On a Sampling Decision System using Virtual Metrology
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On a Sampling Decision System using Virtual Metrology D. Kurz O. Univ.-Prof. Dr. J. Pilz AAU Klagenfurt, Department of Statistics Dr. C. De Luca Infineon Technologies Austria AG 4 December 2013 D. Kurz On a Sampling Decision System usingVirtual Metrology
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The common approach to semiconductor process control is based on physical measurements of a certain number of processed wafers. Therefore, the status of the process is just controlled within certain time lags, which might result in delayed observations of process abnormalities. Moreover, the measurement rules are typically of a statical nature meaning that the measurement policy is not adapted to current production conditions. In this master thesis, we propose a novel approach to semiconductor process control based on virtual measurements. These are predictions on the location of the real measurements in the control chart depending on the status of the equipment while processing. The advantage of the application of virtual measurements is that they are available for every wafer. Therefore, the status of the process can be steadily controlled and process deviations can be realized earlier. Moreover, the usage of virtual measurements allows for adapting the measurement policy to current process conditions. Whenever virtual measurements provide sufficiently strong evidence that the process is running within the control limits, there is no need of triggering physical measurements. However, if process abnormalities are signalized by the virtual measurement, a physical measurement needs to be triggered. Therefore, physical metrology operations can be scheduled in a more efficient way.
Transcript of On a Sampling Decision System using Virtual Metrology
On a Sampling Decision System usingVirtual Metrology
D. Kurz
O. Univ.-Prof. Dr. J. PilzAAU Klagenfurt, Department of Statistics
Dr. C. De LucaInfineon Technologies Austria AG
4 December 2013
D. Kurz On a Sampling Decision System usingVirtual Metrology
Innovation
Semiconductor process control: the current state-of-the-art
Based on physical measurements
Only certain number of wafers measured
Statical measurement rules
Semiconductor process control with a sampling decisionsystem
Based on virtual measurements
Virtual measurements for every wafer
Dynamical measurement rules
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D. Kurz On a Sampling Decision System usingVirtual Metrology
Applied statistical methods
Sampling decision evaluation
Decision-theoretical modeling of virtualmeasurements
Expected utility of measurement information
Lindley information and wafer quality risk values
Monitoring reliability of virtual measurements
Quantification of performance of virtualmeasurements
Detection of unreliable virtual measurements
Update of precision of virtual measurements
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D. Kurz On a Sampling Decision System usingVirtual Metrology
Results
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D. Kurz On a Sampling Decision System usingVirtual Metrology
