Superionic Solid State Stamping (S4)
This dry, single step, electrochemical etch process, developed by the Center, can produce nanoscale 3-D patterns with exceptional fidelity in thin metal films. The process employs a mold of a superionic material with patterns formed using an e-beam or focused ion beam (FIB) which is then placed against a thin metallic film while a potential is applied between the mold and the film. The current causes the film to ionize and "dissolve" into the mold leaving behind the pattern. Since this electrode reaction is contact dependent, occurring only at points of contact, the process is self-controlling.
Large area solid electrolyte stamps have been developed by embossing ionic polymers from pre-formed masters. This process can replicate complex features with a resolution approaching 10 nm. Flexible ionic stamps with a fractal pattern have been embossed into Nafion polymer stamps.
This process has been further extended in conjunction with a hydrofluoric acid etch which allows an S4 pattern to be transferred to a silicon surface creating a new "non-lithographic" manufacturing process for patterning GaAs and silicon.
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