Nanoscale Silicon Fingerprints for Counterfeit Prevention in Microchips

Abstract The increasing vulnerability of microchips to counterfeiting poses a significant threat to nations, companies, and the general public. Creating a unique “fingerprint” on each chip using intrinsic manufacturing variations can significantly prevent the number of fraudulent chips. Since Si‐based semiconductor fabrication processes are now flawless down to a few nanometers, finding a high‐entropy source at the nanoscale has become challenging. Inspired by the concept of physical unclonable function, this work reports the CMOS‐compatible and lithography‐free fabrication of unique nanostructured silicon “fingerprints.” Nanostructuring is achieved via low‐temperature dewetting and metal‐assisted chemical etching, which produces a high level of entropy and unique silicon‐based nanoscale fingerprints with linewidths tunable from ≈8 to 140 nm, commensurate with the dimensions of mainstream microfabrication processes. These Si nanofingerprints are highly reliable for chip authentication and against reverse engineering, providing a large encoding capacity of up to 2 ¹⁶³⁸⁴ /µm ² . For practical applications, detection of fingerprints protected with a polymer coating is demonstrated using back‐scattered electron imaging.