A study on fabrication of silicon mold for polymer hot-embossing using focused ion beam milling

The need for a flexible and high-throughput process for the fabrication of a polymer-based micro-fluidic device is becoming increasingly important as bio-device industry is expanding very fast. The present work investigated the fabrication of a polymer-based micro-fluidic device by using the combination of the focused ion beam (FIB) milling and the hot-emboss process. The milled depth-ion dose curve for Si was investigated, and some silicon molds were prepared by a repetitive-pass milling with FIB. A Si mold was then used for the hot-emboss of poly-methyl-methacrylate (PMMA) to replicate micro-fluidic parts. Prior to hot-embossing, a FIB milled silicon mold was heat-treated at 500 °C for 10 min in vacuum (0.07 Pa). The FIB milled fields in the Si mold could be replicated on the PMMA with the dimensional deviation less than 1% under the temperature of 150 °C, the force of 50 kgf, the loading force velocity of 50 μm/min and the press hold time of 300 s.