Quantitative electron holography of biased semiconductor devices

Abstract

Off-axis and in-line electron holography have been used to determine the electricalproperties of a silicon p–n junction. Specimens were prepared for transmission electronmicroscopy (TEM) by focused ion beam (FIB) thinning and examined in a biasing holder,with holograms recorded as a function of specimen thickness and applied reverse bias. Thedata revealed the important role played by the surfaces of the thin TEM sample whichaffect the electrostatic potential distribution within the specimen. The presence ofelectrically inactive layers, corresponding to the FIB-damaged amorphous surfaceand an additional crystalline layer, was inferred from the experimental results.Such effects must be taken into account if electron holography is to be used in areproducible and quantitative way for the examination of semiconductor devices.