Ultra-high aspect ratio buried silicon nano-channels for biological applications

Abstract

It is reported for the first time a process technology to fabricate sub-100 nm silicon nano-channels with ultra high aspect ratio (~160) for micro fluidics, nano-filtration and pathogen detection applications. A novel double passivation deep reactive ion etching process has been developed to realize ultra high aspect ratio silicon nano-channels which is further narrowed by deposition of polysilicon and thermally oxidized to form sub-100 nm buried nano-channels. This technology further provides for in-situ capping of the nano channels which offers significant stress-relief at the top of the nano-channels during subsequent glass bonding and packaging process. By providing in-situ capping capability for the channels we also eliminate potential leakage issues due to poor bonding contact. This channel capping also helps in preventing breakage of the high aspect ratio structures under high anodic bonding pressure. Though the present work was targeted for biological applications, it can easily be used for mainstream MEMS and NEMS applications such a RF resonators, Sensors and Actuators.