Article

Magnetic Field Imaging for non destructive 3D IC testing

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Abstract

Due to magnetic fields ability to penetrate through all materials used by the semiconductor industry, a unique ability not found in any other techniques, it has become an important technique for detecting shorts, leakages and opens in multi stacked Through Silicon Via samples. We show in this paper how Magnetic Field Imaging is being used to image the current in a TSV stacked silicon device with a new 3D analysis algorithm of the distance from the top of the stacked device to the current path.

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... In general, the resulting integrated-circuit magnetic fields pass through many standard integrated circuit materials, and will vary spatially and temporally in ways that correlate with both integratedcircuit architecture and operational state. Thus, combined high-resolution and wide-field-of-view mapping of magnetic fields may yield simultaneous structural and functional information, and may be suitable for identification of malicious circuitry or Trojans [6,7], counterfeit detection [8], fault detection [9][10][11], and manufacturing flaws [12]. However, leveraging magnetic field emanations is challenging due to the tremendous complexity of circuits integrating billions of transistors of minimum feature sizes down to tens of nanometers, with interconnects distributed across multiple levels of metallization [13]. ...
... To date, the QDM's unique combination of magnetic field sensitivity, spatial resolution, field of view, and ease of use has allowed it to be used to measure microscopic current and magnetization distributions from a wide variety of sources in both the physical and life sciences [21][22][23][24][25][26][27][28]. Complementary to scanning techniques for characterizing integrated-circuit magnetic field emanations, which include wire loops [29], probe antennas [30], magnetic force microscopy [11], superconducting quantum interference device magnetometers [7], and vapor cell magnetometers [31], the QDM employs a nonscanning imaging modality [15] that provides simultaneous highresolution (micron-scale) and wide-field (millimeter-scale) vector magnetic imaging, while operating under ambient conditions. This capability allows for monitoring of transient behavior over sequential measurements of a magnetic field, providing a means to study correlations in signal patterns that can evolve more quickly than a single-sensor scan time. ...
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Current density distributions in active integrated circuits result in patterns of magnetic fields that contain structural and functional information about the integrated circuit. Magnetic fields pass through standard materials used by the semiconductor industry and provide a powerful means to fingerprint integrated-circuit activity for security and failure analysis applications. Here, we demonstrate high spatial resolution, wide field-of-view, vector magnetic field imaging of static magnetic field emanations from an integrated circuit in different active states using a quantum diamond microscope (QDM). The QDM employs a dense layer of fluorescent nitrogen-vacancy (N-V) quantum defects near the surface of a transparent diamond substrate placed on the integrated circuit to image magnetic fields. We show that QDM imaging achieves a resolution of approximately 10μm simultaneously for all three vector magnetic field components over the 3.7×3.7mm2 field of view of the diamond. We study activity arising from spatially dependent current flow in both intact and decapsulated field-programmable gate arrays, and find that QDM images can determine preprogrammed integrated-circuit active states with high fidelity using machine learning classification methods.
... In general, the resulting IC magnetic fields pass through many standard IC materials, and will vary spatially and temporally in ways that correlate with both IC architecture and operational state. Thus, combined high-resolution and wide-field-of-view mapping of magnetic fields may yield simultaneous structural and functional information, and may be suitable for identification of malicious circuitry or Trojans [6,7], counterfeit detection [8], fault detection [9,10], and manufacturing flaws [11]. However, leveraging magnetic field emanations is challenging due to the tremendous complexity of circuits integrating billions of transistors of minimum feature sizes down to tens of nanometers, with interconnects distributed across multiple levels of metallization [12]. ...
... To date, QDM magnetic field imaging has been used to measure microscopic current and magnetization distributions from a wide variety of sources in both the physical and life sciences [17][18][19][20][21][22][23]. Complementary to existing scanning techniques for characterizing IC magnetic field emanations, which include wire loops [24], probe antennas [25], magnetic force microscopy [10], SQUID magnetometers [7], and vapor cell magnetometers [26], the QDM provides simultaneous high-resolution (micron-scale) and wide-field (millimeter-scale) vector magnetic imaging. This capability allows for monitoring of transient behavior over sequential measurements of a magnetic field, providing a means to study correlations in signal patterns that can evolve more quickly than a single-sensor scan time. ...
Preprint
Current density distributions in active integrated circuits (ICs) result in patterns of magnetic fields that contain structural and functional information about the IC. Magnetic fields pass through standard materials used by the semiconductor industry and provide a powerful means to fingerprint IC activity for security and failure analysis applications. Here, we demonstrate high spatial resolution, wide field-of-view, vector magnetic field imaging of static (DC) magnetic field emanations from an IC in different active states using a Quantum Diamond Microscope (QDM). The QDM employs a dense layer of fluorescent nitrogen-vacancy (NV) quantum defects near the surface of a transparent diamond substrate placed on the IC to image magnetic fields. We show that QDM imaging achieves simultaneous $\sim10$ $\mu$m resolution of all three vector magnetic field components over the 3.7 mm $\times$ 3.7 mm field-of-view of the diamond. We study activity arising from spatially-dependent current flow in both intact and decapsulated field-programmable gate arrays (FPGAs); and find that QDM images can determine pre-programmed IC active states with high fidelity using machine-learning classification methods.
... Many scholars have conducted research on the reliability of TSV. Related research includes TSV thermal stress distribution analysis [2][3][4][5][6][7], copper pumping [8][9][10][11], stress testing and failure analysis [12][13][14][15][16][17][18], fatigue and fracture [19][20][21][22][23][24][25][26][27][28][29][30], radiation [31], electromigration [32][33][34][35][36], dielectric failure(TDDB) [37], reliability test [38], and structural optimization design [22,39], etc. However, the research on the reliability of TSV is still in the preliminary stage, and there are still many issues that require in-depth systematic research. ...
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Magnetic current imaging (MCI) is found to image open defects in a fully assembled double-stacked dice inside a mold compound package with ball grid array (BGA) by increasing the bandwidth of the SQUID electronics up to 200 MHz. By imaging the magnetic field of a standing wave in the vicinity of the open, the RF MCI microscope Magma recovers the standing wave current profile and locates the open. In a continuity analysis, a BGA sample containing double-stacked dice revealed that High 1 (H1) was open to Ground 1 (G1) and Ground 2 (G2), showing infinite resistance when this connection pair should have shown 400 kω. Comparison of the physical failure analysis (FA) result confirms that space domain reflectometry (SDR) found the defect accurately. The crack are caused by the through-silicon vias (TSV) manufacturing process. This type of open failure has been a rather common failure in this specific TSV process.
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Space Domain Reflectometry (SDR) is a new technique that has already shown to be a reliable non-destructive method to image open failures in semiconductor chips by pumping a high frequency signal into the open trace. We show in this paper that SDR can be used to accurately find a breakage location in copper wire bond that failed during stress test.
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A point‐contact (SQUID) magnetometer was used inside a shielded room to record the magnetic field of the human heart, without noise‐averaging. The resulting magnetocardiograms, with the peak signal at about 3 × 10<sup>-7</sup> G had a noise level of about 1 × 10<sup>-9</sup> G (rms, per root cycle). They approach good medical electrocardiograms in clarity, and are an order‐of‐magnitude improvement in sensitivity over previous magnetic detectors of the heart. These results suggest new medical uses for this magnetometer.
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As microelectronic technologies continue to develop according to the More than Moore’s law, so that full systems can be confined inside one assembly, failure analysis must take this into account. Magnetic microscopy has achieved successful failure analysis of standard ICs but now it faces new challenges related to the lack of resolution triggered by the long working distances necessary when working on complex 3D architectures. Our new approach can push the present scope of the technique further by using a simulation approach, and by measuring not only the z component of the magnetic field but also the x and the y by tilting the sample. We will show how we can map and localize defects with an increased resolution taking into account three-dimensional geometries.
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The future of integrated electronics is the future of electronics itself. Integrated circuits will lead to such wonders as home computers, automatic controls for automobiles, and personal portable communications equipment. But the biggest potential lies in the production of large systems. In telephone communications, integrated circuits in digital filters will separate channels on multiplex equipment. Integrated circuits will also switch telephone circuits and perform data processing. In addition, the improved reliability made possible by integrated circuits will allow the construction of larger processing units. Machines similar to those in existence today will be built at lower costs and with faster turnaround.
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