ELECTRICAL AND STRUCTURAL CHARACTERISTICS OF ULTRA-THIN TiO_2/Ti-Si-O STACKED GATE INSULATOR FORMED BY RF SPUTTERING TECHNIQUE

摘要

In this paper, we have reported an attempt to decrease equivalent oxide thickness (EOT) of TiO_2 gate insulator by thinning the amorphous layer formed at the TiO_2/Si interface. We have decreased the thickness of the TiO_2/Si interfacial layer to as little as 1.6 nm by suppressing the oxygen flow rate during the TiO_2 sputtering. It was confirmed that the dielectric constant of the interfacial layer revealed higher value than that of SiO_2, depending on the sputtering condition. Titanium in the interfacial layer, which was responsible for the polarization enhancement, was explicitly identified by high spatial resolution TEM-EELS. As a result, EOT of 1.3 nm was realized by TiO_2/Ti-Si-O stacked gate insulator without any degradation in the electrical characteristics.