OPTIMIZING SYNCHROTRON-BASED X-RAY-LITHOGRAPHY FOR 0.1 MU-M LITHOGRAPHY

Of the many factors affecting the image intensity distribution, the va riables that can be controlled are source spectrum, source spatial coh erence, proximity gap, mask linewidth bias, and absorber thickness. To obtain the highest quality aerial image, ah of these parameters must be optimized simultaneously. We describe an optimization of the spectr um of the Hellos synchrotron, located at IBM's Advanced Lithography Fa cility (ALF) EU. To obtain a spectrum better suited to 0.1 mu m-linewi dth x-ray lithography, the vacuum window should be changed from Be to 2 mu m of Si. We present experimental results on the strength of SiNx windows for use as vacuum windows and propose a fabrication procedure for making beamline windows. Using the determined optimum spectrum, we summarize the results of a previous optimization study [2] of the x-r ay aerial image. This optimization is performed using a rigorous elect romagnetic model that accounts for diffraction in the absorber, source partial coherence, and diffraction in the proximity gap. The aerial i mage of 0.1 mu m features at a gap of 10 mu m is optimized.