Convective assembly and dry transfer of nanoparticles using hydrophobic/hydrophilic monolayer templates

A convective directed-assembly process on a flat substrate that does not require motion and is followed by a dry-transfer process of nanoparticles is presented. The convective assembly process was achieved using Au nanoparticles on hydrophobic/hydrophilic-surface-patterned Si substrates as functions of temperature, gap height, and particle size. An investigation of the particle assembly mechanism showed that the effects of temperature, gap height, and particle size were responsible for controlling the evaporation time, the evaporation length, and the assembly speed, respectively. To ensure conformal contact during the dry-transfer process, chemically patterned hybrid templates with elastic and flexible properties were fabricated and used. The hybrid templates provided conformal contact with a target silicon substrate coated with MPTMS (3-mercaptopropyltrimethoxysilane) and successfully transferred Au particles to the target substrates.