Reductive Thermal ALD of Pd and Pd₂Ge From a Novel Recyclable Palladium Chloride Adduct

Abstract In this work, a new ALD process for palladium metal thin films using dichlorobis(triethylphosphine)palladium(II) (PdCl₂(PEt₃)₂) and 1,4‐bis(trimethylsilyl)‐1,4‐dihydropyrazine ((Me₃Si)₂DHP) as reactants, is developed. The metal precursor is chosen based on the known reactivity of metal halides with the DHP‐type reducing agents. Metallic Pd films are deposited at temperatures of 140–180 °C with a growth rate of 0.3–0.4 Å cycle⁻¹. Furthermore using 1,4‐bis(trimethylgermyl)‐1,4‐dihydropyrazine ((Me₃Ge)₂DHP) as the co‐reactant yielded Pd₂Ge thin films. Finally, full recyclability of the PdCl₂(PEt₃)₂ is observed: unused molecules condensed in the exhaust tube can be collected by dissolving them into acetone, purified by recrystallization, and reused.