Adsorption and reaction of NH3 on Ti/Si(1 0 0)

The nitridation of ultra-thin Ti ®lms on Si(1 0 0) have been studied using X-ray photoelectron spectroscopy (XPS) in a temperature range of 120±1000 K. Upon ammonia exposure to the multilayer Ti thin ®lms at 120 K, three N 1s peaks at 397.8±398.1, 400.5±400.8 and 402.2±402.6 eV were observed, attributable to NHx (x ˆ 1 or 2), molecular NH3 and NH4 d‡, respectively. Annealing of the NH3 saturated Ti/Si(1 0 0) surfaces results in the conversion of the NHx species. This species undergo two different pathways between 300 and 800 K, i.e. further dissociation to N(a) and H(a), and recombing with H(a) to form NH3(g). The atomic N reacts with Ti to yield a stable TiN ®lm that retards signi®cantly the interdiffusion at the Ti/Si interface. # 2001 Published by Elsevier Science B.V.