Transistor-limited constant voltage stress of gate dielectrics

Abstract

Conventional methodology gauges gate oxide reliability by stressing with a low impedance voltage source. This is more severe than the stress sustained during circuit operation in which transistors are driven by other transistors. A new test configuration which better approximates circuit stress conditions, the Transistor-Limited Constant Voltage stress, significantly reduces post-breakdown conduction (IBD) as compared to standard Constant Voltage Stress. The smaller the current drive capability of the limiting transistor, the softer the breakdown: If IBD of the broken dielectric is sufficiently reduced while the voltage margin of the circuit is not exceeded, circuits may continue to function even with a failed oxide.