Oxygen ions from a cold cathode ion-gun have been used tor bombarding the growing thin films. The effect of ion bombardment on film packing density and moisture adsorption is examined. Experimental results confirm that the packing density of ZrO2, TiO2 and SiO2 with ion bombardment, measured by a quartz crystal microbalance, is increased to over 0.9. Based on the technique of moisture adsorption the measured drift of the peak transmission wavelength of interference filters consisted of these materials is reduced by a factor of B. It shows that ion assisted technique might be employed to produce films of superior optical and mechanical performances.