"Foundries have come under pressure to release cell libraries too early – which end up with designs that don't work," Bryant said. And now TSMC is trying to launch ten 28-nm designs from seven companies because they wish to be seen to be even-handed with all comers, Bryant said. "At 45-nm, only Nvdia was affected. At 28-nm any problems for TSMC will be problems for many customers."
It was reported in late 2011 that Samsung was ramping production of the A6 quad-core application processor for Apple because TSMC had not yet stabilized its own production of the same chip. Apple's continued reliance on Samsung came despite an increasingly litigious battle between the companies at the system level where both are seeking to prevent the sale of the others smart phones because of alleged patent infringements.
In August 2011 TSMC was reported to have begun trial manufacturing of an A6 processor design for Apple but to be redesigning the chip for volume production in the first quarter 2012. One potential reason of the respin is that TSMC plans to use 3-D stacking technologies along with its 28-nm manufacturing process in the production of the A6 for Apple. The use of a specialized silicon interposer and bump-on-trace interconnect may produce specific requirements in the main processor die.
The Apple iPad 3 tablet computer is expected to launch in March 2012, based on the A6 quad-core processor.
In the analysts conference call Chang said: "We have so far completed 36 individual tape-outs and have scheduled another 132 individual product tape-outs in 2012. While three versions of the 28-nanometer technology, the LP, the HP and the HPL have entered volume production, the fourth version, the HPM has entered risk production this quarter and is expected to begin volume production in the second half of this year."
Regardless of the truth of the details, 28nm has been a real challenge, particularly in the initial ramp up phase. This is more sanely evidenced in the increasing amount of DFM activities being pushed to the designer at these nodes. Things like litho checking, smart fill, pattern based checks, and restricted design rule checks have migrated from recommended to required. This is evidence enough that many of the second and third order effects on yield are becoming first order. Strict adherence and effort spent optimizing these DFM issues in the design phase is probably what is causing such different results on different chips. All designs are not the same from a DFM perspective.