Optical Thin Film Fabricated By Atomic Layer Deposition And Its Computer Simulation

The development in Atomic Layer Deposition (ALD) technology and its potential benefits such as film uniformity, excellent step coverage, precise thickness control and high reproducibility were reviewed. ALD will be more attractive because the conformal, uniform and pure films can be deposited by using this technique. Simulation of ALD process in atomic scale is of great significance to understand deposition mechanism, optimize film growth processes, and improve quality of films. We have made a series of investigation on simulation of Al₂O₃ ALD. The growth conditions, e.g., deposition rate, pressure and temperature were first compared with the conventional deposition methods. Multiple simulation results in different process conditions show that the quality of films is related with reaction chamber vacuum degree, substrate temperature and other factors.We deposited several optical films by atomic layer deposition,such as AL₂O₃, Ta₂O₅, TiO₂ and ZrO₂. Characterization of the films such as optical properties, surface morphology and microstructure was performed by using spectrophotometer, X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), scanning electron microscope (SEM) and atomic force microscopy (AFM). The results show that Al₂O₃, Ta₂O₅,ZrO₂ films are amorphous in the appropriate growth conditions. The films by this technique exhibit good optical properties with low absorption in the spectral region from mid-ultraviolet to near-infrared. The surface roughness, packing densities are excellent compared to other methods. In summary, the results demonstrate that ALD can be a suitable method for depositing optical fluoride thin films.