Efficient full-chip mask 3D model for off-axis illumination

Mask topography (Mask3D) effect is one of the most influential factors in sub-28 nm technology node. To build a successful Mask3D compact model, the runtime efficiency, accuracy and the flexibility to handle various geometry patterns are the three most important criterion to fulfill. In the meanwhile, Mask3D modeling must be able to handle the off-axis illumination (OAI) condition accurately. In this paper, we propose our full chip Mask3D modeling method which is an extension to the edge-based Mask3D model. In our modeling flow, we first review the edge-based Mask3D model and then analyze the impact from the off-axis source. We propose a parameter-based extension to characterize the off-axis impact efficiently. We further introduce two methods to calibrate the OAI-aware parameters by using rigorous or wafer data as the reference. Our experimental results show the great calibration accuracy throughout the defocus range with OAI sources, and validate the accuracy of our two parameter calibration approach.