High resolution x-ray mask repair

Abstract

Several techniques proposed to minimize the effects of redeposition of absorber material during opaque repair, including the use of thinner absorbers, gas-assisted focused ion beam (FIB) etching, and postrepair trim are examined. Opaque repair of most classes of defects on sub-250 nm x-ray masks appears to be a straightforward extension of the existing FIB tooling and technology. Gas-assisted FIB etching is not currently well enough developed to be implemented for high resolution repair. The use of thinner absorbers, though helpful, does not significantly reduce redeposition. Postrepair trimming is found to be more effective than expected in removing redeposited material at high resolution. Finally, a study is presented comparing opaque repair of three different absorber materials currently being considered for the fabrication of future masks: electroplated gold, W, and TaSiN.