Balancing mask and lithography costs

This paper describes a fundamental change in strategy to balance mask and lithography costs at a multi-technology, multi-part number IBM Microelectronics semiconductor fabricator. The strategy is to reduce mask costs by printing fewer chips in each exposure whenever it is cost effective to do so. This paper discusses the advantages and drawbacks of this strategy, describes ways to implement it with the least impact on lithography tool productivity, and shows how to calculate the cost trade-off between mask costs and lithography costs.