Researchers at the Massachusetts Institute of Technology say they have made a breakthrough with light technology that could eventually help chip makers create finer circuits.
The researchers have come up with a way to focus a beam of light on a scale far smaller than was previously possible, allowing chip makers to etch even tinier circuits onto their chips, said Rajesh Menon, a research engineer at MIT's department of electrical engineering and computer science.
Chip makers depend on light to draw circuit patterns on chips, but most of the techniques used today cannot produce patterns that are smaller than the wavelength of light itself.
The MIT researchers came up with a way to draw extremely narrow lines by combining beams of light at different wavelengths. They used so-called interference patterns, in which different wavelengths of light sometimes reinforce each other, and in other places cancel each other out.
They say the technique, which is still several years away from commercial use, could allow chip makers to build interconnects and transistors as narrow as a single molecule, or just two to three nanometers.
“If you make your transistors smaller, they typically work faster, you get more functionality,” and the cost of manufacturing each chip goes down, Menon said.
Chip manufacturers like Intel and Advanced Micro Devices are consistently building smaller and smaller transistors to get faster performance and use less power. They typically etch chip designs onto a glass material called a photomask, which is then used to replicate the pattern onto silicon wafers.
“What Intel does is pattern replication. You have a pattern and that is replicated” from a photomask straight onto the chips, Menon said. Intel's approach involves using electrons, while MIT's approach involves direct pattern creation via light sources, which it says can be more accurate and provide the flexibility to change designs quickly.
“If you do patterning with electron beams, you will always have to worry about accuracy. Your patterns could get slightly distorted, which could have a big impact on device performance. Photons will go where you tell them to go, whereas electrons won't at the nanoscale,” Menon said.
While the researchers managed to produce lines 36 nanometers wide, Menon acknowledged that the technology could hit a wall when it gets down to the atomic scale. “The question then becomes — can you make the molecule smaller? You're probably limited then,” Menon said.
