Oxide Breakdown Spot Spatial Patterns as Fingerprints for Optical Physical Unclonable Functions

Dielectric Breakdown (BD) of the gate oxide in a Metal-Insulator-Semiconductor (MIS) or Metal-Insulator-Metal (MIM) structure has been traditionally considered a major drawback since such event can seriously affect the electrical performance of the circuit containing the device. However, since BD is an inherently random process, when externally detectable by optical means, the phenomenon can be used to generate cryptographic keys for Physically Unclonable Functions (PUFs). This is the case discussed here. Images containing BD spot spatial distributions in MIM devices were binarized and their uniformity, uniqueness and reproducibility evaluated as fingerprints for security applications such as anti-counterfeiting purposes, secure identification and authentication of components. The obtained results are highly promising since it is demonstrated that the generated fingerprints meet all the mandatory requirements for PUFs, indicating that the proposed approach is potentially useful for this kind of applications

A Multi-bit/cell PUF Using Analog Breakdown Positions in CMOS

© 2018 IEEE. A physically unclonable function (PUF) utilizing the analog positioning of breakdown spots in CMOS transistors is presented. In contrast to digital positioning based on a three-transistor cell [3], this new approach has the capability of generating multiple bits from a more compact two-transistor cell. The basic properties and reliability aspects of this PUF are studied based on the test chips fabricated in a commercial 40nm CMOS technology. The breakdown positions in high density arrays have been characterized, proving that indeed multiple bits can be generated from a single nFET. Through consecutive measurements, the long-term stability is found to be reduced, due to shrinking of readout window, especially when more bits are generated. Finally, high temperature also negatively impact the stability, indicating that the analog BD-PUF is a lesser promising candidate for PUF application than the previously presented binarized design.status: accepte