The role of scanning transmission electron microscopy (STEM) in failure analysis has been growing since the introduction of advanced technology nodes (10-nm and beyond), in which transistors (FinFET and nanosheets) have become much smaller and more complex. Four-dimensional scanning transmission electron microscopy (4D-STEM) is a new electron diffraction technique that expands conventional STEM imaging and EDX mapping to enable phase and orientation mapping of crystalline and amorphous phases in deposited thin films at the nanometer resolution. The enhancement of electron diffraction data by beam precession is then fundamental for higher accuracy and precision, especially in the case of strain measurements. The power of precession-assisted 4D-STEM analysis is demonstrated using the example of Germanium separation from within a Ge-rich GeSbTe layer in a phase memory device and with the example of tensile and compressive strain in a Samsung 5-nm technology node. These advanced electron diffraction measurements are now accessible to a broad range of users in routine analytical procedures due to unprecedented high levels of automation and synchronization in the new analytical STEM instrument, TESCAN TENSOR.

This paper presents a large-volume workflow for fast failure analysis of microelectronic devices. The workflow incorporates a stand-alone ps-laser ablation tool and a FIB-SEM system. As implemented, the picosecond laser is used to quickly remove large volumes of bulk material while the Xe plasma FIB provides precise end-pointing to the feature of interest and fine surface polishing after laser ablation. The paper presents several application examples, including a full workflow to prepare artefact-free, delamination-free cross-sections in an AMOLED mobile display and the preparation of devices and packages (including flip chips) of varying size. It also covers related issues such as CAD navigation, data correlation, and the use of bitmap overlays for end-pointing.

As the semiconductor industry demands higher throughput for failure analysis, there is a constant need to rapidly speed up the sample preparation workflows. Here we present extended capabilities of the standard Xe plasma Focused Ion Beam failure analysis workflows by implementing a standalone laser ablation tool. Time-to-sample advantages of such workflow is shown on four distinct applications: cross-sectioning of a large solder ball, cross-sectioning of a deeply buried wire bond, cross-sectioning of the device layer of an OLED display, and removing the MEMS silicon cap to access underlying structures. In all of these workflows we have shown significant decrease in required process time while altogether avoiding the disadvantages of corresponding mechanical and chemical methods.

A protocol for obtaining an advanced TEM lamella geometry using FIB-SEM is presented. Lamella lift-out procedure might require multiple manipulation steps or even breaking the vacuum in order to reach inverted or plan-view lamella geometries. We have developed a setup which enables lamella transfer from a bulk sample onto a TEM grid within a single, very simple manipulation step, with no need to break the vacuum or unload the sample. Most importantly, this approach does not require any additional devices to be installed.

Cross sections of large Through Silicon Vias (TSV) and solder bumps are often prepared using the Focused Ion Beam (FIB). The high current Xe plasma ion source allows fast and precise target preparation of TSV with small diameter. Solder bumps can be accessed due to the high milling rate too. However, the high current milling by plasma FIB causes the worsening of the milled surface quality. An optimized FIB scanning strategy accompanied with the novel rocking stage for the sample tilting during the milling has been developed for the plasma FIB. Whole milling process is observed by the Scanning Electron Microscopy (SEM). Time to prepare a cross section is accelerated and the excellent quality is suitable for subsequent failure analysis. Also important is proper sample cleaving before FIB milling. Using an accurate method to cleave the sample prior to FIB preparation further reduces the overall sample preparation time. The high quality cross sections prepared using this new method are ready not only for SEM but also for EDX and EBSD analysis, either 2D or 3D, when combined with FIB slicing. Broadening the analysis to these techniques increases the obtainable information, allowing the arrangement of materials and their crystalline structure to be studied in a detail.

3D tomography of TSVs was performed by combining Xe plasma FIB milling and lift-out techniques. This approach allows analyzing the structure of TSVs in detail using a method faster than the usual 3D tomography by Ga FIB and more precise than X-ray tomography. Both well-filled TSVs and TSVs with voids were analyzed and the results were compared. The analysis procedure was optimized in order to reduce the analysis time and to increase the throughput. The lift-out of the analyzed block of material was performed to obtain 90° angle between TSV and the ion beam axes, which is critical to reduce the curtaining effect and which allowed to increase FIB beam current significantly, reducing the analysis time.