Excimer Laser Crystallization Polysilicon

The rapid development of TFT-LCD as the mainstream of plane display devices, pushes the research tide to TFT. In TFT, comparing to amorphous-silicon (a-Si) material, polycrystal -line-silicon (p-Si) material has more virtues of higher mobility and integration with peripheral circuits, so more and more researchers have devoted to the researching of the method to prepare p-Si at low-temperature with cheap glass as substrate.In this thesis, by utilizing excimer laser annealing (ELA) crystallization, the study of p-Si has been deployed mainly. Because p-Si is of more special characteristics, comparing to a-Si and c-Si, firstly, I set forth electrical features of p-Si film and acknowledge profoundly electrical mechanism of p-Si film. Then three parameters of Laser annealing , including laser frequency-, accepted -pulse-times and laser power density are studied how to influence crystallization of p-Si. After obtaining optimized Laser frequency 5Hz accepted-pulse-times 10/second by experiments, laser power density increased little by little is focused on study. I find that the crystallization performance is the best at laser power density 300mJ/cm2 .It means crystallization degree is the best, grains are the most uniformity and film stress is the least.On the basis of metal induced crystallization (MIC) and ELA, we have proposed a new method of metal induced excimer laser annealing (MI-ELA). Little grains NiSi2with the characteristics of crystal-lattice-match with c-Si, can induce p-Si under laser radiation. By XRD, it becomes clear that not only highercrystallization degree has been obtained comparing to ELA and MIC in the same conditions, but also p-Si with selective crystal orientation has been achieved under proper conditions with this method. This kind of p-Si with ordered crystal orientation can improves the uniformity of etching and the mobility. But the disadvantage of the p-Si made with this method is the existing of Nickel on the film surface. This will affect the electrical performance of p-Si. So next work should be to study the crystallization mechanisnu Nickel contents and mobility after the Nickel-silicide on the surface is removed.In order to carry out experiments normally, the old equipments partly have been constructed and new-made equipments have been taken part in debugging. I-V testing of a single transistor has been carried out. The p-Si film is prepared by ELA, and electron mobility is calculated about 30cm2/V. s. The TFT arrays drive the OLED to light.