Bias Stress Induced Conduction Mechanism Evolution in Silica Based Inter-Metal Dielectrics
The real-time conduction mechanism evolution during bias stress of three silica based inter-metal dielectrics in Cu damascene structures was investigated. Capacitance measurements at 1 MHz and I-V measurements were intermittently inserted into the process of bias stress to monitor the conduction mechanism evolution with time. All experiments show that the capacitance is constant and the I-V curve slope decreases with bias stress and converges to the half of the initial value. Based on these findings, we conclude that the conduction mechanism changes from a normal Frenkel-Poole emission to an "abnormal" Frenkel-Poole emission with bias stress
Leakage current and dielectric breakdown behavior in annealed SiO2 aerogel films
Leakage current and dielectric breakdown behavior in annealed SiO2 aerogel films for intermetal dielectric applications was investigated in a metal–insulator–semiconductor structure. SiO2 aerogel films with porosities of 70% exhibited Poole–Frenkel conduction both before and after annealing. After annealing at 450 and 700 °C, the leakage current density improved over the current range of the applied field. This behavior was characterized by different chemical evolutions in each annealing step, beginning with the removal of residual organics up to 450 °C and then with the removal of residual surface hydroxyl, along with subsequent microstructural changes, up to 700 °C. Except in the few initial failure modes, intrinsic dielectric breakdown was not observed up to 1 MV/cm for as-deposited or 450 °C annealed films. However, in the case of the 700 °C annealed film, the dielectric breakdown strength was degraded. It was inferred that this early breakdown in 700 °C annealed film was caused by a randomly enhanced...
Structure and self-similarity of silica aerogels.
Small-angle neutron scattering from silica aerogels reveals that they form mutually self-similar volume fractals for a wide range of densities and preparations. The fractal dimension is D=2.40\ifmmode\pm\else\textpm\fi{}0.03. The fractal behavior extends down to near-molecular sizes. Indication for a volume-to-surface fractal crossover is also obtained. These results apply to neutrally prepared or acid-catalyzed materials. Base-catalyzed gels have widely different properties.