7 June 1996 How focus budgets are spent: limitations of advanced i-line lithography
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In order to decide if a given process window is sufficient for volume production without suffering from a significant yield loss, a clear understanding of the process capability is required. Therefore we performed a statistical analysis of all potential contributions for process variations and drifts and evaluated their magnitude for state-of-the-art equipment and processes. Since lithography related fails are not uniformly distributed across the wafer we developed a model to simulate the focus errors across the exposure field and across the wafer. We also developed a yield model, which gives a realistic yield loss number for a given process window. By using these models we show areas of potential improvement, which allow support of processes with significantly less focus latitude. We also investigated field size dependence of focus control and compared the step and repeat and step and scan systems, showing a significant advantage for step and scan systems. All of these findings are not specific to the exposure wavelength, so that they can be easily applied to Deep UV lithography.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Andreas Grassmann, Andreas Grassmann, Rebecca D. Mih, Rebecca D. Mih, Andreas Kluwe, Andreas Kluwe, } "How focus budgets are spent: limitations of advanced i-line lithography", Proc. SPIE 2726, Optical Microlithography IX, (7 June 1996); doi: 10.1117/12.240912; https://doi.org/10.1117/12.240912


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