Photolithography area dispatching scheme for advanced technology in foundry fabs

As advanced IC manufacturing technology processes become more complex and critical, the photo process specifications must be tightened to meet the design targets. For ⩽0.25 μm processes, most photo stages are limited to a dedicated tool, or even the same stepper, to get better overlay control. Dealing with process constraints and balancing tool loading inside the photo area effectively is a major challenge for advanced technology dispatching. In this paper, a photo-dispatching scheme for advanced technology production management in foundry fabs is developed to handle on-line dispatching. The proposed dispatching scheme can be divided into three parts: wafer start dispatching; dedicated tool management; and shop floor dispatching. This dispatching scheme not only automatically assigns a proper tool to each lot to meet the dedicated tool constraint and balance the tool loading, but also integrates with the local dispatching system to assist with shop floor dispatching. The proposed dispatching scheme has been proved to be useful for advanced technology mass production by testing in TSMC fab3