Fabrication and characterization of silicon nitride nanopores

The fabrication of synthetic nanopores with dimensional and electrical properties similar to organic alpha-hemolysin (α-HL) nanopores is required for the development of a novel genotyping device. This thesis details the development of synthetic nanopores with diameters below 5 nm fabricated by sputtering a free standing silicon nitride membrane using a tightly focused electron beam. Nanometer control is achieved with sputtering rates of 0.5 – 0.75 nm/s. This technique is further extended to fabricate a proof-of-concept array of 44 sub-5 nm nanopores in a single membrane to enable the detection of unamplified genomic DNA with acceptable signal-to-noise. As-drilled inorganic nanopores have inferior electrical characteristics compared to α-HL. Careful study, however, revealed electrical noise sources that could be effectively reduced by chemical pretreatment of the pores and surface coating with poly-di-methyl-siloxane (PDMS). The chemical pretreatment targeted 1/f noise, while the PDMS reduced dielectric noise with an overall reduction in RMS current noise by a factor of 10. This resulted in processed nanopores with extremely favorable noise characteristics. These low noise silicon nitride nanopores were used to demonstrate single-molecule DNA translocation and probe capture with exceptional signal-to-noise ratios ranging from 40 – 150.Applied Science, Faculty ofElectrical and Computer Engineering, Department ofGraduat