Remote plasma-deposited GeO 2 with quartz-like Ge- and O-local bonding: Band-edge state and O-vacancy comparisons with SiO 2

Abstract

X-ray absorption spectroscopy (XAS) and many-electron theory are combined to describe symmetries and degeneracies for intrinsic bonding defects in remote plasma-deposited (rpd-) non-crystalline (nc-), rpd-nc-GeO 2 and rpd-nc-SiO 2, hereafter simply GeO 2 and SiO 2. GeO 2 is emerging as an alternative gate dielectric for nano-CMOS devices. High resolution O-vacancy spectral features in O K pre-edge spectra for SiO 2 have been assigned to multiplet transitions and negative ion states based on an extended d 2 equivalent model, including both weaker singlet and as well the stronger triplet transitions discussed in previous publications. This has revealed predominantly mid-gap Ge and Si singlet and triplet bonding arrangements for the electrons in O-vacancy sites. These have been examined as a function of post deposition rapid thermal annealing in Ar ambients for GeO 2 deposited at 300 °C on both Si and Ge substrates, identifying different post-deposition thermal budget processing windows for low defect density GeO 2 on Si and Ge substrates. For ultra thin nitrided SiO x , x < 2 interfacial layers on Si, this is at least 700 °C, but on Ge, independent of surface processing it less than 600 °C.