Measurement of Specimen Thickness by Using Electron Holography and Electron Dynamic Calculation with a Transmission Electron Microscope

A method of transmission-electron microscopy for accurate measurement of specimen thickness has been proposed based on off-axis electron holography along with the dynamic electron diffraction simulation. The phase shift of the exit object wave with respect to the reference wave in vacuum, resulting from the scattering within the specimen, has been simulated versus the specimen thickness by the dynamic electron diffraction formula. Off-axis electron holography in a field emission gun transmission electron microscope has been used to determine the phase shift of the exit wave. The specimen thickness can be obtained by match of the experimental and simulated phase shift. Based on the measured phase shift of the 110 oriented copper foil, the thickness can be determined at a good level of accuracy with an error less than ～10%.