Thermal Stability of Hafnium and Titanium Nitride Diffusion Barriers in Multilayer Contacts to Silicon

The thermal stability of reactively sputtered hafnium nitride (HfN) and titanium nitride (TiN) thin films is investigated for the application as diffusion barriers in metallic contacts to silicon. The temperature range of interest is from 400-800 C. The dominating failure mechanism is associated with loss of adhesion and blistering of the barrier layers. The extent of the failure is related to the compressive stresses in the sputtered nitride layers. With proper constraints imposed on the deposition process, HfN and TiN can perform as effective diffusion barriers up to 800 C.