High barrier iridium silicide Schottky contacts on Si fabricated by rapid thermal annealing

The silicidation of iridium layers by rapid thermal annealing as a function of temperature and processing time is studied for both vacuum and argon atmosphere. The electrical properties of the resulting IrSi/n-type Si diodes are determined and related to the interface properties. I-V-T spectroscopy allows us to detect interface modifications even in the case where other diagnostics cannot be employed. Rapid thermal annealing (RTA) vacuum annealed diodes show inhomogeneous potential distribution at the metal-semiconductor interface. This is related with the coexistence of different metallurgical phases (Ir, IrSi, and IrSi1.75) at the interface as a consequence of the thermal treatments. The estimated value for the Schottky barrier height of the IrSi1.75 is 0.7 eV. In contrast, RTA argon annealed diodes show more reproducible characteristics. The main effect of the reaction atmosphere is to slow down the reaction rate as well as to inhibit the IrSi1.75 formation. This could be related with the residual oxygen contents of the reaction atmosphere. RTA argon annealing at 500 degrees C during 5 min is a reliable procedure for homogeneous IrSi infrared Schottky barrier detectors fabrication that can be employed in an industrial environment. (C) 1999 American Vacuum Society. [S0734-211X(99)06902-4].