Porous silicon oxide improves memory prod'n
A team of researchers from Rice University has developed what they say is a breakthrough silicon oxide technology aimed at high-density, next-generation computer memory that is one step closer to mass production. According to them, this is a result of a refinement that will allow makers to fabricate devices at room temperature with conventional production techniques.
This scanning electron microscope image and schematic show the design and composition of new RRAM memory devices based on porous silicon oxide that were created at Rice University. (Credit: Tour Group/Rice University)
First discovered five years ago, Rice's silicon oxide memories are a type of two-terminal, "resistive random-access memory" (RRAM) technology. In a paper available online in the American Chemical Society journal Nano Letters, a Rice team led by chemist James Tour compared its RRAM technology to more than a dozen competing versions.
"This memory is superior to all other two-terminal unipolar resistive memories by almost every metric," Tour said. "And because our devices use silicon oxide, the most studied material on Earth, the underlying physics are both well-understood and easy to implement in existing fabrication facilities." Tour is Rice's T.T. and W.F. Chao Chair in Chemistry and professor of mechanical engineering and nanoengineering and of computer science.
Tour and colleagues began work on their breakthrough RRAM technology more than five years ago. The basic concept behind resistive memory devices is the insertion of a dielectric material, one that won't normally conduct electricity, between two wires. When a sufficiently high voltage is applied across the wires, a narrow conduction path can be formed through the dielectric material.
This illustration depicts the rewriteable crystalline filament pathway in Rice University's porous silicon oxide RRAM memory devices. (Credit: Tour Group/Rice University)
The presence or absence of these conduction pathways can be used to represent the binary 1s and 0s of digital data. Research with a number of dielectric materials over the past decade has shown that such conduction pathways can be formed, broken and reformed thousands of times, which means RRAM can be used as the basis of rewritable random-access memory.
RRAM is under development worldwide and expected to supplant flash memory technology in the marketplace within a few years because it is faster than flash and can pack far more information into less space. For example, manufacturers have announced plans for RRAM prototype chips that will be capable of storing about one terabyte of data on a device the size of a postage stamp, more than 50 times the data density of current flash memory technology.
The key ingredient of Rice's RRAM is its dielectric component, silicon oxide. Silicon is the most abundant element on Earth and the basic ingredient in conventional microchips. Microelectronics fabrication technologies based on silicon are widespread and easily understood, but until the 2010 discovery of conductive filament pathways in silicon oxide in Tour's lab, the material wasn't considered an option for RRAM.
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