抄録
This paper describes aspheric mirror fabrication technology for an imaging optics of EUV (Extreme Ultraviolet) lithography, which is a candidate of mass-production technology for 0.1-μm design rule ICs. In this optics, accuracy of aspherical mirrors must be sub-nm-order to provide good imaging performance. To clarify technical problems, a multi-tool polishing system for a quarter-size prototype imaging optics were developed. These tools' polishing loads are dynamically controlled to correct local figure error. As a result, 3.4 nm rms figure precision was obtained for a concave aspherical mirror. Furthermore, 0.1-μm line & space patterns were partially replicated in a 1.4 mm-wide ring-field. A major remained problem to the goal is how to decrease mid-frequency figure error caused by tool movement.
