Exploring Accelerated Aging Stress for Physical Unclonable Function Self-Corruption

Silicon-Based Physical Unclonable Functions (PUFs) exploit inherent manufacturing variations to produce a unique, random, and ideally unclonable secret key. As electronic devices are decommissioned and sent for End of Life (EOL) recycling, the encrypted critical program information remains within the device. However, conventional PUFs remain vulnerable to invasive attacks and reverse engineering that with sufficient time, resources, and effort can enable an adversary to bypass the security enclave of the system and extract this secret data. Recent research has started to explore techniques to respond to tamper attempts using electromigration (EM) and time-dependent dielectric breakdown (TDDB) to the PUF entropy source, preventing future authentication attempts with well-known semiconductor reliability failure mechanisms. This work presents a Pre-Amplifier Physical Unclonable Function (Pre-Amp PUF) with a self-corruption function designed and manufactured in a 3 nm FinFET technology. This PUF can perform a destructive read operation as an EOL anti-counterfeit measure against recycled and reused electronics. The destructive read utilizes an accelerated aging technique that exploits both Hot Carrier Injection (HCI) and Bias Temperature Instability (BTI) degradations directly at the PUF entropy source bitcell data. This work demonstrates a silicon proven ability to irreversibly corrupt the encryption key, invalidating the PUF key, and blocking future authentication attempts. By utilizing HCI and BTI aging effects rather than physical damage a PUF that can self-corrupt its own key without being detectable with imaging techniques is demonstrated for the first time. A feedback loop enables corruption of up to ~30% of the PUF entropy source, which is approximately 3× more data corruption than the prior state of the art self-corrupting PUF. Our technique reuses on-chip stable (repeatable) PUF bitcells identifying circuitry and thereby minimizes the area overhead to support this differentiated feature.