The impact of Hot Carrier Injection (HCI) on Voltage Control Oscillator lifetime prediction

This paper presents a comprehensive study of the impact of Hot Carrier Injection (HCI) on differential LC Voltage Controlled Oscillator (VCO) reliability tests. Although Negative Bias Temperature Instability (NBTI) has been recognized as major cause for reliability degradation of advanced circuits, HCI-induced degradation may become significant due to the accelerated aging of reliability tests leading to incorrect circuit lifetime prediction. To distinguish HCI effects, different stress voltages and frequencies are applied in Constant Voltage Stress (CVS) and Ramp Voltage Stress (RVS) tests. It is verified that the stress voltage and frequency dependence of time and voltage exponents in the reliability tests are due to the effect of HCI. Based on the observed results, a methodology is proposed to define proper stress conditions for accelerated circuit reliability tests for better lifetime prediction.