Atomic Layer Deposition of CeO2/HfO2 gate dielectrics on Ge Substrate

Abstract

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(isopropylcyclopentadienyl) cerium [Ce(iPrCp) 3 ] precursors with H 2 O. 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.