15μm-pitch Bump Interconnections Relied on Flip-chip Bonding Technique - for Advanced Chip Stacking Applications

摘要

This paper reports the development of reliable fine-pitch micro-bump Cu/Au interconnections relied on a high-precision room-temperature bonding approach. The accuracy of the bonding process is improved by means of modifying the conventional bump/planar-bonding-pad interconnections, to form self-aligned micro-bumps/truncated inverted pyramid (TIP) bonding pads, i.e., misalignment self-correction elements (MSCEs). Thermosonic flip-chip bonding (FCB) technique is utilized to form reliable bonds between these MSCEs at acceptable low temperatures. Applying the proposed bonding approach, the demonstration of fine-pitch Cu bump to Au bonding pad interconnects chip stacking has been relied. The microstructure analyses reveal that the 15-μm-pitch micro-bump joints were made at room temperature.