Reduction of MOS Interface Defects in TiN/Y₂O₃/Si₀.₇₈Ge₀.₂₂ Structures by Trimethylaluminum Treatment

We report improvement of TiN/Y2O3/ Si0.78Ge0.22metal-oxide-semiconductor (MOS) interface properties by employing the trimethylaluminum (TMA) pretreatment before Y2O3deposition. It is found that the optimum number of the TMA pretreatment cycles for minimizing interface trap density (Dit) and slow trap density (ANst) of TiN/Y2O3/SiGe interfaces with post metallization annealing (PMA) at 450 °C is ten cycles. The reduction in Dit and Δ Nst is attributable to less amounts of Ge-O bonds at the SiGe interfaces. On the other hand, an increase in Dit with further increasing the number of TMA pretreatment is attributable to more amounts of Al-O bonds in ILs.