背照式CMOS图像传感器像素结构的累积辐射效应与机理研究

Because of the high quantum efficiency and high sensitivity compared with the frontside illumination CMOS image sensors (FSI CIS), backside illumination CMOS image sensors (BSI CIS) are going to replace CCDs and FSI CIS for space applications. Components used in space radiation environment should be radiation hardened. In order to anticipate these device behaviors in radiation environment and to possibly improve their hardness, the first step is to understand and localize the degradations. But the possible radiation damage effects and mechanisms of BSI CIS when they meet the radiation environment are still not well understood. .This project is based on the domestic technology platform to research the accumulative radiation effects (Total ionizing dose effects and displacement damage) and damage mechanisms of BSI pixel. The wafer-level devices irradiation test, characterization of electrical and optical parametric analysis and simulation analysis are combined to carry out the research work. We will strive to obtain total ionizing dose effects and displacement damage effects of BSI pixel, to acquire the relationship between the total ionizing dose effects and the technology & structure of pixel, to understand the energy level and attribution of displacement damage defects induced by incident energetic particles. Based on the above work, the physical model of the cumulative radiation damage effects on pixel will be established..The implementation of this project can provide references and scientific evidences for the optimization and the design of anti-radiation technology & structure on BSI CIS. This work may also promote the development of device technology and space imaging application of BSI CIS.

背照式CMOS传感器具有高量子效率、高灵敏度等特点，在空间成像领域有替代CCD与前照式CMOS传感器的趋势。应用于空间的器件必须满足抗辐射要求，背照式图像传感器采用了新型像素结构与工艺，目前对其应用于空间可能导致的辐射损伤效应与机理尚不清楚，无法为器件抗辐射加固提供支撑。. 本项目基于国内自主的CMOS传感器工艺平台开展背照式像素结构的累积辐射效应(电离、位移)与机理研究。将晶片级器件辐照、电学与光学参数测试表征、仿真分析相结合，力求掌握背照式像素结构的累积辐射效应规律；获得电离损伤与像素隔离工艺、背氧层结构的关系；获得辐照在像素内诱发位移缺陷的能级及空间分布规律；揭示电离、位移缺陷导致器件性能退化的物理机理；最终建立背照式像素结构累积辐射损伤物理模型。. 本项目的实施将为背照式CMOS图像传感器抗辐射工艺优化与结构设计提供科学依据与理论参考，对推动其空间领域的应用具有重要意义。

本项目以应用于空间环境中的背照式CMOS图像传感器作为研究对象，针对背照式像素新工艺、新结构引入的辐射效应和损伤机理的科学问题，按照研究目标、研究内容规定的各项研究内容，开展了背照式像素结构不同种类粒子的辐照试验和测试分析。. 通过项目的实施，获得了背照式CMOS图像传感器的电离损伤、位移损伤敏感参数及其退化规律。根据背照式像素制造工艺流程和参数退化模式，研究了电离辐射诱发缺陷的性质及其与器件隔离工艺、氧化物结构的关系。借助退火试验和激活能测试手段，研究了高能粒子辐射诱发位移缺陷的能级、空间分布特征及其对器件性能的影响，揭示了背照式像素结构累积辐射效应的损伤机理。综合粒子和物质相互作用的特点，以及参数退化的物理机理，建立了累积辐射损伤效应物理模型，预测了参数在不同辐射环境下的退化情况。分析不同辐射环境下，敏感参数变化规律，获得背照式CMOS图像传感器辐射效应的关键数据。位移损伤产生的平均体暗电流与位移损伤剂量成正比例，且比例因子为0.141e-·μm-3·s-1·(TeV/g)-1。RTS像素最大跳变幅度可以使用指数分布函数来拟合。对于位移损伤产生的RTS像素，指数分布均值为1200e-/s，而对于电离损伤产生的RTS像素，指数分布的均值为110e-/s。. 项目的实施将为未来空间成像专用的背照式CMOS图像传感器的抗辐射加固提供理论参考，同时为航天工程中CMOS图像传感器的选型、抗辐射性能评估提供理论与技术的支撑。