EUV delay will slow NAND supply growth

SANTA CLARA, Calif. – Delays delivering next-generation lithography will slow the growth in supply of NAND flash, said the chief technologist of SanDisk in a keynote address at the Flash Memory Summit here.

In an otherwise upbeat assessment of the outlook for the flash market, Yoram Cedar waved a yellow flag about delays fielding extreme ultraviolet lithography. The lack of EUV tools will result in the historical increases in flash supply and decreases in cost to be more moderate with future process technologies, he said.

Existing immersion lithography tools will serve flash makers down to geometries of less than 10nm, two generations from today's processes, he said. In addition, vendors are working to create 3-D stacks of NAND strings using existing fab tools to further boost capacity and supply, he added.

Further in the future, chip makers including SanDisk are developing 3-D structures that use changes in resistance to create denser chips. But the so-called resistive RAM will require EUV tools, he said.

Cedar declined to give any specifics about the timeframe for EUV or the status of the current 3-D chip research. However, he did say chip makers expect to ship 64 and 128 Gbit flash devices using immersion tools.

"Many people in the semiconductor industry are very concerned about EUV not only from the standpoint of its availability but also its cost--these things will cost many millions of dollars," said one audience member in question to Cedar after the keynote.

Some pre-production EUV tools reportedly began shipping in January. Costs for the tools could soar as high as $120 million, according to some reports.

Cedar expressed optimism that EUV systems will be affordable. He also noted historical fears of an end to Moore's Law have so far been unfounded.

"When we were at 90nm, we thought 56nm was difficult and may be the end of the game," he said.

The good news is flash demand is broad and strong. Flash is expected to grow 25 percent on a compound basis through 2015, nearly double the rate of hard disk storage and far above DRAM at only one percent, he said.

About a third of all NAND bits will go to smartphones by 2015 when as many as 1.1 billion units ship, Cedar said. Tablets will take another 15 percent of NAND bits for 327 million systems that year, he added.

"Tablets represent a sizeable market that came from nowhere," he said. "There is so much new development here that wasn’t forecast three or four years ago, and there's no reason this will not continue," he added.

He projected solid-state drives will consume 25 percent of NAND bits, selling into 133 million units for clients and 12 million for servers. The rest of NAND supply, about 26 percent, will go into existing systems such as MP3 players, USB drives and digital cameras, he said.

Researchers are working in parallel on 3-D flash structures using current immersion lithography (left) and extreme ultraviolet technology.