Mukta S. Farooq

Schottky device behavior of n-Si/Pd2Si/Al and n-Si/CoSi2/Al contacts with and without a Ta2N diffusion barrier

Abstract Tantalum nitride (Ta2N) has been investigated as a diffusion barrier between (a) Pd2Si and Al, and between (b) CoSi2 and Al. It is found that upon annealing, controls (without diffusion barriers) exhibited interdiffusion and intermetallic formation whereas test samples (with diffusion barriers) showed neither. It was also observed that the current voltage (I–V) characteristics of control Schottky devices always changed in the same direction, upon annealing, irrespective of the metal in the silicide. In the present paper, we discuss the possible causes of the Schottky barrier degradation, and correlate these explanations with our observations. An area distribution model is generated assuming that Al-silicide interactions lead to the presence of Al or an Al-containing intermetallic which has a barrier height different from the silicide and occupies a fractional area in contact with silicon.