Improvement of the Performance of TiHfO MIM Capacitors by Using a Dual Plasma Treatment of the Lower Electrode

We show that a conventional nitrogen plasma treatment is insufficient to suppress the formation of an interfacial layer at the bottom electrode of TiHfO metal–insulator–metal (MIM) capacitors. However, the capacitance density and leakage current of TaN/TiHfO/TaN MIM capacitors monotonically improve by exposing the lower TaN electrode to an additional oxygen plasma treatment. By performing dual oxygen and nitrogen plasma treatments on the lower electrode, the leakage current was $\hbox{4.8} \times \hbox{10}^{-6}\ \hbox{A}/\hbox{cm}^{2}$ (at $-$1 V) at a 28 $\hbox{fF}/\mu\hbox{m}^{2}$ capacitance density.