Extracting 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 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. Performance degradation of NMOS and PMOS transistors mainly due to BTI increases along logarithmic and exponential functions, respectively.