Characterization and Real Time Defect Mitigation in Chemical/Mechanical Polishing of Microelectronic Wafers Using Decision Theory and MultiSensor Fusion
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The objective of this research is to apply the principles of multi-sensor fusion and decision theory for deriving quantitative relationships connecting signal features from various sensors, including, force, temperature, vibration, and others, gathered during chemical mechanical planarization of microelectronics wafers, with specific defect evolutions, towards real-time surface defect mitigation and process control. The approach will be to first induce certain basic defect patterns on wafers, such as indentation, scratching using nanoindentation and nanoscratching techniques. These wafers then will be polished on a chemical mechanical planarization machine instrumented with multiple wireless microelectromechanical systems sensors. It is anticipated that an archive of defect-sensitive sensor features for different defects generated in chemical mechanical planarization will be developed. Decision theory will be used to predict and control the defects. The control action (for example, specific adjustment of down force and platen speed) at each time-epoch will be estimated by maximizing a utility function, so that the control actions are robust to noise. The chemical mechanical planarization platform will be equipped with multiple wired- and wireless-microelectromechanical systems-based sensors, where possible, to monitor temperature, vibrations, chemistry (pH), and forces for defect detection and mitigation.If successful, this research will facilitate industry adoption of micro-electromechanical systems sensor-based approaches to address defects and such critical impediments to wafer yield. The sensor-networked chemical mechanical planarization platform can be used as a test bed for instruction and training of students and industry personnel. The Principal Investigators have a track record for attracting students from diverse backgrounds, and plan to work with local minority institutions to recruit qualified students into this research project. The students will be exposed to fundamental multi-disciplinary research and industry practices in advanced manufacturing processes through mutual visits between university and industry. The highlights of the research will be made available on the website of the Principal Investigators and the results will be published in various journals, trade magazines, and presentations at national and international conferences.