Search Results for thin film defects

Thin film anomalies cause many device failures but they are often difficult to see. In this article, the authors explain how they found and identified an 8 to 10 nm film of tantalum causing pin shorts in a majority of ASIC modules from a particular lot. Initial attempts to delayer some of the failed modules resulted in the loss of the failure signal. It was then decided to use a focused ion beam to selectively mill through the interlayer dielectric. During milling, a secondary electron image revealed anomalous material between the fingers of a power transistor, which was subsequently identified as tantalum. Such defects, as the authors explain, are common in damascene processes when materials are not properly removed during etching.

Over the last few years, new challenges increased the pressure on packaging and assembly analytical resources. Reduced product development cycle time, increased market segmentation, new package and die level materials, ever shrinking device geometries, and fully enabled technologies (i.e. with thermal, retention, and EMI solutions) created these new pressures on fault isolation/failure analysis efforts and package development.

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.

A new and improved sample preparation technique was developed by Wang. This technique uses an FIB instrument for the 90° rotation of a small portion of the specimen on the original grid by taking advantage of static force. All sample preparation steps, including thin-section creation and sample tilting, can be accomplished in a single process. The procedure is monitored in a high-resolution FIB instrument to assure a 100% success rate. Figure 1 shows a scanning electron microscope image of a 3D TEM sample with two rotated sections. The original TEM sample is a lift-out sample laid on carbon film.

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 examines the phenomenon of time-dependent dielectric breakdown (TDDB) in ultrathin gate oxide films and explains why it is no longer considered a catastrophic failure in MOSFET-containing ICs.

Scanning probe microscopy (SPM) is widely used for fault isolation as well as diagnosing leakage current, detecting open circuits, and characterizing doping related defects. In this article, the author presents two SPM applications that are fairly uncommon but no less important in the scope of failure analysis. The first case involves the discovery of nano-steps on the surface of high-voltage NFETs, a phenomenon associated with stress-induced crystalline shift along the (111) silicon plane. In the second case, the author uses an AFM probe in the conductive mode to correlate tunneling current distribution with hot spots in high-k gate oxide films, which is shown to be a better indicator of oxide quality than rms surface roughness.

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.

Shortcuts in failure analysis are sometimes to save time or money or because equipment or expertise is unavailable. This article presents simple but effective solutions in four areas, including deprocessing, FIB milling, microcleaving, and TEM sample preparation, that may help analysts work through or around such situations.

Improved X-ray detector technology continues to be a critical need in the semiconductor industry, particularly for high-spatial-resolution X-ray microanalysis using lowbeam-voltage field-emission scanning electron microscopes (FE-SEMs). In response to this need, a prototype microcalorimeter energy-dispersive spectrometer has been developed. This article discusses the capabilities of the new tool and demonstrates its use in thin-film and particle analysis. It also discusses ongoing development efforts and potential future advancements.

Differential Hall effect metrology (DHEM) provides depth profiles of all critical electrical parameters through semiconductor layers at nanometer-level depth resolution. This article describes the relatively new method and shows how it is used to measure mobility and carrier concentration profiles in different materials and structures.

This article describes how focused ion beam (FIB) technology is being used in combination with various other analytical tools for failure and yield analysis of MEMS devices. It provides examples showing how FIB is used with TEM analysis, AFM analysis, scanning acoustic microscopy, and scanning laser microscopy.

This article provides a summary of the ISTFA 2011 Panel Discussion, which centered on the challenge of finding ever-smaller defects in semiconductor devices.

Broad ion beam delayering is a versatile technique for whole-chip failure analysis. The large area of uniformity coupled with the ability to precisely stop at the layer of interest facilitates repeatable, rapid defect detection anywhere on the chip.

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.

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.

Recent improvements in giant magnetoresistance sensors have increased the achievable spatial resolution of magnetic current imaging on packaged devices without a significant compromise in magnetic field sensitivity. Front and backside current imaging examples show the utility of these new sensors for die-level failure analysis.

This case study describes the difficulties and challenges failure analysts encountered in their nearly year-long investigation into the cause of cracking in a dielectric film. Despite the trend in microelectronics to use ever more costly and sophisticated equipment, this investigation was conducted using only SEM and optical microscope observations coupled with persistent detective work, which eventually uncovered to the cause.

Scanning capacitance microscopy (SCM) has proven to be an effective tool for investigating doping-related failure mechanism in ICs. The examples in this article show how the author used SCM to solve various problems including premature breakdown due to pattern misalignment, threshold voltage variations caused by poly gate doping anomalies, and source-drain leakage due to channeling effects.

This article addresses the considerations related to the development and introduction of new materials in response to the increasing performance demands of microelectronic devices, and how these new materials will affect characterization and failure analysis. The article is largely extracted from the “Deprocessing/Inspection White Paper” generated by the SEMATECH Product Analysis Forum (PAF), with updates from the PAF response to the International Technology Roadmap for Semiconductors.