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
Dielectric Conduction Mechanisms of Advanced Interconnects: Evidence for Thermally- Induced 3D /2 D Transition
Electrical, electro-optical, mechanical and microstructural characterizations explain why the leakage currents in advanced Cu/ultra-low K interconnects can change from bulk (3D) to mostly interfacial (2D) above 150degC. A physical model consistent with all these results is proposed
Joint strength of aluminum ultrasonic soldered under liquidus temperature of Sn–Zn hypereutectic solder
Abstract In order to obtain high-strength aluminum joints, ultrasonic soldering of 1070 aluminum was conducted under liquidus temperature of Sn–Zn hypereutectic solder. A device for ultrasonic soldering was assembled, which propagated ultrasonic vibrations in a direction perpendicular to joining surfaces. This device joined 1070-Al using quasi-melting Sn–Zn hypereutectic solder without using any artificial spacers. The strength of the solder joints was evaluated by tensile tests. The optimum joining conditions were determined, and the effects of solder compositions and soldering temperature on the joint strength and the solder layer thickness were examined. In this ultrasonic soldering process, the highest tensile strength was obtained for the solder joints fabricated at 220 °C for the Sn–23Zn and Sn–40Zn solder compositions. The joint strength was equivalent to that of 1070-Al heat treated at 220 °C. The sound joints were obtained at 300 °C using Sn–82Zn solder, the liquid phase volume fraction of which was theoretically only 0.24. The present work also revealed that the thickness of retained solder layer in the joint after ultrasonic soldering could be estimated. Accordingly, ultrasonic soldering under the liquidus temperature of Sn–Zn hypereutectic solder could be a spacer-free soldering method to obtain high-strength aluminum joints.