Total Ionizing Dose Effects on Quantum Efficiency and Dark Current of CMOS Image Sensors with Deep-Trench-Isolation

摘要

We investigated Total Ionizing Dose (TID) effects on a 1.4 μm-pitch, Deep-Trench-Isolation (DTI) CMOS image sensor for its use in radiation environment. The pixel structure has three TID-sensitive regions: pinned photodiode (PD) surface, transfer gate (TG) and DTI interface. TID impacts on oxide trapped charge and Si/SiO_2 interface states were modeled and TCAD simulations integrating our models were performed. TID-induced degradations in Quantum Efficiency (QE) and dark current (I_(dark)) were evaluated by measurements and simulations (for TID up to 100 krad). There was an agreement between measured and simulated characteristics, which enabled us to better identify key parameters of degradations and different dark current contributions. It has been established that TID causes increasing evolution of interface states, which in turn causes major degradations of these characteristics.