Low temperature preparation of HfO 2 /SiO 2 stack structure for interface dipole modulation

Abstract

In this study, we found that stable interface dipole modulation (IDM) is possible for HfO 2 /1-monolayer TiO 2 /SiO 2 stack structures prepared by using a low temperature annealing process of about 300 °C. We investigated in detail the impact of thermal annealing on IDM characteristics. Even samples fabricated by post metallization annealing (PMA) below 200 °C exhibit the switching, and their width increases until the PMA temperature exceeds 300 °C. This temperature dependence shows a good correlation with a reduction in the sub-oxide component of interfacial Ti oxide caused by thermal annealing, suggesting that the formation of Ti-O bonds at the HfO 2 /SiO 2 interface contributes to IDM. The experimental results observed in this study support the IDM mechanism based on the Ti-O bond breakage/repair process.