process. These models will be then used for improving the process sequence.