Search Results for X-ray imaging

Modified Talbot X-ray interferometry provides three contrast modes simultaneously: absorption, phase, and dark field/scattering. This article describes the powerful new imaging technique and shows how it is used to characterize various types of defects in advanced semiconductor packages.

X-ray ptychography, as recent studies show, has the potential to bridge the gap that currently exists between conventional X-ray imaging and electron microscopy. This article covers the evolution of the technology from basic 2D imaging to computed tomography to 3D ptychographic X-ray laminography (PyXL) with zoom. To demonstrate the capabilities of PyXL, a 16-nm FinFET logic IC was mechanically polished to a thickness of 20 µm and several regions were imaged at various levels of resolution.

Flat-panel X-ray detectors used in medical imaging applications present a challenge to failure analysts due to the scale of the products, the newness of the technology, and the relatively low production rates compared to ICs. This article explains how existing tools are being adapted to accommodate the size of these detectors and the exotic materials from which they are made. It discusses the types of defects that can occur and how they affect critical detector characteristics. It describes the basic approach for defect localization and physical analysis and presents examples of defects in different areas of a flat-panel X-ray detector.

X-ray tomography has been rapidly gaining acceptance in the semiconductor industry since the first demonstration of its use on IC interconnect in 1999. As failure analysts are discovering, X-ray imaging is more powerful than visible light microscopy and can be used to analyze larger samples than those that fit in an electron microscope. This article provides an introduction to the physics, signal processing, and algorithms involved in X-ray imaging and tomography and the factors that affect resolution.

This article describes a proposed novel metric to furnish chip designers with a prognostic tool for x-ray imaging in the pre-silicon stage. This metric is fashioned to provide designers with a concrete measure of how visible the fine-pitched features of their designs are under x-ray inspection. It utilizes a combination of x-ray image data collection, analysis, and simulations to evaluate different design elements.

In this case study, the author describes the investigation of a defective DC-DC converter retrieved from an aircraft following the report of abnormal system behavior. Electrical testing, local probing, X-ray imaging, and cross-sectional analysis led to the discovery of cracks on several pins and in some of the solder material. The cracks were caused by different rates of thermal expansion and were remedied with the help of thermomechanical analysis, EBSD imaging, and phase map comparisons for thick and thin solder joints.

The complexity of sample preparation and deprocessing has risen exponentially with the emergence of 2.5-D and 3D packages. This article provides answers and insights on how to deal with the challenges of increasingly complex semiconductor packages. After identifying pressing issues and potential bottlenecks with state-of-the-art FA flows, the authors present two case studies demonstrating the capabilities of electro-optical terahertz pulse reflectometry (EOTPR), plasma FIB milling, and 3D X-ray imaging. The FA results confirm the potential of all three techniques and indicate that a fully nondestructive integration flow for 3D packages may be achievable with further development and optimization.

This article provides an overview of a commercial 3D X-ray system, explaining how it acquires high-resolution images of submicron defects in large intact samples. It presents examples in which the system is used to reveal cracks in thin redistribution layers, voids in organic substrates, and variations in TSV metallization on 300-mm wafers. As the authors explain, each scan can be done in as little as a few minutes regardless of sample size, and the resulting images are clear of the beam hardening artifacts that often cause problems in failure analysis and reverse engineering.

X-ray computed tomography is a noninvasive technique that can reveal the internal structure of objects in three dimensions with spatial resolution down to 50 nm. This article discusses the basic principles of this increasingly important imaging technology and presents examples of its use on various types of defects in semiconductor packages.

A deep learning-based nondestructive approach for void segmentation in BGA solder balls using 3D x-ray microscopy is presented.

This article is the first in a two-part series analyzing solder connection failures between BGA packages and PCB assemblies. Part I examines failures attributed to oxygen intrusion during reflow, underetched solder resist, and solder paste printing problems. In the latter case, X-ray inspection revealed no abnormalities other than a variation in ball size. To get to the root cause, the corpus of the BGA was progressively ground away, leaving only the balls and an unobstructed view of the PCB surface. A description of the process, supported by detailed images, is included in the article. In Part II, scheduled for the May 2017 issue of EDFA, the author delves deeper into the analysis of voids and presents an alternate FA approach that involves grinding away much of the PCB.

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.

The EDFAS Board of Directors (BOD) has undertaken an initiative to help drive the development of failure analysis methods as leading-edge semiconductor technology approaches the sub-20 nm regime. To streamline efforts and leverage existing work, the BOD recently surveyed its constituency to gauge their opinions on the capability gaps identified by the Sematech councils. This article briefly discusses the methodology of the survey and provides a summary of the responses along with key findings.

The high energy-resolving power of superconducting x-ray detectors reduces unwanted x-ray backgrounds, uses x-ray photons efficiently, and allows for discrimination among multiple chemical elements in a sample. This article discusses the challenges of analyzing the internal structure and composition of integrated circuits, and how 3D imaging can benefit manufacturers and researchers. It covers the development of superconducting x-ray sensors, their advantages over traditional sensors, potential applications, and focus areas for future work to develop this technology.

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.

The Package Innovation Roadmap Council (PIRC) was established as part of the Failure Analysis Technology Roadmap activity at the direction of the EDFAS Board. This column provides an overview of a technical paper by the PIRC that highlights recent innovations, technology gaps, and future development trends in package fault isolation and failure analysis. The paper focuses on three main categories: 1) Artificial intelligence (AI) applications, 2) Sample handling, and 3) FA tool robustness.

This is the second article in a two-part series investigating solder connection failures associated with BGA packages. Part I, in the February 2017 issue of EDFA, examines various cases of open and short circuit failures, discusses the formation of voids, and explains how to reveal important clues by grinding away the BGA package. Part II continues the analysis of voids and focuses in on failures due to circuit board faults. In such cases, the board is ground away from the backside, stopping just short of the first inner copper layer. The alignment of the two uppermost copper layers, the integrity of microvias, and other potential problems are then examined using polarized light which readily passes through the remaining resin and fibers. As the examples in the article show, this approach can reveal a wide range of manufacturing defects in PCBs.

This column is part of a series of reports on the findings to date of the EDFAS Failure Analysis Roadmap Councils. The Failure Analysis Future Roadmap Council (FAFRC) is concerned with identifying the longer term needs of the FA community. This article discusses analysis challenges associated with the growing number of elements being incorporated into integrated circuit fabrication. It includes tables summarizing top challenges in front end and package analysis.

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 presents a case study of an IC failure that occurred in a downhole drilling environment. It describes the tests and examinations that were performed and explains how investigators determined that the Kirkendall effect contributed to the failure.