Formation of Thin NiGe Films by Magnetron Sputtering and Flash Lamp Annealing

Abstract

The nickel monogermanide (NiGe) phase is known for its electrical properties such as low ohmic and low contact resistance in group-IV-based electronics. In this work, thin films of nickel germanides (Ni–Ge) were formed by magnetron sputtering followed by flash lamp annealing (FLA). The formation of NiGe was investigated on three types of substrates: on amorphous (a-Ge) as well as polycrystalline Ge (poly-Ge) and on monocrystalline (100)-Ge (c-Ge) wafers. Substrate and NiGe structure characterization was performed by Raman, TEM, and XRD analyses. Hall Effect and four-point-probe measurements were used to characterize the films electrically. NiGe layers were successfully formed on different Ge substrates using 3-ms FLA. Electrical as well as XRD and TEM measurements are revealing the formation of Ni-rich hexagonal and cubic phases at lower temperatures accompanied by the formation of the low-resistivity orthorhombic NiGe phase. At higher annealing temperatures, Ni-rich phases are transforming into NiGe, as long as the supply of Ge is ensured. NiGe layer formation on a-Ge is accompanied by metal-induced crystallization and its elevated electrical resistivity compared with that of poly-Ge and c-Ge substrates. Specific resistivities for 30 nm Ni on Ge were determined to be 13.5 μΩ·cm for poly-Ge, 14.6 μΩ·cm for c-Ge, and 20.1 μΩ·cm for a-Ge.

Fabrication of Highly n-Type-Doped Germanium Nanowires and Ohmic Contacts Using Ion Implantation and Flash Lamp Annealing

“…The formation of Ni germanide was confirmed by spectrum imaging analysis based on EDXS, although the Ni germanide phase was not possible to determine (Figure ). Ni germanide has different phases including NiGe, Ni 2 Ge, Ni 3 Ge, and Ni 5 Ge 3 , whereby the stoichiometric NiGe phase is formed at higher temperatures and has the lowest resistivity. ,− …”

Ti Interlayer Mediated Uniform NiGe Formation under Low-Temperature Microwave Annealing

“…This result could be also confirmed by the Raman analysis, as shown in Figure 2. The sheet resistance value decreased gradually after annealed at 200 • C, indicating the Ni-rich phase (Ni 2 Ge or Ni 5 Ge 3 ) with higher resistance transition to the Ni mono-nickel germanide phase (NiGe) [23][24][25]. In addition, in order to calculate the morphology and roughness of the Ni x Ge y layers, AFM roughness analysis was carried out, as shown in Figure 1b,c.…”