Design and Fabrication of Silicon Nanowire based Sensor

摘要

This paper reports the process development of silicon nanowires sensor requires both the fabrication ofnanoscale diameter wires and standard integration to CMOS process. By using silicon-on-insulator(SOI) wafer as a starting material, the nanowires is fabricated using a top-down approach whichinvolved Scanning Electron Microscope based Electron Beam Lithography method. The siliconnanowires are well developed with the smallest dimension is 65nm in width. The effect of line widthand exposure dose on the pattern structure is investigated experimentally using the negative photoresistma-N2403 for EBL. The exposure doses for the resist layer are varied in the range of 50C/cm2 to180C/cm2 at 20 kV accelerating voltage with a beam current of 0.075nA. The nanowires resist masksare well developed with dimension less than 100 nm in width for the dose exposure parameters of80C/cm2, 100C/cm2 and 120C/cm2. Subsequently, the two metal electrodes which are designatedas source and drain are fabricated on top of individual nanowire using conventional lithographyprocess. Morphological, electrical and chemical characteristics have been proposed to verify theoutcome of the fabricated device. Finally, the fabricated device is performed as pH level detection.Three types of standard aqueous pH buffer buffer solutions which are pH 4, pH 7 and pH 10 are usedto test the electrical response of the device. The SiNWs sensor show the highest resistance value forpH 4 and the lowest resistance value for pH 10. In terms of sensitivity, the device with smallernanowire is found to be more sensitive than larger nanowire as a result of the high surface-to-volumeratio.