Improving the NBTI characteristics of long-channel PMOSFETs by short channel with source underlap structure

Recently long-channel PMOS transistors are being used in delay circuits to increase delay time. Negative Bias Temperature Instability (NBTI) has channel length dependency which shows that long-channel devices degrade more than short channel devices. We suggest a source underlap structure with short channel transistor to solve this problem. We confirmed the short-channel device with underlap structure shows improved NBTI characteristics compared to normal long-channel device through a device simulation.