Overlay advanced process control for foundry application

Advanced Process Control (APC) on overlay is in use for high-volume production fabs with enough data available to statistically filter out noise contributions. In a foundry that is characterized by multiple products, each with a low production volume, very limited data is available per product. With the proposed advanced process control system we want to solve the issues related to this low amount of data by using data from lots that have a different history, e.g. lots that are exposed on other machines or lots from other products. To be able to do this production data is first corrected for machine contributions by use of monitor data for each machine. The resulting estimated process induced errors are maintained for all products and all layers in a database with reference to used machines, layers, product type and process family. The process induced errors for each lot are selected from the database by sharing available data that is expected to behave most similar. The proposed advanced process control system is partially implemented in production for a couple of layers. Simulations are run on more layers to test the data sharing concept. The simulation results are in reasonable agreement with actual product measurements and predict that the advanced process control system performs similar for lots for which the proposed data sharing concept is used as for lots for which the identical context is available.