A simulation result of trapped charge in PPD CIS induced by total ionizing dose effect

Abstract

This paper describes a method for simulating the total ionizing dose (TID) radiation effect of a PPD CMOS image sensor (CIS) using TCAD. This paper takes the CIS pixel unit as the research object, modeling the device structure and combining it with a gamma radiation model to simulate the distribution of radiation-induced charge generation rate, electron concentration, and potential at each interface in the entire region before and after irradiation with TID equal to 5, 20, 50, 80, 100, 200, and 300 krad(Si). At the same time, the curves of the above parameters changed with the increase of TID radiation have been simulated. Furthermore, the influence of different TIDs on the parameters mentioned above at each interface has been investigated based on the two main damage mechanisms of the TID radiation effect: radiation-induced oxide trapped charge and radiation-induced interface trapped charge. It was also discovered that as the TID increases, the depletion region of the pinned photodiode (PPD) becomes broader, causing the dark current to increase.