Reduction of charge trapping in HfO ₂ film on a Ge substrate by trimethylaluminum pretreatment

Trimethylaluminum pretreatment prior to HfO ₂ deposition is introduced for native oxide reduction. It is identified that the trimethylaluminum pretreatment could effectively reduce native oxide, which is transformed to an aluminum oxide interfacial layer. Formation of the thin aluminum oxide layer suppresses Ge diffusion into HfO ₂, reducing hysteresis in the ca- pacitance-voltage curve. Moreover, the device reliability of the trimethylaluminum pretreated sample is improved in a constant current stress test. This work indicates that trimethylaluminum pretreatment is an effective in-situ method for the gate dielectric stack formation to reduce charge trapping in the HfO ₂ film on a Ge substrate.