Crystal growth printability in an advanced foundry FAB: a correlation study between STARlight and ultra broadband BrightField inspection technologies

In advanced IC manufacturing reticle contamination through crystal growth causing printed defects¹ is a major source of yield loss. This crystal growth requires frequent inspection to ensure reticles are free from such contamination (reticle requalification). STARlight is the industry accepted method for mask inspection in wafer fabs for reticle re-qualification (requal) ². The principal focus of this paper is a study correlating the detection of contamination (crystal growth) on logic product masks found with STARlight to defects that can be found on a print-check wafer (a photo-resist test wafer). A critical component in this study was the translation of reticle coordinates to wafer coordinates and integrating the results between high-resolution broadband DUV BrightField inspection (BF) and scanning electron microscope (SEM) review. All of the STARlight defect locations were reviewed using the SEM regardless if the defect was found on opaque or on clear surfaces of the mask. As such defects being SEM reviewed were classified as either 'printing', 'early-warning' or 'non-printing'. BF defect inspection results after repeater analysis were compared with STARlight results to determine the correlations. SEM Defect Review was performed on STARlight inspection results and the resulting classified data was correlated to the BF defect inspection results.