Novel built-in methodology for defect testing of capacitor oxide in SAR analog to digital converters for critical automotive applications

Mixed signal components are increasingly used to implement controlling loops and digital signal processors in automotive applications. Successive Approximation Register (SAR) analog-to-digital converters based on switched capacitors play a major role in this evolution. Since the defectivity of the intermetal dielectric in vertical parallel plate capacitors is a major concern of this technology, dedicated screening techniques are needed to implement “zero defects” strategies. A novel screening approach is proposed in this paper, which is based on the use of a dedicated embedded circuitry with very low area consumption. A design is presented, which includes the control logic, the high voltage generation, and the leakage detection circuitry. The concept, advantages and the circuits for the proposed built-in reliability test are described in detail and illustrated by layout and circuit simulations.