In-line Monitor of Non-overlay Misalignment Defect by Dark-Field Inspection System

A pattern misalignment defect between DT and AA module caused by none-overlay issue was detected and in-line monitored by the ComPLUS3T dark field wafer inspection system. The misalignment was as small as 5-15 nm and it modulated across the wafer with a periodicity of reticle shot. Signal analysis was performed together with study on other wafer inspection system, and it demonstrated that the dark field wafer inspection system with normal incident illumination was the most effective tool to monitor such defect.