Long term cost of ownership: beyond purchase price [chip manufacture]

An economic cost of ownership model is developed to estimate the total cost per wafer for a given process operation. The model incorporates fixed and variable costs and process tool specific as well as fab specific cost inputs. While all the variables can affect the final outcome, it is shown that the long-term cost per wafer for a given process is directly proportional to both mechanical throughput yield and defect densities. Wafer cost is also extremely sensitive to throughput, which affects both the fixed and variable cost components. Due to the nonlinear relationship of wafer cost and factors affecting equipment utilization capability, cost reduction through reliability improvement may be effective depending on where the nominal baseline points are located on the curves. Changes in inputs such as initial equipment costs or engineering support hours have less impact on the final cost per wafer since these variables affect only one cost component of the model