Molecular Dynamics Simulations for Shave-Off Profiling

Abstract

Shave-off profiling with nano-beam SIMS achieves the highly precise depth profiling with nanometer-scaled depth resolution by utilizing FIB micro-machining process to provide depth profile. This method has its own features: absolute depth scale, pin point depth profiling and application to rough surface and/or hetero interface. However, the discussion of the sputtering mechanism in shave-off profiling is still insufficient because shave-off scan mode has distinctive position of the primary ion beam against the sample. In this study, the sputtering yield and the mixing effects within the primary ion dose amount of up to 1.0×10 16 ions/cm 2 under shave-off condition were investigated using molecular dynamics simulations. These results were compared with those of under conventional raster scan mode. In addition, the ejected region of sputtered atoms was investigated. As a result, it was proved that shave-off scan mode has high sputtering yield and low mixing effects. Moreover, the relationship between the sputtering phenomenon and the atomic displacement under shave-off scan mode was demonstrated.

Analysis of the Shape of Cross Sections Developed under Shave-off Condition Sputtering

“…It could be calculated 2.22 × 10 13 atoms and 2.88 × 10 13 atoms, the results implied that the shave-off scan mode has 1.3 times higher sputtering yield compared with raster scan mode at the same beam condition. This ratio almost agreed with our previously reported results (shave-off scan sputtering yield: 3.6 atoms/ion, raster scan sputtering yield: 2.79 atoms/ion)[3].…”

Investigation of mixing effects of silicon isotopes under shave‐off condition using atom probe tomography

“…Using these techniques, the shave‐off depth resolutions were estimated to be approximately 20 nm . On the other hand, the mixing effects of the primary ion bombardment using the shave‐off scan mode were investigated using molecular dynamics simulations, and results suggested that the mixing effect under the shave‐off scan mode was small. Compared with the shape of the cross section, this mixing effect (thickness of mixing layer) has the potential to be a very important factor for the estimation of the depth resolution under the shave‐off condition.…”