Narrowed Si_0.7Ge_0.3 channel FinFET with subthreshold swing of 64 mV/Dec using cyclic self-limited oxidation and removal process

A narrowed Si_0.7Ge_0.3 channel fin field-effect transistor (FinFET) device is demonstrated in detail by using an accurate cyclic wet treatment process. The Si_0.7Ge_0.3 fin/per side of 0.63 nm in thickness can be accurately removed in each cycle by utilizing a self-limited oxidation with 40% HNO₃ solution in 40 s and oxidation removal can be achieved with 1% HF solution in 10 s. As a result, after the dummy gate removal, the fin width of Si_0.7Ge_0.3 can be narrowed from 20 nm to 8 nm by utilizing 10 cycles of this wet treatment process. Compared with the conventional Si_0.7Ge_0.3 FinFET under a similar process, the narrowed Si_0.7Ge_0.3 channel FinFET can realize a strong gate control capability by using this newly developed wet treatment process, because its subthreshold slope can be reduced by 24%, improving from 87 mV/dec to 64 mV/dec.