Reactive monolayers in directed additive manufacturing – area selective atomic layer deposition

Abstract

Additive manufacturing generally describes a process of producing macro scale 3D-objects by the addition (or formation) of one patterned layer, of the overall object, onto a subsequent layer. In this fashion the target structure is produced in a layer-by-layer process. Selective area atomic layer deposition (SA-ALD) is, fundamentally, an additive manufacturing process where the layer-by-layer process occurs at the atomic level. A patterned surface is generated by exploiting disparate surface chemistries where a metal oxide is deposited in a targeted area. One method of enabling this process is through the use of organic monolayers that can form from a collection of well organized small molecules onto one surface and not another. These self-assembled monolayers (SAMs) can act as effective barriers to block the deposition of up to hundreds of thermal ALD cycles or can be used in combination with repair strategies to extend selective deposition capabilities. Recent efforts have focused on increasing the durability of these monolayer blocking layers. To this end we have designed SAM components that contain an aligning hydrogen bonding component that aid in directing the formation of well aligned monolayers as well as acting as a supramolecular cross-link. Furthermore, the components contain a photoactive diyne moiety that can be subsequently polymerized after irradiation to produce a robust ALD barrier. On structured surfaces this photoactive SAM achieved better deactivation properties than commercially available materials providing access to materials that produce a robust barrier in shorter formation times and withstand a great number of ALD cycles.