Effect of Post Metallization Annealing for La 2 O 3 Thin Film

3.4.1.3 Dependence on the Annealing Timeof PMA withAluminum Upper ElectrodesThus far, the time of PMA was fixed on 10 minutes. The time ofannealing temperature should affect VFB same as the case of PDA asdescribed in section 3.3.3, and also should be optimized. The dependence ofPMA on annealing time from 0 second (spike) to 100 minutes wasinvestigated. Here, the temperature of PMA was fixed on 300 o C andannealing ambience was fixed on nitrogen as well taking the results of thedependence on the temperature described in section 3.1.1.1 into account.Figure 3-28 shows the C-V characteristics dependent on the time of PMA.It was confirmed that VFB shift was recovered to positive side as theannealing time. However, hysteresis still remained slightly in each samples.This result indicates that PMA could not eliminate the defects in films andthat led to the type of charge injected hysteresis. Moreover, to makematters worse, the width of hysteresis was expanded widely in the case ofPMA for 100 minutes.2Al/La O / n-Si(100)/Al2 3Capacitance (µF/cm 2 )1250 o C depo HF-lastPMA 300 o Cspike to 100min.N ambient2Al_PMA_N2_spikeAl_PMA_N2_1min.Al_PMA_N2_10min.Al_PMA_N2_100min.0-2 -1.5 -1 -0.5 0 0.5 1 1.5Voltage (V)Figure 3-28: The C-V characteristics dependent on the time of PMA- 54 -