Method for enhancing topography and material contrast in automatic SEM review

Abstract

The ability to perform an in line SEM based defect review operation that includes defect detection and classification, is strongly dependent on the quality of the generated defect images. The range of defects has to cover different layers, different process steps as well as different defect types. Traditionally, SeM images are thought of as lacking in 'natural' contrast. The key for a SEM to be able to review a wide range of defects is the ability to generate SEM images with enhanced and varying types of contrast, such as edge, material, topography or voltage contrast. We have developed Multiple Perspective SEM Imaging by employing various electron detectors, having different electron energy and direction response. We have shown that by proper combination of defector array and image processing it is possible to generate images that carry enhanced material, edge and topography contrast simultaneously. We demonstrated that the system can be immune to sample charging and be sensitive to voltage contrast variations at the same demonstrated that the system can be immune to sample charging and be sensitive to voltage contrast variations at the same demonstrated that the system can be immune to sample charging and be sensitive to voltage contrast variations at the same time.