Less Is More And More

Two groundbreaking developments recently rocked the world of nanotechnology in the electronics spectrum. First, UK company Surrey NanoSystems launched a new, and what could prove extremely versatile, nanomaterials growth platform. Second, important advances have been made in the development of electronic circuits on graphene, the one-atom-thick carbon material.

The Surrey NanoSystems development, called NanoGrowth-Catalyst, consists of nine nanomaterial processing techniques that can synthesise an array of nanomaterials, including graphene, nanowires, and carbon nanotubes. A multi-chamber design enhances that versatility—it continuously maintains the substrate under vacuum conditions, thus ensuring a pure processing environment. Vacuum processing is important because nanomaterials are very vulnerable to atmospheric contamination.

But it’s not all about technology with this system. There’s an economical advantage to the NanoGrowth-Catalyst method because it can replace multiple items of process equipment with a single automated system.

Processing options include:

  • Low-pressure chemical vapour deposition (LPCVD)
  • Plasma-enhanced (PECVD)
  • Sputtering
  • Delivery of solid- or liquid-phase catalysts/precursors
  • Creation of controlled-density nanoparticle catalysts at room temperature
  • Thermal annealing
  • Rapid thermal processing (RTP)
  • A form of rapid thermal growth for nanomaterials called RTG

In addition to making nanomaterial growth equipment, Surrey NanoSystems is developing nanoelectronics materials and processes to support the continued scaling of semiconductor devices. The NanoGrowth-Catalyst’s automated handling and processing capabilities should support the company’s research into nanomaterial growth at temperatures compatible with mainstream CMOS fabrication.

Advances have already been made regarding the practical fabrication of interconnection vias and low-k dielectrics for inter-layer insulation. That’s significant considering the continuous pressure to shrink semiconductor geometries.

Most manufacturers use copper to provide the interconnections required for IC fabrication, but it has limitations as IC geometries shrink further. Carbon nanotubes (CNTs) can be structured to act as efficient conductors. However, because CNTs require process temperatures of 700°C—far too high for semiconductor processing—it also restricts their use as interconnects.

But with Surrey NanoSystems’ fabrication system and process, CNT structures can be grown at processing temperatures of 350°C or less, which is far more compatible with existing semiconductor manufacturing processes.

Graphene Breakthrough
The second technology breakthrough involves creating nanocircuitry on graphene, a material considered most likely to replace silicon for IC manufacture. Scientists developed an efficient process based on thermo-chemical nanolithography for creating nanowires. It can adjust the electronic characteristics of graphene so that it can act as an insulating material—or a conductive material.

One important property of graphene is that electrons can travel through it much faster than silicon. Another major feature, as mentioned earlier, is that it’s a mere one atom thick.

Graphene is, in effect, a sheet of carbon. Existing forms of carbon basically consist of sheets of graphene, formed on top of each other to create a solid material. For many years, scientists considered separating a free-standing form of graphene impossible. However, after a series of process developments, carbon can now be sliced down into one-atom-thick sheets.

No doubt, technologists are piqued by these breakthroughs, considering the mounting pressure they face to shrink semiconductor geometries in the ceaseless endeavour to pack ever-more functions onto ever-shrinking ICs.

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