Surface science 

& Area Selective Atomic Layer Deposition (AS-ALD) 

Area-selective atomic layer deposition (AS-ALD) is a bottom-up fabrication process that employs surface chemistry to deposit thin-film material in a targeted area while maintaining large area uniformity, excellent conformality, and angstrom-level thickness control. Therefore, it can enable a reduction in the number of lithography and etch steps and in the use of hazardous reagents during the patterning process for electronic device fabrication, resulting in a decrease of edge placement errors as well as a drop in manufacturing costs.


Both standard ALD and AS-ALD processes are strongly dependent on the ALD chemistry used. So, surface engineering is a key technique to enable to control of molecular adsorption. In AS-ALD, the chemical properties of a surface are controlled to activate or deactivate adsorption of the ALD precursors, so that patterns are formed through selective deposition across differently terminated domains. For instance, while nucleation and growth easily occur on surfaces with reactive groups such as −OH that provide facile adsorption sites for the precursors, deposition can be hindered by surface termination with less reactive groups such as −CH3. Therefore, selective chemical deactivation of oxide surfaces has been a major challenge in the implementation of AS-ALD. By tuning this surface chemistry, we can facilitate the selective growth of materials in desired growth areas.