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

Abstract

We report improvement of TiN/Y2O3/ Si0.78Ge0.22 metal-oxide-semiconductor (MOS) interface properties by employing the trimethylaluminum (TMA) pretreatment before Y2O3 deposition. It is found that the optimum number of the TMA pretreatment cycles for minimizing interface trap density ( ${D}_{\text {it}}$ ) and slow trap density ( $\Delta {N}_{\text {st}}$ ) of TiN/Y2O3/SiGe interfaces with post metallization annealing (PMA) at 450 °C is ten cycles. The reduction in ${D} _{\text {it}}$ and $\Delta ~{N} _{\text {st}}$ is attributable to less amounts of Ge–O bonds at the SiGe interfaces. On the other hand, an increase in ${D} _{\text {it}}$ with further increasing the number of TMA pretreatment is attributable to more amounts of Al–O bonds in ILs.