Self-assembled monolayers and atomic layer deposition are two methodologies commonly used to tailor surface properties at the atomic scale and achieve thin films with excellent electrical, chemical, mechanical or optical performances thus leading to a broad portfolio of applications from thin films for flexible electronics to biological surface functionalization.

While ALD film growth is the result of a discretized process where inorganic monolayers are built upon one another through a sequence of reactant exposure/purge cycles until the desired film thickness is achieved (typically 1-100nm), SAMs on the other hand allow the deposition of a single ordered organic monolayer. Both processes are driven by self-limited chemisorbed surface reactions and can be deposited under vacuum conditions at relatively low temperatures, facilitating the integration of these two processes on a single platform.

The current work was implemented on a commercial Cambridge Nanotech hybrid ALD/SAMs platform. The tool is based on a Savannah S200 ALD reactor and integrates a SAMs kit for the accurate delivery of a variety of SAMs reactants. Stable SAMs monolayers are deposited under vacuum conditions using exposure mode (EXPO) characteristic of Cambridge Nanotech ALD tools. Key process metrics such as precursor pulse and exposure times, source and reactor temperatures were investigated for a variety of precursors including non-polar hydrophobic alkylsilanes (DTS), oleophobic fluorinated silanes (FOTS), hydrophilic polyethylene glycol (PEG) and thiols. In all cases, the self-limited surface saturation was achieved within 1 to 15 min minute exposures to the precursor at temperature ranging from 50 to 110°C.

In some instances, oxide ALD films were used to deposit a very thin seed layers (<5Å) to promote the adhesion of a SAM without prior surface cleaning/conditioning. Heterostructures based on oxide ALD (Al2O3, ZrO2, SiO2) and SAMS were also obtained to develop efficient water moisture barriers to be used for encapsulation. Overall the integration of these processes in a single platform provides a versatile and scalable method to surface functionalization where surface properties such as wettability can be tuned by controlling at the atomic level the structures of these hybrid coatings.