Development of Si-Interposers for 3D Heterogeneous Integration

ABSTRACT BRIDG (Bridging the Innovation Development Gap) is working with our foundry operator Skywater 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 × 13mm. The second electrical qualification vehicle has the same body structure along with through silicon vias (TSVs) having dimensions of 10um × 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.