Specimen preparation for electron holography of semiconductor devices

A reliable and quick method of preparing specimens for electron holography of semiconductor devices is described in detail. The method is based on conventional mechanical grinding and polishing, and argon-ion milling, providing a large (∼100 μm) area of electron transparency, no curtaining and thin dead layers on the surfaces of specimens. The vacuum area, necessary for the reference wave, is cut into the specimen by a focused ion beam. The advantages and disadvantages are discussed. The method has a yield greater than 90%, of tests of more than 20 specimens of MOS transistors.