Fabrication of 20 nm Shallow Nanofluidic Channels Using Coverslip Thin Glass–Glass Fusion Bonding Method

Abstract

A simple low-cost method is proposed for the fabrication of nanofluidic channels on glass substrates. In the proposed approach, the channel is patterned on a borosilicate glass coverslip (thickness of 160 µm) using a buffered oxide wet etching process. The patterned coverslip and a blank coverslip are then preheated in a furnace at a temperature of 400 °C for 8 h. Finally, the two cover slips are fusion bonded at a temperature of 580 °C for another 8 h. It is shown that nanofluidic channels with a depth of only 20 nm and an aspect ratio of 0.001 can be reliably obtained. Furthermore, the average surface roughness (Ra) of the nanofluidic channels is found to be only 0.30 nm. The depth uniformity of the sealed nanofluidic channel is examined by scanning electron microscopy. It is shown that the fusion bonding process has no significant effect on the depth of the original channel. Overall, the results show that the proposed fabrication method is ideally suited to the realization of nanofluidic chips for high-magnification optical fluorescence microscopy applications such as protein preconcentration and biomolecule detection.