Area-selective deposition is a promising technique for positional self-alignment of materials at a prepatterned surface. Critical to this is the development of molecular systems that have selective surface binding and can act as templates to material growth. This paper reports how end functionalized polymers can be used to create oxide films through a grafting method. Here, we detail a facile approach for rapid grafting (in seconds) of polymer brush films with complete coverage over large areas with high uniformity (pinhole free). Subsequent conversion to an oxide (∼3−4 nm thickness) is performed via liquid-phase metal ion infiltration. Exposing the covalently grafted polymer brush (P2VP-OH) to a metal salt-solvent solution (using the Al 3+ ion as a model species) swells the polymer, facilitating ion inclusion. Early results suggest that a solvent-mediated approach to polymer film infiltration can be used to develop inorganic films in a facile process. While data shows inclusion into both large-area and patterned films, the mechanism and understanding of these have been limited. In particular, the solution-mediated process described here shows the precise tailoring of nanometer-thin polymer films that are pinhole-free and that can be activated to create semiconductor-compatible oxide films that are parallel in quality to ALD-or CVD-derived processes. A surface deactivation strategy is also realized using a hydroxyl-terminated polystyrene (PS-OH) brush that prevents the deposition of ions. We consider this strategy as a means to prevent electromigration of ions as well as the possibility of coating ALD layers.

We describe a versatile bottom-up approach to covalently and rapidly graft hydroxyl terminated poly (2-vinyl pyridine) (P2VP-OH) polymers in 60 seconds that can subsequently be used to fabricate high quality TiO2 films on silicon substrates. A facile strategy based upon room temperature titanium vapor phase infiltration of the grafted P2VP-OH polymer brushes produces TiO2 nanofilms of 2-4 nm thickness. In order to fabricate coherent inorganic films with precise thickness control, it is critical to generate a high-quality polymer brush film i.e. a complete monolayer. Definition of precise and regular polymer monolayers is straightforwardly achieved for polymers which are weakly interacting with one another and the substrate (apart from the reactive terminal group used for grafting). However this is much more challenging for reactive systems. Crucial parameters are explored including molecular weight and solution concentration for grafting dense P2VP-OH monolayers from the liquid phase with very high coverage and uniformity across wafer scale areas. Additionally, we compare the P2VP-OH polymer system with another reactive polymer PMMA-OH and a relatively non-reactive polymer PS-OH, the latter we prove to be extremely effective for surface blocking and deactivation. Our methodology provides new insight into the grafting of polymer brushes and their ability to form dense TiO2 films. We believe the results described herein are important for further expanding the use of reactive and unreactive polymers for fields including area selective deposition, solar cell absorber layers and antimicrobial surface coatings.

In this work we present the results of a Hard X-ray Photoelectron Spectroscopy (HAXPES) study on the creation of metallic copper layers via metal-salt infiltration into a poly-2-vinylpyridine (P2VP) film. Metal salt inclusion is a wet chemistry process which allows for the fabrication of both metal and metal oxide films by means of infiltrating a receptive polymer thin film with metal salt precursors. A copper infiltrated P2VP film was subject to UV/Ozone treatment to form copper oxide and annealed in-vacuo to reduce the film to metallic copper. HAXPES and transmission electron microscope (TEM) measurements were used to study the polymer film before and after metal salt infiltration, along with analysis of the copper oxide created after UV/Ozone treatment. The results show successful infiltration of the metal salt into the polymer film, as well as complete conversion to copper oxide following UV/Ozone treatment and reduction to metallic copper with a subsequent in-situ anneal, which demonstrates the ability of the technique for the creation of several key integrated circuit features.