Spin Coating of Titanium Ethoxide Solutions

Titanium oxide films are used in anti-reflection interference filters. These layers can be deposited by spinning titanium ethoxide (TEOTi) solutions. By thorough hydrolysis of the TEOTi precursor, optically acceptable coatings can be made even when cured at temperatures below 150°C. The use of acetylacetone to control the reactivity of a TEOTi solution is not suitable when curing the films at 150°C, because at this curing temperature the acetylacetone remains in the coating. A more suitable method to control the reactivity is by adjusting the H⁺ concentration of the solution. Besides the curing temperature the hydrolysis time of the TEOTi solution also has a major influence on the morphology of the final TiO₂ layer.