2018 Volume 61 Issue 5 Pages 280-285
We have investigated characteristics of Al2O3 thin films, which are deposited by plasma-enhanced atomic layer deposition (PE-ALD) and thermal ALD (TH-ALD) with oxygen plasma and H2O as oxidant gas, respectively, and Al(CH3)3 precursor. The Al2O3 film, which was deposited at 50℃, exhibited a large leakage current property. The positive (~1018 cm－3) and negative fixed charges (~1012 cm－2) occurred in Al2O3 film and at SiO2/Al2O3 interface by PE-ALD process at below 150℃, respectively. On the other hand, the opposite fixed charges were observed by TH-ALD process. This is due to the different reactive intermediates of Al-C-O and Al-O-Al-CH groups in Al2O3 film by PE-ALD and TH-ALD processes, respectively. The fixed charge in Al2O3 film disappeared over 200℃. The dipole (~1013 cm－2) also occurs at SiO2/Al2O3 interface and leads to positive flatband shift of 0.6 V. Therefore, we should pay careful attention to ALD condition such as oxidant gas and growth temperature considering to applications.
