Unfolding an Elusive Area-Selective Deposition Process: Atomic Layer Deposition of TiO and TiON on SiN vs SiO.

Area-selective atomic layer deposition (AS-ALD) processes for TiO and TiON on SiN as the growth area vs SiO as the nongrowth area are demonstrated on patterns created by state-of-the-art 300 mm semiconductor wafer fabrication. The processes consist of an in situ CF/N plasma etching step that has the dual role of removing the SiN native oxide and passivating the SiO surface with fluorinated species, thus rendering the latter surface less reactive toward titanium tetrachloride (TiCl) precursor. Additionally, (dimethylamino)trimethylsilane was employed as a small molecule inhibitor (SMI) to further enhance the selectivity. Virtually perfect selectivity was obtained when combining the deposition process with intermittent CF/N plasma-based back-etching steps, as demonstrated by scanning and transmission electron microscopy inspections. Application-compatible thicknesses of ∼8 and ∼5 nm were obtained for thermal ALD of TiO and plasma ALD of TiON.