During a product launch event in October 2011 for the Xilinx Virtex-7 2000T field programmable gate array (FPGA), a programmable logic device with 6.8 billion transistors, Liam Madden, corporate vice president of FPGA Development and Silicon Technology, spoke about the value of so-called "2.5D packaging." Xilinx connects several die to a silicon interposer to enable this FPGA.
The semiconductor packaging industry used to see 2.5 as stepping stone, Madden said. However, while 3D packaging is coming, there are restraints in real active-on-active die stacking: keepout zones, thermal hot spots, etc.
2.5D packaging gets disparate chips to communicate as if they are on one piece of silicon -- a real advance that many more companies are taking advantage of instead of or before a move to 3D, Madden said. He also points out that 2.5 will teach us a lot about 3D ICs.
See the device architecture details on the Xilinx Virtex-7 2000T FPGA here.
-- Meredith Courtemanche