3D-integration is one of the most challenging approaches addressed by researchers in the field of microelectronics in the recent years. With the intension on integrating different components in three dimensions in one device performance and functionality will increase dramatically by reducing the devices footprint. A major challenge in 3D-integration concepts is the electrical interconnection of the stacked individual components. These interconnecting technologies employ micro bumping, temporary wafer bonding, wafer thinning and through silicon vias (TSVs). The increasing complexity and the miniaturization result in new requirements on testing, diagnostics, failure analysis and metrology techniques, methods and tools. Scanning acoustic microscopy (SAM) is a powerful tool for non-destructively inspecting internal structures and features. It employs elastic waves that can be focused and used for imaging and quantitative analyses. However, at conventionally used frequencies (5 MHz - 250 MHz) imaging resolution compromises the application on devices and technologies required in 3D-integration approaches. The current paper reports on the use of acoustic GHz-microscopy for the inspection, defect localization and its ability for identification of abnormalities in through silicon vias. Investigated were artificial and real defects in the TSV-fillings (voids) and the condition of the TSV-walls (rim-delaminations). Acoustic frequencies used in the current work ranged from 400 MHz up to 1.2 GHz allowing for imaging resolutions in the 1 μm - regime. However, highly focused acoustical lenses as employed here require large numerical apertures which inevitably result in a very complex wave propagation and acoustic field inside a solid sample. To improve the understanding and interpretation acoustic intensity fields have been simulated numerically. Results obtained by acoustic GHz-microscopy have been evaluated complimentarily by FIB-cross-sectioning and SEM imaging which gave a valuable insight into the abilities for acoustic TSV-inspection by GHz-SAM
One of the possible target applications of 3D-integration is the high performance computing (HPC). The improved performance of 3D-integrating can base on an Interposer with heterogeneous integration of special high performance fluidic cooling, individual power supply next to the microprocessor and a tailored packaging approach. This paper focuses on the reliability assessment of the interposer regarding the interaction of TSV, wiring and fluid channel integration based on current publications in correlation with the selected specifications for Interposer manufacturing. A further part is the correlation with initial results of stress simulation and measurements applied to the Interposer design specifications of cavities and interconnect features (used for sealing the cooling channels and as electrical interconnect). We give an overview of a new level of complexity of 3D integration and discuss certain failure mechanisms that can influence the performance of 3D integrated devices. We show that the prediction of failure locations becomes possible by the method of finite element modeling but with the necessity to obtain process specific material data as an input for the simulation. An overview shows the possibilites of residual stresses analyses on test vehicles by using special methods of Raman spectroscopy and fibDAC including interpretation challenges of gathered measurement data. Furthermore the application of a new method for fatigue testing is proposed and discussed
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