Yu Andrew C, Srimani Tathagata, Shulaker Max M
Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States.
ACS Appl Mater Interfaces. 2025 Apr 2;17(13):20411-20417. doi: 10.1021/acsami.4c22130. Epub 2025 Mar 18.
Carbon nanotube field-effect transistors (CNFETs) are promising candidates for back-end-of-line logic integration as a complementary path for continued electronic scaling. However, overcoming CNFET ambient drift (i.e., air stability) and reliability is underexplored. Here, we demonstrate that silicon nitride encapsulation limits ambient atmosphere-induced threshold voltage shift (∼8× reduction of median Δ over 90 days). With stabilized nitride-encapsulated CNFETs, we characterize CNFET negative bias temperature instability (NBTI) with both DC and AC stress across the electric field, temperature, gate oxide thickness, and stress frequency. AC pulsed operation significantly improves CNFET NBTI vs DC operation across a wide frequency range of 1 kHz-10 MHz. A 20% duty cycle AC operation at 10 MHz could extend the NBTI time to failure by > 10× vs DC for a target |Δ| tolerance ≤100 mV with a gate bias = -1.2 V at 125 °C. This work improves our understanding of overcoming ambient drift and BTI reliability in CNFETs.
碳纳米管场效应晶体管（CNFET）作为持续电子缩放的补充路径，是后端线路逻辑集成的有前途的候选者。然而，克服CNFET环境漂移（即空气稳定性）和可靠性的研究还不够充分。在这里，我们证明氮化硅封装限制了环境气氛引起的阈值电压漂移（在90天内中位数Δ降低约8倍）。利用稳定的氮化硅封装CNFET，我们通过在电场、温度、栅极氧化物厚度和应力频率上的直流和交流应力来表征CNFET的负偏置温度不稳定性（NBTI）。在1 kHz - 10 MHz的宽频率范围内，交流脉冲操作与直流操作相比显著改善了CNFET的NBTI。在125°C下，当栅极偏置Vgs = -1.2 V且目标|Δ|容差≤100 mV时，10 MHz下20%占空比的交流操作可将NBTI失效时间延长至直流操作的10倍以上。这项工作增进了我们对克服CNFET环境漂移和BTI可靠性的理解。
