Controlled modification of micromachined silicon surfaces using colloidal micro-and nanoparticles

We report a processing technique, based on convective self-assembly, to form densely packed, ordered, arrays of colloidal micro-and nanoparticles on the internal surfaces of geometrically complex, bulk-micromachined, silicon structures. The self-assembled layers exhibit excellent surface coverage and a low density of crystallographic defects. This method can access a wide range of chemistries, particle sizes, and layer thickness. Potential applications include the formation of porous thin film platforms for biomolecules and catalysts; incorporation of catalytic particles inside microreactors; and colloidal lithography. The principal results are summarized in the form of design guidelines.