Further development of the microelectronic technology requires the growing of stable and passivated dielectric thin films. Photochemical processes are very promising methods to obtain silicon dioxide films for microelectronic purposes. In this article, the aging of silicon oxide films obtained by ArF laser chemical vapor deposition at low temperature is studied. The evolution of the properties of films has been followed up using infrared spectroscopy and ellipsometry, and compared with aging of thermally oxidized silica films. The role of moisture in film aging is also clarified by comparing films exposed to humid and to dry atmospheres. Si-OH groups are incorporated into the film in a specific local bonding environment and relaxation in the film structure takes place while new Si-O groups can be created. Moreover, the dependence of the stability of film properties on the processing parameters is analyzed.