Fabrication of Random and Microscale Features on a Photoresist Film

Eşidir A., Pekdemir S., Kalay M., Önses M. S.

10th International Conference on Materials Science and Nanotechnology for Next Generation, MSNG2023, Kayseri, Turkey, 27 - 29 September 2023, pp.35-36

  • Publication Type: Conference Paper / Summary Text
  • City: Kayseri
  • Country: Turkey
  • Page Numbers: pp.35-36
  • Kayseri University Affiliated: Yes


Counterfeit products and identity violations pose an increasing threat to the world economy, national security, and human health. The importance of ensuring the security of critical documents, information, and objects is increasing. Therefore, a new generation of encoding approaches is needed. An approach that has attracted increasing interest in recent years is the use of physical systems instead of mathematical functions. The basis of this approach, known as "Physically Unclonable Functions (PUFs)," is the use of a physical system based on stochastic processes to obtain random features that are inherently resistant to imitation. In this study, we propose a new approach to fabricating hidden codes with high thermal and mechanical stability. To achieve this, we fabricated surface-embedded PUF systems by generating nanometer-deep cavities directly on a substrate surface. This is achieved by fabricating polymeric structures by electrospraying on a negative tone photoresist. Electrohydrodynamic instability processes ensure randomness, while polymeric structures act as masks in the subsequent light exposure step. During exposure to UV light, the photoresist film has been cross-linked, except for the area under the polymer structures produced by electrospraying. By removing the electrosprayed polymer structures and the underlying uncrosslinked photoresist with a solvent, cavities have been formed at random locations. With the reactive ion etching process, random patterns embedded in the surface have been obtained by transferring the cavities opened in the negative tone photoresist to the substrate below. The integration of the cavities into the substrate has enabled the PUFs to have mechanical and thermal stability similar to the substrate. The embedded PUF system showed excellent uniformity and uniqueness.