A study of elucidation and improvement of TiO2 selectivity by first-principles based thermodynamic simulation

Abstract

Area-selective deposition (ASD) enables the deposition of materials in a targeted area, typically a prepatterned surface, while preventing the growth on adjacent surfaces.[1] The technique is appealing for both academia and industry as it offers a vehicle to simplify material developments in nanoelectronics. Consequently, numerous efforts have been dedicated to investigate the factors driving the selectivity mechanisms and to identify optimal process deposition conditions, including surface treatments, that enable highly selective processes. The “selectivity” dimension results from the identification of the right combination of precursors (including co-agents), surface treatments, and reactor operating conditions. This is typically a complex and laborious process that requires many systematic and tightly controlled experiments. As a result, the development of highly selective ASD processes is often a slow and challenging task where any form of guidance provided by modeling insights can be precious.In this context, we studied, by combining thermodynamic considerations and first principle simulations, the reactivities of complex surface chemical reaction networks and the factors impacting on selectivity.In this talk, we will discuss the case of the ASD of TiO2 on SiO2 substrates terminated with either “reactive” (-OH) or “passivated” alkyl-silyl groups. First, we will first briefly discuss the validation of our approach by comparing our model prediction with experimental measurements for the case of the ALD of TiO2 using the precursors TiCl4 and Ti(OMe)4 and then report the insights gained for the identification of optimum Ti precursor and inhibitor for the ASD of TiO2. We will then extend the discussion to the case of the ASD supercycles of TiO2, where the interaction of some Ti precursors (or of their ligands) leads to the degradation of the surface “passivation” and then requires restoringthe surface by injecting of alkyl-silyl functional groups. We will review the strategies that worked with their drawbacks.