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Scanning Electron Microscopes (SEMs) use an electron beam to image and measure features on a semiconductor wafer at a much higher resolution than images captured by optical microscopes.
SEM technology uses a beam of electrons which is shaped and focused by magnetic and electrostatic "lenses" within an electron column. This remarkably precise and narrow electron beam can image dimensions much smaller than the wavelength of visible light. This beam causes secondary electrons and backscattered electron images to be released from the wafer surface; advanced SEMs then analyze the collected electrons using sophisticated software to extract information.
Defect Review (DR) SEMs employ their high resolution to identify and then automatically classify defects on the wafer (such as particles, scratches or residues) that are previously located by defect detection systems, finding the source of the defect, thus enabling the process engineer to apply corrective actions. |
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