Effect of post-silicidation annealing on TiSi2/p+-n Si junctions

Abstract
The reverse‐bias leakage of TiSi2/p+n Si junctions is 2 for 0.1‐μm‐deep p+‐Si with a TiSi2 sheet resistance of 1.7 Ω/sq, and is essentially independent of carrier concentration, and the amount of B consumed during silicidation. Forward‐bias current characteristics show that the TiSi2 contacts are ohmic with significant recombination currents and high‐level injection at voltages below the series resistance limit. Post‐silicidation annealing for 30 min at 920 °C, with or without an overlayer of borophosphosilicate glass, increases the majority‐carrier concentration and does not cause B to diffuse out of the Si. Also, minority‐carrier lifetimes show a twofold increase after annealing and this results in nearly ideal junctions with leakage that is dominated by diffusion currents. Thus, TiSi2/p+n Si is thermally stable under conditions that are compatible with glass flow and reflow processing.