HfO₂ Area-Selective Atomic Layer Deposition with a Carbon-Free Inhibition Layer

Area-selective atomic layer deposition (AS-ALD) is a bottom-up materials synthesis process that provides the opportunity to overcome challenges associated with current top-down fabrication methods. In this study, we develop a surface treatment process by using an aminosilane molecule (di(isopropylamino)silane (DIPAS)) to block the adsorption of Hf precursors for AS-ALD HfO₂. We show that under select conditions, functionalizing SiO₂ by DIPAS attaches only terminal silicon hydrides to the surface without addition of carbon. We test AS-ALD of HfO₂ on SiO₂/TiN substrates using the DIPAS functionalization for three different Hf precursors (tetrakis(dimethylamino)hafnium(IV) (TDMAHf), hafnium(IV) tert-butoxide (Hf(O^tBu)₄), and hafnium tetrachloride (HfCl₄)). After the growth characteristics and film properties for the three precursors are investigated, optimized ALD and surface functionalization processes are determined. Subsequent blocking results show that the resulting hydride-functionalized SiO₂ surface can prevent the adsorption of some Hf precursors, without the need for inhibitors based on carbon species at the surface. This study introduces a new surface treatment together with considerations for ALD precursor selection to enable an AS-ALD process that can be readily compatible with semiconductor manufacturing processes.