Atomic Roughness of Buried Interfaces Studied by Plan-View Transmission Electron Diffraction

We show that surface sensitive forbidden Bragg reflections, such as 1/3 (422) and (110) in the f.c.c. system, can be used to probe quantitatively the roughness of buried interfaces. Results are obtained in plan-view samples for the average roughness of Si-SiO sub 2 interfaces, without removing the oxide and without the projection limitations of high resolution imaging in cross-section. We show the dramatic effects of post-oxidation annealing on the flatness of Si-SiO sub 2 interfaces. Under special conditions for sufficiently flat interfaces, individual atomic steps can be imaged in this fashion.