| Summary: | 碩士 === 國立中興大學 === 機械工程學系所 === 97 === This thesis concerns the crystallization of low temperature poly-silicon films. The sizes of grains in poly-silicon films are determined by optical transmittance and reflectance measurements. These optical measurements allow for the quality control of growing low temperature poly-silicon films for the fabrication of liquid crystal displays.
Amorphous silicon films are annealed to form poly-silicon films under a 308 nm XeCl excimer laser excitation with different laser intensities. The poly-silicon grain size is found to increase by raising the laser excitation intensity. Both the laser intensity and amorphous silicon film thickness affect the grain size and surface roughness of the poly-silicon films, which can be characterized by the wavelength dependence of optical transmittance and reflectance measurements. In addition, the grain size and surface roughness can be characterized by a scanning electron microscope (SEM) and atomic force microscope (AFM), respectively. The grain size and surface roughness determined by the SEM and AFM are then compared with and correlated to the optical transmittance and reflectance measurements. The experimental results show that the transmittance decreases and the reflectance increases while increasing the surface roughness. When the grain size is in the range of 250 nm-450 nm (determined by the SEM), the poly-silicon film on a glass substrate is found to exhibit the transmittance of 30%-35% and the reflectance of 55%-60% on average in the visible light wavelength range of 450 nm-500 nm.
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