Atomic layer deposition of polyimide thin films

The atomic layer deposition (ALD) of different polyimide thin films has been studied. We have demonstrated self-limiting ALD deposition of PMDA-DAH, PMDA-EDA, PMDA-ODA and PMDA-PDA thin films at 160 degrees C. The maximum deposition rate of 5.8 angstrom cycle(-1) was obtained for the PMDA-DAH process. Although the deposition rate was high at 160 degrees C, a sudden decrease was observed when the temperature was increased. Regardless of the process studied, no film growth was obtained at 200 degrees C or above. Deposited polyimide films were analysed by FTIR, AFM and TOF-ERDA. According to the FTIR measurements, imide bonds were formed already in as-deposited films indicating polyimide formation without any additional thermal treatment.