|
|
 |
 |
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.
CD-SEMs are used by semiconductor makers to measure the "critical dimension" (CD) of the sub-micron-sized circuits in a chip, thus assuring the accuracy of their manufacturing process. CD measurements are typically performed after photolithographic patterning and subsequent etch processing.
The most advanced CD-SEM systems are fully automated, processing several cassettes of wafers without operator intervention. The system software automatically "flags" features on the wafer that exceed specification for further review and corrective action by process engineers.
|
|
|
|
|
