20 October 2006 Correlation between OPC model accuracy and image parameters
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Performing MBOPC (model based Optical Proximity Correction) on layouts is an essential part of patterning advanced integrated circuits. With constantly shrinking CD tolerance and tighter ACLV budgets, the model has to be accurate within a few nanometers. The accuracy of a model in predicting wafer behavior dictates the success of the patterning process. Model calibration is a critical procedure to provide an accurate correlation between design and wafer features. The model calibration process consists of arriving at a variable threshold polynomial as a function of aerial image parameters -intensity maximum (Imax), intensity minimum (Imin), Slope, curvature etc.. In this paper, a strong correlation between the accuracy of the model and the image parameters is demonstrated. Data from model calibration of two different layers in 65nm technology node will be shown to demonstrate the dependence of model accuracy on aerial image parameters. Data show that accuracy of the model degrades a function of resolution, i.e. features with low Imax, low slope and low contrast are difficult to model than higher resolution features. During calibration of the model, some parameters can be adjusted to obtain a balance between the model accuracy of weak and stronger resolution features. Suggestions for improving the accuracy of the weaker features based on an analysis of the image parameters are shown. The correlation between accuracy of the model and image parameters will be useful in limiting OPC corrections on features with poor aerial image quality.
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Chidam Kallingal, Chidam Kallingal, Norman Chen, Norman Chen, } "Correlation between OPC model accuracy and image parameters", Proc. SPIE 6349, Photomask Technology 2006, 63494M (20 October 2006); doi: 10.1117/12.686240; https://doi.org/10.1117/12.686240

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