"Recently TSMC said at 20 nm there are no significant differences [in process optimizations], but I don't believe that," said Subramanian Iyer, an IBM fellow and chief technologist in its microelectronics division.
"I believe at same node you can have two [different variations]," he
said in a keynote here.
Iyer of IBM said TSMC's decision to offer one flavor of 20 nm may have been more of an economic than a technical decision.
The historic challenge of offering variations of a process is that each one requires a different set of unique and complex features added to the base process, said Iyer of IBM.
"All the little features we have are like drugs, we can't drop them without severe withdrawal symptoms," he
"This 3-D technology is really powerful and we will see it in many places," said Iyer of IBM which has already made working prototypes of server processors in TSV stacks with DRAMs.
CPUs have 8-12 cores now "and want to go to 24 cores" with 3-D IC modules that stack DRAMs and heat sinks.
is also interested in "systems on an interposer," 2.5-D modules that surround a processor with memory chips on a silicon substrate with de-coupling capacitors to improve power regulation, he
"There's a lot of good stuff happening in this area that will make a significant difference, and the same concepts are applicable in the mobile space with similar advantages," he
The bad news is "as you go to smaller nodes the benefits of scaling are being eroded significantly," said Iyer of IBM.
The culprit is the lack of any new lithography techniques.
Today's 193 nm immersion lithography systems are being asked to create 22 and even 14 nm features.
"This does not come free, the costs are becoming formidable," Iyer
"Complex patterning solutions are the cause of the angst we are having," he
"Until we get to 7 nm or so there are no fundamental issues we see," said Iyer