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

3.4.3.3 Dependence on the Ambience of PMA with PlatinumUpper ElectrodesUp to this point, all of experiments in terms of PMA with platinumupper electrodes were done fixed to nitrogen ambience. Then, the influenceof the annealing ambience through PMA was examined same as PMA withthe case of aluminum and gold upper electrodes.Figure 3-58 shows the comparison of the C-V characteristics of PDAbetween nitrogen and forming gas ambience and PMA between nitrogen,oxygen and forming gas ambience. All of samples were annealed for 10minutes. It should be noted that the values of VFB shift were quitedependent on annealing ambience in the case of not only PDA but PMAalthough there were almost no dependence on annealing ambience in termsof VFB shift in the case of aluminum and gold upper electrodes. Moreover, itwas also found that the annealing in forming gas ambience shifted VFB tonegative side less than the ones in nitrogen ambience in the case of PDA.On the other hand, a recovery of VFB shift by PMA in forming gas ambiencewas less than the ones by PMA in nitrogen ambience. And the annealing inoxygen ambience brought the best recovery of VFB shift but also a decrease ofcapacitance value.Figure 3-59 shows the comparison of the C-V characteristics betweennitrogen and forming gas ambience on each time of PMA from 0 second to100minutes. On each annealing time, it was confirmed that the annealingin nitrogen ambience made the VFB shift recover more than the ones informing gas ambience. And the appearance of hysteresis classified intomobile charge type in the case of spike annealing in forming gas ambience,and charge injection type in the case of 100 minutes annealing in nitrogenambience were observed respectively.In order to verify from numerical view, the plots of the VFB shiftdependent on annealing time was shown in Figure 3-60. It can beconfirmed that the difference of VFB shift between the case of nitrogen andforming gas ambience was maintained on almost same level up to theannealing for 10 minutes. However, it was also found that variations of VFBshift behaved quite different way, toward more positive side in the case ofnitrogen ambience, and toward negative side in the case of forming gasambience, on the annealing for 100minutes.- 80 -