Roland Brunner

Automatized failure analysis of tungsten coated TSVs via scanning acoustic microscopy

Abstract In 3D integrated microelectronics, the failure analysis of through silicon vias (TSVs) represents a highly demanding task. In this study, defects in tungsten coated TSVs were analysed using scanning acoustic microscopy (SAM). Here, the focus lay on the realization of an automatized failure detection method towards rapid learning. We showed that by using a transducer of 100xa0MHz center frequency, established with an acoustical objective (AO), it is possible to detect defects within the TSVs. In order to interpret our analysis, we performed acoustic wave propagation simulations based on the elastodynamic finite integration technique (EFIT). In addition, high resolution X-ray computed tomography (XCT) was performed which corroborated the SAM analysis. In order to go towards automatized defect detection, firstly the commercially available software “WinSAM8” was enhanced to perform scans at defined working distances automatically. Secondly, a pattern recognition algorithm was successfully applied using “Python” to the SAM scans in order to distinguish damaged TSVs from defect-free TSVs. Besides the potential for automatized failure detection in TSVs, the SAM approach exhibits the advantages of fast and non-destructive failure detection, without the need for special preparation of the sample.

Investigation of Pre‐Existing Pores in Creep Loaded 9Cr Steel

Creep failure of materials under service conditions strongly rely on the formation and growth of cavities, encouraging the characterization and modelling of the cavitation process. In the present work pre-existing pores from manufacturing process are investigated in 9Cr steel creep loaded for up to 9000 hours. Scanning electron microscopy (SEM) is used for 2D analysis while Computer tomography (CT) is employed for 3D exploration. Nearest neighbours distances in 3D are calculated from 2D measurements and are decreasing with creep exposure time. The pore growth is studied applying a physical growth model, and experimental results are compared with numerical simulation. From this research it is deduced that damage occurs by agglomeration and growth of pre-existing cavities. The developed model can predict the growth of pores as a function of temperature and load at service.

Selective interface toughness measurements of layered thin films

Driven by the ongoing miniaturization and increasing integration in microelectronics devices, very thin metallic films became ever more important in recent years. Accordingly also the capability of determining specific physical and mechanical properties of such arrangements gained increasing importance. Miniaturized testing methods to evaluate, for example, the mechanical properties of thin metallic multilayers are therefore indispensable. A novel in-situ micromechanical approach is examined in the current study and compared to existing methods regarding their capability to determine the interface toughness of specific interfaces in multilayer configurations. Namely, sputter deposited copper and tungsten thin films with a thickness of approx. 500 nm on a stress-free silicon (100) substrate are investigated. The multilayer stacks consist of different materials that vary in microstructure, elastic properties and residual stress state. We examine the interface toughness via double cantilever beam tests, nano...

Metallization defect detection in 3D integrated components using scanning acoustic microscopy and acoustic simulations

Abstract In the context of More than Moore 3D integration concepts, the μm to nm sized failure detection and analysis represents a highly demanding task. In this work, micron sized artificially induced metallization defects in open TSVs are detected by scanning acoustic microscopy (SAM). Micro X-ray computed tomography (μXCT) and scanning electron microscopy (SEM) are used to validate the SAM results. Notably, the SAM results show that the failures for certain TSVs are located at a different position as illustrated by μXCT and SEM. In order to interpret these controversial results, 2D elastodynamic finite integration technique (EFIT) simulations are performed. We discuss the results by taking the excitation of surface acoustic waves (SAWs) or Rayleigh waves into account which are leading to characteristic interference patterns within the TSV. The simulation and understanding of such interference effects can be highly beneficial for the use of SAM with respect to modern failure detection and analyses.

Micro-Mechanical In Situ Measurements in Thin Film Systems Regarding the Determination of Residual Stress, Fracture Properties and Interface Toughness

The major trend in microelectronics industry is driven by miniaturization and the increase in functionality [1]. According to root cause analysis from determined failures it is often found that failures in microelectronic components are often triggered by various thermal and mechanical loadings during industrial manufacturing processes like the backend of line (BEOL) processes. Here, singleand/or multiple metal layers or structures are deposited mainly on Si-substrates. These processes, due to the combination of different materials, temperature and topologies, cause residual stresses and may induce defects, which affect interface integrity and eventually cause failures of the device during application. This heavily concerns for example 3D integrated microelectronic devices, power electronics, micromechanical devices, sensors, etc. However, it is a great challenge to understand (1) the complex interplay between thin film combinations, (2) resulting residual stresses, (3) interface properties and (4) fracture behavior.

Accretion Detection via Scanning Acoustic Microscopy in Microelectronic Components - Considering Symmetry Breaking Effects

Currently, micro – and nano-electronic devices are pushed towards higher performance, increased functionality and higher integration density. A promising technique to achieve „More than Moore devices“ is 3D integration. Here, layers of active electronic components are connected vertically via socalled through silicon vias (TSVs). These TSVs are practically cylindrical holes with diameters in the range from 5 – 200 μm in silicon which are filled or coated with conducting materials. The processing, design and the performance of TSVs faces many challenges and especially the defect detection, failure characterization and reliability analysis are in the focus of state of the art reliability studies [1, 2].