Methods and apparatus to review defects using scanning electron microscope with multiple electron beam configurations

An apparatus configured to review defects using a scanning electron microscope, the apparatus comprising:

• an electron beam column configured to generate an incident electron beam and scan the incident beam over a surface of a target substrate;
• a detector configured to detect secondary electrons;
• and
• a system controller and data processing system configured to perform steps of selecting a defect location having a defect for review, configuring the SEM to be in a first imaging configuration, imaging the selected defect location using the SEM to generate a first SEM image of the selected defect location, determining whether the defect is visible or non-visible in the first SEM image, and when the defect is non-visible in the first SEM image, then configuring the SEM to be into a second imaging configuration, imaging the selected defect location using the SEM to generate a second SEM image of the selected defect location, and determining whether the defect is visible or non-visible in the second SEM image, and when the defect is non-visible in the second SEM image, then configuring the SEM to be into a third imaging configuration, imaging the selected defect location using the SEM to generate a third SEM image of the selected defect location, and determining whether the defect is visible or non-visible in the third SEM image,
• wherein the first imaging configuration has a lower landing energy, a lower beam current and detects secondary electrons, the second imaging configuration has a higher beam current and images with voltage contrast, and the third imaging configuration has a higher landing energy and detects backscattered electrons.