Electrode dependent interfacial layer variation in metal-oxide-semiconductor capacitor

Abstract

Abstract. The interfacial layer between oxide and semiconductor in metal-oxidesemiconductor(MOS) capacitors depends on the metal electrode material. The metal/HfO2/Siand metal/HfO2/Ge capacitor were made using an atomic layer deposited HfO2 dielectric filmsand Mo, Ru, and Pt electrodes above Si substrate and Ti, Ru, and Pt electrodes above Gesubstrate. The measured saturation capacitance was varied with electrode and evaluated tocapacitance equivalent thickness (CET). In Si-based MOS capacitor, the CET value of thecapacitor with Pt electrode is larger than those with Mo and Ru electrode. In addition, the CETis 27.4 A, 38.2 A, and 30.8 A for Ti, Ru, and Pt electrode, respectively, for Ge-based MOScapacitors. The CET variation with electrode is attributed the variation of dielectric constant ofHfO2 dielectric and the difference of interfacial layer. The CET variation is well in agreementwith the interfacial layer thickness taken by a transmission electron microscopy. The thicknessvariation of interfacial layer results from the oxygen gettering ability of the electrode eventhough they are apart.