Single-Event Effects in CMOS Image Sensors

Abstract

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.

Pixel pitch and particle energy influence on the dark current distribution of neutron irradiated CMOS image sensors

“…electrons, neutrons, protons) which can severely degrade the performance of optical [12] and optoelectronic [13] systems such as Charged Coupled Devices (CCD) or CMOS Image Sensors (CIS) [10,[14][15][16]. In CIS, the particles can produce temporary or destructive Single Event Effects (SEE) [17], but also cumulative effects which lead to the permanent degradation of key performances of the optical detector such as the sensitivity, the dynamic range, the dark current [18,19] or also the charge transfer efficiency in Pinned PhotoDiode (PPD) CIS [20]. The dark current is particularly problematic for low-light optical sensing such as space imaging or inertial confinement fusion plasma diagnostics because it limits the sensitivity of the optical detector (it defines the smallest observable light signal) and increases the shot noise in the pixels (because the dark current acts as a parasitic source of charges).…”

Radiation-Induced Dose and Single Event Effects in Digital CMOS Image Sensors

“…Moreover, passivation layers and metallic lines above the silicon epitaxial layer have to be estimated in order to select constant LETs when ions pass through the epitaxial layer of silicon. Indeed, the LET is not constant along the track in the silicon, and the Bragg peak appears when the particle reaches the maximum of its range [14]. Equivalent Silicon thickness can be deduced for each of the CIS's top layers.…”

“…These materials can be silicon oxide, silicon nitride, copper, aluminum, and even polymer in the case of sensors equipped with microlenses. The top layers for both CIS1 and CIS2 have equivalent silicon thicknesses, close to m, so the LET of each ion is constant in the different epitaxial layers [14], with the exception of Xenon in the "High LET" cocktail. However, the Xenon LET stays above 60 cm mg for the epitaxial layers of both devices, even the m one.…”

“…These charges are collected by one or several pixels depending on their amount. Previous studies report SETs in 3T pixels using conventional photodiodes [14]. This work reports SETs in different pixel pitches and different design architectures.…”

“…Earlier studies [12] [13] have focused on radiation-tolerant devices using hardening-by-design techniques. More recent ones [14] [15] are dedicated to single event effects in basic pixel array structures. However, no dedicated study evaluates these effects in last generation digital imagers integrating electronic functions such as column ADCs, microcontrollers and registers.…”