HRTEM investigation of interface structure of zirconia gate dielectrics doped with various rare earth elements

Abstract

The effects of several rare earth oxide on the C-V characteristics and the SiO₂ interlayer growth of ZrO₂ based gate dielectrics were examined. The width of the hysteresis loop window of Sm₂O₃ stabilized ZrO₂ (SmSZ) gate dielectric was less than half of that of Sc₂O₃ stabilized ZrO₂ (ScSZ) gate dielectric. HRTEM analysis indicated that the growth of SiO₂ interlayer of SmSZ gate dielectric was only the half of gate dielectric. These results indicate the advantage of the ZrO₂ gate dielectric doped with rare earth oxide composed of larger ionic radius cation that makes ionic conductivity of zirconia lower.