TECHNOLOGY FOR CHANGE

Carbon Life Forms to Create Like-Minded Microchips

R. Colin Johnson | Date: 02-24-10 | Comments

Silicon microchips are the mainstay of all current electronic devices today, but could soon be replaced by carbon-based microchips that harness carbon's higher speed but without generating the excess heat plaguing silicon chips today. To prove the point, IBM Research recently demonstrated the world's fastest carbon transistor.

Life on Earth could have evolved from silicon�the same as today's microchips�but natural selection instead evolved carbon-based life. Now human engineers are realizing that the same principles that enabled life to emerge from carbon compounds could also solve the problems facing future electronics.

IBM Research recently created the world�s fastest carbon transistor (top) fabricated on the industry�s first graphene wafers (bottom).

Today, the single most serious problem facing future silicon-based electronics is excess heat generation. The smaller you make silicon chips, the faster they go, but unfortunately they also generate more heat. Carbon electronics, on the other hand, do just the opposite�that is, they run cooler the smaller you make them. For instance, the human brain is more powerful than the world's fastest supercomputer, and yet only consumes a mere 25 watts.

One area where silicon chips have already overheated and run out of steam is radio frequency (RF) communications. Silicon chips today cannot run much faster than 5GHz without generating enough power to melt themselves down. Unfortunately, RF frequencies for future communications devices need to run at up to 1,000GHz (1 terahertz).

The answer, according to the U.S. Defense Department, is switching to carbon-based electronics. The Defense Advanced Research Projects Agency (DARPA) recently tasked Program Manager Mike Fritz with the job of perfecting carbon electronics for RF applications in its Carbon Electronics for RF Applications (CERA) program. CERA funded IBM Research efforts that recently passed a significant milestone along that road by fabricating the world's fastest carbon transistor at 100GHz�more than 20 times faster than the silicon CMOS (complementary metal-oxide semiconductors) transistors used today.

"The 100GHz cutoff frequency recently demonstrated by the IBM team in the CERA program is an exciting milestone," says Fritz.

The first goal of CERA was to perfect a method of laying down pure crystalline sheets of carbon on wafers, the same way that silicon is layered in pure crystalline sheets from which CMOS microchips are made. These carbon sheets are called graphene, and are currently being fabricated onto wafers using the same techniques used to process silicon wafers, albeit at smaller sizes today.

"In addition to pushing the speed metrics, the CERA program will also continue to improve the wafer-scale graphene film quality," Fritz states. "The biggest challenge is achieving high-quality wafer-scale synthesis of thin graphene films."

IBM Research recently reported progress in fabricating these graphene films onto 2-inch wafers, from which it created its world's fastest carbon transistor. There is still a long way to go�silicon chips are made on much larger 12-inch wafers�but CERA is only just concluding the first of three phases, each 18 to 24 months long.