Resource Portfolio Planning Methodology for Semiconductor Wafer Manufacturing

Resource portfolio planning is a frequent task in semiconductor wafer fabrication plants, as process, machine and product technologies evolve rapidly and the plants go through capacity expansion. As wafer fabrication plants are complex integrated factories with conspicuous queuing effects, portfolio planning must take into consideration machine use, factory throughput, and total flow-time simultaneously. This paper describes a resource portfolio planning methodology for wafer fabrication foundry plants. An improved static capacity model is first presented. A portfolio planning procedure based on static capacity estimation and queuing analysis is next described. This procedure enables the solution space of resource portfolios to be explored effectively and has demonstrated a capability superior to the current planning method in an industry case study. A software implementation of the procedure is also used to clarify planning dilemmas. It is shown that empirical formulae can be used to estimate the efficiency of batch machines. It is also used to show three types of portfolio adjustment action: flow-time reduction, cost reduction and effectiveness improvement.