Wednesday, 8 June 2016

Seeing through chips

Rayko Ivanov Stantchev and his team have found a way to look inside computer chips. With terahertz radiation, they are able to look through materials that are otherwise opaque.

Light, but not quite
Terahertz radiation is part of the electromagnetic spectrum. This spectrum also contains radio waves, ultraviolet rays and also visible light. All types of radiation are sorted by wavelength on the spectrum. Terahertz’s wavelength comes right between microwaves and infrared, making its wavelength slightly longer than that of light. This is excellent for looking through materials, because the longer the wave, the bigger the objects the wave can ‘see through’. That’s why your computer has no problem with seeing the WI-FI (that are in fact radio waves), that comes from your router, but you can’t see the router, if you’re not sitting next to it. Radio waves have a way longer wavelength, and thus they can ‘bend’ around your furniture, stairs and cat. While the visible light, that your eyes see, has a shorter wavelength and can’t bend around your cat. But in the ability of waves to bend around things also lays the problem. You don’t want the waves to bend around the thing that you actually want to see. Terahertz waves have just the right wavelength

The electromagnetic spectrum, terahertz radiation comes between microwaves and infrared
Looking straight through
With terahertz radiation, we can look through computer chips, while still being able to see the structures inside it. To be able to look inside the chip, Rayko Ivanov Stantchev and his team beamed patterns of radiation onto a slice of silicon, the material most computer chips are made out of, that was only a hundredth of a centimetre thick. Because of this pattern, the silicon become transparent for the terahertz radiation. But the structures inside the chip don’t become transparent, enabling the scientists to see them. With this technique, they were able to find malfunctioning parts in the chip as small as eight micrometres across. That’s about half as thick as the finest human hair.

Image made with terahertz radiation,
 you can clearly see the structure
Computers and biology
The researchers consider using terahertz radiation a technique with much potential. For now, the possibility to see through silicon is limited by the thickness of the material, and the material can’t be really thick yet. Scientist predict that with improving the techniques, much thicker materials could be used. This can be really helpful with checking computer chips for malfunctioning parts, since the chips can just be ‘scanned’. But terahertz radiation has another interesting use. It could also be used in biology to scan tissues, because water, which is abundant in all living organisms, absorbs the terahertz radiation, making it easy to detect were there’s a lot of water. Because the radiation doesn’t bounce off of those spots. All in all a very promising technique that will benefit both computer sciences and biology.

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