Area-selective atomic layer deposition of Al2O3 thin films for metal versus dielectric selectivity using vapor-dosed alkanethiols

Abstract

Area-selective atomic layer deposition (AS-ALD), a bottom-up approach, has attracted significant attention for its ability to enable precise, self-aligned deposition exclusively within designated growth areas. AS-ALD of self-aligned dielectric barrier layers on dielectric regions between metal lines is essential for integrating fully self-aligned vias in back-end-of-line processes, where conventional misaligned vias are susceptible to electrical shorting issues, primarily stemming from edge placement errors. In this study, we systematically investigate a vapor-dosing process using alkanethiol-based small molecule inhibitors (i.e., 1-hexanethiol) that can chemoselectively adsorb onto metal surfaces, such as Co and Cu, relative to dielectric surfaces like SiO2. ALD of Al2O3, with sequential pulses of dimethylaluminum isopropoxide and H2O, is employed to confer deposition selectivity on alkanethiol-treated metals versus untreated dielectrics. By redosing the 1-hexanethiol inhibitor to enhance blocking ability, we successfully achieve enlarged deposition selectivity greater than ∼10 nm on patterned metal/dielectric surfaces. This approach contributes to the advancement of bottom-up nanofabrication for metal-dielectric patterns. © 2025 Elsevier B.V.