Intrinsic and Database-free Watermarking in ICs by Exploiting Process and Design Dependent Variability in Metal-Oxide-Metal Capacitances

Authentication of integrated circuits (IC) to verify their integrity has emerged as a critical need to address increasing concerns associated with counterfeit ICs in the supply chain. In this paper, novel SAR-ADC based intrinsic and database-free authentication scheme has been proposed. Proposed technique utilizes mismatch in back end of line (BEOL) capacitors used in charge-redistribution SAR ADC to generate authentication signature. BEOL metal-oxide-metal (MOM) capacitors form a reliable source of process variation information and are less sensitive to aging & temperature induced variations. Line edge roughness is the primary source of mismatch in BEOL capacitors and thus, capacitor mismatch variation has been analyzed in terms of LER and geometric parameters. Resource overhead incurred by the proposed modifications to the ADC architecture to incorporate authentication ability is minimal and existing on-chip calibration circuitry is used to extract signature. Proposed technique does not require sophisticated test setup, thereby, simplifying the authentication procedure.