Electron-Beam-Induced Deposition of Metallic Microstructures from a Molten-Salt Film on Conductive and Nonconductive Substrates

摘要

Lithographical processes are among the most important techniques for microfabrication, and applications range from chip fabrication to the structuring of micromechanical and microtluidic devices. In many applications, metallic structures such as chip interconnects are obtained by a sequential process in which, for example, a polymer mask is first lithographically patterned and subsequently coated with metal. Direct, one-step creation of metallic nanostructures is limited to only a few processes. Although the electron-beam-induced deposition (EBID) of nanoscale structures from mostly gaseous organo-metallic precursors is well established, the production of pure metal deposits was demonstrated only recently. Solid metal salts were also used as precursors for the deposition of metal nanoparticles, which were, however, mostly very finely dispersed on the surface, due to the limited material supply by the thin salt film. In addition local catalytic activity, induced by EBID of Fe or by electron irradiation of a SiO_x film, was employed for the local decomposition of a gaseous iron-containing precursor. Similarly, electron- or ion-beam-induced surface defects can serve as nuclei for the electrochemical deposition of metals on a silicon surface. Local electrochemical metal deposition by use of electrochemical scanning probes was also demonstrated.