Proceedings of the 2011 Winter Simulation Conference S. Jain, R. R. Creasey, J. Himmelspach, K. P. White, and M. Fu, eds. AGGREGATE MODELING OF SEMICONDUCTOR EQUIPMENT USING EFFECTIVE PROCESS TIMES L.F.P. Etman C.P.L. Veeger E. Lefeber I.J.B.F. Adan J.E. Rooda Department of Mechanical Engineering Eindhoven University of Technology PO Box 513, 5600 MB Eindhoven, THE NETHERLANDS ABSTRACT Performance evaluation using queueing models is common practice in semiconductor manufacturing. Analytical closed-form expressions and simulation models are popular in capacity planning and the analysis of equipment configurations. However, the complexity of semiconductor processes complicates the modeling of the equipment. Analytical models lack the required accuracy, whereas simulation models require too many details, making them impractical. Aggregation is a way to overcome this difficulty. The various details are not modeled in detail, but their contribution is lumped in the aggregate model, which makes the model more appropriate for both analysis and simulation. This paper gives an overview of our efforts to develop a top-down aggregate modeling approach for semiconductor equipment, starting from the effective process time concept inspired by the Factory Physics book of Hopp and Spearman. The strong feature of our modeling approach is that the aggregate model parameters are estimated directly from industrial data (arrival and departure times), without the need to quantify the various details. 1 INTRODUCTION The development of simple and accurate models for queueing performance analysis in semiconductor manufacturing is an open research problem. With “simple” we mean models that have only few model parameters, and that can be easily used and estimated. With “accurate” we mean models that provide a prediction accuracy that is of practical use in semiconductor applications. This may depend of course on the type of application, but we assume that in most cases an accuracy of 10% or better is desired. Commonly-used simple models are closed form G/G/m queueing expressions, such as the approximation due to Sakasegawa (1977) and Whitt (1993), which is used in the popular Factory Physics book of Hopp and Spearman (2008). Although useful and insightful, this model lacks the necessary accuracy for the typical equipment encountered on the semiconductor factory floor. Modifications to (partially) account for typical semiconductor equipment characteristics such as the simultaneous processing of wafers of multiple lots have been proposed in e.g., Morrison and Martin (2007b) and Morrison and Martin (2007a). Alternatively, discrete-event simulation may be used to arrive at a sufficiently accurate representation of the semiconductor equipment. Simulation modeling allows the inclusion of all relevant factory floor details. This obviously requires the collection of all the necessary input data regarding the various model elements. A a result, a detailed simulation model becomes computationally very expensive and requires significant development time. Including too many details makes simulation modeling impractical. 1795 978-1-4577-2109-0/11/$26.00 ©2011 IEEE