A robust metric for measuring within-wafer uniformity

A robust metric for measuring within-wafer uniformity has been developed and compared to the traditional SNR metric. The new statistic, referred to as the integration statistic, is based on the integration of the volumetric error between the target and the actual surfaces. Comparison with the traditional SNR uniformity metric indicates that the integration statistic provides a more consistent estimate of the uniformity for different numbers of measurements and different orientations of those measurements to the uniformity pattern.