Micron unveils NAND flash with onboard error management

Micron's ClearNAND ECC technology will allow it to keep shrinking its flash products

Micron Technology introduced a line of NAND flash memory products today that it says will lengthen the lifespan of solid-state storage by integrating error management through a special processor chip, and allow it to continue shrinking the size of its circuitry.

Micron's new ClearNAND flash data storage devices, which are expected to be generally available in the first half of next year, will be targeted at enterprise servers, tablet PCs, portable media players, and other consumer applications.

Micron expects to begin phasing out its "raw NAND" storage devices, including its solid state drives (SSDs), in favor of the ClearNAND products over the next several years, said Kevin Kilbuck, the company's director of strategic NAND marketing.

The ClearNAND technology will be used in flash cards, embedded multi-media cards, and Micron's RealSSD drives.

Kilbuck said ClearNAND devices alleviate the challenges traditionally created as NAND flash circuitry shrinks in size. Currently, the smallest NAND flash circuitry being produced by Micron, Intel and others is in the 20 to 30 nanometer size range. A nanometer is a millionth of a millimeter.

At 25nm, which is what Micron is currently using in its lithography technology, NAND flash circuitry is 3000 times thinner than a strand of human hair, which is approaching atomic dimensions.

There are inherent problems with shrinking the size of circuitry used in semi-conductors, most notably an increase in data error rates from electrons bleeding through ever-thinner silicon walls. That requires the development of more sophisticated error correction code (ECC).

However, Traditional ECC requires code redundancy and data read latency as the number of errors that must be corrected goes up. Typically, ECC is performed by host application servers, eating up valuable compute cycles.

"As the industry continues to reduce costs by moving to smaller and smaller geometries, the challenge has been to maintain equivalent system performance and endurance as the previous process generation," said Greg Wong, principal analyst at market research firm Forward Insights.

"With its ClearNAND portfolio, Micron has developed a solution that overcomes these challenges, enabling customers to utilize the most advanced NAND technology in even the most demanding applications," Wong said.

Micron's ClearNAND products are being designed using its 25nm multi-level cell (MLC) process, and are available in two versions: Standard and Enhanced.

ClearNAND technology consist of an application-specific integrated circuit (ASIC) and a NAND die with 8 bytes of capacity that acts as a cache for data being error corrected prior to being laid down on the NAND flash storage. The ClearNAND presents itself as a standard NAND interface to the host processor.

Micron's Standard ClearNAND products come in capacities of 8GB to 32GB, and are intended to remove the ECC burden from the host processor with minimal protocol changes compared with raw NAND. The Standard ClearNAND portfolio is targeted for portable media players and other consumer electronic devices.

In addition to removing the ECC burden from the host processor, Enhanced ClearNAND also provides new enterprise specific features to enable high-capacity designs, delivering improved performance and reliability. Capacities are available in 16GB to 64GB packages. The Enhanced ClearNAND products are targeted at enterprise and computing applications.

Both Micron Standard ClearNAND and Enhanced ClearNAND products are being shipped to equipment manufacturers for testing today and will be generally available in the first half of next year, Kilbuck said.

Kilbuck said Micron's ECC code would clash with existing host ECC and, therefore, Micron will ask its equipment manufacturing partners to disable their code when using its ClearNAND technology.

"That's just the quick and dirty way to enable it," Kilbuck said. "In the future, customers or people developing host processors won't even need ECC in there at all. They can reduce cost on their side by eliminating the ECC engine."

Besides Micron's ClearNAND ASIC, Israeli start-up Anobit Technologies announced earlier this year it had also created a special processor, called a Memory Signal Processor, that boosts MLC NAND flash memory reliability through a special error-correction algorithm.

There are also several materials being explored by memory manufacturers to alleviate the data error problem. One technology several nonvolatile memory companies are exploring is Resistive Random-Access Memory (RRAM). Instead of using silicon as a resistive material, RRAM uses a filament or conduction path in the silicon.

Lucas Mearian covers storage, disaster recovery and business continuity, financial services infrastructure and health care IT for Computerworld. Follow Lucas on Twitter at  @lucasmearian or subscribe to Lucas's RSS feed . His e-mail address is lmearian@computerworld.com.

Copyright © 2010 IDG Communications, Inc.

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