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Focused ion beam induced deposition complements the process of material removal by focused ion beam milling. Together, these two techniques are being used commercially for photomask repair and for repair or restructuring of integrated circuits and are being developed for the repair of x-ray lithography masks. This microsurgery of masks and circuits can be carried out with a precision determined by the minimum diameters of the ion beams which are now approaching 0.05 micrometers . In ion-induced deposition, a local gas ambient in the millitorr range is created on the surface around the point of ion incidence, usually by aiming a miniature gas nozzle at the surface. Incident ions break up the gas molecules that are adsorbed on the surface. The precursor gas is usually an organometallic or a metal halide. Deposits of W, Au, Al, Cr, Ta, and Pt have been produced. Often these deposits have high concentrations of impurities, particularly carbon if organometallics are used, and sometimes also oxygen. The resistivities of the 'metal' films fall in the 70-1000 (mu) $OMEGAcm range that one would expect for pure metals. Nevertheless, even at these resistivities, useful conducting connections can be made for integrated circuit repair. Under special circumstances resistivities approaching the pure metal values have also been demonstrated. For x-ray mask repair, high aspect ratio (e.g., 0.25 micrometers wide by 0.4 to 0.7 micrometers high) deposits of a high-Z material such as Au, W, or Pt are needed. The considerable body of experience in this field is revealed, and the theoretical models of the process are examined.
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