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((OBu)-Bu-t)(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.