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

Abstract

Iridium silicide Schottky barrier diodes fabricated by low temperature rapid thermal annealing (R TA) 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 Ir₁ Si₁ to Ir₁ Si_1-75 occur at lower temperatures when the reaction atmospheres contain a lower oxygen concentration. Complete silicidation to Ir₁Si₁ is obtainedfor all the 400°C RTA samples, but temperatures above 450°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°C. It seems that RTA in vacuum at low temperature (400°C) is the most promising methodfor diode fabrication.

MST/3334