Fluorescence XAFS study of local structures in high-k gate dielectrics HfSiON/SiON/Si annealed at various nitrogen gas partial pressure

Geometric structures for HfSiON/SiON/Si films annealed at various N ₂ gas partial pressures were investigated using fluorescence XAFS measurement at Hf L_III- and L_I-edge. The XAFS analysis has revealed that the local structures around the Hf atoms strongly depend on the N₂ gas partial pressure. For the sample annealed at the N₂ gas partial pressure of 10 Torr HfN and HfSiON coexist, and for the samples annealed at the N₂ gas partial pressure above 100 Torr Hf atoms form HfSiON only. These results indicate that the formation of HfN for HfSiON/SiON/Si films can be suppressed by annealing at proper partial pressure of N ₂ gas.