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

Abstract

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 SiNx. The SiO2 and SiNx 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 −NHx groups on the SiNx 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 SiNx versus SiO2. Upon exposure of the plasma-deposited SiNx 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.