Abstract: | A systematic study of the flat-band voltage (Vfb) shift of Ru gated metal-oxide-semiconductor (MOS) capacitors subjected to thermal treatment in O2 has been performed. The dependence of the Vfb shift on the thickness of Ru, anneal temperature and time is studied. The Vfb shift is ascribed to the shift of metal gates’ work function (WF), and is not significantly dependent on the type of dielectric (HfO2 or SiO2). From time-of-flight secondary ion mass spectrometry (TOF-SIMS) measurement, it was found that after thermal treatment in 18O2, 18O penetrated through Ru and was incorporated in the Ru/dielectric interface region. We believe that the formation of the thin interfacial RuOx layer is responsible for the Vfb shift. |