Fundamental Identification of Defect-Related Electron Trap in Hf1-x Zr (x) O-2 Alloy Gate Dielectric on Silicon: Oxygen Vacancy versus Hydrogen Interstitial

Hf1-xZrxO2 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-xZrxO2 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-xZrxO2 alloys are discussed. The results show that, differing from previous studies suggesting that the oxygen vacancy (V-O) is the main defect of electron trapping, the hydrogen interstitial (H-i), 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-xZrxO2 dielectric. This work, therefore, broadens the understanding of electron trapping effect in high-k dielectrics and gives guidance on improving the reliability in microelectronics.