High-resolution electron microscopy of structural features at the interface

Abstract High-resolution transmission electron microscopy (HREM) allows observation of interface morphology at close to the atomic level. Careful examination of the images yields a wealth of information about the structure studied. Cross-sectional micrographs through a silicon/silicon dioxide/polysilicon structure are presented here, showing interface roughness at the substrate/oxide boundary. The various image features in each region are elucidated. HREM provides a precise method for measuring film thickness and determining the structural uniformity of the oxide and its interfaces. The temptation to regard electron micrographs as two-dimensional slices through the material should, however, be resisted; we briefly discuss the superposition effects that may result from finite sample thickness.