Development of a Lithographic DRC Technique for Interactive Use and Batch Processing

Lithographic DRC which takes optical interference effect into account can find and solve the related optical problems beforehand. That is, it can detect the weak points of pattern layout with respect to optical intensity and identify problems which would have remained unnoticed with geometric DRC. Usual approach comparing the aerial images with the intended shape of pattern takes a quite long time. To improve the processing time of DRC, we set verification points on pattern's edge and classified the individual points by analyzing surroundings within optical interference range. With this approach, it becomes possible to reduce the calculation time, since only a one-time calculation is required for each unique point. Comparing designed pattern layout with its aerial image may result in hundreds of small errors near small jogs or at the corner of patterns. To eliminate these small errors, we used a rounded pattern layout as the intended shape of the resist. Well-fitted condition is used for the aerial image simulation, that is, defocused aerial images and the threshold model are employed for the prediction of the shape of resist. Using these methods, we achieved an improvement with respect to both processing time for DRC and obtained accuracy. We applied Lithographic DRC to actual device patterns, and we could verify that it was possible to detect the point with coupling, shortening and less margin