Bevel Depth Profiling SIMS for Analysis of Layer Structures

We are evaluating the use of bevel depth profiling Secondary Ion Mass Spectrometry (SIMS) for the characterization of layered semiconductor materials. In this procedure, a sub-degree angle bevel is cut into the analytical sample with an oxygen or cesium primary ion beam in a commercial SIMS instrument. The elemental distribution of the resulting bevel surface is then imaged with a focused ion beam in the same instrument. This approach offers maximum flexibility for depth profiling analysis. The primary beam energy, incident angle and species used to cut the bevel can be optimized to minimize ion beam mixing and surface topography independent of the conditions used for secondary ion analysis. In some cases, depth resolution can be greater than available from conventional depth profiling. Removal of residual surface damage/topography created during beveling has also been investigated by the cleaning of the bevel surfaces using gas-cluster ion beam sputtering before imaging analysis.