Aside from the electron column, there are many factors that determine image quality in an ultra high resolution Field Emission Scanning Electron Microscope (FESEM). To obtain quality images, the operator must minimize sample contamination and be able to select the appropriate signal generated from the sample surface. Hitachi has developed a new in-lens FESEM that both minimizes surface contamination and improves signal efficiency.
Sample contamination is reduced by incorporating an oil free vacuum system, consisting of a 300 1/s turbomolccular pump and a 200 1/min scroll pump. For demanding applications, an additional 50 1/s turbomolccular pump can be added to back the main high vacuum pump. Furthermore, sample contamination caused by electron beam irradiation has been reduced by employing a high speed electrostatic beam blanking system. By blanking the beam during scan retrace (flyback), the electron dose accumulated on the sample can be minimized.