The effects of thermal silicidation of the current transport characteristics of Ti/〉111〈Si Schottky-barrier contacts

Abstract

Using the interfacial-layer theory and assuming the Shockley-Read-Hall (SRH) statistics for the nonequilibrium occupancy of the interface states, the effects of Ti/〉111〈Si contact reactions on the nonideality of the current-voltage characteristics measured from the TiSi x (0 ⩽ x ⩽ 2)/ p( n)-Si Schottky-barrier diodes have been studied. From the analyses obtained by Auger Electron Spectroscopy (AES), X-ray diffraction, and I– V measurements, the abrupt change of thermal-equilibrium barrier height with respect to silicidation temperature is shown to be coincident with the drastic change of the measured ideality-factor in the forward I– V characteristics. This phenomenon has been justified to be correlated with the formation of stoichiometric TiSi 2 at the Ti/Si interface by thermal reactions. From the interface-state-apparent-spectrum (ISAS) measurements using both constant-temperature-Schottky-capacitance-spectroscopy (CTSCS) and I– V methods, we have shown that the transition of electrical characteristics should be attributed to the large variations of the ISAS when the TiSi 2 starts to form at the Ti/Si interface. Moreover, with the help of a simplified occupation function model for the interface states, the observed transition can be interpreted as the changes of thermal-equilibrium barrier height, real interface-state density, and effective minority-carrier to majority-carrier capture rate ratio.