Peter Clarke

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EE Times

(04/24/2006 9:34 AM EDT)

LONDON — A reversible resistance change process observed in thin oxide films has enabled the creation of a novel form of non-volatile memory that could come to market as a test product this year, according to a technology analysis report from Web-Feet Research.

Resistive RAM (RRAM) development is a focus for several device manufacturers because it promises high density, low cost and low power consumption, according to semiconductor production equipment maker Tegal Corp. (Petaluma, Calif.), which has provided equipment to researchers. Like many other technologies before it, RRAM promises to provide a replacement for flash memory, if and when that technology should have problems scaling.

Although companies are reluctant to build products around immature or incompletely understood materials and processes, the size of the non-volatile memory market is such that companies are also fearful of missing out on a potential next-generation driver for a multi-billion-dollar market.

The buzz around RRAM has already stimulated dozens of patent applications in the United States alone and numerous semiconductor companies are researching the topic and developing proprietary oxide films for inclusion in standard CMOS processes. ((LOL))

The technology could go on to form the basis of a commercial product in 2008, according to a Japanese website which includes the key findings of the Web-Feet study on its website to promote sales of the research report. Only those technologies and technology variations that could be productized within the next five years are analyzed in this study which was published in 2005.

Companies investigating RRAM include Sharp Corp., Sony Corp., Samsung Electronics Co. Ltd., LSI Logic Corp., Matsushita Electric Industrial Co. Ltd., and Winbond Electronics Corp., according to a review of U.S. patents granted and applied for.

Researchers at Sharp working with the University of Shizuoka have recently developed a prototype of a high-speed RRAM, according to several online reports that referenced the Nikkei Daily Business as their source. Tests showed that the memory allowed writing and reading of data at rates 1000 times faster than those possible with NAND flash memory, the reports said.

The reports did not say what size array the researchers had fabricated or what manufacturing process had been used to create the array.

RRAM cells are usually two-terminal devices based on perovskite-oxide thin film materials and has been the subject of academic research since the discovery of electrical pulse induced resistance change effect in such films in around 2000.

The pulse is thought to create multiple filamentary conduction paths through the film which changes the resistance of the conduction path, but which is also a reversible process.

Samsung was reported by Solid-State Technology to be working on a version of RRAM in 2005 which made use of binary metal oxides instead of perovskite materials. Researchers had made a memory cell using a nickel-oxide (NiO) layer between electrodes, the report said.

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