Strings, loops and pyramids-building blocks for microstructures

By combining the selective deposition of tungsten on silicon with micromachining techniques, several microelectronic devices have been developed. These include ultrathin tungste2 strings with cross-sections ranging from 300 × 300A² to 600 × 2000^A, tungsten loops, and tungsten cladded pyramids. Initial interest of the strings and loops concentrated in studying quantum mechanical effects such as localization and the Aharonov-Bohm effect at cryogenic temperatures. However, the strings can be made free -standing, thus becoming avai lable for vibration sensing and the loops could be used as bearings. The pyramids could find applications in scanning tunneling microscopes, as surgical scalpels, and as Fowler-Nordheim field emitters in flat panel displays and in high current sources.