Analysis of Angular Dependence of Single-Event Latchup Sensitivity for Heavy-Ion Irradiations of ${\hbox {0.18-}}\mu\hbox {m}$ CMOS Technology

This paper presents the impact of ion angle on the single-event latuchup (SEL) cross section with the aim of improving the interpretation of latchup cross section obtained during heavy-ion experiments and the consequences on the latchup sensitivity for parts operating in the quasi-isotropic space radiation environment. First, latchup cross sections obtained from heavy-ion beams are presented and discussed. Then, the electrical I- V measurements are presented that lead to calibration of the TCAD structure and electrical latchup model implemented in MUSCA SEP3 tool. The TCAD simulations highlight the impact of both angle and roll effects on the latchup sensitivity induced by the asymmetric layout dependence of the parasitic latchup circuit. An LET dependence of the impact of angles on the latchup sensitivity has been demonstrated. Finally, the consequences of the angular distribution of the space radiation environment on the in-orbit latchup rate are discussed. The results show that the angular analysis would be necessary if the latchup rate at normal incidence were borderline or higher than acceptable for the specifications of the space mission.