A structure analysis method using a scanning electron microscope includes irradiating a sample with an electron beam having a first landing energy to obtain a first image at a first depth of the sample and accelerating the electron beam to have a second landing energy higher than the first landing energy to obtain a second image at a second depth of the sample.

Multi-beam scanning electron microscope inspection systems are disclosed. A multi-beam scanning electron microscope inspection system may include an electron source and a beamlet control mechanism. The beamlet control mechanism may be configured to produce a plurality of beamlets utilizing electrons provided by the electron source and deliver one of the plurality of beamlets toward a target at a time instance. The multi-beam scanning electron microscope inspection system may also include a detector configured to produce an image of the target at least partially based on electrons backscattered out of the target.

Embodiments of the present disclosure include a scanning electron microscope (SEM) having an electron gun configured to generate an electron beam that is directed along an axis through a column of the SEM towards a sample stage. In some embodiments, the SEM includes a first backscattered electron (BSE) detector mounted along the axis. In some examples, the SEM further includes a second BSE detector mounted off the axis, where the second BSE detector wraps around a bottom portion of the column. The second BSE detector, in some examples, includes a plurality of blades having either a flat shape or an arc shape in a side view. Additionally, in some embodiments, the plurality of blades are arranged in a circular configuration in a top view.