Paper EM-WeM1
Spectroscopic Detection of Conduction Band Edge Defects in HfO₂, Hf Si Oxynitride and Stacked Hf Si Oxynitride/HfO₂ High-k Dielectrics: Extraction of Defect States from O K Edge NEXAS Spectra

Wednesday, October 22, 2008, 8:00 am, Room 210

A novel approach for eliminating Ge-N bonding at Ge-high-k dielectric interfaces from sacrificial Ge nitride interfacial transition regions (ITRs) used to passivate the Ge substrate against oxidation during film deposition. The GeN ITRs can be effectively eliminated during an 800°C post-deposition one minute anneal in Ar leaving the HfO₂ films in direct bonding contact with Ge(100) or Ge(111) substrates. This paper presents a study of band edge electronic structure, including band edge defects as function of annealing temperature by comparing near edge X-ray absorption spectra (NEXAS), O K₁ and N K₁ edges, for films deposited on a ~0.6-0.8 nm interfacial Ge-N layer, and after partial and complete removal of interfacial Ge-N and/or Ge-O bonding for anneals up to 800°C in Ar. Three types of dielectrics have been addressed: i) HfO₂, ii) high Si₃N₄ content Hf Si oxynitride alloys, and iii) stacked dielectrics comprised of high Si₃N₄ content Hf Si oxynitride alloy/HfO₂. One of the primary sources of defects in the HfO₂ films is associated with the incorporation of Ge, which has been detected in SXPS/UPS spectra. Finally defects identified in HfO₂ spectroscopically, explain large differences in the tunneling currents.