Low temperature thermal ALD TaNx and TiNx films from anhydrous N2H4

Highlights: • High conductivity, nearly stoichiometric ALD TiN_x films from TiCl₄ and N₂H₄. • Organometallic grown TaN_x and TiN_x films show low surface roughness. • N₂H₄ acts as a reducing agent and good proton donor to Ta and Ti ligands. Thermal ALD of TaN_x and TiN_x films was performed using hydrazine (N₂H₄) as a reactive N-containing source. Ultralow temperature (100 °C and 300 °C) growth of TaN_x 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 TiN_x 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 TiN_x 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.