Lock-in thermography (LIT) is a widely used nondestructive tool for detecting the failure location in integrated circuits. The image pattern recognition algorithm for detecting LIT hotspots benefits image processing and can be leveraged to automate failure analysis processes.

Engineers at Infineon Technologies have developed a way to detect probing-induced fracture in semiconductor wafers in real-time using acoustic emission sensing and burst-signal energy filtering techniques. In this article, they describe the measurement procedure and demonstrate its use on complex semiconductor pad stacks. They also present experimental results that shed new light on the relationship between probe tip contact force and crack probability in thin, brittle layers typical of BEOL layer stacks in CMOS ICs.

This article explains how to find shorted components on PCB assemblies using infrared-based direct current injection, a nondestructive method that has several advantages over magnetic microscopy and voltage drop measurement techniques. An application example involving a power board failure is also provided.

This article describes a form of lock-in thermography that achieves 3D localization of thermally active defects in stacked die packages. In this approach, phase shifts associated with thermal propagation delay are analyzed as a function of frequency. This allows for a precise localization of defects in all three spatial dimensions and can serve as a guide for subsequent high-resolution physical analyses.

A noninvasive thermal imaging approach based on the thermoreflectance principle is proposed for analyzing advanced semiconductor devices. Several examples illustrate the value of this approach in detecting thermal anomalies and defects missed by other techniques.

Electro optical terahertz pulse reflectometry (EOTPR) is a nondestructive fault isolation technique that is well suited for today’s ICs. This article provides examples of how EOTPR is being used to investigate 2.5D and 3D packages, wafer level fanout packages, and MEMS devices. It also discusses recent advancements in EOTPR systems and software.

Researchers have developed an imaging technique that reveals wiring defects in packaged ICs without requiring decapsulation. The sensing mechanism is based on resistance changes, similar to IR-OBIRCH, but instead of an IR beam, the metal conductors in the chip are heated by ultrasonic waves. This article describes the basic principles of ultrasonic beam induced resistance change (SOBIRCH) imaging and demonstrates its effectiveness in a wide range of applications, including multilayer metal stacks.

Positron spectroscopy can identify defects deep within metals and semiconductors with a resolution better than a single atomic lattice site. This article discusses the basic principles and implementation of positron annihilation spectroscopy and a key development that makes it more a more useful tool for semiconductor applications.

Chip-level 3D integration, where chips are thinned, stacked, and vertically interconnected using TSVs and microbumps, brings as many challenges as it does improvements, particularly in the area of failure analysis. This article assesses the capabilities of various FA techniques in light of the challenges posed by 3D integration and identifies current shortcomings and future needs.

This article provides an overview of the types of failures that tend to occur in photovoltaic (PV) modules in the field and the methods typically used to investigate them. It covers the causes and effects of broken and corroded interconnects, cracked and damaged cells, short and open bypass diodes, delamination, moisture ingress, and encapsulant discoloration. It describes tools and techniques commonly employed in the analysis of PV failures, including IV measurements, electroluminescence, infrared imaging, and visual inspection. It also discusses current and emerging challenges in PV failure analysis and reliability.

This article presents a new technique for monitoring the health of lithium-ion cells. Whereas traditional methods use current, voltage, and temperature data to infer the overall health of the cell, the new method uses ultrasonic measurements to assess structural changes such as swelling, expansion, ruffling, and delamination. The article explains how and why these changes occur, how they are measured, and how they correlate with loss of battery capacity, safety, and failure. It also discusses the effect of charge and discharge cycles and the factors that contribute to gas generation.

This article reviews the basic failure modes of surface-mount tantalum capacitors and the methods used to determine the cause. It discusses the factors that contribute to leakage, shorts, opens, and high series resistance, the characteristics of each failure mode, and the best approaches for failure analysis.

The shrinking geometries in today’s 3-D integrated circuit (IC) designs generate an urgent need for a variety of tools to isolate failures on advanced semiconductor devices. There has been no single technique that adequately addresses all types of failures with the required fast cycle time. Complex failures that are not resolved by the faster global approaches are best addressed by probing technologies, where waveforms or voltages are measured from node to node. These approaches are time-consuming and usually require detailed understanding of the circuit operation. Global techniques that map the secondary effects of defects have been widely used for as many failures as possible. These secondary effects include thermal emission, photon emission, and circuit operation dependencies on localized heating or carrier generation at a defect site. Each technique addresses some segment of the failure mechanisms, but none is universally effective in itself. The use of thermal emission techniques has waned due to the issues of lower power supply voltages, which result in poor sensitivity for older techniques and decrease in minimum resolved feature sizes.

This article discusses the setup and use of thermoreflectance imaging, a thermal mapping technique with a spatial resolution in the submicron range and a time resolution down to tens of nanoseconds. It describes the basic physics of thermoreflectance measurements and the advantages and limitations of the approach. It also provides examples showing how thermoreflectance imaging is used for thermal characterization, design optimization, and reliability analysis of high-power transistors, electrostatic discharge devices, and copper vias.

Failure analysis is becoming increasingly difficult with the emergence of 3D integrated packages due to their complex layouts, diverse materials, shrinking dimensions, and tight fits. This article demonstrates several FA techniques, including high-frequency scanning acoustic microscopy, lock-in thermography, and FIB cross-sectioning in combination with plasma ion etching or laser ablation. Detailed case studies show how the various methods can be used to analyze bonding integrity between different materials, chip-to-chip interface structures, buried interconnect defects, and through-silicon vias at either the device or package level.

Lock-in thermography (LIT) is a powerful fault isolation and characterization tool for solar cell ICs. This article describes the basic LIT imaging process on silicon wafer-based solar cells as well as its various modes, applications, and results.

This column explains why transmission X-ray microscopy (TXM) and X-ray computed tomography (XCT) could become the methods of choice for defect localization in the coming years.

This article presents a failure analysis workflow tailored for complex ICs and device packages. The FA flow determines the root cause of failures using nondestructive analysis and advanced sample preparation techniques. The nondestructive tests typically used are X-ray radiography, scanning acoustic microscopy, time domain reflectometry, and magnetic current imaging. To gain access to interconnect failures, laser ablation is used, typically in combination with chemical etching to finish the decapsulation process. Repackaging is also part of the FA flow and is briefly discussed.

Fluid-filled metallized-polymer-film capacitors have unique failure mechanisms, many of which are related to insufficient fluid level, improper installation geometry, or both. Although such failures can be analyzed using X-ray testing equipment, it is often impractical or cost-prohibitive. This article describes some of the failure modes observed in fluid-filled capacitors and explains how to analyze them easily and inexpensively.

Backside optical analysis is often aided by solid immersion lenses (SILs), but as the authors of this article explain, SILs improve the resolution of front side thermography as well. The authors describe the physics behind solid immersion lenses and provide examples that demonstrate the advantages and limitations of their use from the font side.