Radiation Effects in Pinned Photodiode CMOS Image Sensors: Variation of Epitaxial Layer Thickness

This paper focuses on radiation effects on process optimized CMOS image sensors. Several technological parameters are varying, especially the epitaxial layer thickness, to reach the best electro-optical performances of the image sensors. The goal of the study is to show how radiation damages the gain brought by these parameters. Proton irradiations were used to study cumulative dose effects. As previously observed, the dark current is the main electrical parameter affected by these ionizing and displacement damage doses. The damage sources are investigated and mitigation techniques are provided to optimize CMOS image sensors dedicated to observation satellites.