Fast Predictive Post-OPC Contact/Via Printability Metric and Validation

Yield is one of the most important factors for massive semiconductor circuits production. As process variation tolerances decrease and the number of contacts/vias increase in modern technologies, contact/via failure has increased substantially, which attracts many attentions from both manufacture and design domains. Among all the contact/via failure mechanisms, lithography related ones become more important, the majority of which are rooted in focus and dose variations. Since the lithography image robustness is pattern dependent, conventional design rules are becoming less efficient and effective to convey the information. Models should be established to facilitate the evaluation of the lithography pattern robustness. Meanwhile, the models need to be fast enough to be used in design tools. Since Optical Proximity Correction (OPC) is very expensive to apply, the metric should be computed without doing actual OPC. We develop two new pre-OPC metrics to predict the post-OPC contact/via CD error due to focus variation, which are validated by our simulations. However, the metric for the post-OPC contact/via CD error due to dose variation is found not correlated well to the actual simulation. Further investigation is needed to increase the metric accuracy.