Challenges of systematic defect control in advanced DRAM Fab

We did four experiments to study using electron beam inspection (EBI) to capture small physical defects with weak material contrast (MC) and electrical defects with very weak voltage contrast (VC) for both 7x nm and 6x nm technology nodes. Small physical defects, such as selective epitaxy grow (SEG) missing and epi-to-epi short, usually have very low capture sensitivity by optical defect inspection systems. Weak VC defects, such as bright VC (BVC) caused by short between plugs and dark VC (DVC) caused by partial open of the contact due to the misalignment. We found that low scan rate, low beam current, better charge control and high resolution are the keys to enhance the detection of these defects, especially for next generation design rule.