Search Results for crystal defects

A new preferential etch for (100) and (111) oriented, p- and n-type silicon has been developed. This article describes the basic chemistry of the etching process and provides examples of how it defines critical features such as oxidation-induced stacking faults, dislocations, swirl, and striations with minimum surface roughness and pitting. A relatively slow etch rate of around 1 μm/min at room temperature provides etch good control and a long shelf life allows the solution to be stored in large quantities.

Silicon pipeline defects are a growing concern in semiconductor manufacturing with no proposed methodology on how to effectively analyze them and separate the underlying causes. In light of this need, a study was conducted using complementary FA techniques to examine these unusual silicon crystal defects and gain a better understanding of their signature characteristics and their effect on device failure. This article, authored by the lead investigator, describes the tests that were performed and presents relevant findings and theories on the factors that contribute to "pipeline" and how they can be controlled. It also presents guidelines for distinguishing between pipeline and dislocation defects and explains how they are related.

The third extended European Failure Analysis Network (EUFANET) workshop, “Smart FA for New Materials in Electronic Devices,” was held in Dresden, Germany, September 17-18, 2012. This article provides a summary of the event with highlights from presentations on flexible organic electronics, crystal defects in SiC, nanoprobing, and the capabilities of nano X-ray tomography.

Optical second-harmonic generation (SHG) is a noninvasive technique that provides information about interface properties and crystal defects. This article demonstrates the use of SGH in the study of high-k dielectrics, silicon-on-insulator structures, compound semiconductors, and through-silicon vias.

Localizing defects in one-of-a-kind failures can take days, weeks, or even months, after which a detailed physical analysis is conducted to determine the root cause. TEM and STEM play complimentary roles in this process; TEM because of its superior spatial resolution and STEM because it produces images that are easier to interpret and is less susceptible to chromatic aberrations that can occur in thicker samples. In the past, the use of STEM in FA has been limited due to the time required to switch between imaging modes, but with the emergence of TEM/STEM microscopes with computer controlled lenses, the use of STEM is increasing. This article provides an overview of STEM techniques and present examples showing how it is used to characterize subtle and complex defects in ICs.

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.

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.

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).

Electron beam induced current (EBIC) analysis is a versatile tool that can be used by anyone with access to a SEM. This article explains how failure analysts are using the EBIC mode in SEMs to detect junction and oxide defects, simplify junction delineation, and reveal subsurface damage through multiple layers of metallization.

Reflecting back on the past 45 years in semiconductor failure analysis, the columnist notes that the trend lines have deviated little over that time. He then goes on to point out the relatively few discontinuities, the latest of which, the emergence of the “invisible defect,” takes him back to the beginning of his journey.

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 brief article discusses the various ways curve tracers can help failure analysts detect defects, leakage current, and abnormal device operation.

Voltage contrast followed by electron beam induced current imaging is an effective approach for isolating IC failures. This article briefly reviews the physics of signal generation for both techniques and presents several examples illustrating how this powerful combination contributes to advanced defect localization.

Four-dimensional scanning transmission electron microscopy (4D-STEM) is a spatially resolved electron diffraction technique that records the electron scattering distribution at each sampling point. 4D-STEM provides researchers with information that can be analyzed in a multitude of ways to characterize a sample’s structure, including imaging, strain measurement, and defect analysis. This article introduces the basics of the technique and some areas of application with an emphasis on semiconductor materials.

The combination of microcleaving and precision broad ion beam techniques allows failure analysts to prepare site-specific specimens for SEM analysis with 0.5 μm accuracy. Microcleaving, as the article explains, uses the cleaving characteristics inherent in single-crystal semiconductor substrates. Because the substrate has significantly more mass than the process layers, it dictates the overall cross-section quality and precision of the sample. The cleave loses no material, preserves the integrity of the designated area, and enables analysis of both sides of the cross-section. When the cleave is off-set due to a buried target or when debris lies on the surface of the cross-section, ion beam etching and coating are used to fine tune the cleave location and remove debris prior to SEM analysis.

Electromigration is a wearout mechanism that contributes significantly to IC failures. This article discusses the causes and effects of this often overlooked failure mode and presents practical guidelines to help analysts determine whether or not electromigration is the cause of a particular failure. It also discusses the differences between aluminum and copper electromigration.

Electronic device failure analysis usually starts with electrical testing, followed by visual inspection via optical microscopy, then examination in a scanning electron microscope. When imaging reveals the need to determine the composition of materials, defects, and suspected contaminants, the electron beam produced by the SEM can be used to obtain the necessary information. As the article explains, this is the basic concept behind the method known as energy dispersive X-ray spectroscopy (EDS or EDX) and the key to its widespread use. In addition, the article presents three examples showing how SEM/EDS measurements helped failure analysts identify human contaminants on a die sample, determine the source of a particle embedded in the film stack on a wafer, and conclude that lead spatter from a solder die-attach preform caused wire bond lift.

This article provides insights into the nature of IDDQ and timing defects and the challenges they present to failure analysts based on the findings of a Sematach study.

This is the second article in a two-part series on the causes of failure in electromechanical relays. Part I, in the February 2018 issue of EDFA , examines a variety of failures caused by the formation of oxide on contact surfaces. As the author explains, electric arcing in the presence of silicon oil or vapor creates SiO 2 deposits in the contact region that build up over time. Here in Part II, the author presents examples of failures caused by nitrous gases, phosphoric acid crystals, and wax, which is often found on enameled copper wires.

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.