Specific structural factors influencing on reliability of CVD-HfO₂

We report on two key issues for CVD-HfO₂ gate dielectric which influence on their reliability. The first ones are extrinsic defects, i.e., 1) two types of extrinsic defects which lead to a large electrical leakage. The other ones are interfaces inside the film, i.e., 2) stoichiometric interface due to a Si out-diffusion from substrate and 3) interface defined by dielectric constant transition which was formed by a diffusion mechanism of Si into HfO₂. Lower Weibull slope β is mainly determined by a distance from Si substrate to the k-transition interface. Although the β becomes smaller due to the k-transition interface, it was clarified to be improved by a single layered silicate without k-transition interface.