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Reduction of charge trapping in HfO2 film on a Ge substrate by trimethylaluminum pretreatment



Trimethylaluminum pretreatment prior to HfO2 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 HfO2, 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 HfO2 film on a Ge substrate. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)