SANTA CLARA, Calif. -- NAND flash technology is expected to scale down to the 20-nm node, but there are some questions beyond that process, due in part to the uncertainties with extreme ultraviolet (EUV) lithography, according to the top executive at SanDisk Corp.
At present, NAND vendors are shipping 40-nm-like parts, which are being processed via 193-nm immersion lithography tools. Suppliers of 193-nm immersion lithography equipment have been able to ramp up their tools faster than expected.
After some initial concerns, the immersion lithography ramp "was like a walk in the park," said Eli Harari, chairman and chief executive of SanDisk, during a presentation at the Flash Memory Summit here. SanDisk and its NAND flash partner, Toshiba Corp., are ramping up leading-edge parts in various fabs in Japan.
With immersion, NAND flash vendors are expected to process wafers down to the 32-nm node. This is said to be the theoretical limit for 193-nm immersion tools, even with double-patterning techniques.
"Unfortunately for ASML and Nikon, (immersion) is running out of steam," he said, referring to tool suppliers ASML Holding NV of the Netherlands and Nikon Corp. of Japan. Canon Inc. of Japan has also entered the 193-nm immersion fray. Meanwhile, ASML and Nikon are separately developing EUV tools as well.
Beyond that, the IC industry is bracing for the EUV era. The problem is that EUV has been hit with delays, lack of power sources and cost issues.
Regarding the feasibility of EUV, "unfortunately, we don't know" about the throughput and cost issues, Harari said. But in a brief interview after his presentation, Harari appeared to be more confident about EUV, saying the power sources and other technologies are making progress.
He also dropped hints that the IC industry is exerting pressure on ASML and Nikon to develop and deliver EUV for production fabs. "They had better be ready," he added.