Reverse engineering of Xilinx's Virtex-5 chips has revealed that the 65nm devices are manufactured differently by UMC and Toshiba, the FPGA firm's foundry partners.
Canadian engineering firm Chipworks carried out the stripdown of a pair of XC5VLX50 devices, one from each foundry.
According to the firm, both devices share a common transistor structure, using tensile nitride strain on NMOS transistors. And both use 12 metal layers, 11 copper and one aluminium (pictured below).
However, the work showed "significant differences" in the metallisation and dielectric structures, said Chipworks.
"The Virtex-5 demonstrates Xilinx's use of multiple foundries to expedite 65nm device manufacturing, thus providing them with a hedge against process problems while increasing their volume production capability," said Terry Ludlow, Chipworks' founder and CEO.
"In addition, the relationships with Toshiba and UMC ensure that Xilinx remains at the forefront of technology."
The analysis firm said it would now begin characterising the devices to determine the performance impact from the differing designs.
Chipworks' information comes on the same day that Altera gave further details of its 65nm products - Stratix III.
Crucially, however, Altera will not start sampling these devices until the third quarter of 2007.
Further information from Chipworks