Low temperature thermal ALD TaNx and TiNx films from anhydrous N2H4

Thermal ALD of TaNx and TiNx films was performed using hydrazine (N2H4) as a reactive N-containing source. Ultralow temperature (100 °C and 300 °C) growth of TaNx was observed using N2H4 and tris(diethylamido)(tert-butylimido) tantalum (TBTDET); XPS showed nearly stoichiometric Ta3N5 films were deposited with below 10% O and 5% C incorporation. Stoichiometric TiNx films grown at 300 °C with tetrakis(dimethylamido) titanium (TDMAT) showed an RMS roughness below 2 nm consistent with good nucleation density. High conductivity nitride films were grown by a thermal low-temperature TiNx ALD process using anhydrous N2H4 and titanium tetrachloride (TiCl4) from 300 to 400 °C; uniform, nearly stoichiometric films of 0.44 nm RMS roughness were deposited. Compared to NH3 grown films, XPS confirmed N2H4 grown films contained fewer O, C, and Cl impurities consistent with lower resistivities being observed with N2H4. The data is consistent with N2H4 serving as a reducing agent and a good proton donor to Ta and Ti ligands.