CMOS semiconductor technology will face a dilemma in the 7nm process era in 2024, and graphene is expected to stand out as the best choice to replace this technology - this is according to a special speech at the IEEE Custom Integrated Circuit Conference (CICC) held recently in California, USA.

"Graphene has shown many possibilities that will eventually replace silicon microchips, but I personally think it will take another decade at the earliest, until silicon materials reach their limits, before we will see graphene applications appear." James D. Meindl, professor of electrical and computer engineering at the Georgia Institute of Technology, said. He is also the founding director of the school's Nanotechnology Research Center, which has been committed to graphene research for five years.

In 2024, silicon MOSFETs will reach a bottleneck in terms of the channel length that can be manufactured and the thickness of the insulating gate that can be supported, Meindl said, citing the forecast of the International Technology Roadmap for Semiconductors (ITRS).

Graphene also faces many challenges before it can become an alternative material to replace CMOS. "We have to make billions of transistors on a graphene sheet, but the number of transistors we can currently make is extremely small," said Meindl.

Researchers at the University of Manchester in the UK discovered the new material in a study in 2004. The Nobel Prize-winning research contribution was to find a new way to make a single layer of carbon atoms. “No one thought it could be done, but it was a starting point for what you could do with a single layer of carbon atoms arranged perfectly in a hexagonal honeycomb lattice,” Meindl recalls.

So far, researchers have found at least two techniques for making graphene. They have also made some “pretty crude” working transistors in the material.

Graphene transistors also have better electrical and thermal conductivity and higher current carrying capacity than copper interconnects. Graphene is also attractive for use in MEMS, Meindl says.

“The most impressive graphene transistors to date have been RF transistors,” such as amplifiers for 500-GHz analog signal applications, Meindl said, adding, “Graphene switches are difficult to make for a variety of reasons, including leakage current.”

Meidl’s lab is working on methods to make 15-nm-wide graphene ribbons that could serve as a building block for making graphene switches as fast and efficient as silicon switches. But the main challenge is to make the ribbons with intact edges, which would degrade the material’s forward properties.

To date, nearly 700 researchers from Georgia Tech’s engineering departments have visited Meindl’s lab to explore graphene. "What's interesting about our technology is that it's as broad as engineering and almost as broad as the physical sciences," he said.

The CICC conference agenda also includes a series of papers exploring a variety of research topics, from wired, wireless and optical communications to frequency, PLL, ADC and power components. There are also special topics discussing 3D chip stacking and biomedical technology.