Systems of multiple cluster tools: configuration and performance under perfect reliability

Self Cite

The migration of semiconductor processes to singlewafer vacuum cluster tools has rendered configuration an important decision variable in fab operation and heightened the impact of reliability on fab performance. We address these closely linked issues by deriving the optimal configuration and operation of systems of cluster tools in the presence of scheduled maintenance.The two extremes in the spectrum of possible configurations are the serial configuration, in which the modules in a tool are all different, each representing a step in a process sequence, and the parallel configuration, in which each tool is assigned only one process step. We predict that the latter can offer higher throughputs. However, this advantage may be slight when equipment downtime is relatively schedulable and infrequent, in which the case the serial configuration may be preferable because of its superior cycle times. We also derive optimal lot sizing and release policies for systems of cluster tools. We conclude that fabs will gradually migrate from parallel configurations to serial as cluster tools become more reliable and cycle time becomes more important.Index Terms-Flexible manufacturing systems, manufacturing planning, manufacturing scheduling, performance models, semiconductor cluster tools, semiconductor device manufacture.

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confidence: 81%

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confidence: 99%

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Systems of multiple cluster tools: configuration, reliability, and performance

Lopez

Wood

2003

Self Cite

“…As reliability improves, the sequential cluster tools reduce cycle time. Lopez & Wood (1998) present analytical models for these systems when the tools are perfectly reliable. Dhudshia & Hepner (1996) address issues related to measuring cluster tool reliability.…”

Section: Prior Workmentioning

confidence: 99%

Evaluating the impact of process changes on cluster tool performance

Herrmann

Chandrasekaran

Conaghan

et al. 2000

ISR develops, applies and teaches advanced methodologies of design and analysis to solve complex, hierarchical, heterogeneous and dynamic problems of engineering technology and systems for industry and government. ISR is a permanent institute of the University of Maryland ABSTRACTCluster tools are highly integrated machines that can perform a sequence of semiconductor manufacturing processes. Their integrated nature can complicate analysis when evaluating how process changes affect the overall tool performance. This paper presents two integrated models for understanding cluster tool behavior. The first model is a network model that evaluates the total lot processing time for a given sequence of activities. By including a manufacturing process model (in the form of a response surface model, or RSM), the model calculates the total lot processing time as a function of the process parameter values and other operation times. This model allows one to quantify the sensitivity of total lot processing time with respect to process parameters and times.In addition, we present an integrated simulation model that includes a process model. For a given scheduling rule that the cluster tool uses to sequence wafer movements, one can use the simulation to evaluate the impact of process changes including changes to product characteristics and changes to process parameter values. In addition, one can construct an integrated network model to quantify the sensitivity of total lot processing time with respect to process times and process parameters in a specific scenario.The examples presented here illustrate the types of insights that one can gain from using such methods. Namely, the total lot processing time is a function not simply of each operation's process time, but specifically of the chosen process parameter values. Modifying the process parameter values may have significant impacts on the manufacturing system performance, a consequence of importance which is not readily obvious to a process engineer when tuning a process (though in some cases, reducing process times may not change the total lot processing time much). Additionally, since the cluster tool's maximum throughput depends upon the process parameters, the tradeoffs between process performance and throughput should be considered when evaluating potential process changes and their manufacturing impact .2

“…Throughputs and cycle times of systems of cluster tools with the same sequences of process steps and the same total numbers of modules, but in which the modules are grouped in different ways, are studied in [20]. The two extreme module configurations are called serial and parallel configurations.…”

Section: Introductionmentioning

confidence: 99%

Cluster Tools With Chamber Revisiting—Modeling and Analysis Using Timed Petri Nets

Zuberek

2004

Abstract-Timed Petri nets are formal models of discrete concurrent systems. Since the durations of all activities are included in the model descriptions, many performance characteristics can be derived from such models. In the case of cluster tools, net models represent the flow of wafers through the chambers of the tool as well as consecutive actions performed by the robotic transporter. Steady-state performance of cluster tools with chamber revisiting is investigated in this paper. A systematic development of detailed tool schedules, based on a general behavioral description of the tool, is proposed and is used to derive the corresponding Petri net models. Symbolic performance characteristics of the modeled tools are obtained by using place invariants, without exhaustive reachability analysis. Simple examples presented in the paper can be easily extended in many ways.