Dynamic ISD scheme for the AVM system - a preliminary study

Reducing the sampling rate to as low as possible is a high priority for many factories to reduce production cost. Automatic-Virtual-Metrology (AVM) based Original Intelligent Sampling Decision (Original ISD) scheme had been previously developed for reducing the sampling rate and sustaining the VM accuracy. However, the desired sampling rate of the Original ISD scheme is fixed and set manually. Hence, whenever the VM accuracy gets worse, it cannot dynamically increase the desired sampling rate in the Original ISD scheme. As a consequence, it would take more time to collect enough samples for improving the VM accuracy. Moreover, when the VM accuracy performs well all the time, it cannot automatically decrease the desired sampling rate in Original ISD, which may result in unnecessary waste. Accordingly, this paper proposes a preliminary study of a Dynamic ISD scheme to dynamically and automatically modify the sampling rate online and in real time. The Dynamic ISD scheme can monitor the VM accuracy on line as well as update the VM models in real time for maintaining the VM accuracy when the VM accuracy becomes poor. Also, the Dynamic ISD scheme can automatically reduce the sampling rate while the VM accuracy performs well.