A characterization technique for the degradation characteristics of Ti/Si schottky-barrier diodes and ohmic contacts after thermal silicidation

Abstract

The effects of thermal silicidation on both the nonideal current-voltage characteristics of the Schottky-barrier diodes and the degradation properties of the ohmic contacts have been self-consistently characterized by using a simple interfacial-layer theory. The abruptly changed nonideality of the measured I– V characteristics as TiSi 2 is formed can be interpreted as the variations of the interface properties, such as the thermal-equilibrium barrier height, the interfacial-layer capacitance, and the density distribution of the interface state. Moreover, different work functions for Ti and TiSi 2 and the change of the dominant type of the interface states and their density distributions are shown to be responsible for the fluctuations of the thermal-equilibrium barrier height after thermal silicidation. Furthermore, the interface parameters extracted from the fabricated Schottky-barrier diodes are used to calculate and compare the simultaneously-processed specific contact resistivities, and satisfactory agreement is obtained. Thus, the silicidation-related degradation characteristics of the ohmic contacts can be directly related to the variations of the interface properties at the Ti/Si interface.