The introduction of EUV lithography into the semiconductor fabrication process will enable a continuation of Moore's law below the 22nm technology node. EUV lithography will, however, introduce new sources of patterning distortions which must be accurately modeled and corrected with software. Flare caused by scattered light in the projection optics result in pattern density-dependent imaging errors. The combination of non-telecentric reflective optics with reflective reticles results in mask shadowing effects. Reticle absorber materials are likely to have non-zero reflectivity due to a need to balance absorber stack height with minimization of mask shadowing effects. Depending upon placement of adjacent fields on the wafer, reflectivity along their border can result in inter-field imaging effects near the edge of neighboring exposure fields. Finally, there exists the ever-present optical proximity effects caused by diffraction-limited imaging and resist and etch process effects. To enable EUV lithography in production, it is expected that OPC will be called-upon to compensate for most of these effects. With the anticipated small imaging error budgets at sub-22nm nodes it is highly likely that only full model-based OPC solutions will have the required accuracy. The authors will explore the current capabilities of model-based OPC software to model and correct for each of the EUV imaging effects. Modeling, simulation, and correction methodologies will be defined, and experimental results of a full model-based OPC flow for EUV lithography will be presented.
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