Dual-Phase Virtual Metrology Scheme

• Published in: IEEE transactions on semiconductor manufacturing 2007-11, Vol.20 (4), p.566-571
• Main Authors: CHENG, Fan-Tien, HUANG, Hsien-Cheng, KAO, Chi-An
• Format: Article
• Language: English
• Subjects: Applied sciences; Cassettes; Chemicals; Display; Electronics; Electronics industry; Exact sciences and technology; General (including economical and industrial fields); Glass; Global similarity index (GSI); Liquid crystal displays; Manufacturing engineering; Metrology; Microelectronic fabrication (materials and surfaces technology); phase-I virtual metrology value ({\rm VM}_{I}); phase-II virtual metrology value ({\rm VM}_{II}); Process control; Process controls; Production facilities; reliance index (RI); Retraining; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Semiconductors; Studies; Thin film transistors; Transistors; Tuning; Virtual manufacturing; Workpieces
• ISSN: 0894-6507; 1558-2345
• DOI: 10.1109/TSM.2007.907633

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 ) 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 ) 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 and 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.