Stress of needle specimen on the three‐dimensional atom probe (3DAP)

Abstract

The three-dimensional atom probe (3DAP) is one of the ways to image materials three-dimensionally on atomic scale. However, some technical issues in 3DAP are still unresolved. One of them is the rupture of a specimen that sometimes occurs when the atoms are field-evaporated at the apex of a needle specimen. This is caused by the high electric stress around the tip of the needle specimen. One way to reduce the stress is to enlarge the taper angle of the needle specimen. In this study, adapting this idea to 3DAP, we estimated the appropriate values of not only the taper angle of the needle specimen but also its diameter, length, radius of curvature, and distance between the tip and local electrode by simulation. Furthermore, we calculated the average value of field-induced stress on each plane for z-direction in the specimen.

Study of the field evaporation mechanism of laser-assisted atom probe

“…The specimen was mounted on the sample holder with the local electrode and set in to the 3DAP [6,7]. The electrode was made by platinum and has a hole with 200 um diameter.…”

Dependence of Field Evaporation Voltage on Polarization Angle of Femtosecond Laser in 3D Atom Probe

“…Both the sample holder and electrode holder were mounted on the sample stage together as one part. The apex of the specimen and electrode were then aligned by moving the sample holder into an appropriate position as estimated by simulation [11]. The specimen apex was set in the center of the hole in the electrode by moving the electrode holder.…”

Evaluation of the instrument for three‐dimensional atom probe (3DAP)

“…The function of the extraction electrode was reported by Nishikawa and Kimoto. [4] The shape of the extraction electrode was determined by computer simulation, and the ideal shape was reported by Mayama et al [5] The hole on the electrode was made by focused ion beam on the molded foil (the diameter is 40-100 µm).…”