Suitable particles may be deposited within an extremely small high-aspect ratio via by flowing the particles in a suspension using supercritical carbon dioxide. The particles may be made up of diblock copolymers or silesquioxane-based materials or oligomers of phobic homopolymers or pre-formed silica-based particles stabilized using diblock copolymers and may include chemical initiators to permit in situ polymerization within the via.