Fundamental Identification of Defect‐Related Electron Trap in Hf_1−xZr_xO₂Alloy Gate Dielectric on Silicon: Oxygen Vacancy versus Hydrogen Interstitial

Hf1−x Zr x O2 alloy is recently employed as gate dielectric in complementary metal–oxide semiconductor (CMOS) devices because of its relatively low carrier trapping ability, low threshold voltage shift, and good reliability. Experimentally it is found that as the Zr concentration x increases, the device reliability caused by the defect-related electron trapping would be improved. However, the trap nature in Hf1−x Zr x O2 alloy is still not yet well understood. Herein, using first-principles hybrid-functional calculations, the transition energies of some possible defects tending to occur in the experimental process for Hf1−x Zr x O2 alloys are discussed. The results show that, differing from previous studies suggesting that the oxygen vacancy (VO) is the main defect of electron trapping, the hydrogen interstitial (Hi), which can successfully explain the experimental observations of a reduction of the electron trapping ability as the Zr concentration increases, is more likely to be the origin responsible for the electron trapping in Hf1−x Zr x O2 dielectric. This work, therefore, broadens the understanding of electron trapping effect in high-k dielectrics and gives guidance on improving the reliability in microelectronics.