REPAIR OF OPAQUE X-RAY MASK DEFECTS - APPLICATION AND RESOLUTION

In this paper we report an X-ray mask repair making a circuit work and, moreover, resolution tests of the focused ion beam repair system for opaque defects. A complex multi-inverter test circuit was produced by a mix-and-match technique including a final X-ray lithography step for patterning the metallization layer. An electrical short circuit, caused by opaque killer defects on the X-ray mask, made the test circuit useless. However, after repairing these defects, the subsequent processing resulted in an operating circuit. Furthermore, on an X-ray mask with sub-0.5-mu-m absorber structures the resolution capability of the repair system was demonstrated by repairing opaque defects smaller than 200 nm. The repair of the smallest defect (75 nm) is shown in detail.