The increasingly demanding challenge in nanoelectronics of patterning structures with nanometer alignment accuracy, motivates the development of bottom-up and self-aligned fabrication schemes. Area-selective atomic layer deposition (ALD) aims at the deposition of material only on specific surfaces, without performing additional lithography and etching steps, and thereby eliminates this alignment challenge. Moreover, area-selective ALD offers new and unique opportunities for the synthesis of nanoparticles in the field of catalysis. In this presentation, two novel approaches for achieving area-selective ALD of oxides will be described, and the underlying surface chemistry that makes these ALD processes selective will be adressed. Furthermore, the main challenges, opportunities, and future directions of the field of area-selective ALD will discussed. The first approach relies on the use of small inhibitor molecules in ABC-type (i.e. three-step) ALD cycles. By choosing an inhibitor molecule that is able to selectively adsorb on specific surfaces, and block the precursor adsorption during the subsequent step, area-selective ALD is acquired on those surfaces on which the inhibitor is not able to adsorb. This strategy was demonstrated for area-selective ALD of SiO2 on GeO2, SiNx, or WOx (without coating Al2O3, HfO2, or TiO2 non-growth surfaces) using acetylacetone inhibitor, bis(diethylamino)silane precursor, and O2 plasma pulses. The second approach focuses on area-selective ALD of metal oxides on noble metals by exploiting the catalytic activity of the metal surface. When using O2 gas as the co-reactant, ALD of Fe2O3 from t-butyl ferrocene precursor or NiO from nickelocene only occurs on surfaces that are able to catalyze dissociative chemisorption of O2. Area-selective ALD was demonstrated for Fe2O3 and NiO on Pt and Ir surfaces, whereas no deposition was observed on the inert surfaces of SiO2, Al2O3 or Au. In addition to performing depositions on patterned surfaces, this area-selective Fe2O3 ALD process was used for the synthesis of Pt/Fe2O3 core/shell nanoparticles.

New approaches for area-selective atomic layer deposition of oxides

255th National Meeting (2018)

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