IBM announces a breakthrough in the field of chips: carbon chips

Researchers from the IBM Corporation have demonstrated an innovative approach to carbon nanotechnology, which they claim paves the way for the commercial production of chips that include transistors composed of carbon nanotubes

Researchers from the IBM Corporation have demonstrated an innovative approach to carbon nanotechnology, which they claim paves the way for the commercial production of chips that include transistors composed of carbon nanotubes.

Many believe that carbon nanotubes will one day in the future replace the silicon technology that dominates the field of semiconductors, a development that will be able to further minimize the chip structure. Carbon nanotubes have better electrical properties than silicon, especially for building nanometer transistor devices.

The IBM Corporation claims that its scientists have succeeded, for the first time ever, in integrating more than ten thousand active nanotube transistors into a single device, using processes common in the semiconductor industry. Until now, according to IBM, scientists have been able to place only a few hundred units of carbon nanotube devices at a time, an amount that is far from meeting the requirements for commercial applications. According to the corporation, their innovative approach paves the way for the production of circuits that include a large number of carbon nanotube type transistors at predetermined points on the surface. In the end, the researchers claim, more than a billion transistors of the carbon nanotube type in a single device will be required to enter the commercial arena.

"The motivation to work on transistors of the carbon nanotube type lies in the fact that, with extremely tiny nanometer dimensions, these structures outperform transistors composed of any other material," says the director of the physical sciences department at the corporation's research laboratory. "At the same time, it is still necessary to face considerable challenges in the field, such as the highest level of cleanliness required of the carbon nanotube and precise positioning at the nanometer level. We managed to make a lot of progress on these two issues."

Scientists from all over the world are harnessing the structures known as carbon nanotubes, which they found in the world of chemistry, for applications ranging from integrated circuits, energy storage and conversion devices to biomedical sensing and DNA sequencing.

BMW admits that there are still real challenges preventing carbon nanotubes from becoming a commercial technology, including the level of cleanliness and the placement of the devices themselves on the substrate. Normally, carbon nanotubes come in the form of a mixture of metallic and semi-conducting materials and must be perfectly positioned on top of the chip surface in order to have functional electrical circuits. In order for the device to function properly, it is necessary to completely remove the metallic nanotubes and this to prevent defects in the integrity of the circuits. In order to reach a commercial level, say the IBM researchers, it is essential to allow complete control over the position and arrangement of the carbon nanotubes on the substrate.

In order to overcome these bumps, the IBM researchers developed a method, based on the chemistry of ion exchangers, which allows for a precise and controlled positioning and arrangement of the carbon nanotubes on top of the substrate while organizing them tightly. The process involves mixing the carbon nanotubes together with a surfactant - a type of soap-like substance - which causes them to dissolve in water. A substrate consisting of two types of oxides, hefnium oxide and silicon oxide, which contains chemically adjusted channels, is immersed in a solution of carbon nanotubes. In this reaction the nanotubes are chemically bound to regions of the hafnium oxide while the rest of the surface remains unbound.

Many believe that the miniaturization of transistors made of silicon is approaching its physical limits. The ever-smaller dimensions of the transistors - which reach the nanometer scale - prevent future profit in terms of performance, due to the nature of the silicon material and due to the laws of physics themselves. Within a few years, many researchers believe, the popular miniaturization method of silicon transistors will come to an end.

On the other hand, carbon nanotubes are monoatomic sheets of carbon rolled into a tube. The carbon nanotube forms the core of the transistor device that can operate similarly to the current silicon transistor, but with better performance, according to IBM researchers. At the beginning of the year, researchers showed that transistors composed of carbon nanotubes can function as excellent switches on a molecular scale of less than ten nanometers - a thickness ten thousand times smaller than a human hair and smaller than half the sizes prevalent in today's leading silicon technology.

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