A First-Principles Investigation of the Driving Forces Defining the Selectivity of TiO2Atomic Layer Deposition

Area-selective deposition (ASD) is a technique to deposit material only on a defined area of a prepatterned surface, while no deposition occurs on adjacent surface areas. It is the subject of intense investigations by the scientific and engineering communities as it offers the prospect to simplify and improve patterning processes for fabrication of nanoelectronic devices as well as to reduce the manufacturing costs. Numerous efforts have been dedicated to identify process conditions for highly selective ASD processes. Still, the search for optimal conditions is often an empirical process due to the limited understanding of the mechanisms that take place at the atomic scale. Understanding the links between precursor reactivity, surface treatments, and the reactor operating conditions could greatly contribute to the development of highly selective ASD processes. In this paper, we therefore combine first-principles calculations with statistical thermodynamics to understand the role of the precursors in area-selective TiO2atomic layer deposition (ALD). First, we investigate the selectivity loss mechanisms for TiCl4/H2O ALD on SiO2nongrowth surfaces with different surface terminations (e.g., OH groups and trimethylsilyl groups). We link the resulting thermodynamic driving forces to experimental reports. Subsequently, we extend the investigation to a total of 26 commercially available titanium precursors and to three different oxygen sources and rank their potential for TiO2ASD for the SiO2surfaces with different surface terminations (OH groups and trimethylsilyl groups). We find that the combination of TiCl4with H2O offers the best performance in terms of selectivity. The theoretical approach proposed here is expected to greatly assist and accelerate the design of precursors for different ASD approaches.