title: Ultrathin NiGe films prepared via catalytic solid-vapor reaction of Ni with GeH(4).
abstract: A low-temperature (225-300 °C) solid-vapor reaction process is reported for the synthesis of ultrathin NiGe films (∼6-23 nm) on 300 mm Si wafers covered with thermal oxide. The films were prepared via catalytic chemical vapor reaction of germane (GeH4) gas with physical vapor deposited (PVD) Ni films of different thickness (2-10 nm). The process optimization by investigating GeH4 partial pressure, reaction temperature, and time shows that low resistive, stoichiometric, and phase pure NiGe films can be formed within a broad window. NiGe films crystallized in an orthorhombic structure and were found to exhibit a smooth morphology with homogeneous composition as evidenced by glancing angle X-ray diffraction (GIXRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and Rutherford back-scattering (RBS) analysis. Transmission electron microscopy (TEM) analysis shows that the NiGe layers exhibit a good adhesion without voids and a sharp interface on the thermal oxide. The NiGe films were found to be morphologically and structurally stable up to 500 °C and exhibit a resistivity value of 29 μΩ cm for 10 nm NiGe films.
authors.affiliation: Imec , Kapeldreef 75, B-3001 Leuven, Belgium.
authors.forename: Antony P
authors.initials: AP
authors.lastname: Peter
authors.forename: Karl
authors.initials: K
authors.lastname: Opsomer
authors.forename: Christoph
authors.initials: C
authors.lastname: Adelmann
authors.forename: Marc
authors.initials: M
authors.lastname: Schaekers
authors.forename: Johan
authors.initials: J
authors.lastname: Meersschaut
authors.forename: Olivier
authors.initials: O
authors.lastname: Richard
authors.forename: Inge
authors.initials: I
authors.lastname: Vaesen
authors.forename: Alain
authors.initials: A
authors.lastname: Moussa
authors.forename: Alexis
authors.initials: A
authors.lastname: Franquet
authors.forename: Tokei
authors.initials: T
authors.lastname: Zsolt
authors.forename: Sven
authors.initials: S
authors.lastname: Van Elshocht