Atomic layer deposition of palladium thin film from palladium (II) hexafluoroacetylacetonate and ozone reactant

Highlights: • Atomic layer deposition of Pd thin films using Pd(hfac)₂ and O₃ as the precursors. • The evolution of morphology of Pd thin films was studied. • Deposition on sapphire, Si and SiO₂ substrates. • Pd films with extremely low roughness and controllable thickness. Palladium thin films have been grown by thermal atomic layer (ALD) process using Palladium (II) hexafluoroacetylacetonate (Pd(hfac)₂) and O₃ as the precursors without molecular hydrogen or formalin in a temperature range of 180–220 °C. The palladium films were deposited on sapphire (α-Al₂O₃, (0001)), silicon (Si, (111)) and silica (SiO₂, (100)) substrates at a constant growth rate of about 0.25 Å per cycle. The metallic palladium films produced were highly uniform without fluorine contamination. The surface roughness was only 0.2 nm. The resistivity of the metallic palladium film at ∼25 nm in thickness deposited at 200 °C was around 63 μΩ cm. The morphology of Pd thin films on sapphire, silicon and silica surfaces revealed the island growth and these islands finally coalesced after applying 800 cycles. Thickness-controllable palladium films were obtained with shortened pulse time of both reactants (Pd(hfac)₂ and ozone). Our work provides important guidelines for fabrication of metals by adjusting reaction parameters in thermal ALD process.