CMOS有源像素传感器的中子辐照位移损伤效应

Neutron irradiation induced displacement damage effects on CMOS active pixel image sensor

为研究空间高能粒子位移损伤效应引起的星用CMOS图像传感器性能退化,对国产CMOS有源像素传感器进行了中子辐照试验,当辐射注量达到预定注量点时,采用离线的测试方法,定量测试了器件的暗信号、暗信号非均匀性、饱和输出电压、像素单元输出电压等参数的变化规律。通过对CMOS图像传感器敏感参数退化规律及其与器件工艺、结构的相关性进行分析,并根据半导体器件辐射效应理论,深入研究了器件参数退化机理。试验结果表明,暗信号和暗信号非均匀性随着中子辐照注量的增大而显著增大,饱和输出电压基本保持不变。暗信号的退化是因为位移效应在体硅内引入大量体缺陷增加了耗尽区内热载流子产生率,暗信号非均匀性的退化主要来自于器件受中子辐照后在像素与像素之间产生了大量非均匀性的体缺陷能级。另外,还在样品芯片上引出了独立的像素单元测试管脚,测试了不同积分时间下像素单元输出信号。

Displacement damage effects due to neutron irradiations of CMOS active pixel sensors manufactured by a 0.5μm CMOS N-Well technology are presented through the analysis of the dark signals behavior in pixel arrays.When the fluence of neutron reached the predetermined point,the changes of dark signal,dark signal non-uniformity,saturated output signal and pixel unit output signal were measured off line.Experiment shows that the mean dark signals and the dark signals,non-uniformity increased dramatically with the increasing neutron fluence.Saturation output signal voltage did not degrade obviously even at the highest fluence.It is concluded that a great deal of inhomogeneous defect energy levels occur between pixels irradiated by neutrons,which enhances the dark signals.In addition,individual pixel unit test pins are introduced from the sample chip,and the output signal of the pixel unit is tested under different integration time.