Measuring Contact Hole Distributions for Use in Predicting Missing Contact Hole Rates

Today’s most advanced semiconductor devices contain tens of billions or hundreds of billions of contact holes with dimensions near or less than 20 nm, and often even one missing hole can result in a non-functioning device. Current defect inspection capabilities are hard pressed to meet the need at the most advanced nodes.This paper will use a lithography-inspired model of the “fat tail” that predicts the typical skewed distribution with higher rates of undersized holes as compared to a Gaussian distribution. We will examine CD-SEM metrology and evaluate its ability to measure holes as their size approaches this regime, which will become critical for the next generation of nodes at 2nm and beyond.