Traditionally, mask defect analysis has been done through a visual inspection review. As the semiconductor industry moves into smaller process generations and the complexity of mask exponentially increases, "Mask" issues have emerged as one of the main production problems due to their rising cost and long turn-around time. Mask-making specifications related to defects found on advanced masks also becomes more difficult to define due to the complex features involved (e.g. OPC (Optical Proximity Correction), SRAF (Sub Resolution Assist Features), etc.). The Automatic Defect Severity Scoring (ADSS) module of i-Virtual Stepper System from Synopsys offers a fast and highly accurate software solution for defect printability analysis of advanced masks in a real production environment. In this paper, we present our case study of production pilot run in which the ADSS is used to automatically quantify the impact of a given defect on the surrounding features, basically filtering out killer defects and nuisance defects in terms of production viewpoints to reduce operators' intervention. In addition, an automation workflow is also tested, in which the production issues, such as the communication feasibility of mask quality control between mask house and wafer fab, are also considered.

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 waferfab operation point of view. What kind of benefits can be achieved and how it works will be also presented.