Amorphous TiPO films grown with four-component chemical vapor deposition

Amorphous titanium phosphate (TiPO) films are prepared by low-pressure chemical vapor deposition (CVD) using a mixture of titanium tetrachloride (TiCl4), trimethyl phosphite (P(OCH3)3), CO2, and H2. Two systems are studied: one is the TiCl4/P(OCH3)3/CO2/H2 system with varied TiCl4 inputs or the TiCl4 system and the other the TiCl4/P(OCH3)3/CO2/H2 system with the varied CO2/H2 inputs or the CO2/H2 system. Growth and properties of CVD TiPO films are functions of deposition temperature, the TiCl4 input, and the CO2/H2 input. Higher TiCl4 and H2 inputs are detrimental to film growth. Higher deposition temperature enhances the growth rate and the P content in films. Variations of growth rate and film composition with the TiCl4 input for the TiCl4 system and with the CO2/H2 flow ratio for the CO2/H2 system are rationalized by the proposed growth mechanism, where the site occupation of the reactive Cl3TiOH reactants on substrate is the main focus. The variation of the internal stress with process parameters is attributed to film thickness. The variations of electrical properties (dielectric constant and resistivity) and film composition with process parameters are related to the Ti ratio in films.