Leakage current characteristics of metal (Ag,TiN,W)-Hf:Ta2O5/SiOxNy–Si structures

Metal–dielectric-silicon structures containing 8 nm thick dielectric stack obtained by deposition of Hf doped Ta2O5 high permittivity dielectric grown on p-type N2O nitrided silicon substrates were studied. W, TiN and Ag metal gates obtained by magnetron sputtering were used as top electrodes. It has been shown that structures with Ag gate have two orders of magnitude lower leakage currents than the structures with W gate and four orders of magnitude lower than the structures with TiN gate. Thus obtained low defect density both in the Hf:Ta2O5 high-k layer and in the SiOxNy interfacial layer combined with the low resistivity of the Ag gate, makes these structures suitable for applications as capacitors in memory devices.