Enio L. Carpi

Investigation of fast and accurate reticle defect assessment methods using STARlight for chrome-on-glass reticle defects

Fast and accurate reticle defect assessment becomes increasingly important because wafer critical dimensions continue to shrink and mask inspection equipment has moved into the UV range thereby increasing the number of detected reticle defects. Defect size is not sufficient in determining if a defect prints or does not print and the threshold size for printing defects can vary broadly between 0.35 (lambda) /NA. At the low k1 factors required to print current technology feature sizes, correlation between reticle and wafer CDs ceases to be linear. The impact of reticle defects on CDs therefore, is more critical than for previous technologies and defect size, shape, and proximity to other features must be taken into consideration. Presented in this paper is an evaluation of different methods to determine the accuracy of imaging prediction for reticle defects, decreasing the time to results in a prediction environment by accelerating the decision process. These methods include printability based on aerial image and the in-line STARlight Contamination Printability Index.