ELDRS in Bipolar Linear Circuits: A Review

Enhanced Low Dose Rate Sensitivity (ELDRS) in bipolar linear transistors was first identified in bipolar microcircuit transistors in 1991 and demonstrated in bipolar linear circuits in 1994. Since then it has been a major topic of research, characterization and analysis. Data compendia of low dose rate enhancement factors were presented in 1996, 2001 and 2008, identifying 30 unique widely used circuit types as susceptible to ELDRS. Early work on ELDRS was directed toward identifying mechanisms, characterizing circuits and developing hardness assurance methods, concentrating on accelerated testing techniques. More recently the research on ELDRS has focused on the effects of pre-irradiation elevated temperature stress (PETS), final passivation layers and molecular hydrogen in the package. This review paper provides an update on ELDRS in bipolar linear circuits, including the most recent results of mechanisms research, and the effects of post metallization processing on the total ionizing dose response.