Fabrication of Nanochannels on Polymer Thin Film

Recent advances in nanotechnology allow the fabrication of structures down to the nanometer range. Various theoretical and experimental studies on the characteristics of fluid in nanochannels have been carried out in recent years. The results show that transport phenomena in nanoscale promise a wide range of applications in biological and chemical analysis. Practical applications require fabrication of nanochannels with a short production time and at a low cost. Polymer is considered as a suitable material for mass production of nanochannels due to the wide range of properties available, as well as the low cost of material and fabrication process. This paper reports the fabrication of planar nanochannels using hot embossing and thermal bonding technique on a polymer thin film. The mold for hot embossing was fabricated on a silicon wafer using photolithography and Reactive Ion Etching (RIE). Polymethylmethacrylate (PMMA) thin film with a thickness of 250 μm was used as the base material to emboss the nanochannels from the silicon mold. Temperature and pressure were controlled and recorded continuously during the embossing process. The channels then were examined by Atomic Force Microscope (AFM) in tapping mode to verify the width and the depth of the channel. Next, another piece of PMMA thin film was bonded to the first piece by thermal bonding process to make closed nanochannels. Temperature and pressure during the bonding process were controlled and recorded. Access to the channels was made on the thin film by a laser cutter before embossing. The results showed that open planar channels with the depth down to 30nm can be fabricated on PMMA thin film with a process time less than 30 minutes. Width and depth of the channels agree well with appropriate dimensions on the mold. Bonding can be achieved within 40 minutes. Closed planar channels with the depth of 300nm were fabricated successfully by a combination of embossing and thermal bonding processes. This project demonstrates the possibility of fabricating nanochannels with low cost and short processing time using polymer material. The processes are suitable not only for nanochannels but also for more complicated nanostructures. The presented technique allows the fabrication of nanodevices with various designs.