Sputtered depth profile resolution on some samples could be improved by sputtering from the backside of the wafer; utilizing the lower profile broadening of a leading edge measurement, as opposed to the trailing edge. This work develops a technique for simple and accurate backside thinning using a Si-on-insulator substrate. A combination of backside grinding and selective wet etching results in a planar and smooth surface for accurate measurements. Using 800eV O sputtering, the measured slope due to the sputter broadening was 1.6nm/decade of concentration for a P distribution. The technique was used to evaluate shallow P diffusion from doped polysilicon to provide calibration for diffusion modeling.

Backside Sputter Depth Profiling of Phosphorus Diffusion from a Polysilicon Source. P.Ronsheim, D.Chidambarrao, B.Jagannathan, D.Hunt: Journal of Vacuum Science and Technology B, 2002, 20[1], 448-50