Redistribution of Alloy Elements During Nickel Silicide Formation: Benefit of Atom Probe Tomography

摘要

The unique capabilities of atom probe tomography (APT) to characterize internal interfaces and layer chemistry with sub-nanometer scale resolution in three dimensions have been recently opened up to materials with poor electrical conductivity by the use of ultrafast laser pulses. The progress in sample preparation (focused ion beam) as well as in instrument performance enable now the analysis of relatively large volumes with typical diameters of 100 to 200 nm and depths of several hundred nm (this corresponds to an increase by several order of magnitude compared to the former instrument) of site specific samples. In this work, APT is used to study the effects of Pt on the formation and stability of Ni silicides. The precise location of this alloy element has been determined at the nanometer scale: In particular, APT allows us to quantify the amount of Pt in the grain boundaries (GB) of Ni_2Si for about 100 different grain boundaries and thus to better characterize the GB diffusion and segregation.