Effects of bottom electrodes on dielectric properties of ECR-PECVD Ta2O5 thin film

Abstract

The effects of interfacial oxide layers formed on the bottom electrodes on the dielectric properties of Ta2O5 thin film were studied as one of the promising candidates as charge storage capacitor material for high-density dynamic random access memory (DRAM) devices. Ta2O5 thin film was prepared by electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD) on various bottom electrodes, such as Si, Pt, TiN and W. The oxidation mechanism of the bottom electrode surfaces during the Ta2O5 film deposition was studied. Ta2O5 film started to be deposited after some incubation period (P), and the incubation period depended on the oxidation of the electrodes by the ECR oxygen plasma: P-W > P-Si > P-TiN > P-Pt. TiN and W bottom electrodes had interfacial oxide layers with SiO2-equivalent thickness (d*) of 0.9 nm and 2.1 nm, respectively, which were smaller than that of Si electrode (d(SiO2)*, = 4 nm).