Cell suffering from poor yields?
IBM Semiconductor & Technology Services VP Tom Reeves has revealed
an interesting tidbit about the Cell processor
in a recent interview
with Electronic News. Cell's novel multi-core architecture was co-developed by IBM, Sony, and Toshiba, and will make its grand appearance in
the PlayStation 3 this November. However, word seeped
earlier this year that the processor's yields are below-par.
IBM's Tom Reeves has now revealed some numbers that seem to give a
clearer picture of how Cell fabrication is faring.
Electronic News: What’s the defining factor that makes
some chips better than others?
Reeves: Defects. It becomes a bigger problem the bigger the chip
is. With chips that are one-by-one and silicon germanium, we can get
yields of 95 percent. With a chip like the Cell processor, you’re lucky
to get 10 or 20 percent. If you put logic redundancy on it, you can
double that. It’s a great strategy, and I’m not sure anyone other than
IBM is doing that with logic. Everybody does it with DRAM. There are
always extra bits in there for memory. People have not yet moved to
logic block redundancy, though.
While Reeves says yields of 10-20% with Cell are "lucky," yields could be in the order of 20-40% if IBM has implemented logic redundancy in Cell. AMD and Intel are notoriously secretive about their yields, so it's
difficult to find other numbers to compare. Nevertheless, saying 20%
yields are "lucky" may not bode well for Cell. Additionally, as X-bit
sources believe Sony will decrease Cell's clock speed in the PlayStation
3 from 3.2 GHz to 2.8 GHz, and Merrill Lynch analysts think Cell chips
will cost the company about $230 a pop.