Extreme-ultraviolet light (EUV) is the key to state-of-the-art mass production of the classical electronics which drives the continuing information revolution. Scientists from PSI, UCL, EPFL and ETHZ have now used the Swiss Light Source (SLS) to perform the first experiments to demonstrate the potential of EUV for the manufacture of silicon-based quantum nanoelectronics, the building block for truly scalable quantum computers.
In the rapidly advancing domain of semiconductor technologies and quantum computing, scientists have developed methods to engineer devices at the atomic scale. Yet, the challenge of patterning large-scale devices remains a significant obstacle to scale-up, particularly when it comes to fabricating extensive arrays required for dopant-based qubits in silicon. One traditional method relies on the scanning tunnelling microscope (STM), where the high current density of electrons tunnelling from a sharp tip are used to pattern hydrogen-passivated silicon with an atomic-scale precision. But what if we could accomplish this feat using photons instead?
Photons, which are integral to high-volume semiconductor manufacturing through extreme ultra-violet (EUV) lithography, enable the patterning of arrays of billions of transistors to then yield high performance microprocessor, GPU or memory chips, thanks to the use of reflective masks. Now, a team of researchers led by Dr Procopios Constantinou from the Paul Scherrer Institute (PSI) and Associate Professor Steven Schofield from University College London (UCL) have demonstrated for the first time that hydrogen atoms can be desorbed from hydrogen-passivated silicon surfaces using EUV light instead of an STM. This ground-breaking research, published in Nature Communications, provides a path to patterning dopant atoms into silicon over large areas, bridging the gap between atomic-scale STM patterning and large-scale industrial semiconductor manufacturing.
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Image: This image provides an artist’s interpretation of the experiment, complemented by actual data. The black and blue spheres symbolize hydrogen and silicon atoms, respectively. A beam of incident EUV light hits the sample, triggering the desorption of hydrogen atoms from the surface. This process enables the execution of hydrogen desorption lithography. The bottom two panels display data from Scanning Tunnelling Microscopy (STM). The left panel shows an STM of hydrogen-terminated silicon, revealing an atomically clean and smooth surface. Each ‘hole’ in the hydrogen mask appears as a bright protrusion, representing a dangling bond. The right panel presents an STM after EUV exposure. It reveals that the surface is now covered with dangling bonds due to the desorption of hydrogen.