Two methods of estimating sample thickness in FIB-TEM sample fabrication
SHI Jin-an;ZHANG Qing-hua;GU Lin;Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences;
The sample thickness is an important parameter in the characterization of transmission electron microscope( TEM). It is necessary to estimate the sample thickness quickly for making a high-quality sample. In this article,focused ion beam( FIB) was used to fabricate samples( including Si,Sr Ti O3 and La Al O3) with thickness gradient and two methods of estimating sample thickness in FIB-TEM sample preparation were proposed. One method was estimating sample thickness by the contrast of scanning electron microscope( SEM) experientially. The other was cutting the sample's edge into a slope and deducing the thickness from the width of the slope in SEM images geometrically. Both convergent beam electron diffraction( CBED) and electron energy loss spectrometers( EELS) were used as a reference to verify the thickness. By comparison,the method of contrast was preferred to be used when the sample was thinner,while the geometrical method was preferred to be used when the sample was thicker.