Area-selective atomic layer deposition of Al₂O₃ on SiN_x with SiO₂ as the nongrowth surface

Area-selective atomic layer deposition (ALD) of dielectrics on chemically similar growth and nongrowth surfaces is very challenging. In this study, we use aminosilane inhibitors to achieve selective blocking of ALD of Al₂O₃ on plasma-deposited SiO₂ versus plasma-deposited SiN_x. The SiO₂ and SiN_x surfaces were exposed to bis(dimethylamino)dimethylsilane followed by (N,N-dimethylamino)trimethylsilane through the vapor phase at 150 °C. At the same substrate temperature, Al₂O₃ films were grown by ALD using dimethylaluminum isoproxide and H₂O. In situ surface infrared spectroscopy shows that aminosilane inhibitors react with almost all the surface −SiOH groups on SiO₂, but reaction with surface −NH_x groups on the SiN_x surface is incomplete, thereby leaving potential growth sites for ALD of Al₂O₃. In situ ellipsometry results shows that a ∼2.7 nm Al₂O₃ film can be selectively deposited on SiN_x versus SiO₂. Upon exposure of the plasma-deposited SiN_x to the atmosphere, a higher attachment of aminosilanes and longer nucleation delay during the ALD of Al₂O₃ were observed, indicating the need to remove the native surface oxynitride prior to functionalization. This study shows that while fully passivating the nongrowth surface is necessary for achieving growth inhibition, ALD can initiate on a partially passivated growth surface.