A simulation-based defect disposition flow for incoming mask quality assurance

As the industry transitions to 90 and 65nm photolithography, the increased complexity and costs of advanced photomask remain an industry focus. Mask makers and wafer fabs must develop new techniques in photomask inspection and quality control to improve turnaround time and ultimately the mask and wafer production yield. Specific to wafer fabs, this requires an increased focus on the incoming quality control techniques combined with improved communication with the mask shop. For incoming mask inspection "mask-level" defect inspection and dispositioning is no longer adequate. Aggressive OPC on PSM masks, combined with tighter CD requirements increases the burden on both machine and operator increasing the risk of mission a killer defect. For 90nm and beyond, simulation-based defect disposition techniques will be required to predict the wafer-level printing behavior and disposition the defects appropriately. A simulation-based defect disposition flow using Synopsys's i-Virtual Stepper System (iVSS) for incoming mask quality assurance is presented in this study. This paper will examine the feasibility of implementing such a flow from a wafer-fab operation point of view. What kind of benefits can be achieved and how it works will be also presented.