Towards Molecular Electronics: Solution-Based Methods for Selective Deposition of Metals and Semiconductors

Walker, Amy V.

doi:10.1063/1.3646768

Cited by 1 publication

(1 citation statement)

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“…In the past decade, atomic layer deposition (ALD) has become a well-established and widely used deposition technique in the semiconductor industry. , ALD is based on two or more sequential self-limiting surface reactions, enabling atomic level control over the thickness, combined with excellent uniformity and conformality of the deposited material. − ALD is highly sensitive on the reactive sites that terminate the surface, which makes ALD a relevant deposition strategy for ASD . This surface sensitivity can, in some cases, lead to selective precursor or coreactant adsorption enabling area-selective ALD (often termed inherent selectivity). − In general, however, the non-growth area needs to be functionalized by using inhibitor molecules to achieve selectivity. To this end, self-assembled monolayers (SAMs) have been studied as inhibaition layers for area-selective ALD. − More recently, small molecule inhibitors (SMIs) , that can be applied in the vapor/phase during the ALD process are being investigated for area-selective ALD to better meet the requirements for high-volume manufacturing. − In our previous work, area-selective ALD of SiO 2 , and WS 2 has been achieved on SiO 2 based on the selective adsorption of acetylacetone (Hacac) as SMI on various oxides (e.g., Al 2 O 3 ) as non-growth area.…”

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confidence: 99%

Relation between Reactive Surface Sites and Precursor Choice for Area-Selective Atomic Layer Deposition Using Small Molecule Inhibitors

et al. 2022

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Implementation of vapor/phase dosing of small molecule inhibitors (SMIs) in advanced atomic layer deposition (ALD) cycles is currently being considered for bottom-up fabrication by area-selective ALD. When SMIs are used, it can be challenging to completely block precursor adsorption due to the inhibitor size and the relatively short vapor/phase exposures. Two strategies for precursor blocking are explored: (i) physically covering precursor adsorption sites, i.e., steric shielding, and (ii) eliminating precursor adsorption sites from the surface, i.e., chemical passivation. In this work, it is determined whether steric shielding is enough for effective precursor blocking during area-selective ALD or whether chemical passivation is required as well. At the same time, we address why some ALD precursors are more difficult to block than others. To this end, the blocking of the Al precursor molecules trimethylaluminum (TMA), dimethylaluminum isopropoxide (DMAI), and tris(dimethylamino)aluminum (TDMAA) was studied by using acetylacetone (Hacac) as inhibitor. It was found that DMAI and TDMAA are more easily blocked than TMA because they adsorb on the same surface sites as Hacac, while TMA is also reactive with other surface sites. This work shows that chemical passivation plays a crucial role for precursor blocking in concert with steric shielding. Moreover, the reactivity of the precursor with the surface groups on the non-growth area dictates the effectiveness of blocking precursor adsorption.

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