Interfacial characteristics of HfO2 films grown on strained Si0.7Ge0.3 by atomic-layer deposition

The interfacial characteristics of gate stack structure of HfO2 dielectrics on strained Si0.7Ge0.3 deposited by atomic-layer deposition were investigated. An interfacial layer including GeOx layers was grown on a SiGe substrate, and the thickness of the GeOx layer at the interfacial layer was decreased after the annealing treatment, while SiO2 layer was increased. The ∼50-Å-thick HfO2 film with an amorphous structure was converted into a polycrystalline structure after rapid annealing at temperature of over 700 °C for 5 min. The interfacial silicate layer was effectively suppressed by GeOx formation, while the silicate layer was formed after the annealing treatment. GeOx formation in an as-grown film resulted in a decrease in the accumulation capacitance and an increase in the oxide trap charge.