Optimizing Extreme Ultraviolet Lithography Process Metrics and Aberrations in the Cut Layer Through Source Mask Co-Optimization(SMO)

Source-Mask Co-Optimization (SMO) techniques have significantly supported semiconductor manufacturing quality by enhancing imaging contrast and lithographic process control in advanced lithography nodes over the past decade. Through jointly optimizing the design of the illumination source and modifying the reticle patterns on the mask, the SMO techniques have provided a viable method to find the best lithography process for a given design rule. In SMO, process parameters such as the Exposure Latitude (EL), the Depth of Focus (DoF), the Mask Error Factor (MEF) can be improved through the definition of a cost function. In this presentation, we provide an example with a minimum pitch of 40 nm, which is commonly used for the 2~3 nm Back-End-Of-the-Line (BEOL) logic technology nodes. In this example, we will discuss the challenges and potential of our SMO technique and will offer recommendations for EUV SMO compensations for aberration. Our analysis indicates that SMO can continue to improve optimal pattern transfer capabilities by simultaneously optimizing both illumination source and mask design.