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

• Published in: Nanomaterials (Basel, Switzerland) Vol. 10; no. 4; p. 648
• Main Authors: Begeza, Viktor, Mehner, Erik, Stöcker, Hartmut, Xie, Yufang, García, Alejandro, Hübner, Rene, Erb, Denise, Zhou, Shengqiang, Rebohle, Lars
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 31-03-2020; MDPI
• Subjects: Annealing; Chemical vapor deposition; CMOS; Contact resistance; Crystallization; Electric contacts; Electrical properties; Electrical resistivity; flash lamp annealing; Flash lamps; Germanides; Germanium; Hall effect; Intermetallic compounds; Investigations; Low temperature; Magnetron sputtering; Microscopy; Morphology; Nickel; Nickel compounds; Spectrum analysis; sputtering; Structural analysis; Substrates; Temperature; Thin films; X-ray diffraction; United States > US; germanides; nickel; germanium; flash lamp annealing; sputtering; thin films
• ISSN: 2079-4991; 2079-4991
• DOI: 10.3390/nano10040648

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.