OPC and other complicated geometric structures are increasingly common on production masks. These features may be small, have highly irregular shapes and may not be repeated in a nearby region. These features make it difficult for a repair operator to know where the defect stops and the desired pattern begins. We are increasingly called upon to write masks with these complicated patterns, high densities and long write times. In order to meet our customers demand for shorter turnaround times and high throughput, it makes sense to implement new, more sophisticated repair techniques. We have recently acquired a new, state of the art Seiko SIR3000 FIB (focused ion beam) mask repair system. This system is a sophisticated secondary ion mass spectrometer (SIMS) that uses a focused primary beam of gallium ions to both image and repair mask defects. Both opaque and clear defects can be reconstructed by the gallium beam. The SIR3000 system uses a proprietary material (alpha-gas) to reduce glass damage caused by the sputtering process. We have performed some preliminary measurements to determine the extent of the glass damage and performed some introductory work into methods of reducing the damage further. We present some of the data we use to monitor its performance, a number of examples illustrating its utility and our expectations for the tool in the near future.
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