Search Results for 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.

Scanning acoustic tomography (SAT) is widely used to detect defects such as voids and delamination in electronic devices. In this article, the authors explain how they improved the spatial resolution and detection sensitivity of SAT by switching from a conventional piezoelectric probe to a capacitive micromachined ultrasound transducer (CMUT) and by using pulse compression signal processing. They also present examples showing how the improvement makes it possible to detect very small defects in multilayer stacks and BGA packages whether in through-transmission or reflection imaging mode.

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.

Recent developments in two relatively new failure analysis techniques, Seebeck effect imaging (SEI) and thermally-induced voltage alteration (TIVA), have greatly improved their defect detection sensitivity and image acquisition times for localizing open and shorted interconnections. This article presents several examples demonstrating the enhanced capabilities of these two methods.

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.

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.

A wide range of electrical faults are revealed through thermal laser stimulation (TLS). In principle, an electrical parameter, typically current or voltage, is monitored for changes caused by the heating effects of the laser. Most test setups are designed to limit the activity of the device in order to minimize the signal-to-noise ratio, but in some cases, the fault’s electrical footprint can only be detected when the device is stimulated in a dynamic way. This article describes the setup and implementation of various dynamic TLS methods and presents example applications demonstrating the advantages and limitations of each approach.

This column provides a ten-year retrospective on laser-based fault isolation techniques and the important role of laser signal injection microscopes.

Conventional backside imaging takes advantage of silicon’s transmission of light which, based on the Plank relation ( E g = hc/ λ ), occurs at wavelengths greater than 1 µm. Because of diffraction, the lateral spatial resolution of backside imaging techniques is limited to about half the wavelength of the light source used, which is far too coarse to isolate faults in a typical IC. In this article, the authors explain how they overcome this limitation by reprofiling the backside of the silicon, forming spherically shaped domes. The raised convex surfaces act as solid immersion lenses that are shown to improve spatial resolution by nearly an order of magnitude. The degree of improvement is evaluated using backside emission microscopy (EMS), optical beam induced current (OBIC) imaging, and laser voltage probing (LVP) and the results are presented in the article.

Scanning probe microscopy (SPM) refers to a suite of techniques that measure the interaction between a fine probe or tip and a sample in contact or close proximity. These interaction measurements allow the study of properties such as topology, magnetic and electric fields, capacitance, temperature, work function, and friction. The information obtained from SPM plays an important role in IC failure analysis.

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.

This article provides an introduction to liquid crystal hot spot detection and its use in electronic device failure analysis. It describes how liquid crystal responds to temperature changes and the equipment typically used to observe it. It explains how to apply these materials to test specimens, how to optimize measurement sensitivity, and how to interpret the results. It also presents hot spot detection procedures and describes failure scenarios for which the method is particularly effective.

This article provides a qualitative overview of several new defect localization techniques, including charge-induced voltage alteration (CIVA), light-induced voltage alteration (LIVA), thermally-induced voltage alteration (TIVA), and Seebeck effect imaging (SEI). It explains how each method works in terms of the physics of signal generation and the types of images they produce. It also includes a summary highlighting the similarities and differences of each technique.

This article provides a practical overview of energy-dispersive spectroscopy (EDS) and its various uses in semiconductor device manufacturing and failure analysis. It explains how EDS techniques are typically implemented, compares and contrasts different methods, and discusses the factors that determine spatial and energy resolution, measurement depth, sensitivity, signal-to-noise ratio, and ease of use.

Magnetic current imaging is a proven fault-isolation technique. Its unsurpassed sensitivity and resolution coupled with the fact that magnetic fields are unaffected by packaging and die materials make it a valuable FA tool for a wide variety of ICs and devices. This article reviews the basic measurement physics of magnetic current imaging, describes the general implementation, and presents several practical examples of its use.

This article describes the basic measurement physics of scanning nitrogen vacancy (NV) microscopy and the various ways it can be used in semiconductor device failure analysis. Scanning NV microscopy can measure topography as well as magnetic fields, local current density, ac noise, and local temperature variations.

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.

Quantum diamond microscopy is an innovative nondestructive tool. This article describes detailed operations from a failure analyst's perspective, showing how the technique integrates into standard workflows. Case histories are included comparing its performance to established FA methods and highlighting QDM's specific advantages.

This article discusses some of the early uses of emission microscopy in semiconductor device failure analysis and the challenges that were overcome to make it the invaluable tool it is today. One of the impediments early on was a misconception that silicon cannot emit light when, in fact, it has several light emission mechanisms that have proven useful in electron microscopy. One such mechanism, avalanche luminescence, occurs in junctions during reverse breakdown and is useful for resolving low breakdown voltage and problems with ESD protection circuits. Other light emission mechanisms discussed in the article include forward bias emission, MOS transistor saturation, and dielectric luminescence, which is used to examine oxide test structures and detect oxide defects.

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.