Focused ion beam fabrication of microelectronic structures

The development of the capability focusing many species of ions to beam diameters well below 0.1 micron has led to many applications, from many applications, from the repair of photomasks and integrated circuits to the fabrication of quantum effect devices. The work reported here has concentrated on ion induced deposition. This novel method of film growth combines patterning and deposition in a single step. It is used in repair processes to locally add material, and it may also be useful in making conductors and contact in situ, for example, on III-V compounds which cannot be exposed to the ambient between MBE growth steps. In ion induced deposition a local gas ambient of, for example, an organometallic, is created where the ion beam is incident. A film grows where the beam is scanned. Focused ion beam induced deposition of gold and platinum was demonstrated, characterized, and developed. Features down to 0.1 micron line width have been written as well as, thick (approx. 1 micron) features with steep sidewalls. The microstructure of the gold and platinum deposits has been studied by transmission electron microscopy (TEM). The Pt deposits were found to be amorphous while the gold growth begins as islands an becomes columnar. Measurements were made of the dependence of growth rate on average ion current, ion energy, ion species, and precursor gas pressure and a macroscopic and microscopic model of the process developed.