Silicon transistors have been made smaller year after year, but they are approaching a point of physical limitation. Continuing to shrink the size of the transistor – including the channels and contacts – without compromising performance has become a major technology hurdle..


Researchers have known that carbon nanotube (CNT) chips could provide an answer, greatly improving the capabilities of high performance computers and other devices, The carbon nanotubes form the core of a transistor device whose superior electrical properties promise several generations of technology scaling beyond the physical limits of silicon. The promise of CNTs centers on the fact that electrons in carbon transistors can move more easily than in silicon-based devices, and the ultra-thin body of carbon nanotubes provide additional advantages at the atomic scale


The trouble is as devices become smaller, increased contact resistance for carbon nanotubes has hindered performance gains. Inside a chip, the contacts are the valves that control the flow of electrons from metal into the channels of a semiconductor. As transistors shrink in size, electrical resistance increases within the contacts, which impedes performance


But now IBM researchers say they have found a way to forego traditional contact schemes and have invented a metallurgical process akin to microscopic welding that chemically binds the metal atoms to the carbon atoms at the ends of nanotubes. This ‘end-bonded contact scheme’ is said to allow the contacts to be shrunken down to below 10 nanometers without deteriorating performance of the carbon nanotube devices.


IBM, which had previously shown that carbon nanotube transistors can operate as excellent switches at channel dimensions of less than ten nanometers, says that the new development can overcome contact resistance challenges all the way to the 1.8 nanometer node – four technology generations away, Dario Gil, IBM vice president of Science and Technology characterized the breakthrough as bringing us “a step closer to the goal of a carbon nanotube technology within the decade.”.