PEALD ZrO2 films deposition on Ti and Si substrates

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Scanning Acoustic Microscopy versus Colored Picosecond Acoustics to detect interface defects in hybrid wafer bonding

International audienceNowadays, microelectronics is making progress in miniaturization and diversification of chips by 3D integration: dies are stacked together to gain space and performances. The stacking used here is called hybrid bonding [1], as stacked surfaces are heterogeneous: part Cu and part oxide. After the bonding, it exists some defects at the interface which size can be milimetric to nanometric. Acoustic waves are very useful for detecting defects. In the field, the most used technique is the Scanning Acoustic Microscopy (SAM) which makes an image of the interface using ultrasonics (10-1000 MHz) with a XY resolution of 20 �m [2]. To detect smaller defects, Transmission Electron Microscopy (TEM) is used. Its resolution is about 0,1 nm, making this technic very local compared to SAM. Like the SAM, Colored Picosecond Acoustics (APiC) is based on acoustic waves but at higher frequencies (10-500 GHz) using of a femtosecond laser in a pump-probe scheme [3,4]. Such a technique is closer to TEM resolution. In this work, both acoustic techniques (SAM and APiC) are applied to the characterization of the same samples made of bonded wafers. APiC is first used to characterize the stack (thickness, velocity). Then, the interface contributions is focused on: Cu/Cu, Cu/oxide, oxide/oxide. As the technic makes a local measurement (typically 1-2 �m), the process is repeated at different points of the surface to get an interface image comparable to SAM result. In this work will be presented the APiC results obtained on wafers also studied by SAM to compare both approaches, especially about the resolution enhancement ApiC brings. The minimal size of the defects that APiC is able to detect will be explored

Coastal flood vulnerability assessment, a satellite remote sensing and modeling approach

International audienceAlthough there are numerous case studies assessing coastal vulnerability, many of these studies have been performed in places where notable efforts have been carried out to provide information on the different variables that affect the coast. However, this is not the case for most places worldwide given the lack of long-term datasets. This study makes use of information from satellite remote sensing and analytical models to derive two vulnerability indices along a 9.5 km stretch of the coast of Langue de Barbarie, Saint Louis, Senegal (Western Africa). The first is a coastal vulnerability index (CVI) to sea level rise due to climate change and results in a five-category classification: Very Low, Low, Moderate, High, and Very High. The second is a flood vulnerability index (FVI) to coastal flooding due to extreme events and results in a three-category classification: Low, Moderate, and High. Results for the CVI index show that 70% of the coast presents High and Very High vulnerability values, largely located in the most densely populated areas. The FVI is assessed for one of the most energetic storms for the 1979–2021 period which occurred in February 2018 using a beach configuration of March 2021. Results show that 29% of the coastline presents High FVI values (i.e., are likely to be overtopped) concentrated in the central sector of the most-populated districts. This provides relevant tools to improve coastal management when in situ data are not available

Multi-timescale dynamics of extreme river flood and storm surge interactions in relation with large-scale atmospheric circulation: Case of the Seine estuary

The present work investigates the multi-timescale dynamics of extreme fluvial-surge interactions (EFS) in a rivertide environment, in the case of the Seine estuary. This environment is considered an excellent natural laboratory to analyze river-surge interaction because of its time-varying flow and the available water-level records provided by tide gauges along the estuary. A spectral approach has been used to investigate the multi-timescale changes in EFS, governed by fluvial and marine contributions, in relation to the historical events of flood-storm concomitance and the large-scale atmospheric circulation. The spectral components of EFS, calculated at five stations along the estuary, highlighted a series of variability modes varying from the inter-month (-3-6 months) to the inter-annual (-2-, -3-5- and -6-8-years) scales and exhibiting, respectively, 55% and 20% of the total variability. The contribution of marine and fluvial effects in the EFS varies along the estuary and according to the timescale from seasons, when the interaction is governed by tidal deformation, to years. The connection of the historical flood-storm events with the EFS signal changes in their spectral signature according to their severity as well as the energetic physical drivers acting in each event: events with high return period are manifested at larger scales while events with low return period are limited to small scales.Finally, the examination of the physical relationships between the EFS and the global climate mechanisms has demonstrated the key role of the Sea Level Pressure (SLP) and the North Atlantic Oscillation (NAO) acting, respectively, in anti-phase at -1-2-yr and in phase at scales larger than 3-yr. The signature of the climate drivers operates differently according to the timescale; they are identified within the -80% of the inter-annual EFS. This signature is more significative since the 2000s when the increase in the NAO generates a rise in EFS variability. -20% of EFS would be related to the non-linear effects of the timescale interactions and other local mechanisms operating at such scales.This finding highlights the non-stationarity of the multi-timescale dynamics of marine storms and fluvial floods, and the relevance of the climate connection use for assessing the compound multi-hazard events at largescales

Impact of Process Variations on the Capacitance and Electrical Resistance down to 1.44 μm1.44\ \mu\mathrm{m} Hybrid Bonding Interconnects

International audienc

Mapping of Estuarine Transport from Spatial Remote-Sensing Products: Application to Authie Bay (France)

International audienceIn many domains of application such as sedimentology, remote sensing may be used to fill the gap of field sampling. This gap is often due to unavailable logistics or inaccessible areas. It is recognized that sediment transport directions can be assessed from grain-size parameters of sediment samples, but the determination of transport trend patterns from grain-size remote sensed products has still not been carried out. The main objective of this study was to determine sediment transport trends in the Authie estuary (North of France) using Sentinel-2 data for different periods. This estuary is marked by a critical erosion of the northern shore due to a prograding sandy spit and a general sandfilling. In order to analyse seasonal variations, a set of 4 images were analysed for a period between 2016 and 2018, two during summer and two during winter. A new methodology was developed for mapping sediment transport trend based on grain-size parameters (mean, sorting and skewness) determined from remote sensing data. Three sectors of the estuary were selected according to their main morphodynamics characteristics (e.g. critical erosion and sandfilling sectors). The resulting transport vectors were spatially coherent with sedimentary bedforms (i.e. megaripple) and consistant with known transport directions. Maps of potential sediment transport show spatial variation between summer and storm periods. Our results suggest a changes according the period and some vectors demonstrate a change in direction following the formation of new structures or channel deviations. This study demonstrates that remote sensing combined to grains-size trend analysis can be a useful approach for sediment transport trends determination with a high spatial resolution. Further investigations are needed to identify the role of topographic variations and to obtain a long-term transport trend in order to understand as the spatial variability in sandfilling and erosion processes within the estuary