Characterization of Low-Height Solder Microbump Bonding for Fine-Pitch Inter-Chip Connection in 3DICs

We have fabricated microbump daisy chains with a low-height solder thickness of 2.5 μm in order to evaluate flip-chip bonding capabilities. Electrical characteristics of the bonded microbumps in three-dimensionally stacked chips were compared between a very thin non-conductive film (NCF) and capillary underfill (CUF). The resulting I- V behaviors showed that the resistance of the daisy chain with the NCF was lower than that with the CUF, inDICating that the low-height solder microbumps with combination of the thin NCF can be a promising candidate for future fine-pitch inter-chip connection in 3DICs.

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