Hot Embossing Of Polymer Nanochannels Using PMMA Moulds

Nanofluidic chips have a broad range of applications, such as biological detection, chemical analysis and so on, and the fabrication of nanochannels is one of the critical parts of nanofluidic chips. Hot embossing is one of the main methods for fabricating nanochannels, but one silicon mould can only be used to replicate10～20chips. In order to increase the device yield of the silicon nanomould, a novel hot embossing method was developed to fabricate polymer nanochannels. The pattern on the silicon nanomould was transferred to multiple polymethylmethacrylate (PMMA) plates, and then polyethylene terephthalate (PET) nanochannels were embossed by using the PMMA mould. It was proved that one PMMA mould can be used to repeatedly emboss at least30PET substrates.The fabrication of nanochannels require expensive nanolithography equipments, to reduce the cost of silicon nanomoulds, a method based on conventional UV-lithography was put forward to fabricate silicon nanomoulds with sub-micrometer width. First of all, based on UV lithography and dry etching, we fabricated nanochannels with width of1.68μm and depth of194nm; Than, the width of microchannels were decreased to811nm by cover a SiO2layer on the silicon wafer using plasma enhanced chemical vapor deposition (PECVD). We discussed the feasibility of using thermal oxidation to narrow down the microchannels as well, and proved that requires a long time.We have researched about the replication process of PET nanochannels. First of all, we optimized the embossing temperature of PMMA plates. Than, we optimized the embossing temperature of PET plates by using PMMA daughter mould, and good pattern fidelity of nanochannels were obtained at90℃. By using the PMMA mould, the variations in width and depth between PET nanochannels and the PMMA mould were1.44%and1.99%, respectively. The reproducibility of the hot embossing method was also evaluated, and the relative standard deviations in width and depth of8PET nanochannels were4.91%and9.74%, respectively.Furthermore, based on electron beam lithography(EBL), we fabricated nanochannels with width of105nm and depth of204nm, The patterns on the silicon nanomould were transferred to PMMA plate with width of113nm and height of88nm, then PET nanochannels were embossed by using the PMMA mould, and the average width and depth of PET nanochannels embossed at90℃were149nm and66.8nm. By using the PMMA mould, the variations in width and depth between PET nanochannels and the PMMA mould were24.2% and14.2%, respectively. And the relative standard deviations in width and depth of8PET nanochannels were12.2%and13.2%, respectively.