The acquisition of the Xenon difluoride release system, by Cornell Nanoscale Facility (CNF), a member of the National Nanotechnology Infrastructure Network (NNIN) will make possible the development of reproducible etch capability for fabricating released micro- and nanostructures. Released structures are formed by the selective removal of a sacrificial material contained beneath a surface micro-machined layer. The dissimilar material is removed selectively leaving the surface layer suspended from the substrate. Suspended structures are employed in a range of science and engineering experiments and applications. In characterization, very common forms are the suspended probes used in atomic force, tunneling, magnetic resonance, and optical probe instruments. In biology and electronics applications of micro-electro-mechanical systems, these include sensitive mass detection through resonance, ultra-fine integrated sharp probes used to access regions of soft materials, and resonators. In physics, these include sensitive single electron transistor based detection of position and charge. Fabrication of such structures requires reproducibility and reliability, and since the fragile suspended structures are commonly released through a liquid medium, surface tension during the release process, leads to failure. Xenon difluoride (XeF2) dry gas etching is a technique for achieving this release directly through the gas phase. XeF2 etches silicon spontaneously with high selectivity to other materials. The NNIN, of which CNF is a member, provides equipment, education and technical support to the scientific community. The resources of NNIN are openly available to the entire nation. The presence of a XeF2 Etch System at CNF will represent the first such dry gas etch capability within the NNIN and immediately support an estimated 70 projects in a variety of disciplines involving over 125 users of CNF. The structure of NNIN will enable users throughout the network to take advantage of this process. By leveraging the unique infrastructure contained within the network, the addition of this capability will lead to interesting new directions of research involving new materials, nanoscale released structures, devices with novel 3-D geometries, and other interdisciplinary applications.
