Back-end soft and hard defect monitoring using a single test chip

The objective of this paper is to present a mixed test structure designed to characterize yield losses due to hard defect and back-end process variation (PV) at die and wafer level. A brief overview of the structure, designed using a ST-Microelectronics’ 130 nm technology, is given. This structure is based on a SRAM memory array for detecting hard defects. Moreover each memory cell can be configured in the Ring Oscillator (RO) mode for back-end PV characterization. The structure is tested in both modes (SRAM, RO) using a single test flow. The test data analysis method is presented and applied to experimental results to confirm the ability of the structure to monitor PV and defect density.     

Reliability indicator for layered composites with strongly non-linear behaviour

This paper set out a method to determine safety factors when designing composite laminate with strongly non-linear behaviour. The failure probability is used to assess the laminate reliability.     

Multi-scale roughness transfer in cold metal rolling

We report on a comparative Atomic Force Microscope (AFM) multi-scale roughness analysis of cold rolled Al alloy and steel roll, in order to characterize the roughness transfer from the steel roll to the workpiece in cold strip rolling processes. More than three orders of length-scale magnitudes were investigated from 100 microns to 50 nanometers on both types of surfaces. The analysis reveals that both types of surfaces are anisotropic self-affine surfaces. Transverse and longitudinal height profiles exhibit a different roughness exponent (Hurst exponent) ζ=0.93±0.03 and ζ=0.5±0.05 Different length-scale cut-offs are obtained in each direction l^sup=50μm, l^sup>100μm. Height and slope distributions are also computed to complement this study. The above mentionned self-affine characteresitics are found to be very similar for the roll and the strip surfaces, which suggest that roughness transfer takes place from the macroscopic (100 μm) to the very small scale (50 nm).     

Der Einfluß der Luftdichte nach den neuen IEC-Mittelwerten für Kugelfunkenstrecken

Zusammenfassung Aus den neuen IEC-Mittelwerten wird auf Grund von Ähnlichkeitsgesetzen der Einfluß der Luftdichte errechnet. Die FunkenspannungU ist nur in erster Annäherung der Luftdichte proportional. In Wirklichkeit hängt der Einfluß der Luftdichte (Korrektionsfaktork, U=k · U _n ) in verwickelter Weise vom KugeldurchmesserD, von der Schlagweites, von den Potentialen der Kugeln gegen Erde, der Polarität und der Größe der Luftdichte selbst ab. Dies rührt davon her, daß man die Korrektion eigentlich nicht an der Spannung, sondern an den Elektrodenabmessungen (Schlagweite und Kugeldurchmesser) anzubringen hat. Die Funkenspannung ändert sich durchweg weniger als proportional mit der Luftdichte, am wenigsten bei kleinem Verhältniss/D und beliebiger Potentialverteilung und Polarität und bei großem Verhältniss/D und einpoliger Erdung. Dazwischen liegt eine Stelle, bei der sich der Funkenspannungsverlauf am meisten der Proportionalität mit der Luftdichte nähert. Diese Stelle (Minimum vonk bei < 1) stimmt mit der Stelle des Minimums der Durchbruchfeldstärke überein, wie überhaupt der Verlauf vonk dem Verlauf der Durchbruchfeldstärke auch bezüglich der Abhängigkeit vons/D, D, dem Potentialverlauf und der Polarität ähnelt.Bei symmetrischer Spannungsverteilung an den Polen überwiegt oberhalb vons=0,5 cm der Einfluß des Kugeldurchmessers, so daß es berechtigt ist, Korrektionsfaktorenk nach Tafel 4 aufzustellen, die nur vonD und von abhängen.Auch bei gestörter Funkenstrecke (Käfigfunkenstrecke) gelten die Ahnlichkeitsgesetze, dagegen nicht mehr bei Auftreten von Vorentladungen, insbesondere bei Stoßspannungen.Die auf Grund von Meßwerten (IEC-Mittelwerte) bestimmte Luftdichtenabhängigkeit wird mit Angaben von Peek und Ver Planck verglichen, die beide nicht von Meßwerten, sondern von Formeln abgeleitet und daher, insbesondere bei Ver Planck, nicht genau sind.     

A computational tool based on voxel geometry for dose reconstruction of a radiological accident due to external exposure

In the case of overexposure to ionising radiation, estimation of the absorbed dose in the organism is an important indicator for evaluating the biological consequences of this exposure. The physical dosimetry approach is based either on real reconstruction of the accident, using physical phantoms, or on calculation techniques. Tools using Monte Carlo simulations associated with geometric models are very powerful since they offer the possibility to simulate faithfully the victim and the environment for dose calculations in various accidental situations. Their work presents a new computational tool, called SESAME, dedicated to dose reconstruction of radiological accidents based on anthropomorphic voxel phantoms built from real medical images of the victim in association with the MCNP Monte Carlo code. The utility was, as a first step, validated for neutrons by experimental means using a physical tissue-equivalent phantom.     

A Bayesian approach to object detection using probabilistic appearance-based models

In this paper, we introduce a Bayesian approach, inspired by probabilistic principal component analysis (PPCA) (Tipping and Bishop in J Royal Stat Soc Ser B 61(3):611–622, 1999), to detect objects in complex scenes using appearance-based models. The originality of the proposed framework is to explicitly take into account general forms of the underlying distributions, both for the in-eigenspace distribution and for the observation model. The approach combines linear data reduction techniques (to preserve computational efficiency), non-linear constraints on the in-eigenspace distribution (to model complex variabilities) and non-linear (robust) observation models (to cope with clutter, outliers and occlusions). The resulting statistical representation generalises most existing PCA-based models (Tipping and Bishop in J Royal Stat Soc Ser B 61(3):611–622, 1999; Black and Jepson in Int J Comput Vis 26(1):63–84, 1998; Moghaddam and Pentland in IEEE Trans Pattern Anal Machine Intell 19(7):696–710, 1997) and leads to the definition of a new family of non-linear probabilistic detectors. The performance of the approach is assessed using receiver operating characteristic (ROC) analysis on several representative databases, showing a major improvement in detection performances with respect to the standard methods that have been the references up to now.This revised version was published online in November 2004 with corrections to the section numbers.