A one-step process for the repair of micron and submicron sized clear defects in photomasks is described. Opaque films are deposited at the intersection of the flux of organic monomers from a gas jet and a focused Ga ion beam. Focused ion beam induced deposition differs from other ion-induced, electron beam, and laser processes due to the very high ion current density, and the sputtering of the material as it is being deposited. We have explored the deposition–sputtering rate competition for several precursor materials as a function of gas jet pressure (molecular flux) and ion beam dose rate (scanning conditions). The deposition rate for our process is linear with ion dose at 330 Å per 1017 ions/cm2 and independent of dose rate over a wide range of conditions. The deposited films are cross-linked polymers containing as much as 25 at. % Ga, adhere to either Cr or glass, and are chemically inert. Scanning slit microdensitometry measurements show a white-light extinction coefficient of 2.2×10−3 Å−1. As a result, opaque deposits can be made at the same ion dose and beam scanning conditions used for Cr removal in mask repair.

Harriott, L. R., & Vasile, M. J. (1988). Focused ion beam induced deposition of opaque carbon films. Journal of Vacuum Science & Technology B: Microelectronics Processing and Phenomena, 6(3), 1035–1038.