Effect of Radiation & HEI on Flicker noise in 0.5 μm CMOS transistor

Abstract

The ubiquitous flicker or 1/f noise deteriorates low-frequency (LF) signals. For high reliability in CMOS devices, factors leading to degradation of SNR in LF domain need to be understood and minimized, especially for devices processing low-frequency signals. With transistors scaling down, power consumption decreasing and advancement in system integration, portable integrated CMOS sensors are being used in labs, hospitals, space applications etc. In such field applications, continuous radiation exposure degrades the sensors as well as deteriorates the signal to noise ratio. Also, in certain applications, continuous operation of sensors with high voltage stress on transistors causes hot electron injection (HEI) which also deteriorates the SNR by increasing the trap density in the gate oxide and making the sensor unreliable over time. To address the issue of SNR deterioration and to understand the reliability aspects of the sensors due to such operational stresses, we present a study of the impact of γ$\textbf{radiation exposure and hot electron injection on flicker noise of CMOS transistors. While flicker noise has been characterized in other processes, we chose the commonly available, low cost 0.5 um CMOS process for our study.