Effect of deuterium postmetal annealing on the reliability characteristics of an atomic-layer-deposited HfO2/SiO2 stack gate dielectrics

The characteristics of atomic-layer-deposited (ALD) HfO2(30 Å)/SiO2(10 Å) stacks gate dielectrics were investigated after annealing in a deuterium (D2) ambient. Compared with oxides annealed in a forming gas containing hydrogen (H2), the stack dielectrics annealed in D2 ambient exhibited various advantages such as less charge trapping, less generation of interface state density (Dit), a larger charge-to-breakdown (Qbd), and longer time-dependent dielectric breakdown characteristics under conditions of electrical stress. The improved reliability can be attributed to the strength of the deuterium bond. This deuterium postmetal annealing of a high-k gate dielectric has considerable potential for future use in ultralarge-scale integration device applications.