Invited Speaker

"Stability and Performance Analysis of Mixed Product Run-To-Run Control"

Dr. Shi-Shang Jang and Dr. David SH Wong
Department of Chemical Engineering, National Tsing-Hua University

Run-to-run control has been widely accepted in semiconductor manufacturing industry as one element of advanced process control technology for improving product quality and process capability. Most theories of run-to-run control have been developed based on the assumption that there is only one product. However, in reality, many different products are fabricated with the same set of process tool but with different technologies and different recipes.

How RtR should be implemented in a high mix production environment remains an open question. In this paper, several literature methods of RtR will be reviewed and classified.

We found that there are two intuitive ways of defining a RtR control scheme for a mixed production mode. In a 'threaded' approach, a controller is defined for each specific tool-product combination, control action is determined by information of previous runs of the same tool-product combination. In an alternate 'distributed' approach, contributions to disturbance by difference products and different tools are estimated by different runs on different tools. A model two-product plant was developed to investigate the pros and cons of these two approaches. Control scheme selection and tuning guidelines will be derived from these simulations and options for further improvement will be discussed.

About the Authors

Dr. Shi-Shang Jang

Professor Shi-Shang Jang received his MS degree from National Taiwan University, Taiwan, and Ph.D. degree from Washington University in St. Louis, both in Chemical Engineering. Currently, he is Professor in the Chemical Engineering Department of National Tsing-Hua University, Hsin Chu, Taiwan since 1992. He was Chairman of the Department from 2000 to 2004.

Dr. Jang has been involved in projects granted by many institutes. He has worked in many topics related to AEC/APC in recent years. He is an expert in modeling the mixed run product processes. Particular applications of those models have been successfully implemented in virtual metrology and run-to-run process control. Many related papers are published in many conferences and refereed journals. Dr. Jang works closely with the industries. He is the technical consultant of ACS and ITRI. Recently, he also serves as a technical consultant of TSMC.

Dr. Jang has been an invited speaker of the 4th International Semiconductor Conference, Shanghai , China (2005). He was also a keynote speaker of National Science Council Workshop on Experimental Design (2000). He also organized the nation-wide process control workshop in 1998. Dr. Jang received many research awards from the National Science Council. He also received award from the Ministry of Education as Teacher of the Year in 1992.

Dr. David SH Wong

Professor David Wong obtained his Ph.D. degree in chemical engineering from University of Delaware (USA) in 1982 and has been teaching in the Department of Chemical Engineering, National Tsing Hua University since 1983. He has engaged in the research and teaching of process system engineering and molecular thermodynamics over the past 20 years. He has also been actively involved in consulting for a wide variety of manufacturing companies (such as China Petroleum, China Steel, and Taiwan AutoDesign) and research and development organization such as the Industrial and Technology Research Institute in the area of development and application of process simulation.

He has also visited many other academic institutions in Asia, spending his sabbatical years in Hong Kong University of Science and Technology, National University of Singapore, University of Petroleum in Beijing. Recently he became interested in the theoretical aspects and practical development of run-to-run control technology for a high-mix plant.