Microfluidic to Nanofluidic Interface via a Thermally Decomposable Sacrificial Polymer

We present an original batch process to connect a bulk microfluidic channel to a surface nanofluidic channel for a wide variety of microfluidic and lab-on-chip applications. The approach relies on a two-step lithography process using a thermally decomposable polynorbornene resist unity to form the sacrificial channel layer. A high aspect ratio silicon via is deep reactive ion etched to the subsurface microchannel. Lithography of a high viscosity unity plug is followed by lithography of a low viscosity unity sacrificial layer to form the nanofluidic channel. A plasma-enhanced chemical vapor deposition nitride layer is deposited to encapsulate the nanochannel and the sacrificial polymer is decomposed by baking. This technique enables fabrication of complete off-chip to nanochannel fluidic systems. We emphasize the benefit of sacrificial polymers to form long 3-D nanofluidic channels.