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 length 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-Si films on a Si substrate and to lithographically define channel and reservoir 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 have 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 ionic constituents by many orders of magnitude, according to their diffusion coefficients. (C) 1997 American Vacuum Society.