CNT-PUFs: Highly Robust Physical Unclonable Functions Based on Carbon Nanotubes

In this work, we explore a highly robust and unique Physical Unclonable Function (PUF) based on the stochastic assembly of single-walled Carbon NanoTubes (CNTs) integrated by a cost-efficient printing approach on 200mm silicon wafers. PUFs are hardware security primitives that leverage small physical variations to generate device fingerprints that are hard to simulate or clone. Our work demonstrates exceptionally robust CNT-based PUFs exhibiting a highly uniform distribution of 53.8% 0s and 46.2% 1s with an average fractional intra-device Hamming distance (ℋD
intra
) of 0.01. For the first time, ℋD
intra
was calculated from over 28 cyclic electrical measurement sequences for 144-bit PUFs consisting of passivated CNT field-effect transistors. Moreover, we present a broad stability window for the threshold defining the PUF response. It is based on the clearly distinguishable states of the encapsulated PUF cells, leading to fully stable hardware-stored binary keys.