Development of automated contact inspection system using in-line CD SEM

We developed automated contact inspection system using in-line CD SEM and applied to monitor the contact etching processes. As the design rule shrinks, monitoring of the contact etching, which cannot be detected by the conventional optical inspection systems, are becoming one of the most critical issues in semiconductor process. Though there are e-beam based inspection systems or manual inspection sequence with in-line SEM (Scanning Electron Microscope), monitoring small and electrical defects has a few fundamental limitations. E-beam inspection systems have low throughput and the high price as a mass production tool. And in case of the manual inspection system, the inspection result depends on operator and it is difficult to quantify the defect data. We have developed an automated contact inspection system to overcome these limitations. The system is composed of the data processing system and the in line SEM (Scanning Electron Microscope). Automated in line SEM inspects and stores the images of specified points on the wafer. Data processing system receives and manipulates the images to tell the etching problem. It was shown that scanning electron image of the contact is related with failures such as insufficient etching or residuals inside the contact.