Thermal stability improvement of nickel germanide utilizing nitrogen plasma pretreatment for germanium-based technology

In this paper, a novel nitrogen plasma pretreatment (NPP) has been experimentally demonstrated to improve the thermal stability of thin NiGe film. The root mean square (RMS) roughness of NiGe film pretreated by NPP technique is reduced to 0.52nm, illustrating more uniform and smooth NiGe film than that without pretreatment. The thermal stability of NiGe film is improved to at least 600°C by this technique. The NPP process time is also optimized to be 30s~120s. The very thin interfacial layer of GeN
_x
formed on Ge surface by NPP technique is believed to suppress oxygen diffusion, thus improving the surface morphology of NiGe film. The formation of Ge-N and/or Ni-N chemical bonds, which inhibits the agglomeration of NiGe, may also help to improve the thermal stability. Therefore, this technique shows great potential for Ge-based technology.