Aerosol Deposition of Alumina Coatings on Micropillar-patterned Substrates: An Interfacial Analysis

Aerosol deposition (AD) is a novel technique for producing dense, crack-free nanocrystalline coatings at room temperature. Although most research has focused on flat substrates, the need for deposition on structured or patterned surfaces is crucial for micro-device applications. In this work, we utilized AD to deposit alumina onto micropillar-patterned Si substrates. To explore the coating formation mechanisms, we characterized coating cross-sections using scanning electron microscopy, x-ray diffraction, and high-resolution transmission electron microscopy. Numerical simulations, including computational fluid dynamics, finite element modeling, and molecular dynamics, were also employed to study gas flow and particle impact behaviors. The results demonstrate that substrate patterns significantly affect the coating microstructure and growth mechanisms in AD. Our in-depth analysis revealed the formation of amorphous regions at particle boundaries and at the coating-substrate interfaces, suggesting that pressure-induced amorphization may play a key role in coating adhesion. These insights expand the potential applications of AD, particularly in surface sealing and 3D microelectronic devices.