32nm Half Pitch Node OPC Process Model Development for Three Dimensional Mask Effects Using Rigorous Simulation

摘要

32 nm half-pitch node processes are rapidly approaching production development, but most tools for this process are currently in early development. This development state means that significant data sets are not yet readily available for OPC development. However, several physical mask effects are predicted to become more prominent at the 32 nm half-pitch node. One of the most significant effects is the three dimensional (3D) mask effects where the mask transmittance and phase are impacted by the mask topography. Already at larger process nodes this effect impacts imaging performance, especially when sub-resolution assist features are employed. For the 32nm node it is essential that this effect is correctly captured by the OPC model. As wafer data for the 32nm half-pitch is difficult to obtain, the use of rigorous lithography process simulation has proven to be invaluable in studying this effect. Using rigorous simulation, data for OPC model development has been generated that allows the specific study of 3D mask effect calibration. This study began with Kirchhoff based simulations of 32 nm node features which were calibrated into Hopkin's based OPC process models. Once the standard Kirchhoff effects were working in the OPC model, 3D mask effects were included for the same data by performing fully rigorous electromagnetic field (EMF) simulations on the mask.