The stress in silicon surrounding a tungsten-filled through-silicon via (TSV) is measured using confocal Raman microscopy line scans across the TSV both before and after etch removal of an oxide stack used as a mask to define the TSV during fabrication. Stress in the silicon arose in response to both athermal deposition and thermal expansion mismatch effects. The complex three-dimensional stress and strain field in silicon surrounding the TSV is modeled using finite element analysis, taking into account both athermal and thermal effects and the elastic anisotropy of silicon. Comparison of the measurements and model results shows that no one component of the stress tensor correlates with the Raman peak shift generated by the deformed silicon. An analysis is developed to predict the Raman shift in deformed silicon that takes into account all the components of the stress or strain tensor; the results of the model are then used as inputs to the analysis for direct comparison with measured peak shifts as a function of distance from the TSV. Good agreement between the measured and predicted peak shifts is obtained for the case of the intact oxide stack. A discrepancy between the measured and predicted shifts was observed adjacent to the TSV with the oxide stack removed; further modeling suggests the discrepancy is explained by the formation of a small void at the TSV-silicon interface during etching. The combined measurement-modeling approach serves to both validate the model, in this case for TSV design, and to extend the measurement capability of confocal Raman microscopy to complex stress fields.
We report a CMOS-compatible embedded siliconcarbon (eSiC) source/drain stressor technology with NMOS performance enhancement. The integration includes up to 2.6% substitutional carbon (Csub) epitaxial Si:C and laser spike annealing (LSA) for increased Csub incorporation. 26% channel resistance (Rch) reduction and ll% Idlin-loff enhancement for 0.5% Csub and 60% Rch reduction for 2.2% Csub are demonstrated.
Three-dimensional natural convection flow and heat transfer were numerically studied for a three-by-three array of discrete protruding heat sources on a horizontal substrate in an air-filled, rectangular, narrow-aspect-ratio enclosure with length, width, and height ratio of 6:6:1. The governing equations for natural convection in air, coupled with conjugate conduction and radiation within the enclosure were solved using a finite volume method. The study examines the complex thermal interactions between the heat sources, substrate, and enclosure walls as affected by the thermal conductance of the walls and substrate with the intent of determining which physical effects and level of detail are necessary to accurately predict thermal behavior of discretely heated enclosures. The influence of radiation on the overall heat transfer is given particular attention. The three-dimensionality of the problem was evident in the overall flow characteristics and in the convective heat transfer edge effects on the heat source surfaces. Excellent agreement between temperature predictions on the heat sources and substrate and experimental measurements was obtained for modified Rayleigh numbers in the range of 9.7 × 105 to 1.6 × 107.
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