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X-ray technique creates nanometer-scale 3D reconstructions of computer chips



The chips in our devices are powered by transistors and integrated circuits so small that they can barely be detected by our most advanced imaging techniques. How chip makers manage to do quality control when they can’t even see what they’re working on is a really good question. But a new method from Swiss researchers provides an incredibly detailed look at details on the level of nanometers — and in 3D, to boot.

That entire circle in the image above? 10 micrometers wide. Impressive, right?

Normally in a post like this, I, the well-informed tech writer, would try to walk you, the poor benighted reader, though the technology step by step. But I’ve got to be honest with you: This time I’m as lost as the next guy. So let’s try to work through it together. Sayeth mine authors at the Paul Scherrer Institut:

Modern X-ray optics paired with synchrotron light sources have changed the landscape, with Fresnel zone plates and Kirkpatrick-Baez mirror pairs producing small (7 nm in diameter at 20 keV; ref. 15), intense beams which could be used for scanning probe microscopy.

Kirkpatrick and Baez invented the X-ray microscope in the 1940s, but it and fresnel stuff have come a long way. Synchrotrons create super-precise light beams. So basically this is not an entirely new concept, but technological limitations have prevented it from being used this way before.

Self-explanatory, right? The synchrotron sends the X-rays through the lens array, through the sample and onto the detector. The dots are the locations of individual scans as the sample is spun around.

Okay, next:

Highly coherent radiation produced by undulators at third-generation X-ray synchrotrons has allowed the development of a mixed real-space/reciprocal-space imaging technique, called ptychographic X-ray computed tomography (PXCT).

Real-space scanning would be like getting an X-ray of your arm, where you record the signal strength on the other side; different substances absorb different amounts and frequencies of the radiation. Reciprocal space has to do with the… well, it’s kind of like a quantum shadow that can tell you about the makeup of an atomic lattice.

This video explains it, kind of: