Generic technological platform for microfabricating silicon nitride micro- and nanopipette arrays

In this paper, the design and the characterization of batch fabricated Si_xN_y micropipette arrays with diameters ranging from 6 µm down to 250 nm are described. The process used to fabricate the micromachined pipettes includes a deep reactive ion etching step, followed by the deposition of two successive layers, a thermal oxide layer and a low stress, low pressure chemical vapor deposited silicon nitride layer, respectively. The diameter of the micropipettes could be modulated simply by choosing the thicknesses of the oxide sacrificial layer and of the nitride walls of the micropipettes. The reactive ion etching of the micropipette top layer in deep cavities and in confined and deconfined configurations is discussed. The mechanical resistance of the micropipette array was qualitatively tested and it was demonstrated that a force of 0.25 mN/micropipette could be applied without rupture of the micropipettes.