Performance of the EL-4+maskwriter for advanced chrome on glass reticles

The IBM EL-4+ maskmaker, installed in the Advanced Mask Facility in Burlington site has been undergoing extensive evaluation of its ability to fabricate advanced 4X chrome on glass (COG) reticles. In previous years on 1X x-ray masks, the EL-4+ maskmaker has demonstrated image placement of 20nm 3 sigma minimum feature size to 100mn, image size uniformity to below 10nm while maintaining availability of 97% during the last 6 months of 1998. So far, in 1999, the EL-4+ system has demonstrated minimum etched features to 100nm in COG using ZEP7000 resist and dry etching. Promising results have also been achieved using a gate level 0.18um ground rule mask as a learning vehicle. COG learning is continuing, with indications that we should be able to achieve 35nm image placement. There are a number of significant advantages to be realized in COG reticle fabrication on the EL-4+. Resolution, coupled with a 1/640 tool grid permits features to be patterned with sharp corners and precisely located edges without any impact on writing speed. An advanced proximity correction algorithm exploiting the systems dose modulation capabilities insures image fidelity across a wide spectrum of pattern density.