Shot averaging for fine pattern alignment with minimal throughput loss

摘要

A way to average alignment measurements that obtains the advantage of multiple alignment marks per shot without requiring actual measurement of all alignment marks on all wafers of a batch. All alignment marks on all sampled shots are measured and averaged on the first wafer of a batch. The offset between a single sampled alignment mark and the average total offset for the wafer is characterized and applied when that alignment mark is sampled on succeeding wafers.