International audienceA Radiation Hard CMOS Active Pixel Image Sensor has been designed, manufactured and exposed to X and 60Co γ-ray sources up to several MGy of Total Ionizing Dose (TID). It is demonstrated that a Radiation-Hardened-By-Design (RHBD) CMOS Image Sensor (CIS) can still provide useful images after 10 MGy(SiO2) (i.e. 1 Grad). This paper also presents the first detailed characterizations of CIS opto-electrical performances (i.e. dark current, quantum efficiency, gain, noise, transfer functions, etc.) in the MGy range. These results show that it is possible to design a CIS with good performances even after having absorbed several MGy. Four different RHBD photodiode designs are compared: a standard photodiode design, two well known RHBD layouts and a proposed improvement of the gated photodiode design. The proposed layout exhibits the best performances over the entire studied TID range and further optimizations are discussed. Several original MGy radiation effects are presented and discussed at the device and circuit levels and mitigation techniques are proposed to improve further the radiation hardness of future Rad-Hard CIS developments for extreme TID applications (e.g. for nuclear power plant monitoring/dismantling, experimental reactors (e.g. ITER) or next generation particle physics experiments (e.g. CERN))
International audienceThe Total Ionizing Dose (TID) hardness of digital color Camera-on-a-Chip (CoC) building blocks is explored in the Multi-MGy range using 60Co gamma-ray irradiations. The performances of the following CoC subcomponents are studied: radiation hardened (RH) pixel and photodiode designs, RH readout chain, Color Filter Arrays (CFA) and column RH Analog-to-Digital Converters (ADC). Several radiation hardness improvements are reported (on the readout chain and on dark current). CFAs and ADCs degradations appear to be very weak at the maximum TID of 6 MGy(SiO2), 600 Mrad. In the end, this study demonstrates the feasibility of a MGy rad-hard CMOS color digital camera-on-a-chip, illustrated by a color image captured after 6 MGy(SiO2) with no obvious degradation. An original dark current reduction mechanism in irradiated CMOS Image Sensors is also reported and discussed
Abstract-Total Ionizing Dose (TID) effects are studied on a radiation hardened by design (RHBD) 256x256-pixel CMOS image sensor (CIS) demonstrator developed for ITER remote handling by using X and γ-rays irradiations. The (color) imaging capabilities of the RHBD CIS are demonstrated up to 10 MGy(SiO2), 1 Grad(SiO2), validating the radiation hardness of most of the designed integrated circuit. No significant sensitivity (i.e. responsivity and color filter transmittance) or readout noise degradation is observed. The proposed readout chain architecture allows achieving a maximum output voltage swing larger than 1 V at 10 MGy(SiO2). The influence of several pixel layout (the gate oxide thickness, the gate overlap distance and the use of an in-pixel P+ ring) and manufacturing process parameters (photodiode doping profile, process variation) on the radiation induced dark current increase is studied. The nature of the dark current draining mechanism used to cancel most of the radiation induced degradation is also discussed and clarified.
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