Comparison between furnace and rapid thermal annealed iridium silicide Schottky barrier diodes

Iridium silicide Schottky barrier diodes fabricated by low temperature rapid thermal annealing (RTA) either in vacuum or in an argon atmosphere are investigated. A comparison with furnace annealed diodes is made in terms of their electrical characteristics. An ideality index close to unity has been obtained. Measured values of Schottky barrier height were close to that reported for Ir1Si1/n type silicon [111] diodes. An increase in series resistance with annealing time is detected for diodes fabricated in the gas atmosphere by either furnace annealing or RTA: this effect seems to be related to oxygen diffusion through the iridium layer. The effect of atmosphere control on the grown material is also significant: silicidation and a phase change from Ir1Si1, to Ir1Si1.75 occur at lower temperatures when the reaction atmospheres contain a lower oxygen concentration. Complete silicidation to Ir1Si1 is obtained for all the 400 degrees C RTA samples, but temperatures above 450 degrees C are required for open tube furnace argon annealed samples to obtain the same reaction. A low barrier silicide phase appears only for RTA in vacuum at 450 degrees C. It seems that RTA in vacuum at low temperature (400 degrees C) is the most promising method for diode fabrication. (C) 1995 The Institute of Materials.