Inkjet-Printed BaTiO₃ Nanoparticle-Embedded Capacitor Array for Physical Unclonable Function

Nanoparticle (NP)-based physical unclonable functions (PUFs) have attracted attention as a digital fingerprint technology that alternates with microfabrication-based PUFs by utilizing natural randomness at the nanoscale. Mostly NP-based optical PUFs have been proposed due to the absence of nanomaterial fabrication method compatible with microelectronics, but the need for a bulky optical readout system makes it difficult to utilize them in microelectronics. In this work, we developed the NP-based capacitor PUF (CAP-PUF) technology that can be read electrically and integrated into microelectronics while utilizing the benefit of the natural physical randomness of NPs. We incorporated a high-k BaTiO₃ NP inkjet printing micropatterning process for the fabrication of the NP-embedded CAP-PUF array. The inkjet-printing parameters have been optimized to maximize the natural randomness of the BaTiO₃ NP micropatterns by increasing the intrinsic stochasticity, especially the fluid dynamics that occurring during the multilayer printing. The BaTiO₃ NP-embedded CAP-PUF array shows high security performance, showing the inter-hamming distance of 0.52, uniformity of 0.44, entropy of 0.989, and intra-hamming distance up to 0.064. High-k NP inkjet-printing-based CAP-PUFs can provide highly unique digital fingerprints based on the intrinsic randomness in nanoscale for microelectronics.