Fabrication of self-encapsulated nickel microchannels and nickel nanowalls by reactive ion etching

Self-encapsulated nickel microchannels and nickel nanowalls were fabricated with a new approach using reactive ion etching (RIE) process. The simple microfabrication process consists of nickel deposition, lithography, nickel RIE, and plasma ashing. Well-aligned nickel nanowalls and nickel self-encapsulated microchannels were accomplished. Helium backside cooling played a key role in this experiment. For the RIE process condition without helium backside cooling, the top surfaces of the photoresist were burnt. The sputtered nickel particles were thus redeposited on the sidewalls of the patterned photoresist, producing well-aligned nickel nanowalls with 100 nm in thickness. For the RIE process condition with helium backside cooling, the patterned photoresist was not damaged owing to the low processing wafer temperature. The sputtered nickel particles were successfully redeposited on the side and top faces of the patterned photoresist, producing self-encapsulated nickel microchannels. The proposed process could be applicable for microdevices and nanodevices that need good mechanical properties, or for micropackagings and nanopackagings that need hermetic sealing by metal self-encapsulation.