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

3.4.2.4 Dependence on the Ambience of PMA with Gold UpperElectrodesThe influence of annealing ambience on the electrical characteristicsafter PMA with aluminum upper electrodes, almost no dependence onannealing ambience, was already described in section 3.4.1.4. And up tothis point, all of experiments in terms of PMA with gold upper electrodeswere done fixed to nitrogen ambience. Then, the influence of the annealingambience through PMA was examined same as PMA with the case ofaluminum upper electrodes.Figure 3-47 shows the comparison of the C-V characteristics of PMAbetween nitrogen and oxygen ambience on each annealing time from 0second (spike) to 100 minutes. It was confirmed that there was, roughlyspeaking, nothing different between nitrogen and oxygen ambience in termsof VFB shift. However, the higher capacitance value was observed in thecase of annealing in oxygen ambience. To be precise, the value of EOT inthe case of annealing in oxygen ambience was decreased about 0.2 ~ 0.3 nmcompared to the one in the case of annealing in nitrogen ambience althoughthe value of EOT was not almost changed dependent on annealing ambiencein the case of PDA as shown in Figure 3-48 in which plots of the result ofannealing in oxygen ambience are added to Figure 3-45. And it was alsofound that variations of EOT were almost proportional to the time of PMAand a degree of variation slope was sharper than the one in the case ofnitrogen ambience. However, the tendency dependent on annealing timewas not observed in terms of VFB same as in the case of nitrogen ambience asshown in Figure 3-49 in which plots of the result of annealing in oxygenambience are added to Figure 3-46.- 70 -