Flash devices pack for data storage
January 9, 2001
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John Day
Although the current shortage of flash memory devices of all kinds is expected to continue for most of this year, industry watchers predict that an overcapacity in random-access NOR-type flash memory devices may also occur before the end of 2001.
With overcapacity in NOR memories a real possibility, manufacturers will be shifting their resources to the fast-growing market for serial access NAND-type flash chips, which are used primarily for storing data.
Some vendors have already been addressing the flash data market with NAND components, using technology developed by and licensed from Toshiba America Electronic Components Inc. (Irvine, Calif.). Others are marketing devices based on a derivative technology they call AND. A third option is simply to position NOR-type flash devices as being suitable for data-storage applications.
Alan Niebel, principal analyst at Web-Feet Research (Monterrey, Calif.), estimates the aggregate capacity of the 15 top suppliers of all types of flash memory devices at 4.2 billion units in 2001 (each unit representing 16 megabits of storage). Conceding a 500-million-unit margin of error, he estimates total demand at 4.5 billion units, for a shortfall of 300 million units.
Niebel pegged the capacity of NOR-type flash parts, which are used primarily for storing program code, at 3.1 billion units, compared with demand for less than 2 billion such devices. Manufacturing capacity for NAND and other types of data storage flash, on the other hand, is 1.1 billion units against demand for 2.6 billion units.
For 2002, Niebel predicted, there will be more of the same, only worse, with NOR (code) supply exceeding demand by better than 2 billion units and data flash demand exceeding supply by 5.3 billion units. He said his estimates factor in the vendors' current plans for adding capacity.
By far the largest market for random-access NOR-type flash devices is cell phones, which account for as much as 30 percent of dollar volume, according to Sam Young, vice president of marketing for the flash business unit at Hyundai Electronics America (San Jose, Calif.). Other markets include DVD players, set-top boxes, personal computers and workstations, automotive and instrumentation.
Young noted that NOR devices generally offer faster read speeds with acceptable write speeds, whereas parts for data storage boast faster write speeds, higher latency and lower read speeds. That combination suits digital cameras and MP3 audio players, which are the largest markets for serial-access NAND flash architecture and its derivatives.
Jackie Traeumer, business development manager at Toshiba America Electronic Components, explained that each memory cell in a NOR design requires both a word line and a bit line connection. In a NAND device, memory cell transistors are connected to each other, and only the first and last cells are connected to word and bit lines. Because NAND cells can be packed more tightly together, NAND flash devices offer greater density.
Nevertheless, NOR flash memory vendors "want to play in digital camera and other consumer markets, where the requirement is to receive and store large amounts of file data," according to Rich Wawrzyniak, who follows the flash market from Semico Research Corp.'s Irvine, Calif., office. "NAND is better suited for those kinds of applications, and that's what customers will tend to pick if the price is the same," he said.
While NOR devices are available in densities as small as 256 kilobytes, NAND devices are clustered in higher densities, generally 32 megabits and above.
The leading NAND vendors, according to Wawrzyniak, are license-holder Toshiba, plus AMD, Fujitsu and Samsung. The largest supplier of flash memory devices is the joint venture between AMD and Fujitsu, FASL (Fujitsu and AMD Semiconductor Licensing company). SanDisk also holds a NAND license, but is just ramping up the technology.
"There will probably be other NAND vendors by 2004 if NAND does come to represent a significant percentage of the total flash market," Wawrzyniak said. Estimates of the NAND/data storage market hover near 10 percent, but Wawrzyniak sees it climbing higher than 40 percent by 2004.
Intel Corp. (Santa Clara, Calif.) is generally credited with pioneering the flash memory market in the late '80s. The incentive for developing flash was to find a way to erase memory cells electrically, rather than with ultraviolet light, which required that memory devices first be removed from PC boards. The flash explosion has been driven by the comparatively small size of flash devices and the ability to program them within a system, even remotely.
Now, NAND devices are finding homes where low-density hard drives used to be, according to Toshiba's Traeumer. "In Web server applications, for example, NAND devices used for cache have the microsecond seek times required to handle millions of hits per day," she said, estimating that with 0.16-micron process technology, the cost of NAND storage should approach 75 cents per megabyte. Using multilevel cell technology, with two bits per cell instead of one, by the end of 2001 NAND cost-per-megabyte should hit 50 cents, she said. Multilevel cell devices, on the other hand, take longer to program. Traeumer said Toshiba expects to have multicell NAND flash devices on the market sometime during 2001.
A large percentage of NAND storage is configured in the form of cards, for which SanDisk Corp. (Sunnyvale, Calif.) originally developed the form factors. Ed Cuellar, director of marketing, said the company in recent years has focused on lowering the cost-per-megabyte of storage and has benefited from higher-density chips and higher yields per wafer. SanDisk was among the first to hit the market, offering chips at 32 , 64 , 80 and 256 Mbits. With help from Toshiba it recently launched a 512-Mbit device. In turn, it's helping Toshiba with multilevel cell technology.
Sharp Microelectronics of the Americas (Camas, Wash.) intends to develop flash for data storage, according to Rob Bernardi, vice president of operations and marketing. "We see the [Internet infrastructure] market going nuts in the next five to ten years," he said.
Vendors like Mitsubishi Electric and Electronics USA Inc.'s Electronics Device Group (Sunnyvale, Calif.) have a foot in each camp. Narayan Purohit, vice president of the memory division, said Mitsubishi makes divided bit-line NOR (Dinor), which is comparable to conventional NOR, as well as AND flash, which competes with NAND. It sells Dinor into wireless and networking markets that require fast access, and AND for automotive, MP3 and other entertainment applications.
Purohit said Mitsubishi's Dinor design gave the company a leg up in developing a single-supply, low-voltage (3-V) flash. It was among the first vendors to bring such a product to market. Also, the memory cells in Mitsubishi's Dinor flash were, when first introduced, 20 percent smaller than those in conventional NOR flash devices.
Mitsubishi's AND flash is said to offer smaller cell sizes and better voltage scalability compared with NAND flash. Purohit said the company focuses on high-density, low-voltage flash devices and claims more than half of the market for 64-Mbit flash devices.
Hitachi Semiconductor (America) Inc. (San Jose, Calif.), meanwhile, has been marketing AND flash devices for storage applications for the past five years, according to Mark D'Arcangelo, strategic marketing manager at the company's System Memory Business unit.
Hitachi's edge, according to D'Arcangelo, is multilevel cell flash, the kind that Toshiba has in development. Hitachi has been producing 256-Mbit MLC flash devices for more than a year.
Along with Samsung and Toshiba, Hitachi also offers "mostly good memory," in which 2 percent of the sectors can be bad. Control bytes at the end of each 512-kbyte sector let the flash controller know which sectors are good and which are bad.
NAND devices are smaller than NOR, but NAND sectors are larger, according to John Bryant, vice president of marketing for flash memories at Atmel Corp. (San Jose, Calif.). Atmel specializes in NOR devices. Its AT29 series of NOR flash devices was developed for applications requiring updates of small portions of data throughout the memory array.
Bryant said the parts' small (64-kbit to 256-kbit) memory sector sizes make the parts suitable for data as well as code storage. Atmel's AT45 DataFlash family of serial flash devices was designed for storing voice, images or text, but can also be used for program code-shadowing applications.
"Our low-cost code storage products can also be used for mass storage," agreed Bing Yeh, president and CEO of Silicon Storage Technology Inc. (Sunnyvale, Calif.), "and the higher the density, the lower the cost per megabyte, just like in the DRAM business." Yeh conceded that NAND currently offers lower costs per megabyte, but added that NAND is comparatively slow, and "with proper design, NOR can achieve similar densities and cost structures."
The flash market is different from other memory markets, countered Scott Dunagan, marketing manager at Intel Corp.'s Folsom, Calif.-based flash products group. "The DRAM business, for example, grew up around PCs, but flash has grown up around different applications, with different requirements," he said. "The 1.8-volt, read-while-write part with security and a burst interface that we sell for wireless applications won't go over well in telecommunications applications, where they want 3-volt, even-sectored parts with no burst.
Continued life in NOR
We'd love to be in both NAND and NOR," continued Dunagan, whose company focuses on NOR, "but we're sold out of flash and are working diligently to keep our capacity up with demand." Intel is the flash industry's largest single supplier. Further evidence of continued life in the NOR market is Samsung's planned entry into it this year, though Samsung will continue to push its NAND devices.
"Process reduction can come faster with NOR than with NAND," said Bryan Connington, product manager for flash memories at Micron Technologies Inc. (Boise, Idaho). "Most flash vendors are starting to ramp to 0.18-micron processing."
"Nearly every semiconductor maker is focusing on flash," noted Kevin Plouse, vice president of technical marketing and business development at AMD's Memory Group, (Sunnyvale, Calif.). "There is spot oversupply for some parts," he added, "but overall, the industry is sold out and prices have firmed." Plouse said the flash market has experienced two shortages and one major oversupply period since 1991. "During the oversupply there was price erosion, and investment dropped off.
"Demand has since escalated because of the high rate of adoption of cell phones by consumers, and because of the Internet," Plouse continued. "There is flash memory in just about every piece of equipment. Demand has grown exponentially, which led to the current supply shortage. . . . We expect the shortage to continue at least through 2001 and probably for a large part of 2002."
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COMPANY CONTACTS
AMD
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Atmel Corp.
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Fujitsu
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Hitachi Semiconductor (America) Inc.
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Hyundai Electronics America
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Intel Corp.
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com/design/flash
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Micron Technology Inc.
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Mitsubishi Electronics America Electronic
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Samsung
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SanDisk Corp.
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Sharp Microelectronics
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Silicon Storage
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Toshiba America Electronic Components Inc.
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Copyright c 2001 CMP Media Inc.
By John Day |
