DUV inspection and defect origin analysis for 22nm spacer self-aligned double-patterning

Spacer self-aligned double-patterning (SADP) offers a patterning solution to alleviate the dependency on mask1 and mask2 overlay accuracy in the litho-etch litho-etch (LELE) double-patterning scheme. However, the SADP process sequence introduces additional challenges in defect detection and hence higher risk to production yield. In this work, we developed a methodology to systematically trace the sources of SADP patterning defects by scanning the wafers through consecutive process steps, followed by SEM defect review to identify the major defect types at each step. SEM review was performed at each defect location during the process, and a defect library was established for each step. Our approach and results can be used to develop the inspection strategy during process development and create a defect library to support SADP defect monitoring in production.