Cutting-Edge Imaging Reveals Microchip Transistor Details

A groundbreaking X-ray imaging technique has been developed, allowing for the visualization of internal structures in various samples, such as microchips and catalyst particles, with nanometer resolution over a large field of view without causing any damage. This innovative method, primarily developed at DESY´s high-brilliance X-ray source PETRA III, has captured the interest of the industry as a new characterization tool for research and development, as highlighted by the developer team led by DESY scientist Mikhail Lyubomirskiy in the journal Advanced Science.

Unlike visible light, X-rays possess the ability to penetrate matter to significant depths while offering remarkable resolution in the order of a few nanometers, all thanks to a technique known as ptychography. This technique involves scanning the sample in fine steps and observing how the X-rays are diffracted or scattered by it. Ptychography can achieve the highest possible resolution, but it requires the step size during scanning to be smaller than the diameter of the X-ray beam.

However, the penetration depth is influenced by the radiation wavelength, with a shorter wavelength necessary for larger sample sizes. Bright X-ray sources, such as synchrotron light sources, experience a decrease in generation efficiency as the wavelength decreases. Additionally, only a fraction of X-rays can be utilized, and the focusing efficiency of conventional X-ray optics diminishes as well. PETRA III, boasting the largest circumference among synchrotron radiation sources globally, can provide this technique at shorter wavelengths compared to other X-ray sources.

One of the challenges faced in performing imaging experiments with shorter wavelengths is the significant increase in measurement time. To address this issue, the authors introduced a method called Multibeam Ptychography, which involves using an array of six to twelve nano lenses printed by a high-definition 3D printer to direct a manifold beam of the synchrotron source onto the sample. This approach allows for the illumination of the sample with X-rays of very short wavelengths, making it particularly appealing in industries like microelectronics and catalysis research.

To apply this new technology effectively, the team had to tackle two main challenges: developing optics that could be densely packed while still providing sufficient focusing power to spread X-rays over a large area at the detector without saturating it, and devising algorithms capable of separating signals from multiple parallel beams. Lyubomirskiy explains, “Our new approach combined the development of revolutionary optics manufactured by cutting-edge 3D printing technology, enabling parallel irradiation of thick samples with X-rays of very short wavelengths while maintaining sufficient focusing power and smart algorithms capable of disentangling signals from multiple parallel beams.”