Maskless patterning of metal nanoparticles and silicon nanostructures by a droplet deposition and etching process

This paper introduces a droplet-based method to deposit metal nanoparticles (named: droplet deposition) and etch silicon surfaces creating silicon nanostructures (named: droplet etching). The droplet deposition and etching process is a simple and cost-effective method that only requires a pipette tip for silver and gold nanoparticle coating and fabrication of silicon nanostructures. Besides, it also eliminates the need for mask designs or other fabrication facilities, simplifying the nanoparticle and silicon nanostructure patterning process. For the noble metal nanoparticle coating by droplet deposition, we investigate the influence of various process parameters such as metal ion concentration, hydrofluoric acid concentration, deposition time, and temperature effects on the resulting nanoparticle plating. And for silicon nanostructure creation, we use the droplet etching technique that selectively etches the silicon in regions where metal nanoparticles have been deposited while other regions remain unaffected and well-preserved. Finally, we demonstrate the capability of hand-writing geometric patterning, transferring pre-defined patterns by shadow masking and mass production for droplet deposition and etching using a multi-channel (8-channel) pipette.