Growth and properties of chemical-vapor-deposited Ti-P-O films grown under the CO2- and H2-existing conditions

Amorphous titanium phosphate (Ti-P-O) films are prepared by low-pressure chemical vapor deposition (CVD) using a mixture of titanium tetrachloride (TiCl₄) and trimethyl phosphite (P(O-CH₃)₃). Two systems are studied: one is the TiCl₄/P(O-CH₃)₃/CO₂ or the CO₂ system and the other is the TiCl₄/P(O-CH₃)₃/H₂ or the H₂ system. Growth and properties of the CVD Ti-P-O films are functions of deposition temperature and the CO₂ and H₂ inputs. The films have a higher growth rate and a lower Ti content at higher deposition temperature. A high CO₂ input favors for film growth, but a high H₂ flow rate is detrimental. Variations of growth rate and film composition with the CO₂ and H₂ inputs are rationalized by the proposed growth mechanisms. The changes in internal stress with deposition temperature and the CO₂ and H₂ inputs are mainly attributed to film thickness. The large difference in electrical resistivity of films of the two systems deposited at 500 °C can be related to the drift of defect protons on the oxygen sites under an electric field.