Experimental Realization of Thermal Stability Enhancement of Nickel Germanide Alloy by Using TiN Metal Capping

Chen-Han Chou, Yi He Tsai, Chung Chun Hsu, Yu Hau Jau, Yu Hsien Lin, Wen Kuan Yeh, Chao-Hsin Chien

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


In this paper, we demonstrated the enhancement of thermal stability of nickel germanide (NiGe) alloy up to 600 °C by using titanium nitride (TiN) metal capping. A high IONIOFF ratio of 2.9× 105 was achieved by capping TiN metal on Ni for NiGe alloy formation at 600 °C. Detailed analyses were performed for realizing the mechanism for TiN capping on NiGe/Ge, including vertical element diffusion profile observation through depth-profiling X-ray photoelectron spectroscopy (XPS), element diffusion distribution by energy-dispersive X-ray spectroscopy mapping, and direct junction leakage current path detection by conductive atomic force microscopy. The experimental results indicated that TiN capping can reduce the risk of agglomeration and form a graded NiGe/Ge Schottky junction that is beneficial for suppressing the degradation of junction leakage. Subsequently, we compared the electrical performance of TiN/NiGe/n-Ge at various N/Ti ratios of TiNs. Based on the depth-profiling XPS results and electrical performance, TiN with an N/Ti ratio of approximately 1:1 can resist the Ni and Ge diffusion, which facilitates the suppression of the agglomeration process. However, the TiN capping layers with an N/Ti ratio of less than approximately 1:1 (Ti-rich) were not favorable for resisting Ni and Ge diffusion.

Original languageEnglish
Article number7885604
Pages (from-to)2314-2320
Number of pages7
JournalIEEE Transactions on Electron Devices
Issue number5
StatePublished - 1 May 2017


  • Agglomeration
  • germanium
  • nickel germanide (NiGe)
  • Schottky junction
  • thermal stability
  • TiN capping


Dive into the research topics of 'Experimental Realization of Thermal Stability Enhancement of Nickel Germanide Alloy by Using TiN Metal Capping'. Together they form a unique fingerprint.

Cite this