Lumped parameter modeling of the litho cell

Litho cells, are the most expensive equipment in a wafer fab. To support decision-making on this equipment, accurate simulation models for throughput and cycle time are helpful. The simulation models that are typically developed incorporate various shopfloor details. To properly model these details, they should be quantified, which is difficult and time-consuming.In this paper, a lumped parameter model is proposed for the litho cell. The model consists of two parts: a detailed representation of the processing inside the track and scanner, and an aggregate representation of the factory floor feeding the loadport.The track-scanner is modeled as a tandem flow line with blocking. The shop floor is represented by a delay distribution that incorporates all contributions outside the machine. Simulation results show that the suggested method provides a simple, yetaccurate approximation of the litho cell.