300mm Time Constrained Queue Loop Management

Prior process technology experience identified several segments in 300 mm process flows as cycle-time sensitive. The time between a wafer leaving an operation and being processed at a subsequent operation must be managed or else process defects may occur. These time constrained steps are referred to as "queue loops" because wafers are held in queue until there is high confidence they can be processed within the predetermined timeframe. The problem resides in synchronizing production capacity within each loop while balancing factory favorable cycle-time and cost effective toolset capacity. This paper will discuss the simulation modeling methodology that was utilized to analyze the trade-offs between output and quality-induced operational controls under varying wafer start levels.