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

3.4.4 Examination of PMA for Another Rare Earth OxideIn order to investigate a relationship between a recovery of VFB causedby PMA with aluminum upper electrodes and La2O3 thin films, PMA foranother rare earth oxide was examined for the purpose of the comparisonwith La2O3 thin films. In this examination, Gd2O3 were used. Figure 3-66shows the comparison of C-V characteristics between PDA and PMA forGd2O3 thin films with aluminum upper electrodes. It should be noted thatVFB shift recovered toward positive side in the case of Gd2O3 shin films sameas in the case of La2O3 thin films. Moreover, the similar tendency such as aslight increase of hysteresis was also observed. From these results, it canbe said that the effects of PMA were not dominated by the materials of gateinsulator, but by the materials of upper metal electrodes, and thisassumption indicates that PMA treatment investigated in my study could beapplied to other materials which have the problem of VFB shift towardnegative side. Finally, it was found that PDA for Gd2O3 decrease thecapacitance value compared to the ones of as-deposition (not described)although the value of PMA was maintained on a level with the one ofas-deposition. This phenomenon was quite contrary to the case ofaluminum upper electrodes.2Al/Gd O / n-Si(100)/Al2 3Capacitance (µF/cm 2 )1250 o C depo C.O.PDA 300 o C&PMA300 o CN ambient2Al_C.O._PDA300_10min._N2Al_C.O._PMA300_spike_N2Ideal V FB0-2 -1.5 -1 -0.5 0 0.5 1 1.5Voltage (V)Figure 3-66: The comparison of C-V characteristics between PDA and PMAfor Gd2O3 thin films with aluminum upper electrodes- 88 -