Implications of Total Dose on Single-Event Transient (SET) Pulse Width Measurement Techniques

Most pulse width characterization circuits measure single-event transients (SETs) using a target circuit consisting of long inverter chains or temporal latches exposed to heavy-ions over extended periods of time. For these approaches, circuit-level effects eliminate shorter pulses due to prolonged heavy-ion exposure providing the worst case estimate of measurable transients. Simulation results in the IBM 180 nm and 90 nm technologies corroborate this effect and discuss the resulting factors affecting single event (SE) error cross-sections. Experimental evaluation of such a SET pulse width characterization circuit under heavy-ion exposure showed reduced number of events measured due to total dose effects as expected. Additional experimental and simulation results show that the length of the propagation chains in the target circuit (for capturing SETs), the exposed flux and time (total dose) affect the resulting number of SEs measured.

I. Introduction

In nanoscale technologies, Single-Event Transients (SETs) dominate the soft-error response of advanced digital CMOS integrated circuits (ICs) [1]–[5]. As a result, it is important to know the SET pulse characteristics (specifically, SET pulse width) to estimate the vulnerability of a given circuit. Various techniques have been used to characterize these SETs, which are temporary perturbations initiated in logic gates. Some of these approaches measure pulse widths directly using on-chip circuits [6], [7] or using off-chip oscilloscopes [8], while others have tried to measure the pulse width indirectly by calculating the cross-section of events generated from such SETs [1], [2]. The type of measurement circuit used decides to a large extent the accuracy achievable.