The effect of forming gas annealing on Al/Ti/n-Si contacts

Abstract

Al/Ti/n-Si contacts without and with post-metallization annealing in forming gas atmosphere are fabricated and characterized. X-ray diffraction measurements are performed in order to identify possible types of silicides that appear after annealing. The results show different phases of Ti silicide, such as TiSi2 and Al5Ti7Si12. The metal/semiconductor contacts are electrically characterized at different temperatures, over a wide range (60 - 500K). For the as-deposited sample, an ohmic-like behavior is observed over almost the whole temperature domain. Instead, the annealed Al/Ti/n-Si contact exhibits Schottky-like behavior with very good performances, as assessed with our p-diode model. It is evinced that, for the 140 - 420K temperature range and 1μA -100mA current interval, a single dominant contact region is responsible for forward current flow. Under lilA and below 140K, it is necessary to consider two additional contact regions in the p-diode model.