Low Temperature Sputtered Graphenic Carbon Enables Highly Reliable Contacts to Silicon

Titanium silicide (TiSi) contacts are commonly used metal-silicon contacts [1]-[3] but are known to diffuse into the active region under high current stress. Recently we demonstrated [4], [5] that graphenic carbon (GC) deposited by CVD has the same low Schottky barrier on silicon as TiSi, but a much improved reliability against high current stress. The drawback of the CVD-GC is the required deposition temperature of ~ 900 °C. In this paper we demonstrate now that the deposition of graphenic carbon is possible at 100-400 °C by a modified sputter process. We show that the sputtered carbon-silicon (SC-Si) contact is over 10
⁹
times more stable against high current stress pulses than the conventionally used TiSi-Si junction, while it has the same or even a lower Schottky barrier. Doping SC by nitrogen (CN) leads to an even lower resistivity and improved stability. The finding that there is a low temperature approach for using the superb carbon properties has important consequences for the reliability of contacts to silicon and opens up the use of GC in a plethora of other applications.