NANOCHANNEL FABRICATION FOR CHEMICAL SENSORS

In a novel chemical sensor, the chemical charge coupled device (CCD), electrostatic fields in nanocapillary channels smaller than a Debye le ngth will be used to separate and concentrate ions in solution with a predicted detection limit of < 1 x 10(-13) M. Conventional integrated circuit techniques are used to deposit thin dielectric and amorphous-S i films on a Si substrate and to lithographically define channel and r eservoir structures. Hollow Si3N4 nanochannels with heights between 20 and 100 nm, widths between 0.5 and 20 mu m, and lengths up to 5 mm ha ve been fabricated by wet chemical etching of a sacrificial amorphous- Si layer in tetramethylammonium hydroxide. Initial modeling of a three -phase chemical CCD predicts the ability to select and concentrate ion ic constituents by many orders of magnitude, according to their diffus ion coefficients. (C) 1997 American Vacuum Society.