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Z-RAM to Take on DRAM with Hynix Deal

Swiss company's technology could double the density of memory chips

2 min read

Samuel K. Moore is IEEE Spectrum’s semiconductor editor.

13 August 2007—The Swiss memory company Innovative Silicon says it has struck a deal to license its technology to the No. 2 maker of standalone DRAM memory chips, Hynix Semiconductor, based in Inchon, South Korea. The technology, called Z-RAM (for zero-capacitor DRAM), could potentially double the density of Hynix’s memory chips. Until now, Innovative Silicon’s technology had been considered only for use as memory embedded on microprocessors and other logic chips, where it would replace or augment caches of SRAM. The deal moves Innovative Silicon, based in Lausanne, Switzerland, into a new market worth more than US $30 billion, making the total market it could serve more than $100 billion. During an interview with IEEE Spectrum last year, Innovative Silicon’s CEO, Mark-Eric Jones hinted that a DRAM license was in the works.

Sung-Joo Hong, vice president of R&D at Hynix calls Z-RAM ”an elegant approach to manufacture dense DRAMs.” The technology could help Hynix create a whole new platform of products, he adds.

Terms of the deal were not disclosed. Innovative Silicon would say only that the license and engineering fee would be worth ”eight figures” and that if Hynix puts the technology into production there would be royalties at that time. It is the Swiss firm’s second license. The first went to the U.S. microprocessor firm Advanced Micro Devices (AMD) in late 2005.

Z-RAM replaces the six transistors of SRAM and the transistor-plus-capacitor structure of DRAM with a single transistor. While the semiconductor industry has been able to steadily shrink the size of transistors for some 40 years, DRAM makers have the added difficulty of shrinking capacitors, which are used to store bits. Capacitors cannot shrink at the same rate, because they must be able to store a recognizable amount of charge. The capacitor in a DRAM cell is therefore much larger and more difficult to construct than the transistor.

In a Z-RAM cell, the bit is stored as charge within the transistor itself, doing away with the capacitor. However, Z-RAM works only if the chip is built from a silicon-on-insulator (SOI) wafer. Such wafers contain a layer of silicon dioxide insulation buried below a silicon surface. Certain microprocessor makers, notably Sunnyvale, Calif.�based AMD, make their chips on SOI wafers to reduce the amount of power they draw and improve performance. At the moment, none of the major DRAM makers, Hynix included, uses SOI.

Before developing Z-RAM at Ecole Polytechique Fédérale de Lausanne, Innovative Silicon cofounder Pierre Fazan, was an engineer at one of Hynix’s competitors, Micron Technology Inc., in Boise, Idaho.

Also on Spectrum Online

Masters of Memory,” January 2007

Price Fixing in the Memory Market,” December 2004

Embedded DRAM Chips on the Rise,” March 2007

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