Surface contamination and electrical damage by focused ion beam: conditions applicable to the extraction of TEM lamellae from nanoelectronic devices

Abstract

Focused ion beams (FIBs) are widely applied during manufacturing and for failure analysis, as a preparation tool for cross sectional scanning electron microscopy or for the extraction of lamellae for (scanning) transmission electron microscopy investigation of nanoelectronic devices. The impact of the ion beam milling on surface contamination is investigated by time-of-flight secondary ion mass spectroscopy, while the electrical surface damage is analyzed by a micro four-point probe. It is shown that the redeposition of milled Ga and Cu reaches levels below sensitivity (5 × 10 10 at cm −2 ) at less than 10 mm from FIB structures while the lateral range of electrical surface damage is an order of magnitude smaller. The major source of the redeposition is the resputtering of sputtered material from the sample that was previously deposited on the SEM column. The 2D distribution of the redeposition is asymmetric and is simulated well based on a simplified model of the column and sample configuration. The electrical surface damage mainly relates to the beam tails. Pt deposits for surface protection require much lower Ga + ion doses, and therefore have less impact on the wafer surface contamination. However, the range of electrical surface damage is larger for Pt deposits due to increased beam scattering in the low vacuum during the Pt deposition. With these contamination and damage levels and ranges, 'wafer return', i.e. continuing the wafer processing after the FIB, can be considered feasible for back-end of line processes with the loss of only the analyzed die or, potentially, also its neighbor. For front-end of line processes the acceptable contamination levels are more stringent and the feasibility of wafer return will be more process specific.

Designing Synergistic Nanocatalysts for Multiple Substrate Activation: Interlattice Ag–Fe3O4 Hybrid Materials for CO2-Inserted Lactones

“…The sliced octahedron was then analyzed by SEM–EDX mapping to determine the distribution and morphology of the Ag 0 dopants inside the octahedral architecture relative to the unmodified structure (Figure f–o). In order to avoid potential Ga + ion contamination in the FIB milling process and resulting structure, ultramicrotome slicing of the Fe 3 O 4 @Ag-40B octahedron was also performed as a parallel analysis (Figure p–t). The FIB and microtome experiments are consistent; at high loadings, Ag 0 appears as nanoparticles on the Fe 3 O 4 surface and within the octahedral framework (open circles, Figure k–n).…”

“…The sliced octahedron was then analyzed by SEM−EDX mapping to determine the distribution and morphology of the Ag 0 dopants inside the octahedral architecture relative to the unmodified structure (Figure 2f− o). In order to avoid potential Ga + ion contamination in the FIB milling process and resulting structure, 58 ultramicrotome slicing of the Fe 3 O 4 @Ag-40B octahedron was also performed as a parallel analysis (Figure 2p The XPS interrogation (Figures S8−S9) and depth profile analyses of the Ar + beam (4 keV)-etched (destructive) octahedron from 0 to 10 min (Figure 3) reveal Fe 2p 1/2 and Fe 2p 3/2 features from photoelectrons with binding energies of 724.85 and 711.20 eV, respectively (Figure 3a). Additional features confirming the presence of Ag 3d 5/2 and Ag 3d 3/2 photoelectrons with binding energies of 374.20 and 368.20 eV, respectively, are also observed (Figure 3b) and match well with The atomic concentrations of Fe, O, and Ag were determined from integration of the transitions associated with each element as a function of sputter time (Figure 3d).…”

Electron beam irradiation for the formation of thick Ag film on Ag3PO4

“…Mechanical cutting to perform cross-section measurements of the metallic layer was used, since cutting the relative Ag thick layer by more advanced techniques, such as the Focused Ion Beam (FIB), would induce silver growth, amorphization and deposition of gallium ions during the milling process, modifying the structure of the material. [70][71][72][73][74] X-ray diffraction (XRD). The crystal structure and long-range ordering of all prepared pellets were characterized by X-ray diffraction (XRD) in a D/Max-2500PC diffractometer (Rigaku, Japan) using Cu Ka radiation (l ¼ 1.54056 A), in range of 10-110 2q at a scan rate of 0.5 min À1 .…”

A Fast and Implantation-Free Sample Production Method for Large Scale Electron-Transparent Metallic Samples Destined for MEMS-Based In Situ S/TEM Experiments

“…These may impact the final quality of a specimen and possibly affect the reliability of the results generated during MEMS experiments within a S/TEM. Many metallurgical samples, such as those made from Al-based alloys, may strongly interact with either Ga ions [ 15 ] or Pt/C layers often used as a top-protective coatings [ 14 , 16 ], resulting in contamination and subsequent formation of undesirable artefacts. The advent of plasma-based FIBs (using Xe ions) is reported to mitigate some deleterious effects found in Ga-based FIBs [ 15 ], but the use of Xe ions can impact electron-transparent metallic lamellae in different ways including radiation-induced damage or even the formation of nanometer-sized Xe bubbles [ 17 ].…”