Advanced photomask repair technology for 65-nm lithography

Abstract

We have reported the FIB repair system with low acceleration voltage is applicable to 65nm generation photomasks. Repair technology beyond 65nm generation photomasks requires higher edge placement accuracy and more accurate shape. We developed two new functions, "Two Step Process" and "CAD Data Copy". "Two Step Process" consists of primary process and finishing process. The primary process is conventional process, but the finishing process is precise process to control repaired edge position with sub-pixel order. "Two Step Process" achieved edge placement repeatability less than 3nm in 3sigma. At "CAD Data Copy", defects are recognized with comparison between shape captured from a SIM image and that imported from a CAD system. "CAD Data Copy" reproduced nanometer features with nanometer accuracy. Thus the FIB repair system with low acceleration voltage achieves high performance enough to repair photomasks beyond 65nm generation by using "Two Step Process" and "CAD Data Copy".

Surface Morphology of Diamond-Like Carbon Film and Si Wafer Milled with 30 keV Gallium Focused Ion Beam

“…Focused ion beam (FIB) technology is becoming increasingly important for submicron device processing such as mask and device repairs [1][2][3] by maskless etching and deposition, as well as for lithography. 4) The technology may also be important for the microfabrication of fine mechanical parts [5][6][7][8] and sensors, which are usually made of single-crystal or polycrystalline silicon and are mainly fabricated by anisotropic chemical etching.…”