Reliability of 3D-integrated chips: The role of metallic surfaces and interfaces

Abstract des Vortrages: The reliability-limiting effects in 3D IC structures using TSVs including mechanical stress distributions and the resulting effects on material integrity (e.g. failure modes like interface delamination, cohesive cracking, metallurgical degradation at joints, and chip-package interaction) and finally on device performance degradation are challenges in advanced 3D integration technologies and product development. Managing internal mechanical stress is a key task to ensure high reliability of products manufactured in advanced CMOS technology nodes, and it is a highly ranked concern for 3D TSV technologies. It requires the determination of materials properties, including Young’s modulus, Poisson ratio and coefficient of thermal expansion (CTE), for each material used. For polycrystalline materials, their microstructure has to be considered. In this talk, one reliability-limiting effect, interface delamination and so-called “pop-up” of copper TSV structures will be addressed. Shear stress along the Cu/Si interface and adhesion of the interfaces in a complex stack (Si/liner/barrier/seed/Cu) are parameters that have to be considered. Metal barrier and seed films and the respective surfaces will be discussed in the context of interface strength. Nano X-ray tomography is currently the only analytical technique to study the so-called “pop-up” effect quantitatively, without modifying the region of interest

Reliability of 3D-integrated chips: The role of metallic surfaces and interfaces

Abstract des Vortrages: The reliability-limiting effects in 3D IC structures using TSVs including mechanical stress distributions and the resulting effects on material integrity (e.g. failure modes like interface delamination, cohesive cracking, metallurgical degradation at joints, and chip-package interaction) and finally on device performance degradation are challenges in advanced 3D integration technologies and product development. Managing internal mechanical stress is a key task to ensure high reliability of products manufactured in advanced CMOS technology nodes, and it is a highly ranked concern for 3D TSV technologies. It requires the determination of materials properties, including Young’s modulus, Poisson ratio and coefficient of thermal expansion (CTE), for each material used. For polycrystalline materials, their microstructure has to be considered. In this talk, one reliability-limiting effect, interface delamination and so-called “pop-up” of copper TSV structures will be addressed. Shear stress along the Cu/Si interface and adhesion of the interfaces in a complex stack (Si/liner/barrier/seed/Cu) are parameters that have to be considered. Metal barrier and seed films and the respective surfaces will be discussed in the context of interface strength. Nano X-ray tomography is currently the only analytical technique to study the so-called “pop-up” effect quantitatively, without modifying the region of interest

Editorial for the special issue “characterization of nanomaterials: Selected papers from 6th dresden nanoanalysis symposium”

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Correlation of ultra-fine real-geometry FEM models of diatoms derived from nano-X-ray tomography with in-situ nanomechanical testing

Diatoms are unicellular, photosynthetic microalgae with complex hierarchical shell morphologies and features. The unique, three-dimensional anatomy of their silica exoskeletons (frustules) contain structure features ranging from the nano-, submicro- to the micrometer-scales (Figure 1). Due to their extraordinary properties, these frustules have drawn attention from a variety of research fields and they have been proposed to be used in a range of applications, including templates for drug delivery carriers, oil and water separation membranes, optical devices, metal alloy components as well as metamaterials designs. Several studies have shown that diatom frustules show unique mechanical properties such as high specific strength and resilience against fracture. Most of these properties arise from the hierarchically arranged structural features. Please click Additional Files below to see the full abstract

The influence of surface roughness on elastic nanoindentation measurements

The characterization of mechanical properties of layered thin-film structures is an important issue with respect to the better understanding and for improving the design of microelectronic devices. Due to the small investigated volume and the easy implementation of the measurement procedure, nanoindentation is an appropriate method for determination of the mechanical properties of thin films systems. Chudoba and Schwarzer et al. [1] developed an analytical approach that allows to derive values of Young´s modulus from load-displacement curves measured within the elastic range of interaction. This analytical approach together with nanoindentation using spherical indenter geometries is employed in this study. Preliminary investigations have been conducted on Fused Silica (FS) standard samples with known values of surface roughness and Young’s modulus (E=72 GPa). Different surface roughness values were adjusted by different times of etching the samples with hydrofluoric acid (HF). It could be shown that the roughness has a strong influence on the statistics of the measured load-displacement curves as well as on the derived Young’s modulus values (see Figure 1). Therefore, in the current study the influence of surface roughness shall be investigated in a more detailed way. This is done by applying a model that was developed for contact stiffness measurements using AFM-based methods. The model takes into account the contact stiffness of the indenter tip and the investigated sample as well as the contact stiffness of the multiasperity contact, arising from the roughness of the sample and the indenter. The aim of the study is to combine the analysis approach used for AFM data with the nanoindentation measurements and thereby proof the AFM model on a bigger length scale. Please click Additional Files below to see the full abstract

On the Alternative Movies in China

“另类电影”是二十世纪九十年代以来，中国电影界出现的一种新的创作倾向。“另类电影”的导演们处于现代/后现代生存环境中，面临中国社会从传统农业向现代工业的重大转型。他们在直视现实，独立思考，保持个性的创作原则之上，一反主流电影（主旋律电影和商业电影）的民族寓言的宏大叙事，把镜头的意象指向了城市“深描”和个人记忆的书写，追求质朴、写实的美学风格。他们还采用独特的制片方式、传播途径来对抗主流电影。对民间与个人、历史与现在、文化与文明的思考，则具体体现出他们在精神内涵上的特质。 本文结合本雅明、阿多诺的“文化工业”理论、利奥塔的“宏大叙事”理论、福柯的“话语权力”理论和陈思和提出的“民间”概念，从作...“Alternative movies” is a new artistic trend of movies, which came out in the field Chinese movies in 1990s, which brings Chinese movies to the pluralism pattern. With Walter Benjamin and T.W.Adorno ’s major key words, cultural industry and the basic principle of Michel Foucault ’s theory, discourse, I analyzes the characteristics of alternative movies throughout its subject matter, content, and s...学位：文学硕士院系专业：人文学院中文系_戏剧戏曲学学号：20010103

Multi-scale X-ray Tomography of Solder Interconnects in Microelectronics

Advanced packaging, including 3D IC integration, is one of the main drivers in packaging and system integration to meet the requirements for miniaturized smart systems with high functionality and high performance. For 3D stacking of wafers or dies, interconnections like micro solder bumps and Cu pillars are used. Figure 1 (left) shows a stack with a TSV interposer structure [1]. 3D-stacked products and advanced packaging challenge materials and process characterization. The control of the micro-bump quality is a particular issue. Special tasks are the characterization of the geometry of the solder bumps to estimate the stress enhancement risks, the nondestructive imaging of micron-size pores and of intermetallic phases as well as the visualization of cracks. Several NDE techniques for metrology and failure analysis are currently under discussion. In this paper, the potential and the limits of micro XCT and nano XCT for NDE of solder interconnects are described. Strategies for nondestructive evaluation of geometry, materials and defects are discussed. It is shown that multi-scale imaging with several resolution ranges is one potential approach. Micro XCT (resolution about 1 m) and nano XCT (resolution about 50 nm) are very useful lab-based techniques with a promising prospect for the future. We demonstrate the capabilities for nondestructive imaging of multi-die stacks with TSVs and micro solder bumps. Figure 1 (middle and right) right demonstrates a micro XCT overview and a nano XCT ROI study of such a multi-die stack with solder interconnects. An analysis of individual solder bumps reveals mismatches in relative positioning, variability in the shape, micron-size pores, and the distribution of intermetallic phases. This information is important to evaluate the respective process steps (process control) and the product reliability (quality control). Since deviations from the targeted geometry and defects are difficult to locate precisely from a two-dimensional image, X-ray computed tomography has to be applied

High‐resolution structural‐mechanical characterization and simulation of novel barrier coatings

Ceramic matrix composites and non-oxide ceramics are potential near-future materials for high temperature applications in gas turbines for energy production and aviation. Mechanical strength and the capability to withstand temperatures up to 1500 °C under load make these ceramic materials perfect candidates to increase efficiency and to lower emissions. However, corrosive attack by water vapor is still a reliability- and lifetime-limiting factor. Also, thermal insulation is important for oxide ceramic matrix composites because of their low temperature limit in comparison to non-oxide ceramics, e.g. silicon nitride. Therefore, protective coatings are a substantial component in such advanced applications. A new type of coating is investigated which shall act as an environmental and thermal barrier. As a novel approach, a single phase material with high corrosion resistance and low thermal conductivity will be deposited. Solid-state reactions between the substrate material and the coating should provide strong adhesion. In addition, a defined pore distribution should provide good thermal insulation and high tolerance against defects. As a result, a novel, superior coating system is supposed to be achieved for the industrial applications mentioned above. The development of new material systems and coatings requires extensive studies of structure-property relationships and knowledge about the material behavior in dependence on its structure. As a new approach, 3D reconstruction methods will be used to describe the material, using non-destructive micro-X-ray computed tomography and scanning electron microscopy combined with cross-sectioning using a focused ion beam. Especially the non-destructive X-ray technique has the distinct advantage of performing corrosion testing and studying several stages of the evaluation of weak spots in the material-coating system. On the other hand, electron microscopy allows to create 3D images of pores or cracks down to 1 nm resolution in order to improve the understanding of their formation and evolution. Both techniques are well-suited to quantify important structural parameters such as the pore size distribution and pore topology, which can hardly be measured with other methods. The structural information is supplemented by extensive multi-scale mechanical property studies using nano- and microindentation covering the scales from the nano- to the micro-range. To link the multi-scale structural to the multi-scale mechanical material information, both are combined in finite element simulations. With these simulations, the relations between the macroscopic barrier coating properties and the microscopic coating structure will be studied