EUV modeling accuracy and integration requirements for the 16nm node

EUV lithography is widely viewed as a main contending technology for 16nm node device patterning. However, EUV has several complex patterning issues which will need accurate compensation in mask synthesis development and production steps. The main issues are: high flare levels from optical element roughness, long range flare scattering distances, large mask topography, non-centered illumination axis leading to shadowing effects, new resist chemistries to model very accurately, and the need for full reticle optical proximity correction (OPC). Compensation strategies for these effects must integrate together to create final user flows which are easy to build and deploy with reasonable time and cost. Therefore, accuracy, usability, speed and cost are important with methods that have considerably more complexity than current optical lithography mask synthesis flows. In this paper we analyze the state of the art in accurate prediction and compensation of several of these complex EUV patterning issues, and compare that to 16nm node expected production needs. Next we provide a description of integration issues and solutions which are being implemented for 16nm EUV process development. This includes descriptions of OPC model calibration with flare, shadowing, and topography effects. We also propose a realistic (in terms of accuracy and mask area) flare parameter calibration flow to improve short and longer range flare correction accuracy above what can be achieved with only a measured EUV flare PSF.