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By using a simplified Coulomb explosion model, the laser-driven Coulomb explosion processes of three deuterated alkane clusters, i.e., deuterated methane (CD4)N, ethane (C2D6)N and propane (C3D8)N clusters are simulated numerically. The overrun phenomenon that the deuterons overtake the carbon ions inside the expanding clusters, as well as the dependence of the energetic deuterons and fusion neutron yield on cluster size, is discussed in detail. Researches show that the average kinetic energy of deuterons and neutron yield generated in the Coulomb explosion of (C2D6)N cluster are higher than those of (CD4)N cluster with the same size, in qualitative agreement with the reported conclusions from the experiments of (C2H6)N and (CH4)N clusters. It is indicated that (C2D6)N clusters are superior to (CD4)N clusters as a target for the laser-induced nuclear fusion reaction to achieve a higher neutron yield. In addition, by comparing the relevant data of (C3D8)N cluster with those of (C2D6)N cluster with the same size, it is theoretically concluded that (C3D8)N clusters with a larger competitive parameter might be a potential candidate for improving neutron generation. This will provide a theoretical basis for target selection in developing experimental schemes on laser-driven nuclear fusion in the future. [ABSTRACT FROM AUTHOR]

Micro-Raman spectroscopy was employed to study the near-surface stress distributions and origins in Si around through silicon vias (TSVs) at both room temperature and elevated temperatures for Cu-filled and carbon nanotube (CNT)-filled TSV samples. From observations, we proved that the stresses near TSVs are mainly from two sources: (1) pre-existing stress before via filling, and (2) coefficients of thermal expansion (CTE) mismatch-induced stress. CTE-mismatch-induced stress is shown to dominate the compressive regime of the near-surface stress distribution around the two types of Cu-filled TSV structures in this work and in previous work, while pre-existing stress dominates the full range of the stress distribution in the CNT-filled TSV structures studied. These results show the importance of the pre-existing stress and support the use of a liner technology with lower stress introduction such as deposited oxide instead of thermal oxide. It is specifically important for CNT-filled TSVs, where the pre-existing stress is much larger than the CTE-mismatch-induced stress as observed in this work. [ABSTRACT FROM AUTHOR]

Through-silicon-via (TSV) used in three-dimensional (3D) stacked dies must present small electrical parasitic, such as capacitance, to allow for low latency signal transmission. Stable TSV capacitance is desired to overcome the spatial circuit performance variation caused by non-uniform hot-spot heating. In this work, a novel combination of low-k with ultrathin Al2O3 bilayer liner is successfully integrated in the TSV. The TSV capacitance is reduced by ∼26% as compared to plasma-enhanced tetrahydrothosilicate (PETEOS) oxide liner. Stable TSV capacitance within the operating voltage of interest (∼0–5 V) is achieved by operating the TSV in a stable accumulation capacitance region. The positive shift in the flat-band voltage (ΔVFB = +19 V) is achieved by utilizing Al2O3-induced negative fixed charge (|Qf| = 1.3 × 1012 cm−2) at the Si/low-k interface. Leakage current density of the bilayer liner is improved to a level comparable with the PETEOS oxide liner post annealing [forming gas (N2/H2) at 350 °C for 2 h or 400 °C for 0.5 h]. Low-k material with a smaller elastic modulus improves the thermo-mechanical stress exerted on the surrounding Si substrate compared with PETEOS oxide. [ABSTRACT FROM AUTHOR]