The building block of all matter, including metals, is the atom. This chapter initially provides information on atomic bonding and the crystal structure of metals and alloys, followed by a description of three crystal lattice structures of metals: face-centered cubic, hexagonal close-packed, and body-centered cubic. It then describes the four main divisions of crystal defects, namely point defects, line defects, planar defects, and volume defects. The chapter provides information on grain boundaries of metals, processes involved in atomic diffusion, and key properties of a solid solution. It also explains the aspects of a phase diagram that shows what phase or phases are present in the alloy under conditions of thermal equilibrium. Finally, a discussion on the applications of equilibrium phase diagrams is presented.

In a perfect crystalline structure, there is an orderly repetition of the lattice in every direction in space. Real crystals contain a considerable number of imperfections, or defects, that affect their physical, chemical, mechanical, and electronic properties. Defects play an important role in processes such as deformation, annealing, precipitation, diffusion, and sintering. All defects and imperfections can be conveniently classified under four main divisions: point defects, line defects, planar defects, and volume defects. This chapter provides a detailed discussion on the causes, nature, and impact of these defects in metals. It also describes the mechanisms that cause plastic deformation in metals.

This appendix provides a detailed overview of the crystal structure of metals. It describes primary bonding mechanisms, space lattices and crystal systems, unit cell parameters, slip systems, and crystallographic planes and directions as well as plastic deformation mechanisms, crystalline imperfections, and the formation of surface or planar defects. It also discusses the use of X-ray diffraction for determining crystal structure.

Alloying, heat treating, and work hardening are widely used to control material properties, and though they take different approaches, they all focus on imperfections of one type or other. This chapter provides readers with essential background on these material imperfections and their relevance in design and manufacturing. It begins with a review of compositional impurities, the physical arrangement of atoms in solid solution, and the factors that determine maximum solubility. It then describes different types of structural imperfections, including point, line, and planar defects, and how they respond to applied stresses and strains. The chapter makes extensive use of graphics to illustrate crystal lattice structures and related concepts such as vacancies and interstitial sites, ion migration, volume expansion, antisite defects, edge and screw dislocations, slip planes, twinning planes, and dislocation passage through precipitates. It also points out important structure-property correlations.

The ultimate goal of the failure analysis process is to find physical evidence that can identify the root cause of the failure. Transmission electron microscopy (TEM) has emerged as a powerful tool to characterize subtle defects. This article discusses the sample preparation procedures based on focused ion beam milling used for TEM sample preparation. It describes the principles behind commonly used imaging modes in semiconductor failure analysis and how these operation modes can be utilized to selectively maximize signal from specific beam-specimen interactions to generate useful information about the defect. Various elemental analysis techniques, namely energy dispersive spectroscopy, electron energy loss spectroscopy, and energy-filtered TEM, are described using examples encountered in failure analysis. The origin of different image contrast mechanisms, their interpretation, and analytical techniques for composition analysis are discussed. The article also provides information on the use of off-axis electron holography technique in failure analysis.

Deformation within a crystal lattice is governed principally by the presence of dislocations, which are two-dimensional defects in the lattice structure. Slip from shear stress is the most common deformation mechanism within crystalline lattices of metallic materials, although deformation of crystal lattices can also occur by other processes such as twinning and, in special circumstances, by the migration of vacant lattice sites. This appendix describes the notation used to specify lattice planes and directions and discusses the mechanisms of slip and twinning as well as the effect of stacking faults.

This article addresses the ancillary issues regarding the nanoprobing and characterization of transistors, probing copper metallization layers, and the various imaging techniques. The discussion includes several characterization examples of known transistor failure types, namely four probe transistor characterization, two probe transistor characterization, and probing and characterizing metallization issues. The imaging techniques discussed are those that are specific to atomic force nanoprober or scanning electron microscope based tools. They are current contrast imaging, scanning capacitance imaging, e-beam absorbed current imaging, e-beam induced current imaging, e-beam induced resistance change imaging, and active voltage contrast imaging.

With semiconductor device dimension continuously scaling down and increasing complexity in integrated circuits, delayering techniques for reverse engineering is becoming increasingly challenging. The primary goal of delayering in semiconductor failure analysis is to successfully remove layers of material in order to locate and identify the area of interest. Several of the top-down delayering techniques include wet chemical etching, dry reactive ion etching, top-down parallel lapping (including chemical-mechanical polishing), ion beam milling and laser delayering techniques. This article discusses the general procedure, types, advantages, and disadvantages of each of these techniques. In this article, two types of different semiconductor die level backend of line technologies are presented: aluminum metallization and copper metallization.

Welded joints in any component or structure require a thorough inspection. The role of nondestructive evaluation (NDE) in the inspection of welds is very important, and the technology has become highly developed as a result. This article describes the applications, methods, evaluation procedures, performance, and limitations of NDE. It provides information on the training and certification of NDE operators, evaluation of test results, and guidance to method selection. Typical examples of various NDE methods for welds are also described.

Thermal barrier coatings (TBCs) are applied using thermal spray coating (TSC) processes to components that are internally cooled and operated in a heated environment. The TSC microstructures are prone to interactions with common metallographic procedures that may result in artifacts and misinterpretation of the TSC microstructure. This article aims to aid in identifying metallographic TSC artifacts, specifically in the air plasma spray zirconia-based TBC, including both of its common constituents, the bond coating and the top coating. Artifacts that result from specific sectioning and mounting practices, as well as from different polishing times, are presented. Additionally, the article discusses the factors in optical microscopy and scanning electron microscopy that affect microstructure interpretation.

This chapter concentrates on very low-temperature martensitic transformations, which are of great concern for cryogenic applications and research. The principal transformation characteristics are reviewed and then elaborated. The material classes or alloy systems that exhibit martensitic transformations at very low temperatures are discussed. In particular, the martensitic transformations and their effects in austenitic stainless steels, iron-nickel alloys, practical superconductors, alkali metals, solidified gases, and polymers are discussed.

This chapter discusses the use of nondestructive inspection methods, including visual, ultrasonic, radiographic, and thermographic techniques, and the types of flaws and damages they can reveal in composite parts and assemblies. It describes the basic principles behind each method along with best practices and procedures.

This chapter introduces many of the key concepts on which metallurgy is based. It begins with an overview of the atomic nature of matter and the forces that link atoms together in crystal lattice structures. It discusses the types of imperfections (or defects) that occur in the crystal structure of metals and their role in mechanical deformation, annealing, precipitation, and diffusion. It describes the concept of solid solutions and the effect of temperature on solubility and phase transformations. The chapter also discusses the formation of solidification structures, the use of equilibrium phase diagrams, the role of enthalpy and Gibb’s free energy in chemical reactions, and a method for determining phase compositions along the solidus and liquidus lines.

The solidification process has a major influence on the microstructure and mechanical properties of metal casting as well as wrought products. This appendix covers the fundamentals of solidification. It discusses the formation of solidification structures, the characteristics of planar, cellular, and dendritic growth, the basic freezing sequence for an alloy casting, and the variations in cooling rate, heat flow, and grain morphology in different areas of the mold. It also describes the types of segregation that occur during freezing, the effect of solidification rate on secondary dendrite arm spacing, and the factors that contribute to porosity and shrinkage.

Discontinuities are interruptions in the desirable physical structure of a weld. This article describes the types of weld discontinuities that are characteristic of the principal welding processes. Discontinuities covered are metallurgical discontinuities, discontinuities associated with specialized welding processes, and base metal discontinuities. In addition, information on the common inspection methods used to detect these discontinuities is provided.

The first step in die-level failure analysis is to narrow the search to a specific circuit or transistor group. Then begins the post-isolation process which entails further localizing the defect, determining its electrical, physical, and chemical properties, and examining its microstructure in order to identify the root cause of failure. This chapter assesses the tools and techniques used for those purposes and the challenges brought on by continued transistor scaling, advanced 3D packages, and new IC architectures. The areas covered include sample preparation, nanoprobing, microscopy, FIB circuit edit, and scanning probe microscopy.

The scanning acoustic microscope (SAM) is an important tool for development of improved molded and flip chip packages. The SAM used for integrated circuit inspection is a hybrid instrument with characteristics of both the Stanford SAM and the C-scan recorder. This chapter presents the historical development of SAM for integrated circuit package inspection, SAM theory, and analysis considerations. Case studies are presented to illustrate the practical applications of SAM. Other non-destructive imaging tools are briefly discussed, as well as SAM challenges and methods including spectral signature analysis and GHz-SAM.