Beyond 7-nm, the most pressing challenges to continued scaling will come from economics, not technology, Chiang said in a keynote address at the ARM TechCon event.
Chiang said he has faith that the semiconductor industry will solve technical hurdles associated with moving past 7-nm over the next decade, but acknowledged that the new technologies might make volume manufacturing of chips with critical dimensions smaller than 7-nm cost prohibitive.
"From node to node, we have found the wafer price has increased much more than previous nodes," Chiang said.
In another ARM TechCon keynote later, Chi-Ping Hsu, senior vice president of R&D at in EDA vendor Cadence Design Systems' Silicon Realization Group, presented data on dramatic cost increases associated with moving from the 32/28-nm node to the 22/20-nm node. The amount of money invested by the semiconductor industry in process R&D, for instance, jumped from $1.2 billion at 32/28 to between $2.1 billion and $3 billion at 22/20, Hsu said. Design costs for a chip jump from $50 million to $90 million at 32-nm to $120 million to $500 million at 22-nm, Hsu said.
At the 32-nm node, a chip needs to sell about 30 to 40 million units to recoup the costs associated with it, Hsu said. At the 20-nm node, the "breakeven" point jumps to between 60 and 100 million units, Hsu said.
FinFETs are three-dimensional transistors in the early stages of being adopted by chip makers. Intel Corp., which refers to its 3-D transistor technology as "tri-gate," is expected to begin sampling 22-nm chips with 3-D transistors later this year.
Chiang said the 20-nm node will be the last generation at which the semiconductor industry can possibly use a planar transistor. "After that, it will run out of steam," Chiang said.