Growth of Al2O3/Y3Al5O12 Eutectic Fiber by Micro-Pulling-Down Method and Its High-Temperature Strength and Thermal Stability
Fiber growth of Y3Al5O12 (YAG) matrix composite reinforced with the sapphire phase was investigated to manufacture sapphire/YAG eutectic composites using the micro-pulling-down (µ-PD) method. Both the sapphire and YAG phases were crystalline. We have controlled the fiber diameter from 200 µm to 2 mm. The maximal length was about 500 mm. The eutectic fibers have superior high-temperature strength properties, 580 MPa at 1500°C. In the tensile test at this temperature, the fiber showed considerable (about 10%) plastic deformation due to dislocation motion. The microstructure of this eutectic fiber has a very high thermal stability. No grain growth was observed after even 75 h of heat treatment at 1500°C in air atmosphere.
Upstream Electromigration (EM) study was performed on different multiple via structures with different Cu line dimensions. EM performance was found to be dependent on both via layout and Cu line dimension. Failure analysis showed different EM failure modes and diffusion paths on these structures with their different grain morphology. Finite element analysis is applied to find out the current density profiles of these structures and explain their EM results. Simulated resistance increase was found to be dependent on the size and location of EM induced void in these structures.