Image field upgrade to improve tool productivity

Some semiconductor tools are used for the development of products and at the same time, stay a long time within production. Process requirements may change during the lifetime of a tool - photolithography of critical layers, for example, may get even more critical due to CD and overlay requirements. The same tool may now be used for non-critical layers, but productivity will always be important. Productivity is measured in wafers per hour (wph) and the image field size of a stepper plays a large role in this productivity. The main contribution of this paper is the realization that an increased image field size on an Ultratech 1X stepper gives increased wafers per hour on both a 5X Canon i-line reduction stepper and the 1X Ultratech stepper.