Development of EUV lithography tools at Nikon

Full-field EUV exposure tool named EUV1 integrated and exposure experiments were started with the numerical aperture of the projection optics of 0.25 and conventional partial illumination with coherence factor of 0.8. 32nm elbow patterns were resolved in full arc field in static exposure. In the central area 25nm line-and-space patterns were resolved. In scanning exposure, 32nm line-and-space patterns were successfully exposed on a full wafer. Wavefront error of the projection optics was improved to 0.4nmRMS. Flare impact on imaging was clarified depend on the flare evaluation using Kirk test. Metal oxide capping layer and oxygen injection method were developed for the contamination control in EUV exposure tools. High-NA projection optics design is also reviewed.