Numerical investigation on optical and heat transfer characteristics of a rapid thermal annealing system for LCD manufacturing

The objectives of present study are to propose a method to evaluate the quality of polycrystalline silicon film by using the thin film optics analysis, and to investigate heat transfer characteristics in a rapid thermal annealing system for liquid crystal display (LCD) manufacturing. The transmittance of polycrystalline silicon film is calculated by the characteristic transmission matrix method, and predicted results are compared with the experimental data for two different samples. The transient one-dimensional conduction and radiation heat transfer equations are additionally solved to predict the surface temperature of thin films. The two-flux method is employed to evaluate radiation heat transfer, and the ray-tracing method is utilized to take into account of the wave interference effect. As the film thickness increases, the peak transmittance value increases and the wavelength where the peak appears becomes longer due to wave interference. These characteristics can be used for in situ and practical estimation of the extent of crystallization of the silicon film during the process. From the thermal analysis, it is shown that the selective heating in the multilayer film structure acts as an important mechanism during the annealing of silicon film deposited on the glass.