Research on the variation of dark current of 5T CMOS image sensor under γ-ray irradiation

CMOS image sensor (CIS) is widely used in aerospace, aviation, industrial machine vision and other fields due to its low power consumption, high integration, easy development and other advantages. Among them, CMOS image sensor, as the “eyes” of satellite payload, belongs to the core device, which needs to withstand the severe test of harsh space radiation environment. Radiation environment of high-energy electrons, protons and other high-energy particles and sensors in the semiconductor components interact with the radiation effect, affecting the performance of the CMOS image sensor or even lead to its failure. Among them, dark current is a key index to determine the imaging quality of CMOS image sensors, so it is necessary to study the effect of irradiation of energetic particles on the dark current index of CMOS image sensors. In this study, the scientific CMOS image sensor CIS2521 is selected as the research object, and after the total ionizing dose irradiation experiments on this device, the dark current change rule of CIS2521 is obtained by analyzing the experimental image data at different cumulative dose points, and then the physical mechanism study of the degradation of dark current parameters of CIS2521 is carried out by comparing and analyzing the 5T pixel structure with the 4T-PPD pixel structure under the irradiation of total ionizing dose. Then the physical mechanism of dark current degradation of CIS2521 under total ionizing dose irradiation is investigated. Finally, it is concluded that the 5T-PPD pixel structure has no obvious advantage in improving the dark current performance index under γ-Ray Irradiation compared with the 4T pixel structure.