High Total Ionizing Dose Effects on Backside-Illuminated CMOS Image Sensors

We recently evaluate the high total ionizing dose (TID) effects on 0.18-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>m backside-illuminated CMOS image sensors (BSI CISs) with different epitaxial layer thicknesses and backside oxide passivation techniques. <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\gamma $ </tex-math></inline-formula>-irradiated device exhibits a huge dark current increase and quantum efficiency (QE) degradation. Moreover, a significant dark current nonuniformity on the whole array is observed at high TID. Results show that the BSI CIS does not capture images and all the functionality is lost after 4 Mrad(SiO2). It is observed that BSI CIS using Al2O3 film as the passivation technique is proven to be more efficient in mitigating high TID effects compared to the imagers using boron implant, suggesting that passivation technique options play a crucial role in determining the performance of BSI CIS at high TID level.