A test circuit based on a ring oscillator array for statistical characterization of Plasma-Induced Damage

We propose a test circuit for characterizing Plasma-Induced Damage (PID) based on a ring oscillator array for collecting high-quality BTI statistics. Two types of ring oscillators, PID protected and PID damaged, with built-in antenna structures were designed to separate PID from other effects. A beat frequency (BF) detection scheme was adopted to achieve high frequency measurement precision (>0.01%) in a short measurement time (>1μs) to prevent unwanted BTI recovery. The proposed circuit enables accurate PID-induced BTI lifetime prediction with different Antenna Ratios (ARs) in any type of device with any topology of antenna structure under any fabrication process. Measured frequency statistics from a 65nm test chip shows a 1.15% shift in the average frequency as a result of PID.