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

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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.