Effects of laser wavelength and pulse energy on the evaporation behavior of TiN coatings in atom probe tomography: A multi-instrument study.

Abstract

The impact of the laser wavelength on accuracy in elemental composition analysis in atom probe tomography (APT) was investigated. Three different commercial atom probe systems - LEAP 3000X HR, LEAP 5000 XR, and LEAP 6000 XR - were systematically compared for a TiN model coating studying the effect of shorter laser wavelengths, especially in the deep ultraviolet (DUV) range, on the evaporation behavior. The findings demonstrate that the use of shorter wavelengths enhances the accuracy in elemental composition, while maintaining similar electric field strengths. Thus, thermal effects are reduced, which in turn improves mass resolving power. An important aspect of this research includes the estimation of energy density ratios of the different instruments. The reduction in wavelength is accompanied by increasing energy densities due to smaller laser spot sizes. Furthermore, advancements in the detector technology were studied. Finally, the detector dead-times were determined and dead-zones were evaluated to investigate the ion pile-up behavior in APT measurements of nitrides with the LEAP 6000 XR.