Abstract
Electron-beam-induced deposition of materials has been known for almost 40 years from contamination writing. It has developed into "additive lithography" with nanometer resolution employed in scanning electron microscopes, in dedicated lithography systems, in reducing image projection systems, and in scanning tunneling microscopes. The technique allows deposition of nanometer- to micrometer-size structures with nanometer precision in three dimensions without supplementary process steps such as lift-off or etching procedures. Depending on the deposition conditions, novel compound materials are created from organometallic precursors which form resistors with a resistivity ranging from 103 Ω· cm to 2×10-3 Ω· cm and sustain current densities higher than 5×105 A/cm2 without damage. High-resolution transmission electron microscope analysis of the deposits reveals a new class of nanocrystalline compound materials. Crystals of metals or metalcarbides and oxides are immersed in a matrix of carbonaceous material. The deposition process is compatible with conventional VLSI technology. Tips for atomic force and scanning tunneling microscopy can be produced with radii of curvature as small as 5 nm. Field electron emission is obtained from deposited tips starting at an extraction voltage of 8 V and yielding 180 µ A of current at 20 V. Three-dimensional conducting structures can be produced as sensors.