WAFER MAKER Globalfoundries has announced that it demonstrated chip stacking using through-silicon vias (TSV) on its 20nm process node.
Spun off from AMD and perhaps best known for fabbing AMD's processors, Globalfoundries has been investigating TSVs as a method of stacking chips, much like rival chip foundry TSMC. Now the firm just announced that it has demonstrated working 20nm silicon that incorporates TSVs.
According to Globalfoundries, it inserts the TSVs after the Front End of the Line flow and before the Back End of the Line flow, meaning it can use copper for the TSV fill material. The firm claims it developed its own contact protection scheme in order to make TSVs possible during its transition from 28nm to 20nm.
AMD has already said that it is waiting for the move to 20nm, presumably with Globalfoundries, however it is likely that fabbing TSVs at 20nm will take longer. At the GPU Technology Conference Nvidia announced that it will use TSVs to stack DRAM on its upcoming Volta GPUs.
David McCann, VP of packaging R&D at Globalfoundries said, "Our industry has been talking about the promise of 3D chip stacking for years, but this development is another sign that the promise will soon be a reality.
"Our next step is to leverage Fab 8's advanced TSV capabilities in conjunction with our OSAT [outsourced semiconductor assembly and test] partners to assemble and qualify 3D test vehicles for our open supply chain model, providing customers with the flexibility to choose their preferred back-end supply chain."
Globalfoundries didn't say when its 20nm TSV process will be ready for volume production, but the firm's announcement that it has working silicon might be tempting for potential customers. µ