Application of HfSiON to Deep-Trench Capacitors of Sub-45-nm-Node Embedded Dynamic Random-Access Memory

In this study, the potential of HfSiON as the node dielectric of deep-trench (DT) capacitors was investigated for the first time. It was found out that a uniform thickness and a uniform depth profile of each component in DT can be obtained by the ALD process which utilizes the catalytic effect of the Hf precursor and Si precursor. In addition, the mechanism underlying leakage current was analyzed and it was revealed that residual carbons in the film contribute to the Poole–Frenkel current through the film. On the basis of these findings, we propose the sequential high-pressure ozone treatment (SHO) and Al₂O₃/HfSiON/Si₃N₄ stack for DT applications. Finally, the DT capacitors of 65-nm-node embedded dynamic random-access memory (eDRAM) were fabricated and a capacitance enhancement of 50% from the conventional dielectric (NO) was obtained at the same leakage current.