Quantifying Loading Efficiency Losses on Lithography Clusters

The high cost of lithography clusters requires fabs to continuously work to optimize their utilization and output. Unfortunately, due to their highly complex nature and the parallel processing capability of the cluster, accurately determining the utilization and output detractors can be very difficult. Without the ability to accurately identify and quantify the equipment capacity loss it is obviously very difficult to improve the equipment performance, as well as to synchronize actual equipment performance with capacity planning. At Qimonda, we have measured several speed losses on our Lithography clusters with interrupts to takt time consistently being the largest. Interrupt losses can be divided into two general categories of causes: equipment alarms/aborts and loading efficiency.