A FeCrMnNi concentrated solid-solution alloy was irradiated with a 2 MeV proton beam up to 1 dpa and 6 dpa at temperatures of 400 °C and 600 °C. The microstructural changes induced by irradiation were characterized using Transmission Electron Microscopy (TEM). In samples irradiated at 400 °C, Frank loops were the predominant form of lattice damage at 1 dpa, whereas small defect clusters were more prevalent at 6 dpa. For the sample irradiated to 1 dpa at 600 °C, both Frank loops and small defect clusters were present in similar density. Nanoindentation was employed to assess the changes in mechanical properties (hardness) post-irradiation, revealing significant hardening in all irradiated samples. The results indicated that the hardening effect began to saturate at 1 dpa or earlier. Additionally, nanoindentation creep tests with a 1200-second dwell period produced stress exponents comparable to those obtained from conventional creep testing. The findings suggest a shift in the deformation mechanism from dislocation glide to dislocation climb in the sample irradiated to 6 dpa at 400 °C.

Physical FA innovations in advanced flip-chip devices are essential, especially for die-level defects. Given the increasing number of metal layers, traditional front-side deprocessing requires a lot of work on parallel lapping and wet etching before reaching the transistor level. Therefore, backside deprocessing is often preferred for checking transistor-level defects, such as subtle ESD damage. This paper presents an efficient technique that involves precise, automated die thinning (from 760µm to 5µm), high-resolution fault localization using a solid immersion lens, and rigorous KOH etch. Using this technique, transistor-level damage was revealed on advanced 7nm FinFET devices with flip-chip packaging.