Atomic layer deposition of stoichiometric Co₃O₄ films using bis(1,4-di-iso-propyl-1,4-diazabutadiene) cobalt

We report the deposition of cobalt oxide films at 120–300 °C using alternating injections of a novel liquid cobalt precursor, bis(1,4-di-iso-propyl-1,4-diazabutadiene)cobalt [C₁₆H₃₂N₄Co, Co(dpdab)₂], and ozone. The saturation doses of Co(dpdab)₂ and O₃/O₂ were 4 × 10⁶ and 1 × 10⁸ L, respectively. The atomic layer deposition (ALD) temperature window was between 120 °C and 250 °C with a maximum growth per cycle of 0.12 nm/cycle. The deposited films showed excellent step coverage. Cobalt oxide films deposited at 250 °C consisted of stoichiometric and crystalline Co₃O₄. - Highlights: • Cobalt oxide films were grown by ALD using a novel cobalt precursor and O₃. • The ALD temperature window was 120–250 °C with a growth per cycle of 0.12 nm/cycle. • Cobalt oxide thin films showed excellent step coverage. • Cobalt oxide films deposited at 250 °C were stoichiometric and crystalline Co₃O₄