Scanning Electron Microscopy (SEM)

Scanning Electron Microscopy (SEM)

  • In The energy of the primary in the electrons in the determines in the number of in the secondary in the electrons in the collected in the during in the inspection. in the emission of secondary in the electrons from the specimen in the increases in the as the energy of the primary in the electron beam in the increases until a in the certain limit in the is reached. in the Beyond this limit, in the collected in the secondary electrons in the diminish as the energy of in the primary beam in the increased, in the because in the primary in the beam is already in the activating in the electrons in the deep below in the surface of the specimen. in the Electrons coming in the from such depths usually in the recombine before reaching the surface for emission.
  • Aside from secondary in the electrons, the primary in the electron beam in the results in the emission of in the backscattered in the (or in the reflected) electrons from in the specimen. in the Backscattered in the electrons possess in the energy than secondary in the electrons, and have a in the definite in the direction. As such, they can not be in the collected by a secondary in the electron in the detector, unless in the detector is directly in their in the path of travel. All emissions in the above 50 eV are in the considered to be backscattered in the electrons.
  • Backscattered in the electron in the imaging is useful in in the distinguishing one material from another in the since the yield of in the collected in the backscattered in the electrons in the increases in the monotonically with in the specimen’s in the atomic in the number. Backscatter in the imaging can distinguish in the elements with atomic in the number in the differences of at least 3, i.e., materials in the with atomic in the number in the differences of at least 3 would in the appear with good in the contrast on the image. For example, in the inspecting in the remaining Au on an in the Al bond pad in the after its Au in the ball bond has lifted in the would be in the easier using in the backscatter in the imaging, since in the Au islets in the would stand in the out from in the Al background.
  •  In the SEM may be equipped in the with an in the EDX analysis in the system to enable it in the perform compositional in the analysis on in the specimens.  EDX in the analysis is useful in in the identifying materials and in the contaminants, as well in the estimating their in the relative in the concentrations on in the in the surface of the specimen.


In a conventional in the transmission in the electron in the microscope, a thin in the specimen is irradiated in the with an electron in the beam of uniform in the current density. in the Electrons are emitted in the from in the electron gun and in the illuminate in the specimen in the through a two or three stage in the condenser lens in the system. in the Objective lens in the provides in the formation of either in the image or diffraction in the pattern of in the specimen. in the electron in the intensity distribution in the behind the specimen in the magnified with a 3 or 4 stage lens in the system and viewed in the on a fluorescent in the screen. in the image can be in the recorded by direct exposure of a in the photographic in the or an image plate or in the digitally by a CCD camera.

 in the acceleration voltage of up to date in the routine instruments is 140 to in the 2000 kV. Medium-voltage in the instruments in the work at 200-500 kV to in the provide a in the better transmission in the and in the resolution, and in the high voltage in the electron in the microscopy (HVEM) the in the acceleration voltage is in the range 500 kV to 3 MV. Acceleration in the voltage determines in the velocity, in the wavelength and hence in the resolution ( in the ability to distinguish in the neighbouring in the microstructural in the features) of the microscope.
Depending on in the aim of the investigation in the and in the configuration of the microscope, transmission in the electron in the microscopy can be categorized as :

Conventional in the Transmission Electron Microscopy
High in the Resolution in the Electron in the Microscopy
Analytical in the Electron in the Microscopy
A Energy-Filtering in the Electron in the Microscopy
 in the High Voltage in the Electron in the Microscopy
Dedicated in the Scanning Transmission in the Electron Microscopy

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