New Insight Into Negative Bias Temperature Instability Degradation During Self-Heating in Nanoscale Bulk FinFETs

Abstract

In this letter, we investigate the threshold voltage shift (ΔV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> ) by negative bias temperature instability (NBTI) coupled with the self-heating effect (SHE) in a 14-nm bulk p-FinFET. To analyze the effect of NBTI in the presence of the SHE, the DC stress was performed under high-bias conditions, i.e., gate bias V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GS</sub> = -1.3 V and drain bias V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS</sub> up to -1.3 V at room temperature, which was usually referred to as hot-carrier degradation (HCD) stress. It has been observed that the long-time (10 s ~ 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> s) power-law time exponent (n) decreases as VDS increases, and n was very close to that of NBTI-induced ΔV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> rather than HCD-induced ΔV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> at V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GS</sub> = V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS</sub> = -1.3 V. For the first time, computer-aided design simulations were performed in combination with SHE and NBTI. The effect of NBTI in p-FinFET is confirmed to contribute significantly to ΔV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> under DC HCD stress because of SHE. The influence of SHE is mitigated in high-frequency circuit operation, but special attention should be paid to NBTI issues due to the potential occurrence of SHE as the technology nodes shrink.