Utilizing run-to-run control to improve process capability and reduce waste in lithography: case studies in semiconductor and display manufacturing, and a vision for the future

Run-to-run (R2R) control is now a required component of microlithography processing. R2R control is a form of discrete process control in which the product recipe with respect to a particular process is modified between runs; a "run" can be a lot, wafer or even a die ("shot"). Deployment experience reveals that a cost and technology-effective R2R control solution must be part of a complete Advanced Process Control and equipment automation solution that includes Fault Detection. This complete solution must leverage event-driven technology to support flexibility and reconfigurability, be re-usable via model libraries, be deployed in a phased approach, utilize robust control algorithms, be easily integratable with other components in the manufacturing process, and be extensible to incorporate new technologies as they are developed. In microlithography applications, R2R control solutions are shown to improve process centering and reduce variability resulting in process capability improvements of up to 100%. In the near future, virtual metrology, which harnesses the power of microlithography fault detection along with a prediction engine, will better enable wafer-to-wafer and shot-to-shot feedback control by predicting metrology values for each wafer or die without incurring extra metrology cost or unnecessary waste.