This paper proposes a dual-phase virtual metrology scheme. To consider both promptness and accuracy, this scheme generates dual-phase virtual metrology (VM) values. Phase I emphasizes promptness, that is to immediately calculate and output the Phase-I VM value (denoted VM ) of a workpiece (wafer or glass) once the entire process data of the workpiece are completely collected. Phase II improves accuracy, that is not to recalculate and output the Phase-II VM values (denoted VM ) of all the workpieces in the cassette (also called FOUP in the semiconductor industry) until an actual metrology value (required for tuning or retraining purposes) of a workpiece in the same cassette is collected. Also, in this scheme, the accompanying reliance index (RI) and global similarity index (GSI) of each VM and VM are also generated. The RI and GSI are applied to gauge the degree of reliance. If the reliance level of a VM value is lower than the threshold, this VM value may not be adopted. An illustrative example involving fifth-generation thin-film transistor liquid crystal display (TFT-LCD) chemical-vapor deposition equipment is presented. Experimental results demonstrate that the proposed scheme is applicable to the wafer-to-wafer or glass-to-glass advanced process control for semiconductor or TFT-LCD factories.Index Terms-Global similarity index (GSI), phase-I virtual metrology value (VM ), phase-II virtual metrology value (VM ), reliance index (RI).
This paper proposes an intelligent prognostics system (IPS) for semiconductor and TFT-LCD manufacturing. The IPS comprises several generic embedded devices (GEDs) and remote clients. The GED can be easily embedded into various types of equipment to acquire equipment engineering data and meet the specification requirements of Interface A for supporting semiconductor industry equipment engineering capabilities. Furthermore, the GED has an open-standard application interface offering pluggable and customized intelligent applications. With this feature, the intelligent applications can be distributed and localized, releasing the factory network burden and enhancing equipment reliability and processing quality. This paper also develops two typical pluggable applications: the predictive maintenance scheme (PMS) for detecting equipment faults and the virtual metrology scheme (VMS) for conjecturing equipment-processing quality. Integrating the PMS into the IPS and the VMS into the IPS are, respectively, accomplished using the conveyor equipment and the sputtering equipment in a TFT-LCD factory. These two illustrative examples clearly demonstrate that IPS is versatile, configurable, and effective.Index Terms-Equipment engineering system (EES), generic embedded device (GED), predictive maintenance, virtual metrology.
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