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Abstract: For several years, new tip‐based or laser‐based patterning techniques have been attracting increasing attention as alternative lithography approaches. Most tip‐based techniques are based on the use of commercial or modified atomic force microscopes (AFM) and have so far only been demonstrated at the micrometer scale. Direct laser writing is mostly based on galvanoscanners or (similar to the AFM methods) on piezo drives. The biggest disadvantage in all cases, however, is the insufficient measurement and positioning technology.
At the TU Ilmenau, nanopositioning and nanometrology machines based on advanced laser interferometers have been successfully developed over many years, which are able to overcome this deficit. Consequently, this technique is therefore applied to processes of tip‐ and laser‐based manufacturing. This will enable measurement and patterning at the atomic level on both flat and non‐flat surfaces (e.g. precision optical surfaces).
The laser interferometer‐based high‐precision machines now have resolution up to 5 picometers and sub‐nanometer reproducibility in measurement ranges up to 200 mm x 200 mm. They can be used with AFM heads for both lithography purposes and high‐resolution measurement of fabricated structures. In addition, direct laser writing was demonstrated with both single‐photon processes (at 405 nm) and two‐photon processes based on femtosecond lasers. New effects for laser‐based writing below the Rayleigh resolution limit were found and used.
UV nanoimprint lithography on flat as well as on curved surfaces was demonstrated as another technology. For direct laser writing on curved surfaces, a metrologically traceable 5‐axis machine concept was developed and experimentally tested. Combining advanced nanofabrication technologies with ultra‐precise nanopositioning and nanometrology, a unique symbiosis is created for alternative cross‐scale lithography approaches. |
