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Startup readies RRAMs for mass production

Posted: 11 Feb 2009 ?? ?Print Version ?Bookmark and Share

Keywords:RRAM technology? resistive RAM? memory universal?

Australian startup 4DS Inc. claims to have made a major breakthrough in resistive RAM (RRAM) technology.

A subsidiary of an Australian company called 4D-S Pty. Ltd, 4DS has also garnered a new round of funding and is now looking for manufacturing partners to commercialize its RRAM technology. The startup is not giving a paper at the International Solid-State Circuits Conference (ISSCC), but it appears to want to crash the party.

For years, chipmakers have been talking about the development of RRAM, a non-volatile memory and potential "universal memory" that combines the density of flash memory and the speed of DRAM. But to date, RRAM technology has been stymied due to material and manufacturing challenges.

A number of companies in Europe, Japan, Korea and the United States are scrambling to develop RRAMs. 4DS claims to have beaten its rivals to the punch, by demonstrating RRAM cells and a process within its small-scale fab in Fremont.

The company is now looking for a manufacturing partner to bring its so-called "4DS memory" into mass production, said Kurt Pfluger, CEO of 4DS. "It's a simple process," Pfluger said. "This has the potential to replace DRAMs and flash."

RRAM quest
FRAM, MRAM, phase-change, RRAM, spin-transfer torque RAM and other technologies are vying for dominance in the "universal memory" race. RRAMs have been the subject of academic research since the discovery of the electrical pulse induced resistance change effect in such films around 2000.

RRAM cells are usually two-terminal devices based on perovskite-oxide thin film materials. Resistive switching memories are based on materials whose resistivity can be electrically switched between high and low conductive states. RRAM is becoming of interest for future scaled memories, because of their intrinsic scaling characteristics compared to the charge-based flash devices, and potentially small cell size, enabling dense crossbar RRAM arrays using vertical diode selecting elements.

Over the years, a slew of companies have explored RRAMSwith little or nothing to show for it. Sharp, Sony, Samsung, LSI, Panasonic, Winbond, Unity, Hynix, Micron, Elpida and others have or are exploring RRAM. In fact, Japanese chipmakers have reportedly poured a combined $100 million in RRAM development, but they have failed to deliver a product.

The latest major effort is taking place in Europe. In order to explore the scaling limitations of conventional flash memory cells, European research institute IMEC has started looking at RRAM cells. Five of the leading memory makersSamsung Electronics Co. Ltd, Hynix Semiconductor Inc., Qimonda AG, Elpida Inc. and Micron Technology Inc.are involved in the IMEC core CMOS research program and are set to share the cost and benefit from the results of the research.

IMEC's research activities on RRAM mainly focus on investigating the switching behavior of the RRAM cell concept that uses metal oxides as a switching element, and on demonstrating its scaling capability down to 25nm. The leading material candidate is nickel-oxide, which has been the subject of study by Samsung at geometries greater than 100nm.

At 4DS, the startup is taking a different approach than IMEC, but it did not reveal its secret sauce. The startup was formed in 2007, after it acquired some technology from an intellectual-property house. At the time, 4DS obtained some funding from a number of investors in Australia and other regions.

"PricewaterhouseCoopers (PwC) is the Australian advisor to 4DS, and has helped to arrange funding for 4DS from Australian investors, as well as advise the company on its commercialization path. "PwC itself has not invested funds in 4DS," Pfluger said.

Last year, Pfluger joined the company as CEO. He has held various management positions at Apogee, In Electronics and others. Other key executives at 4DS include Dan Brors, director of engineering, and Lee Cleveland, director of product development.

Move to production
Last month, 4DS received a new round of funding from Poly Plant Project Inc., a designer and builder of manufacturing plants for the production of polysilicon. Tetsunori T. Kunimune, chairman and CEO of the company, has joined 4DS' board.

Now, it is gearing up for the commercialization stage. "4DS memory has the potential to replace all existing semiconductor memories and can be manufactured in a fraction of the process mask steps above standard CMOS as comparable memory technologies such as flash and DRAM," Pfluger said. "The 4DS method uses existing semiconductor processes and requires fewer changes to the semiconductor manufacturing equipment, enabling simple manufacturing through a technology that can be scaled significantly farther than NAND or NOR flash."

4DS' RRAM is a high-capacity, non-volatile memory with fast switching speeds measured below 5ns, and with an endurance of 1 billion write/read cycles. Compared to flash memory, RRAM requires lower voltages and lower currents, enabling its use in low power applications, he said.

RRAM exhibits lower programming currents than phase-change memory or PRAM, the company said. Compared to MRAM, RRAM has a simpler, smaller cell structure. MRAM has a 16F? structure, while 4DS makes use of a 4F? technology.

The real question is whether or not the technology will move into real production. So far, RRAM and other next-generation memory types have failed to live up to their promises. "With the right partner, we will see our RRAM technology move into production within the next 18 to 24 months," he added.

- Mark LaPedus
EE Times

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