When the semiconductor industry is heading towards the final climb to hit the wall in taking the present semiconductor chip making technology to its last stop, some of the chip vendors who rely on selling-point of complexity and density of logic elements in their semiconductor devices started finding alternate ways to continue packing more logic elements in smaller space. The way out is stacking of multiple chips in a single package, a common sense solution.
FPGA industry is highly driven by the growth in density of logic elements in their devices, so they are leading the industry in adopting latest nodes in manufacturing FPGAs. But due to the tough challenges in moving to deeper nodes, companies started exploring alternate avenues to increase the density, FPGA maker Xilinx has shown a product where the monolithic FPGA chips are placed one next to the other on a silicon base material acting like a micro-PCB. The interconnecting silicon base material is called silicon interposer with through-silicon vias. To get better idea have a look at this picture below. The connection between monolithic chips are made through 200 -300 micron length connectors created on silicon interposers and are contacting the monolithic chips via copper metal based micro-bumps.
The advantages of such stacking of chips one next to the other is same as Moore's law benefits. The benefits include save in space, increase in bandwidth but not much on power consumption but surely the end-user finds this more time and money saving along with performance improvements.
For the end-user, the stacked multi FPGA device is just like single monolithic FPGA chip. Same software and tools can be used for stacked FPGA device. The telecom and ASIC chip developers who use multiple number of FPGAs on a single PCB are the immediate customers, Xilinx is targeting.
The fab partner for Xilinx to achieve this kind of a semi tech-breakthrough is TSMC. TSMC has mastered this technology ahead of others. TSMC is delivering Xilinx the 28nm monolithic chips and the silicon interposer. Amkor Technology is doing the final assembly and packaging of stacked silicon. The package substrate is provided by the Ibiden.
This is just the start of semiconductor packaging companies moving into the domain of system-in-package service area, taking the revenue pie from complex PCB board makers but for a better cause.
Can we call this tech "Internetworked Chips in a Package"? or "Internetworked Chips on a Silicon die"?