Focused Ion Beams in Microelectronic Fabrication

For more than 20 years the designers and fabricators of integrated circuits and microstructure devices have strived toward smaller features as a means of achieving higher packing density, better performance, and lower cost. The new field of microlithography has emerged as a result of these pressures. The results of these efforts are a wide array of advanced development and production techniques using photooptics, electrons, and X-rays as energy sources for pattern generation and replication. Over the past 3-4 years a new technique, focused ion beam lithography, has emerged as a challenger to these lithography tools for very large-scale integration (VLSI) research and production applications. A number of significant advantages exist when using focused beams in microelectronic fabrication that are not available in the technologies mentioned above. For example, the focused ion beam (FIB) may allow manufacturers to eliminate many of the process steps associated wish conventionai implantation since FIB implants can be performed without lithography and chemical processes. Special implant steps can also be done that are neither practical nor even possible with conventional photomasking techniques.