Plan-View Transmission Electron Diffraction Measurement of Roughness at Buried Si/SiO sub 2 Interfaces.

We have developed a novel technique for determining inerfacial roughness from plan-view transmission electron diffraction. Certain bulk forbidden Bragg reflections can occur due to crystal termination at surface and are very sensitive to steps on crystal boundaries. We demonstrate the technique in the study of Si/SiO sub 2 interfaces and observe that interfaces appear to be significantly flatter than previously found, especially after post-oxidation annealing. The technique is simply quantified and is more reliable than those which require stripping of the oxide to expose the interface.