Yield Mask, the first commercial Yield Management tool specifically developed for a Mask House, has been introduced and the necessity for such Yield Management system, given the current demands on high-end mask production, ascertained. In particular, Yield Mask has been shown to be a highly effective, defect-data analysis tool, with fully automated data collection and a database structure facilitating fast and flexible data retrieval and correlation, for process, inspection, SEM-review and repair data. The latest features of Yield Mask are now reported, including macros, user-definable sampling, user-definable grouping and defect tracking. These features are shown to enhance the efficiency of Yield Mask in a production environment. Macros are shown to significantly decrease the manpower required to run standard analysis routines, accommodating continuous monitoring and analysis of the data. User-definable sampling is shown to allow users to select defects of particular interest, within a given inspection report for subsequent SEM review. This significantly increases the efficiency of review carried out using basic sampling criteria. Lastly, user-definable grouping, along with defect tracking are shown to be advantageous in the selection of any, desired combination of data, for comparison and/or correlation.
To support the continuing Defect Engineering activities in the Infineon Mask House, a professional analysis tool has been developed for Defect Yield Management, in collaboration with EGsoft. EGSoft is the software division of Electroglas Inc. and suppliers ofthe YieldManager TM product, used for Yield Management in numerous wafer fabs. The requirement for such a tool was catalysed by the ever-increasing demand for sophisticated defect analysis, to accelerate defect learning and the identification of major and minor defect-related-yield detractors. Yield Mask consists of a database, which centrally stores all relevant information from Defect Inspection, Repair and Review tools in the Infineon Mask House and an analysis tool, which allows users to analyse the data collected on their PC. The analysis tool can be divided into six major modules: Data Set Builder, Mask Map, Map Gallery, Image Gallery, Charting and Customise: The functionality of the above-mentioned modules is presented and their application in the analysis of defect data demonstrated. The tool is shown to be an invaluable, cost-effective labour-saving device in a high-end Mask House, where the time required to analyse and resolve defect problems can be dramatically reduced.
The monitoring of defects on photomasks is becoming increasingly critical with ever decreasing feature sizes and higher mask-error-enhancement factors. This makes the characterization and a thorough understanding of the origin of different defect types essential in improving the first- pass defect level in a process. Two complementary approaches are presented, which are used to run an effective defect density engineering group, to aid in the production of high-end masks (equals 0.14 technology PSM). Firstly, an in-depth investigation of all defect- related reject masks is carried out. This includes SEM review, classification and storage of all defect - related information in a database. This allows the causes of defect- related rejection to be monitored. Secondly, a classical, in-line-monitoring concept is implemented. Here, an inspection and review is carried out on a regular basis, after each of the process steps involved in the production of high-end masks. For continuity and to ensure that all process steps are capable of handling the most challenging of masks, the most critical mask of any, given technology is used for all in-line monitoring. This gives a real, online status for every process and rapidly helps to identify potential problems very early.