Reaction Chemistry during the Atomic Layer Depositionof Sc2O3and Gd2O3fromSc(MeCp)3, Gd(iPrCp)3, and H2O.

The reaction chemistry during theatomic layer deposition (ALD)of Sc2O3and Gd2O3fromSc(MeCp)3, Gd(iPrCp)3, and H2O was investigated by in situtime-resolvedquadrupole mass spectrometry. Despite the similarity of the ligandsof the Sc and Gd precursors, the growth characteristics and liganddissociation patterns of the Sc2O3and Gd2O3ALD processes showed considerably differentbehavior. For both processes, the precursors reacted with the hydroxylatedsurface by proton transfer and release of the protonated ligand. Theremaining ligands were then removed by hydrolysis during the H2O pulse. However, for the Sc(MeCp)3/H2O process, ∼56% of MeCpH was released during the Sc(MeCp)3exposure, whereas in the case of the Gd(iPrCp)3/H2O process, as much as 90% of iPrCpHwas released during the Gd(iPrCp)3pulse. Theobservation that almost all iPrCp ligands were removedduring the initial Gd(iPrCp)3absorption stepcan be ascribed to CVD-like reactions between the Gd(iPrCp)3precursor and excess hydroxide or physisorbed H2O on the hygroscopic Gd2O3surface. The influenceof the growth temperature on the ligand exchange behavior and theresulting film properties (thickness uniformity, impurity concentration)was studied in the temperature range between 200 and 350 °C.In addition, the transient growth behavior of Gd2O3on Sc2O3and vice versa was studied,indicating that the hygroscopic nature of Gd2O3also strongly influences the deposition of GdxSc1–xO3ternaryoxides. [ABSTRACT FROM AUTHOR]