February_EDFA_Digital

edfas.org 31 ELECTRONIC DEV ICE FA I LURE ANALYSIS | VOLUME 24 NO . 1 and indicates points where electromigration can occur. Finally, in Fig. 3d (left) the quantilever is placed on the loop and the applied current is varied. This allows extract- ing a typical value of DC current densities that are mea- surable in this setup, amounting to a detection threshold | j | = 1 × 10 4 A/cm 2 . Note that this number can be an order of magnitude improved when applying AC sensing pro- tocols. The measurement is repeated inside the loop and | j | is varied (middle) and the distance to the plane (right). Also in the loop, the magnetic field increases linearly with applied current, as expected. The trace shows it is possible to safely resolve magnetic fields down to 10 µT. Furthermore, a current density of | j | = 1 × 10 6 A/cm 2 is still detectable at a height > 2 µm. Thus, also embedded integrated circuits can be detected using this technique. THE WIDE RANGE OF CAPABILITIES THAT SNVM OFFERS Thus far, the ability to sense local currents using scan- ning NVmicroscopy has been described. To bring this into context of IC failure analysis, it is anticipated that leaks in integrated circuits can be characterized with large preci- sion. Using the Qnami ProteusQ NV microscope a coarse defect localization is possible by investigating the light emission of the device. Such characterization, as used in EMMI (emission microscopy), is naturally available with the optical components of the scanning NV microscope. Also optical beam induced resistivity change (OBIRCH) is possible within the setup, and one would expect that the diamond tip helps to improve the OBIRCH resolution. In a next step, the defect can be investigated using scan- ning NV microscopy with a spatial resolution of 50 nm, an order of magnitude better as compared to standard numbers obtained in all-optical techniques such as EMMI and OBIRCH. In addition, the information obtained is quantitative, the operator thus knows howmuch current is flowing through the defect. Beyond that, the scanning NV technique allows to sense a local temperature change, since the strain in the diamond, which changes with temperature, affects the energy levels. The NV center is sensitive to local tem- perature variations on the order of 1 K. In the context of IC failure analysis, SNVMmay reveal local hotspots of wires. At these hotspots, problems such as electromigrationmay be especially pronounced. Furthermore, SNVM can lo- cally sense sources of AC noise, ranging from the kHZ to theGHz regime. Evenmore, it is also sensitive toAC signals applied to e.g., RF resonators. As this is an emerging capability of SNVM, its use-cases are now being explored. Finally, scanning NV microscopy is the method of choice for any magnetic memory devices, [1] be it race-track memory (RTM) or any type of magnetic random access memory (MRAM). In summary, SNVM is a versatile technique [5] that allows to locally sense not only currents with high spatial resolu- tion but also temperature, minutemagnetic fields, and AC fields andmay thus play an important role in future failure analysis procedures. REFERENCES 1. U. Celano, et al.: “ProbingMagneticDefects inUltra-ScaledNanowires withOptically Detected Spin Resonance inNitrogen-Vacancy Center in Diamond,” Nanoletters, 2021 , DOI: 10.1021/acs.nanolett.1c03723. 2. M.W. Doherty, et al.: “The Nitrogen-vacancy Colour Centre in Diamond,” Physics Reports, Vol. 528, July 2013, p. 1–45. 3. Qnami AG, “Fundamentals of Magnetic Field Measurement with NV Centers in Diamond,” 2020. 4. J.F. Barry, et al.: “Sensitivity Optimization for NV-diamond Mag- netometry,” Reviews of Modern Physics, Vol. 92, Mar. 2020. 5. F. Casola, T. Van Der Sar, and A. Yacoby: “Probing Condensed Matter Physics with Magnetometry based on Nitrogen-vacancy Centres in Diamond,” Nature Reviews Materials, Vol. 3, 2018. Fig. 4 Measurement capabilities of SNVM.