In this work, 3T Active Pixel Sensors (APS) are exposed to heavy ions (N, Ar, Kr, Xe), and Single Event Effects (SEE) are studied. Devices were fully functional during exposure, no Single Event Latch-up (SEL) or Single Event Functional Interrupt (SEFI) happened. However Single Event Transient (SET) effects happened on frames: line disturbances, and half or full circular clusters of white pixels. The collection of charges in cluster was investigated with arrays of two pixel width (7 and 10 µm), with bulk and epitaxial substrates. This paper shows technological and design parameters involved in the transient events. It also shows that STARDUST simulation software can predict cluster obtained for bulk substrate devices. However, the discrepancies in epitaxial layer devices are large-which shows the need for an improved model.
This paper focuses on radiation-induced dose and single event effects in digital CMOS image sensors using pinned photodiodes. Proton irradiations were used to study cumulative effects. As previously observed, the dark current is the main electrical parameter affected by protons. The mean dark current increase appears proportional to Srour's universal damage factor. Therefore, the degradation is mainly attributed to displacement damage in the pinned photodiode. Heavy ion tests are also reported in this work. This study focuses on single event effects in digital CMOS imagers using numerous electronic functions such as column ADCs, a state machine and registers. Single event transients, upsets and latchups are observed and analyzed. The cross sections of these single events are transposed to specific space imaging missions in order to show that the digital functions can fit the mission requirements despite these perturbations.
Index Terms-Active pixel sensor (APS), CMOS image sensor (CIS), displacement damage () dose , monolithic active pixel sensor (MAPS), pinned photodiode (PPD), random telegraph signal (RTS), single event effects (SET), total ionizing dose (TID).
This paper describes how Single Event Effects (SEEs) produced by heavy ions disturb the operation of Pinned Photodiode (PPD) CMOS Image Sensors (CISs) in the frame of space and nuclear applications. Several CISs with 4T and 5T pinned photodiode pixels were exposed to ions with a broad Linear Energy Transfer range (3.3 to 67.7 MeV.cm²/mg). One sensor exhibited Single Event Latchups (SELs). Physical failure mechanism and latchup properties were investigated. SELs are caused by the level shifters of the addressing circuits, which create frame perturbations-following which, in some cases, parts of the addressing circuits need to be hardened. In the second part of the paper, the effects of anti-blooming capabilities on the Single Event Transient effects (SETs) are analyzed. SETs in pixels can be partially mitigated by anti-blooming through the transfer gate and/or a dedicated transistor. This work also shows that the number of pixels disturbed by SETs can be reduced by using appropriate anti-blooming techniques.
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