Thermogravimetric evaluation of the suitability of precursors for MOCVD

A method based on the Langmuir equation for the estimation of vapour pressure and enthalpy of sublimation of subliming compounds is described. The variable temperature thermogravimetric/ differential thermogravimetric ( TG/ DTG) curve of benzoic acid is used to arrive at the instrument parameters. Employing these parameters, the vapour pressure temperature curves are derived for salicylic acid and camphor from their TG/ DTG curves. The values match well with vapour pressure data in the literature, obtained by effusion methods. By employing the Clausius-Clapeyron equation, the enthalpy of sublimation could be calculated. Extending the method further, two precursors for metal-organic chemical vapour deposition ( MOCVD) of titanium oxide bis-isopropyl bis tert-butyl 2-oxobutanoato titanium, Ti((OPr)-Pr-i)(2)( tbob)(2), and bis-oxo-bis-tertbutyl 2-oxobutanoato titanium, [TiO( tbob)(2)](2), have been evaluated. The complex Ti( OiPr) 2( tbob) 2 is found to be a more suitable precursor. This approach can be helpful in quickly screening for the suitability of a compound as a CVD precursor.