The substantial technologies for the 3D stacked LSI are the interconnections of the microbumps on the through-hole electrodes and the encapsulation of the narrow gaps through the layered devices. Regarding with the interconnections, the high-accurate bonding (HAB) process was achieved for the interconnections in 20μm pitch utilizing the gold bumps. The mounting accuracy was in +/-2μm. As for the advanced bonding processes at the lower temperature and the stress, the two metallurgical bonding processes were evaluated. One is the ultrasonic flip-chip bonding (UFB) process on the gold bumps and the other is the copper-bump bonding (CBB) process with the thin-metal caps. The possibility of the microbump interconnections in 20μm pitch and the basic process conditions were confirmed. Moreover, the optimized resin properties and the process control were applied to the encapsulation process for the microthin gaps less than 10μm to realize the advanced 3D LSI structure.
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