Atomic layer deposition of CeO_2/HfO_2 gate dielectrics on Ge substrate

摘要

We systematically investigated atomic layer deposition (ALD) of HfO_2, CeO_2 and Ce-doped HfO_2 thin films on Ge substrates by using tetrakis dimethylamino hafnium (TDMAH) and tris(isopropyl-cyclopentadienyl)cerium [Ce(iPrCp)3] precursors with H_2O. The growth characteristics, chemical and electrical properties were comparatively characterized. On the basis of X-ray photoemission spectroscopy analyses, it was confirmed that the ALD CeO_2 on Ge can form a stable interfacial layer composed of Ge~(1+) and Ge_(3+), leading to improved interfacial properties. In addition, Ce-doped HfO_2 films with various Ce compositions (Ce : Hf = 1:1, 1:2, 1:4 and 1:8) were prepared by an ALD supercycle process on Ge substrates. Thereby, we demonstrated that overall electrical properties including dielectric constant, interface state density, hysteresis and leakage current density are significantly improved.