Unfolding an Elusive\nArea-Selective Deposition Process:\nAtomic Layer Deposition of TiO₂ and TiON on SiN vs SiO₂

Abstract

Area-selective atomic layer deposition (AS-ALD) processes\nfor TiO₂ and TiON on SiN as the growth area vs SiO₂ as\nthe nongrowth area are demonstrated on patterns created by state-of-the-art\n300 mm semiconductor wafer fabrication. The processes consist of an\nin situ CF₄/N₂ plasma etching step that has\nthe dual role of removing the SiN native oxide and passivating the\nSiO₂ surface with fluorinated species, thus rendering the\nlatter surface less reactive toward titanium tetrachloride (TiCl₄) precursor. Additionally, (dimethylamino)trimethylsilane\nwas employed as a small molecule inhibitor (SMI) to further enhance\nthe selectivity. Virtually perfect selectivity was obtained when combining\nthe deposition process with intermittent CF₄/N₂ plasma-based back-etching steps, as demonstrated by scanning and\ntransmission electron microscopy inspections. Application-compatible\nthicknesses of ∼8 and ∼5 nm were obtained for thermal\nALD of TiO₂ and plasma ALD of TiON.