Combinatorial Initiated CVD for Polymeric Thin Films

A new combinatorial initiated (i)CVD system is fabricated and used to efficiently determine the deposition kinetics for two new polymeric thin films, poly(diethylaminoethylacrylate) (PDEAEA) and poly(dimethylaminomethylstyrene) (PDMAMS). The results of combinatorial depositions are compared to blanket iCVD under identical conditions using the appropriate vinyl monomer with tert-amylperoxide as the initiator. Fourier transform infrared spectroscopy (FTIR) reveals similar chemical structure in blanket and combinatorial films. FTIR also shows that functional groups are retained in iCVD of PDMAMS, whereas essentially all fine chemical structure of the material is destroyed in plasma-enhanced (PE)CVD. The maximum observed growth rates of PDEAEA and PDMAMS were 43 and 11 nm min–1, respectively. The activation energy of growth with respect to filament temperature (Ea,filament) was 88.4±1.6 kJ mol–1 for PDEAEA and 42.0±1.7 kJ mol–1 for PDMAMS. Activation energies for growth with respect to substrate temperature (Ea,substrate) are –59.5±2.7 kJ mol–1 for PDEADA and –82.7±2.6 kJ mol–1 for PDMAMS, with the negative values consistent with adsorption-limited kinetics. The molecular weight of PDEAEA films ranges from 1 to 182 kDa as a function of substrate temperature. It is found that in all cases the combinatorial system agreed (within experimental uncertainty) with results of blanket iCVD, thus validating the use of the combinatorial system for future iCVD studies.