Thermal atomic layer etching of germanium-rich SiGe using an oxidation and “conversion-etch” mechanism

The thermal atomic layer etching (ALE) of germanium-rich SiGe was demonstrated using an oxidation and “conversion-etch” mechanism with oxygen (O2) or ozone (O3), hydrofluoric acid (HF), trimethylaluminum [TMA, Al(CH3)3] as the reactants. crystalline film prepared physical vapor deposition had a composition Si0.15Ge0.85. In situ spectroscopic ellipsometry employed to monitor thickness both surface oxide on during ALE. Using reactant sequence O2-HF-TMA, etch rate increased progressively temperatures from 225 290 °C. At °C, decreased linearly at 0.57 Å/cycle 18–19 Å. This obtained pressures 25, 0.2, 0.4 Torr doses 1.5, 1.0, 1.0 s for O2, HF, TMA, respectively. TMA HF reactions were self-limiting O2 reaction reasonably O3-HF-TMA sequence, ALE 0.42 15, dose times 0.5, O3, all Atomic force microscopy images revealed that O2-HF-TMA sequences did not roughen film. etched selectively compared Si Si3N4 °C sequence. >10 faster than Si(100) low-pressure chemical deposition. selectivity will be useful fabricate nanowires nanosheets sacrificial layer.