Speaker
Description
Reliable, cost-effective and scalable interconnects are essential for next-generation detectors. Within the CERN EP-R&D programme and the DRD3 and AIDAinnova collaborations, the University of Geneva and CERN (together with other research partners) have built a semiconductor assembly platform targeted to single-die processing. The platform unifies several bumping and bonding techniques, focusing on maskless bumping (ENIG or Au studs) combined with adhesive bonding (Anisotropic Conductive Adhesives (ACA) or Non Conductive Paste (ACP)).
The developed ENIG plating line, performed at a single-die level, delivers uniform plating with variations below 1 µm from pad to pad. For pixel detector hybridization, pixel connection yields above 95% in multiple detector demonstrators, ranging from 0.1 to >2+ cm² bonding area and pixel pitch from 25 to 1500 µm, have been achieved. One of the advantages of the developed bonding line is its customization capability, depending on the application needs. In particular, the processing can be performed at low temperatures, which has enabled successful hybridization of highly irradiated pixel sensors without unwanted annealing.
Beyond pixel hybridization, we have successfully integrated the RDL/TSV connections from the Timepix4 chip with a carrier chip-board (with successful tests up to 10 Gbps of data transmission), as well as the IO pads of large-area monolithic active pixel sensors into lightweight flexible circuits, replacing wire-bonding and enabling 4-side buttable assemblies.
With the combined interconnection platform, we have managed to shorten prototyping turnaround from months to weeks and cut material costs significantly. These results provide a flexible, high-yield pathway for the next collider vertex-detector R&D programmes and other advanced imaging applications.
This contribution introduces the developed bumping and interconnect processes and presents examples of recent achievements.
