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

We report improvement of TiN/Y
₂
O
₃
/ Si
_0.78
Ge
_0.22
metal-oxide-semiconductor (MOS) interface properties by employing the trimethylaluminum (TMA) pretreatment before Y
₂
O
₃
deposition. 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/Y
₂
O
₃
/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.