质子辐照下正照式和背照式图像传感器的单粒子瞬态效应

Single event transient effect of frontside and backside illumination image sensors under proton irradiation

CMOS图像传感器应用于空间任务时容易受到质子单粒子效应影响.本文采用商用正照式(FSI)和背照式(BSI)CMOS图像传感器开展了不同能量的质子辐照实验,实验中通过在线测试方法分析质子单粒子效应.其中,质子能量最高为200 MeV,总注量为10^(10) particle/cm^(2),结果未发现外围电路的单粒子效应,但观察到像素阵列出现不同形状的单粒子瞬态亮斑.通过提取瞬态亮斑沉积能量和尺寸大小两个特征参数,比较了不同能量质子对瞬态亮斑特征的影响,以及FSI和BSI中瞬态亮斑特征的差异.最后,结合仿真方法,与实验结果进行比较,预测了质子在CMOS图像传感器像素单元产生瞬态亮斑的能量沉积分布.仿真结果验证了光电二极管耗尽区厚度减小和外延层减薄是导致BSI图像传感器中质子能量沉积分布左移的主要因素.

Complementary metal oxide semiconductor(CMOS)image sensor is susceptible to proton single event effect when being applied to space environment.Proton irradiation experiments with different energy values are carried out on a commercial FSI and BSI CMOS image sensors.The proton single event effect is analyzed by on-line testing,the maximum proton energy is 200 MeV,and the total fluence is 10^(10) particle/cm^(2).The single-event transient bright spots of different shapes are observed in the pixel array.By extracting the deposition energy and size,the effects of different energy protons on transient bright spot characteristics are compared,and the transient bright spot characteristics between FSI and BSI are also compared.Finally,the energy deposition distribution of the transient bright spot generated by proton in CMOS image sensor pixel unit is predicted by comparing the simulation method with the experimental results.The simulation results verify that the decrease of PPD depletion region thickness and the thinning of epitaxial layer are the main factors leading the proton energy deposition distribution to shift leftward in BSI image sensor.