Mask model analysis and its application in 28 OPC modeling

With minimum half-pitch shrinking to 28nm, the accuracy requirement imposed on OPC model is getting harder to achieve. In order to meet the much more challenging requirement, uncertainty in the modeling should be diminished as much as possible. The major factors of OPC modeling accuracy consist of OPC model calibration flow, data analysis of mask modeling, lithographic process parameters, and photoresist CD. In this paper, the parameters of mask modeling are analyzed and the mask induced errors are calculated, such as mask bias, mask corner rounding, and mask 3D effect. Furthermore, the interactive relations among these mask parameters are also investigated. A 28nm test model was constructed with optimized mask modeling approaches. The rms of the test model is significantly reduced to half of that of the traditional modeling approaches.