Ozone-Based Atomic Layer Deposition of Gd₂O₃ from Tris(isopropyl-cyclopentadienyl)gadolinium: Growth Characteristics and Surface Chemistry

The atomic layer deposition (ALD) of Gd₂O₃ from tris(isopropyl-cyclopentadienyl) gadolinium (Gd(ⁱPrCp)₃) and O₃ is studied as a function of the O₂/N₂ ratio used to generate O₃. ALD using O₃ with low N₂ content leads to the formation of a hydroxyl-terminated surface after combustion reactions during O₃ exposure followed by proton transfer and ligand release during the Gd(ⁱPrCp)₃ half cycle. This condition leads to the presence of parasitic chemical vapor deposition (CVD) due to the hygroscopicity of Gd₂O₃. By contrast, long O₃ pulses with high N₂ content lead to the dehydroxylation of the surface and to the suppression of both the proton transfer during the Gd(ⁱPrCp)₃ half cycle as well as the parasitic CVD reactions. The atomic layer deposition of Gd₂O₃ from Gd(ⁱPrCp)₃ and O₃ is studied using in situ quadrupole mass spectrometry. O₃ with low N₂ content leads to the formation of a hydroxyl-terminated surface after combustion reactions with O₃ followed by proton transfer and ligand release during Gd(ⁱPrCp)₃ chemisorption. By contrast, O₃ with high N₂ content leads to the dehydroxylation of the surface and the suppression of the proton transfer.