Fundamental Research of Epitaxial Growth of Insulator Films Using Ultra-Violet Irradiation

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In order to grow epitaxially insulator films (Al_2O_3) on Si substrates, absorption of Al(CH_3)_3 and N_2O gases and reaction between Si surface and the gases were investigated using X-ray photoelectron spectroscopy (XPS). It was found that TMA adsorption on Si clean surface at room temperature was physical adsorption, and that SiC layers were formed at the interface by annealing at 600゜C. To keep away from this phenomenon, it is very useful to cover the Si surface with a few atomic layers of oxide. From these results, epitaxial growth of Al_2O_3 films was sudied by four kinds of method : Solid phase epitaxy, laser CVD, MO-MBE, and LP-CVD. We succeeded in epitaxial growth of Al_2O_3 films on Si substrates using MO- MBE, and LP-CVD methods. Heteroepitaxial growth by MO-MBE method was performed onto (100) and (111) Si substrates at growth temperatures between 720゜C and 800゜C, in the case of LP-CVD, the growth temperature was 1000゜C. The epitaxial films had a structure of <gamma>-Al_2O_3, and the oientation relationships of (100) <gamma>-Al_2O_3/(100)Si and (111) <gamma>- Al_2O_3/(111)Si. The lattice mismatch was 2.4%, which was smaller than that of Si on Sapphire (<gamma>-Al_2O_3).