Formation and detection of subpellicle defects by exposure to DUV system illumination

As DUV lithography becomes more ubiquitous in the manufacture of semiconductors, the importance of detecting mask anomalies that can be attributed to the exposure of mask materials to 248 nm exposure becomes necessary. The requirement to find and eliminate the sources of these types of defects becomes even more important with low k1 lithography. The authors wish to report a new class of defects that can significantly impact mask performance and semiconductor chip manufacturing yields. This paper will discuss the techniques and defect detection systems used to identify the presence of these sub-pellicle (or pellicle-related) defects. Additionally, the mechanism of defect formation and micro-analytical results identifying both the composition and possible sources of the defects will be presented.