US Patent 7696487 Circuit pattern inspection apparatus

The via chain conduction failure due to non-conduction caused by insufficient etching in a contact plug/via plug forming process can be detected precisely in a short time. For its achievement, a defect is detected at high speed by taking advantage of characteristics of a potential contrast method using a via chain defect inspection structure and an electron beam defect detection apparatus which can perform continuous inspection while changing an inspection direction without rotating a wafer. Accordingly, the capturing efficiency of a critical electric defect and search efficiency of a defect point can be improved.