Impact of ultra thin oxide breakdown on circuits

Oxide breakdown evolves in a continuous, voltage-driven manner from initial BD to higher conductance. This permits a redefinition of the oxide failure criterion at the device or circuit level. Instead of the time to first (soft) BD, the appropriate failure criterion is a critical leakage current that disrupts circuit operation. Lifetime estimates may be increased by one or more orders of magnitude over traditional first-BD projections (B. Kaczer et al., 2004). This new oxide failure criterion has two key elements: understanding and characterizing the post-breakdown defect growth and conduction, and understanding and characterizing the circuit sensitivity to leakage currents in gates that have experienced BD. Circuit simulations can be used to estimate circuit sensitivity to BD, by adding a voltage-dependent current source between the gate and one diffusion of a transistor.