Photolithography run-to-run metrology control using multiple algorithms for mass production enhancement

In this paper a detailed description of how to get a better photo overlay performance is provided. In a way, the overlay feedback model is relative complexity because it is variable and difficult to keep perfect control using traditional run-to-run feedback model that lacks previous layer's residual, non-photo induced chamber bias and real time shifting of exposure tool's baseline. Hence, we developed a new overlay feedback model to enhance lithography performance by multiple algorithms, including real time tool offset, vertical offset ,and pre-process chamber offset for overlay accuracy and mass production environment. The traditional run-to-run becomes one of scenarios driven by the proposed model.