Extracting Voltage Dependence of BTI-induced Degradation Without Temporal Factors by Using BTI-Sensitive and BTI-Insensitive Ring Oscillators

Measuring bias temperature instability (BTI) by ring oscillators (ROs) is frequently used. However, the performance of a semiconductor chip is fluctuated dynamically due to bias, temperature and etc. BTI-sensitive and -insensitive ROs are implemented in order to extract BTI-induced degradation without temporal fluctuation factors. A test chip including those 840 ROs was fabricated in a 65 nm process. BTI-induced degradation without temporal fluctuation was successfully measured by subtracting results of BTI-insensitive ROs from those of BTI-sensitive ones. Extraction of BTI-induced degradation is useful in any supply voltage. Performance degradation of NMOS and PMOS transistors mainly due to BTI increases along power law function and fitting parameters decreases as the supply voltage decreases.