EETimes.com – ISSCC: Expert picks winner for post-CMOS era
(02/08/2010 6:09 $� EST)
| SAN FRANCISCO — Chip scaling is expected to continue for at least the next 15 years, according to one expert, who also predicted perhaps the next technology after the post-CMOS era.The winner in the post-CMOS era has not been declared yet, but graphene holds great promise, said James Meindl, director of the Joseph M. Pettit Microelectronics Research Center and Pettit Chair Professor of Microelectronics at the Georgia Institute of Technology in Atlanta, Georgia.
”We will continue to scale vigorously for the next 15 years,” he said during a keynote at the International Solid State Circuit Conference (ISSCC) here. “Beyond silicon microchip technology, revolutionary developments in nanoelectronics, perhaps centering on graphene, may evolve.”
For processors, silicon could scale to the 7.9-nm node, which is slated for 2024. Before or after that, graphene could enable future terascale computing, he said.
So why graphene over the other post-CMOS technology candidates, such as spintronics, molecular electronics, and others? Some claim graphene chips are 100-to-1,000 times faster than silicon. Graphene is the crystalline form of carbon that self-assembles into two-dimension hexagonal arrays perfect for fabricating electronic devices.
Unfortunately, when conventional deposition techniques are used with carbon to grow sheets much larger than one inch, they tend to degenerate into irregular graphite structures. Graphene has higher carrier mobility than silicon, but has been hampered by the lack of a band gap, which has kept the on-off ratio of graphene transistors dismally low–usually less than 10 compared to hundreds for silicon.
Recently, several companies have made headlines in the area. A 100-GHz transistor has recently been demonstrated by IBM Research. Fabricated on new 2-inch graphene wafers and operating at room temperature, the RF graphene transistors are said to beat the speeds of all but the fastest GaAs transistors, paving the way to commercialization of high-speed, carbon-based electronics.
The next-generation of semiconductors could be based on carbon instead of silicon, according to Penn State researchers, who recently claimed to have perfected a method of fabricating pure sheets of carbon semiconductor–called graphene–on 100 millimeter (4-inch) wafers.
Here’s six reasons why Meindl thinks graphene will drive the industry in the post-CMOS era:
1. Graphene has ”a mechanical strength-to-weight ratio exceeding that of any known material.”
2. ”Carrier mobility exceeds 200,000-cm2/Vs.”
3. ”Carriers with zero effective mass that propagate as ‘Dirac fermions’ in a manner similar to photons with a velocity 300 times less than the speed of light without scattering for distances in the micrometer range.”
4. ”The capacity to conduct current densities as large as one thousand times greater than copper without electromigration.”
5. ”Record values of more than 5,000W/mK for room temperature thermal conductivity.”
6. ”The capability to serve as a source, channel drain regions of a field effect transistor (FET) and as an interconnect.”