Authored By:
Charles Woychik, Chris Nichols, Alan Huffman
SkyWater Technology, Inc.
FL, USA
John Allgair
BRIDG
FL, USA
Summary
SkyWater is working with our partner BRIDG (Bridging the Innovation Development Gap) to establish a domestic supply chain for Si-Interposers with and without through silicon vias (TSVs). BRIDG is leveraging a strategic advanced packaging partnership with imec by licensing and transferring the imec silicon interposer technology to the Center for NeoVation in NeoCity, Florida, making the State-of-the-Art technology available to the US Industrial Base for low volume production.
Si-Interposers provide a platform to assemble multiple types of chips (chiplets) to achieve a very high-density multi-chip module. This is especially important when accommodating very fine pitched die (50um and less) that require a higher density circuity (1um lines/spaces L/S and less) offered by a semiconductor back end of line (BEOL) process. Current metallization processes used for organic substrates can only effectively go down to about 5um, which limit the die pitch to 150um or greater. Future chiplet designs are projected to scale below 20um pitch, and this is where Si-Interposers offer the advantage.
Two silicon interposer electrical qualification vehicles will be discussed in this paper. The first one is a bridge interposer, having two metal Cu Damascene layers with 1um lines/space on a Si-substrate with a body size of 9mm x 13mm. The second electrical qualification vehicle has the same body structure along with through silicon vias (TSVs) having dimensions of 10um x 100um. For these two offerings, the basic process flows will be presented, along with supporting technical data. In addition, examples of applications for both offerings will be presented.
Keywords:
Conclusions
Through the IBAS program, we have successfully installed and performed initial electrical qualification for the Phase I Cu damascene process, which can be used to support bridge interposer applications. The program is currently in Phase II with the integration of the TSV and Cu damascene processes scheduled to be completed in late 2022.
The Phase II interposer offering will be a fully process design having TSVs that can be assembled to a standard organic substrate. Our partnership is currently designing a 30mm x 40mm Si interposer test vehicle demonstrator, that will incorporate multiple daisy chained die assembled to the topside using solder capped Cu-pillars and conventional C4 bumps on the bottom side to connect to a mating substrate, as shown in Figure 16. This test vehicle will provide the opportunity to characterize the reliability of a fully assembled exemplar system and serves as a “pipe cleaner” ahead of a functional system demonstrator.
The continuing development and advancement of this interposer technology in the IBAS program, the test vehicle program, as well as future programs, will establish SkyWater and BRIDG to provide an open access interposer capability for commercial and government customers.
Initially Published in the SMTA Proceedings
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