Effect of Post-Metallization Annealing on Electrical Characteristics of La2O3 Gate Thin Films

Abstract

Annealing conditions of a lanthanum oxide (La2O3) metal–insulator–semiconductor (MIS) capacitor were studied in order to optimize the flat-band voltage (VFB). It was confirmed that in the case of using Al electrodes, negative VFB shift was increased by post-deposition annealing (PDA) (before metallization) compared to as-deposited sample, while all other characteristics, such as EOT, leakage current and interface state density, were improved. It was also confirmed that post-metallization annealing (PMA) suppressed the VFB shift. Finally, the combination of PDA and PMA resulted in the recovery of VFB shift with suppression of the decrease of EOT. However, it was confirmed that in the case of using Au electrodes, PMA resulted in a slight negative VFB shift. Judging from these results, it is conceivable that the reaction of the metal with La2O3 exerts a significant influence on the VFB shift.