Austin, Texas — In a counterattack against NAND memory vendors moving onto its cell phone turf, Spansion LLC will begin sampling a newly architected MirrorBit flash that is pin-to-pin compatible with NAND flash memories.
The memory architecture, named Ornand, includes parallel banks of NOR-type flash, with a NAND interface. In a presentation at the company's Fab 25 here, CEO Bertrand Cambou said the structure improves on the relatively poor write speeds seen in typical NOR devices, with burst-write speeds that are four times faster than NAND chips.
"NOR is slow at programming and writing. NAND is slow to read. With Ornand, we believe we have picked the best of each, for the ultimate reliable solution for multimedia systems," Cambou said.
The device family will sample at hefty 1-Gbit densities, using Spansion's newly qualified 90-nanometer process at Fab 25.
Ed Keyes, chief technology officer at Semiconductor Insights Inc. (Kanata, Ontario), said Spansion executives "see Ornand as their NAND killer in the high-density cell phone market. That is where NAND is starting to nibble at the high-density NOR." Just as a pseudo-RAM is a DRAM configured to look like an SRAM, the Ornand is a NOR device that works like a NAND chip, he said.
While the design does not support XIP (execute in place), Ornand is designed for applications that either use a separate NOR device for XIP, or in systems in which code is shadowed from an Ornand into an SDRAM memory, the "store and download" mode that, according to some market researchers, is gaining traction against the XIP mode.
With an ability to store both code and data, Ornand will enable Spansion to "participate in the part of the NAND market that is the highest-price niche," said Jim Handy, a Semico Research analyst.
Ornand "probably will find its niche," Handy said.
Spansion — which is a joint venture owned by Advanced Micro Devices Inc. and Fujitsu Ltd. — is coming out with the product at a time when it's preparing to make an initial public offering en route to becoming an independent company.
Spansion had $2.4 billion in revenue last year.
After the presentation, Spansion's vice president of system engineering, Robert France, demonstrated a board-level mockup of a video-capable cell phone that used Ornand flash to buffer video directly into a Texas Instruments Inc. Omap applications processor, at 15 frames per second. On a separate daughterboard, a NOR device was stacked in a multichip package with the baseband processor.
France said Ornand is optimized for handling MPEG-4 video and for rapid-fire digital images in "multishot" cameras within high-end cellular phones. Other applications may include car navigation systems and video cameras, and in the handheld dictionaries popular in the Far East for translating words from Asian languages into English.
Ornand memories will have higher reliability than NAND devices, Cambou asserted, due to less stress on the oxide layer during programming.
Phone makers are reluctant to use NAND architectures for storage of critical code because a phone can go dead if bits are corrupted. To program and erase, NAND memories use Fowler-Nordheim tunneling, while MirrorBit devices employ hot carrier electrons.
Cambou said NAND's susceptibility to drop bits requires error correction circuitry (ECC) on NAND while NOR devices are reliable without ECC.
Also, while NAND usually shines in terms of density, Cambou said Ornand's die size is 81 square millimeters for the gigabit part made in a 90-nm process. Samsung, he said, requires 80 mm2 for its single-level-cell gigabit-density NAND.
A Samsung spokesman said it has not placed any multilevel-cell (MLC) parts on the market thus far. That will change soon, as it begins ramping a 4-Gbit MLC part aimed at digital audio and other markets.
