Characterization Of Thermal Stresses And Plasticity In Through-Silicon Via Structures For Three-Dimensional Integration

Through-silicon via (TSV) is a critical element connecting stacked dies in three-dimensional (3D) integration. The mismatch of thermal expansion coefficients between the Cu via and Si can generate significant stresses in the TSV structure to cause reliability problems. In this study, the thermal stress in the TSV structure was measured by the wafer curvature method and its unique stress characteristics were compared to that of a Cu thin film structure. The thermo-mechanical characteristics of the Cu TSV structure were correlated to microstructure evolution during thermal cycling and the local plasticity in Cu in a triaxial stress state. These findings were confirmed by microstructure analysis of the Cu vias and finite element analysis (FEA) of the stress characteristics. In addition, the local plasticity and deformation in and around individual TSVs were measured by synchrotron x-ray microdiffraction to supplement the wafer curvature measurements. The importance and implication of the local plasticity and residual stress on TSV reliabilities are discussed for TSV extrusion and device keep-out zone (KOZ).Microelectronics Research Cente

Thermomechanical Characterization And Modeling For TSV Structures

Continual scaling of devices and on-chip wiring has brought significant challenges for materials and processes beyond the 32-nm technology node in microelectronics. Recently, three-dimensional (3-D) integration with through-silicon vias (TSVs) has emerged as an effective solution to meet the future technology requirements. Among others, thermo-mechanical reliability is a key concern for the development of TSV structures used in die stacking as 3-D interconnects. This paper presents experimental measurements of the thermal stresses in TSV structures and analyses of interfacial reliability. The micro-Raman measurements were made to characterize the local distribution of the near-surface stresses in Si around TSVs. On the other hand, the precision wafer curvature technique was employed to measure the average stress and deformation in the TSV structures subject to thermal cycling. To understand the elastic and plastic behavior of TSVs, the microstructural evolution of the Cu vias was analyzed using focused ion beam (FIB) and electron backscattering diffraction (EBSD) techniques. Furthermore, the impact of thermal stresses on interfacial reliability of TSV structures was investigated by a shear-lag cohesive zone model that predicts the critical temperatures and critical via diameters.Microelectronics Research Cente

Quantifying the GCM-related uncertainty for climate change impact assessment of rainfed rice production in Cambodia by a combined hydrologic - rice growth model

The effects of climate change on agriculture are a major concern for global food security. In this study, the impacts of climate change on rainfed rice production in the granary of Cambodia were examined on a basin scale by developing and applying a combined model consisting of a crop model and a basin-scale distributed hydrological model. The response of rice production to soil-water availability was simulated for past (1981–2000) and future (2041–2060, 2081–2100) periods. From 34 general circulation models (GCMs) that participated in the Coupled Model Intercomparison Project Phase 5 (CMIP5), 5 GCMs were selected by evaluating monthly rainfall in the past. Although annual rainfall was projected to increase by all five selected GCMs, notable decreases in rainfed rice production were projected with 3 GCMs, while small changes were projected with the other 2 GCMs. The main factor restricting future rice production was soil water availability, brought by the projected change in the seasonal distribution of rainfall and the projected more severe dry spells in the early monsoon season. The results suggest the importance of the selection and bias correction of GCMs to force rice crop models and of the simulation of soil water flow on a basin scale for the assessment of rain-fed rice production. In particular, improvements in projections of rainfall amounts over shorter periods rather than annual or seasonal periods, which fit within the time scales of rice plant growth, were suggested to be important

The origin of the phase separation in partially deuterated κ\kappa-(ET)2_2Cu[N(CN)2_2]Br studied by infrared magneto-optical imaging spectroscopy

The direct observation of the phase separation between the metallic and insulating states of 75 %-deuterated $\kappa$-(ET)$_2$Cu[N(CN)$_2$]Br ($d33$) using infrared magneto-optical imaging spectroscopy is reported, as well as the associated temperature, cooling rate, and magnetic field dependencies of the separation. The distribution of the center of spectral weight ($$) of $d33$ did not change under any of the conditions in which data were taken and was wider than that of the non-deuterated material. This result indicates that the inhomogenity of the sample itself is important as part of the origin of the metal - insulator phase separation.Comment: 4 pages, 3 figures, accepted for publication in Solid State Commu

Analisa Penanganan Pertama Cedera Olahraga pada Tim Atlet Bola Voli Putra IKIP PGRI Bali

Dalam penelitian ini, peneliti mengadakan penelitian tentang analisa penanganan pertama cedera olahraga pada tim bola voli putra IKIP PGRI Bali. Jenis penelitian yang digunakan dalam penelitian ini adalah deskriptif kualitatif dengan menggunakan teknik pengumpulan data populasi. Dalam melaksanakan penelitian ini, peneliti bertujuan untuk mengetahui jenis cedera yang sering terjadi serta penyebabnya. Selain itu juga untuk mendapatkan gambaran tentang penanganan pertama terhadap cedera yang terjadi serta metode-metode yang dapat dilakukan untuk mencegah terjadinya cedera. Hasil yang diperoleh dari 30 responden melalui angket yaitu: atlet yang mengalami cedera olahraga memperoleh hasil 56 % yang tergolong cukup kuat. Cedera olahraga yang sering dialami adalah memar dan keseleo, memperoleh hasil 52 % skala tergolong cukup kuat. Penyebab terjadinya cedera olahraga adalah kurangnya pemanasan memperoleh hasil 58 % skala tergolong cukup kuat. Cedera ringan ditangani oleh pelatihnya sendiri dengan hasil 86 % skala tergolong kuat, begitu pula cedera berat juga ditangani oleh pelatihnya sendiri dengan hasil 74 %, skala tergolong kuat. Pasca cedera hanya sebagian saja atlet yang mengalami trauma yang diperoleh hasil 38% skala tergolong lemah, yang masih terasa sakit dengan hasil 86 % skala tergolong sangat kuat dan berlatih kembali setelah 3 hari dengan hasil 96 % skala tergolong sangat kuat. Pencegahan melalui pemanasan dengan hasil 88 % skala tergolong sangat kuat. Penanganan pertama cedera menggunakan RICE dengan hasil 59 % skala tergolong cukup kuat.pemulihan cedera menggunakan terapi latihan dengan hasil 72 % yang tergolong kuat. Dari hasil tersebut peneliti menyimpulkan bahwa cedera yang sering terjadi adalah memar dan keseleo karena kurangnya pemanasan. Penanganan pertama yang sering dilakukan adalah menggunakan metode RICE, serta untuk pencegahan diharapkan atlet untuk memaksimalkan pemanasan sebelum melakukan kegiatan olahraga

SPOT-VEG Based Analysis of Siberian Silkmoth Outbreak

The spatial and temporal dynamics of an outbreak of the Siberian silkmoth were correlated with topographic features of the affected area using SPOT-VEG data and a high resolution digital elevation model (DEM). In 2002-2003 an outbreak affected approximately 20,000 ha in the South Siberian mountains of Russia. The outbreak began between the elevations of approximately 430- 480 m and on southwest slopes with steepness < 5 degrees. As the pest searched for food it moved up and down slope, resulting in an elevation distribution split within a range of approximately 390-540 m and slope steepness up to 15 degrees. In the final phase the azimuth distribution of damaged stands became even. The correlation between the initial phase and topographic features can be used to prioritize monitoring forest areas most vulnerable to destruction by pests

Growth factor restriction impedes progression of wound healing following cataract surgery: identification of VEGF as a putative therapeutic target

Secondary visual loss occurs in millions of patients due to a wound-healing response, known as posterior capsule opacification (PCO), following cataract surgery. An intraocular lens (IOL) is implanted into residual lens tissue, known as the capsular bag, following cataract removal. Standard IOLs allow the anterior and posterior capsules to become physically connected. This places pressure on the IOL and improves contact with the underlying posterior capsule. New open bag IOL designs separate the anterior capsule and posterior capsules and further reduce PCO incidence. It is hypothesised that this results from reduced cytokine availability due to greater irrigation of the bag. We therefore explored the role of growth factor restriction on PCO using human lens cell and tissue culture models. We demonstrate that cytokine dilution, by increasing medium volume, significantly reduced cell coverage in both closed and open capsular bag models. This coincided with reduced cell density and myofibroblast formation. A screen of 27 cytokines identified nine candidates whose expression profile correlated with growth. In particular, VEGF was found to regulate cell survival, growth and myofibroblast formation. VEGF provides a therapeutic target to further manage PCO development and will yield best results when used in conjunction with open bag IOL designs