Thermal Stability of W‐Contacted Junction Diodes

Abstract

This work investigates the thermal stability of W‐contacted p+n junction diodes, in which the tungsten contact was formed by selective chemical vapor deposition (CVD) or sputtering process. Reaction of Al and CVD‐W at elevated temperature leads to the formation of , and the barrier capability of CVD‐W film was dependent on the consumption of W. The sputter‐W film has a columnar structure and contains a higher content of oxygen. The presence of oxygen retarded the formation of and thus enhanced the thermal stability of the Al/W/Si structure. However, degradation of the Al/sputter‐W (100 nm)/p+n diodes occurred after 30 min annealing at 550°C, presumably due to Al diffusion along the grain boundary of sputter‐W film. For the CVD‐W contacted junction diodes, insertion of a thin TiN barrier layer between the Al and W film was effective in suppressing the formation of and thus improved the device's thermal stability.