The best spatial resolution that can be achieved with far-field optical fault localization techniques is around 20 times larger than the critical defect size at the 45 nm technology node. There is also a limit on the laser power that can be safely used on 45 nm devices, which further compromises fault localization precision. In this article, the authors explain how they overcome these limitations using pulsed laser-induced imaging techniques and a refractive solid immersion lens. Two case studies show how the combination of pulsed-laser scanning optical microscopy and a solid immersion lens improves localization precision and detection sensitivity.

The use of a pulsed laser with a lock-in amplifier has been shown to increase the detection sensitivity of scanning optical microscopes by a factor of ten. In this article, the authors explain how they implement laser pulsing without a lock-in amplifier through software control. The detection sensitivity of their method, which is based on a digital signal integration algorithm, has been shown to be comparable to that achieved with a lock-in amplifier. Several case studies illustrate the effectiveness of the technique for locating various types of defects.

Single contact optical beam induced currents (SCOBIC) is a variation on the OBIC failure analysis technique that requires only one point of contact with the junction being examined. This article discusses the basic principles of this new method and how it compares with OBIC in terms of measurement performance. It also presents examples showing how SCOBIC can be used to analyze CMOS devices from the front and back side without need for complex FIB and microprobing procedures.

Recent demonstrations of high-repetition-rate, high-brightness soft X-ray lasers are opening new possibilities for the development of compact imaging systems with spatial resolution approaching the illumination wavelength. This article examines some of configurations that have been used in these extreme ultraviolet (EUV) imaging systems and their general capabilities. One of the systems discussed uses the output from a 46.9 nm argon laser to render transmission and reflection-mode images with a spatial resolution of 120 to 150 nm. Another uses a 13 nm AgCd laser with Fresnel zone plate optics, producing transmission-mode images with a spatial resolution of 38 nm.

Laser-assisted device alteration (LADA) is an effective tool for identifying speed-limiting paths in ICs. When implemented with a continuous wave laser, it can reveal where the speed-limiting path resides but not when the slow (or fast) logic transition is occurring. To overcome this limitation, an enhanced version of the technique has been developed. This article discusses the capabilities of the new method, called picosecond time-resolved LADA, and explains how it complements the existing failure analysis toolset, facilitating faster resolution of issues and root-cause identification.

This article discusses the basic principles of terahertz time-domain spectroscopy (THz-TDS) and the function and limitations of key components in a THz-TDS system. It also provides examples of some of the ways THz-TD imaging is used alone and in combination with other analytical techniques.

Laser voltage probing (LVP), an IR-based technique, facilitates through-silicon signal waveform acquisition and high frequency timing measurements from active p-n junctions on CMOS ICs. The ICs can be in flip-chip as well as wire-bond packages with backside access to the IC. As the article explains, LVP significantly improves silicon debug and failure analysis throughput time compared to electron-beam probing because it eliminates the need for backside trenching and probe-hole generating operations.

Technologies relatively new to failure analysis, like time-correlated photon counting, electro-optical probing, antireflective (AR) coating, Schlieren microscopy, and superconducting quantum interference (SQUID) devices are being leveraged to create faster, more powerful tools to meet increasingly difficult challenges in failure analysis. This article reviews recent advances and research in fault isolation and circuit repair.

This article explains how hardware and software enhancements bring new capabilities to one of the most widely used soft-defect localization techniques. It discusses the basic concept of electrically enhanced laser-assisted device alteration (EeLADA) and demonstrates its use on different types of soft and hard defects. It also discusses the relative advantages of hardware and software implementations.

This article discusses the development of resonance-enhanced AFM-IR spectroscopy and demonstrates its effectiveness on silicon test wafers with nanoscale skin particles and polyester contaminants.

Soft electrical failures caused by monograin defects can have a significant impact on yield in technology nodes below 40 nm. Moreover, the failures are hard to identify and the defects give very few signatures during localization testing. In this article, the authors explain how they used nanobeam diffraction with automated crystal orientation and phase mapping to pinpoint a single grain orientation causing the problem and, as a result, are now able to recognize the symptoms of this type of failure, observe the defect, and limit the impact on electrical timing margins through both design and process corrections.

One of the pioneering developers of induced voltage alteration (IVA) measurement techniques assesses the current state of the technology, the impact of major advancements, and the potential for further improvements. The assessment pays particular attention to biasing approaches, phase-locked loop detection techniques, the effect of solid immersion lenses on spatial resolution, and the emergence of production-type sample preparation methods.

This article provides a summary of the presentations given at the four User’s Group meetings at ISTFA 2012. Each user group focused on one of the following topics: nanoprobing, contactless fault isolation, focused ion beam, and sample preparation.

This column assesses the current state and outlook for superconducting device technology and its application in exascale computing.

This article discusses the types of defects that occur in vertical cavity surface-emitting lasers (VCSELs) and the tools typically used to detect them and identify the cause. It describes the basic design and operation of VCSELs and explains that most failures are due to dislocations in the crystal structure of the materials from which the devices are made. Of the various methods used to analyze such defects, electroluminescence (EL) is by far the most powerful as demonstrated in several EL images included in the article. The article also discusses the use of EBIC analysis, FIB cross-sectioning, and thermally induced voltage alteration (TIVA).

The transition to “flip-chip” packaging forced a renaissance in failure analysis methods, usually referred to as backside failure analysis. This article describes one such technique based on active laser probing. The technique uses the optical properties of the silicon substrate to produce a high-sensitivity, high-resolution thermal map of the device active area. This map can locate shorting defects and be used as a thermal management tool.

This article summarizes major discussion points from four User’s Group meetings held at the ISTFA 2009 conference. The topics addressed are "Optical Techniques: Growth and Limitations," "Resolution of Nanoprobing for 45 nm and Beyond: New Challenges," "FIB," and "Fast ASIC Fault Isolation: Efficiency and Accurate Resolution of Software-Based Fault Isolation."

This article discusses the concept of a virtual known good device (VKGD) and how it used in the development of advanced 3D packaging. It explains that a VKGD is essentially an electromagnetic model of an IC package, including bumps, interposers, and through-silicon vias. These models, used in conjunction with reflectometry data, help engineers isolate faults in the early stages of IC package development, greatly reducing cycle times.

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.

This article discusses the basic procedures involved in atom probe tomography (APT) and demonstrates its use on complex material stacks. Although still a relatively new technique, APT has moved to the forefront of semiconductor failure analysis because it can provide 3D chemical composition of a wide range of materials on a near-atomic scale.