Graphenic Carbon: A Novel Material to Improve the Reliability of Metal-Silicon Contacts

Contact resistance and thermal degradation of metal-silicon contacts are major challenges in nanoscale CMOS as well as in power device applications. Titanium silicide (TiSi) is commonly used to establish low-barrier height contacts to silicon, in state-of-the-art FinFETs or Schottky diodes. But the metal is known to diffuse into the active region under high current stress, as during an electro-static discharge event. This work shows with a Schottky diode as test vehicle that a carbon-silicon (C-Si) contact has the same low Schottky barrier height as a TiSi-Si junction but is over 100 million times more stable against high current pulses. A Schottky barrier height between 0.36 eV and 0.45 eV can be obtained by a variation of the deposition process. This makes C-Si a promising candidate for future high current density and temperature stable contacts and even for applications that require low contact resistances.