T. Aoyama et al., LEAKAGE CURRENT MECHANISM OF AMORPHOUS AND POLYCRYSTALLINE TA2O5 FILMS GROWN BY CHEMICAL-VAPOR-DEPOSITION, Journal of the Electrochemical Society, 143(3), 1996, pp. 977-983
The leakage current mechanism of the chemical vapor deposition Ta2O5 f
ilm has been investigated. In the case of an as-deposited amorphous fi
lm, the presence of impurities such as carbon and hydrogen remaining i
n the film leads to the Poole-Frenkel type leakage current. The oxidat
ion of these impurities results in a reduction in leakage current. O-2
plasma is especially effective for oxidizing impurities, leading to a
drastic reduction of the leakage current. However O-2 plasma cannot r
educe the leakage current of the Ta2O5 film crystallized at 700 degree
s C. This leakage current is not due to C and H, but rather to Si pene
traed into the Ta2O5 film from the underlying poly-Si electrode. There
fore, the amorphous Ta2O5 film treated by O-2 plasma is most suitable
for DRAM use.