Pinhole defect detection and printability prediction

Photomask defect criteria normally specify pinholes by size, regardless of other factors that may affect printability (e.g., transmission, reflectivity, phase, or proximity to features). This paper is an initial study of the effect of pinhole defect transmission, size, and location on inspection tool sensitivity and defect printability. Two masks with varying defect properties were built, inspected on a mask inspection tool, and exposed on a DUV wafer stepper and an aerial image simulation microscope. On the wafer, defect printability was measured as either the presence of an isolated defect or the variation in line size for a line with a defect in close proximity. A prototype inspection-based tool was used to estimate defect printability, and the results were correlated to on-wafer defect printability. The goal of this work is to find a quantifiable measurable that may be used at inspection review to reliably predict printability.