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[April 2002]
Additional Detector Brings Enhanced Backscattered Electron Detection
The imaging versatility of the ultra-high resolution in-lens S-5200 FESEM from Hitachi High-Technologies Corporation has been further enhanced by the introduction of an optional electron detector for imaging backscattered electrons at low accelerating voltages. This new accessory takes full advantage, says the company, of the outstanding resolution of the S-5200 of 1.8nm at 1kV.Backscattered electrons give valuable elemental composition information in an image, since contrast is dependent on the average atomic number of the material being imaged. Previously, it has only been possible to obtain backscattered compositional images using accelerating voltages in excess of around 5kV. This new arrangement allows compositional information to be acquired at accelerating voltages as low as 500V, reducing the chances of specimen charging or sample damage and giving increased surface sensitivity and information.
The additional detector can be used as an alternative to a conventional YAG backscattered electron detector and is fitted above Hitachi's proprietary E X B electron detection system. It is used in conjunction with a conversion plate which converts high angle backscattered electrons into secondary electrons for collection.
This upper detector produces images using only high angle backscattered electrons. The S-5200's standard detection system will allow detection of secondary electrons or, by adjusting the detection system operating conditions, mixtures of secondary electrons and low angle backscattered electrons. Signals from both detectors can be mixed to give a wide variety of electron contributions to obtain the optimum balance between compositional and topographic detail in the image.
ENDS