That brings us to cost. Cost is, of course, always a huge issue. No exception here. “When you compute the target cost for a silicon interposer, you need to do it at the complete system level or at least die/package level to find the intrinsic cost of the interposer itself,” Yannou says.
Interested in a universal cost metric for a TSI? According to Yole’s cost simulations, it’s going to need to cost about 1 cent/mm2 or less for a TSI, otherwise it doesn’t stand a chance of becoming a competitive solution. Yannou determined that for an 8-in. depreciated fab that cost target could hardly be achieved, but shifting to a 12-in. fab can drop the cost even further down to 0.87 cent/mm2 —using three metal routing layers and TSVs filled with copper (100µm thickness) and a via diameter of 30µm.
(Courtesy of Yole Développement, 3D Glass & Silicon Interposers ? 2010 Report)
If you’re looking for a much more detailed analysis and a breakdown by application, Yole’s latest report, 3D Silicon & Glass Interposers, delves deeply into the drivers, benefits, target prices, and all critical things that need to be considered, application by application because they’re very different for each one. Notwithstanding the uncertainties inherent to this emerging technology trend, the report even risks presenting wafer forecasts by application.