AB-INITIO MOLECULAR-ORBITAL STUDY OF WATER-ABSORPTION AND HYDROLYSIS OF CHEMICAL-VAPOR-DEPOSITED SIOF FILMS .2.

In part I; we reported the mechanism of water absorption and hydrolysi s of SiOF films theoretically using the ab initio molecular orbital (M O) method with small SiFn(OH)(4-n) (n = 0-3) tetrahedral model cluster s. It was revealed that the multiple F-substituted Si atoms had a high er reactivity against both OH- and H2O than Si atoms with one or no Si -F bonding. Also, defect sites such as non bridging oxygens (NBOs) and free spaces around Si-F bonding were proved to promote the hydrolysis and successive water adsorption. The structure required to initiate t he hydrolysis reaction was the multiple F-substituted Si: in particula r; = SiF2. In part 2, we attempt to show the possibility of suppressin g the formation of = SiF2. The results of a Monte Carlo investigation corresponding to such as an F-ion implantation into SiO2 suggested the possibility of achieving higher doping of F with suppression of the f ormation of SiFx by modulating the probability of F substitution into SiO2.