ABSTRACT
The complementary holographic techniques for the examination of semiconductor device structures reveal a layered electrostatic potential structure. Electron holography can be used to obtain both the phase and the amplitude of an electron wave that has passed through a transmission electron microscope (TEM) sample. Off-axis electron holography has been used successfully to generate two-dimensional maps of phase modulations arising from a TEM membrane containing a semiconductor device. However, a quantitative interpretation of the measured phase is complicated by many problems, which include the effects of sample preparation and charging of the TEM sample in the electron beam. In-line electron holography can also be used to examine the electrostatic potential across important features such as a p-n junction. Phase profiles obtained using off-axis electron holography can, in contrast, be interpreted directly. The contrast variation present in the Fresnel data was too small to be consistent with the results obtained by applying off-axis electron holography to the same sample.
