Laser Instead Of Photolithography Reduces Ultra-surface Production Costs

Researchers at the Moscow Institute of Electronics Technology, a Russian state research university, have developed a new technology for creating components for information display devices using laser pulses instead of lithography. This will accelerate the reduction of production costs for next-generation displays and ultra-surfaces for various optical systems. The findings are published in the new issue of Applied Surface Science.
Hypersurfaces are structures with periodic patterns that can be used to control electromagnetic and light waves. On this basis, dielectric and metallic materials as well as phase change materials can be used. And phase change materials can change the phase state and thus the properties that depend on the external radiation.
On the basis of hypersurfaces made from the phase change material GST (compounds of the germanium-antimony-tellurium system), researchers have developed new compact devices that can display information with the help of light waves. These include ultra-thin displays, augmented and virtual reality headsets, and holographic projectors. However, the process of nanostructuring thin-film surfaces to transform them into multifunctional surfaces has so far been carried out using labor-intensive and costly photolithography. The necessary super-surface image is first created on a template (mask) and then transferred to the object at a selected resolution.
In order to reduce the cost of thin-film structure formation and to speed up the process, the Moscow Institute of Electronics and Technology, together with other scientific institutions, uses laser pulses instead of photolithography. According to the researchers, with the help of laser irradiation in ultrashort pulses, ordered nanostructures can be created on GST faster and easier. To form an ordered surface, a pre-implemented process is utilized, in which the previous material is destroyed in the presence of the laser. The main advantage of the solution is that the pulse triggers the self-organization of structures on the surface. Depending on the intensity and number of pulses, 3 different types of structures may be formed, the most intriguing of which are periodically arranged nanospheres of the same size. These shapes are difficult to form and have a radius of up to 150 nanometers.
Previously, it was impossible to obtain them in these materials without the use of additional techniques, but now, no equipment is needed to obtain nanospheres of the same style, except for the laser device and the film itself. These spheres are produced as a result of the decay of melted filaments. In this case, the increase in the energy of laser irradiation causes a mass transfer process, which leads to the transformation of the nanosphere chains into periodic relief. The above technique makes it possible to create highly ordered nanolenses and optical nanogratings, which are expected to be further integrated with various optical systems, including information display systems.