Comparison of etching methods for subquarter-micron-rule mask fabrication

Dry-etching process has possibility for fabricate small features and to enhance resolution limit because of smaller CD shift during etching. Recently, optical proximity patterns (OPC) like serif decorations begin to be adopted for mass-production masks, Dry etching is effective for OPC patterns fabrication. However, in order to bring dry-etching into production, some issues have to be overcome. In this paper, we evaluate etching characteristics such as selectivity to resist, edge roughness, edge shape, loading effect, micro-loading effect, critical dimension uniformity, and performance of optical proximity pattern fabrication using inductively coupled plasma, plasma etch, and reactive ion etching. It was confirmed that dry-etching process reduced edge roughness of chrome patterns. Among three plasma sources, ICP was most effective for reducing loading effect and micro-loading effect and obtaining vertical edge shape. The issue of dry process with ICP was low selectivity to resist. It was approximately 1. CD loss uniformity processed with each dry etching system was not satisfied with our target. Finally, we demonstrated to fabricate capacitor patterns of 0.15 micrometers -design rule with serif decorations.