Improvement of depth resolution in secondary ion mass spectrometry depth profiling of silicided poly contacts

Abstract

Performing secondary ion mass spectrometry (SIMS) depth profiles with high depth resolution, <10 nm, through silicided polysilicon contacts is made difficult by the inherent roughness of the silicide/poly interface. This interface roughness results in a loss in depth resolution and leads to the subsequent broadening of the dopant profile under the silicide. In some instances, where the junction is less than 100 nm, it is not possible to obtain an accurate and reliable depth profile of the dopant in the poly or the substrate Si. In this article, the practical application of polishing techniques for planarization and subsequent high depth resolution SIMS analyses are presented. This article will focus on the application of this technique to silicided poly contacts over diffusion areas.