Room-Temperature ALD of Metal Oxide Thin Films by Energy-Enhanced ALD

Room temperature ALD (RT-ALD) processes are of interest for applications using temperature-sensitive substrates, yet they are not so commonly reported. The challenges associated with RT-ALD arise when surface groups are not sufficiently reactive toward incoming precursors and vice versa, the precursors are not sufficiently volatile, and purge times become impractically long. These challenges can be overcome using energy-enhanced ALD. We demonstrate here viable energy-enhanced RT-ALD (25 °C) processes for Al2O3 and SiO2 from trimethylaluminium (TMA) and bis(diethylamino)silane (SAM.24) precursors, enabled using an O2 plasma or ozone as co-reactants. Saturated ALD growth was obtained at room temperature for the TMA/O2 plasma, TMA/ozone, and SAM.24/O2 plasma processes, whereas the SAM.24/ozone RT-ALD process gave no growth. Using these results, the essential and desirable criteria that are necessary to obtain a viable RT-ALD process are discussed