As semiconductor process design rules continue to shrink, the ability of optical inspection tools to separate between true
defects and nuisance becomes more and more difficult. Therefore, monitoring Defect of Interest (DOI) become a real
challenge (Figure 1). This phenomenon occurs due to the lower signal received from real defects while noise levels remain
almost the same, resulting in inspection high nuisance rate, which jeopardizes the ability to provide a meaningful, true
defect Pareto. A non-representative defect Pareto creates a real challenge to a reliable process monitoring (Figure 4).
Traditionally, inspection tool recipes were optimized to keep data load at a manageable level and provide defect maps with
~10% nuisance rate, but as defects of interest get smaller with design rule shrinkage, this requirement results in a painful
compromise in detection sensitivity. The inspection is usually followed by defect review and classification using scanning
electron microscope (SEM), the classification done manually and it is performed on a small sample of the inspection defect
map due to time and manual resources limitations. Sample is usually 50~60 randomly selected locations, review is
performed manually most of the times, and manual classification is performed for all the reviewed locations.
In the approach described in this paper, the inspection tool recipe is optimized for sensitivity rather than low nuisance rate
(i.e. detect all DOI with compromising on a higher nuisance rate). Inspection results with high nuisance rate introduce new
challenges for SEM review methodology & tools. This paper describe a new approach which enhances process monitoring
quality and the results of collaborative work of the Process Diagnostic & Control Business Unit of Applied Materials® and
GLOBALFOUNDRIES® utilizing Applied Materials ADRTrueTM & SEMVisionTM capabilities.
The study shows that the new approach reveals new defect types in the Pareto, and improves the ability to monitor the
process and identify excursion for low magnitude defect of interest.