Microstructure and Schottky barrier height of iridium silicides formed on silicon

Abstract

Direct correlations between iridium silicides and their Schottky barrier heights on Si have been studied by combining TEM observations and I-V and C-V measurements. It has previously been shown that three iridium silicides IrSi, Ir2Si3, and IrSi3 can be formed by annealing Ir films on Si at temperatures around 400, 600, and 960 °C, respectively. The Schottky barrier height of these silicides on 〈100〉 Si have been determined to be 0.93 eV (IrSi), 0.85 eV (Ir2Si3), and 0.94 eV (IrSi3). Along with the I-V measurement, a computer fitting of current transport across Schottky diodes has been used to analyze the I-V data so that the barrier height from nonideal diodes can be determined. The question of a parallel diode formed by a mixture of two phases at the contact area has also been addressed. It is shown that I-V measurements, which are very sensitive to the presence of a lower barrier phase, tend to give a lower barrier height than a corresponding C-V measurement since the latter depends on the major phase in the contact area.