低能电子轰击引起氧化铝钝化膜BCMOS传感器暗电流变化研究

Dark Current of Aluminum Oxide Passivation Film BCMOS Sensor Increased by Low Energy Electron Bombardment

针对低能电子(电子能量为300~1500 eV)轰击引起氧化铝钝化层BCMOS(Back-thinned Complementary Metal-Oxide-Semiconductor,BCMOS)图像传感器暗电流增加问题,设计了电子轰击BCMOS图像传感器实验,经统计发现,对于厚度为10 nm的氧化铝钝化层BCMOS图像传感器,轰击能量大于600 eV时暗电流增加速率明显;轰击电子能量不超过1.5 keV时,暗电流存在最大值,约为12000 e-/pixel/s;电子轰击后的BCMOS图像传感器在电子干燥柜中静置时,其暗电流呈指数趋势下降。通过分析指出入射电子引起氧化铝钝化层与硅界面处缺陷态增加,是引起上述现象的主要原因。

This study designed a buried channel metal-oxide-semiconductor(BCMOS)image sensor experiment to address increased dark current caused by low-energy electron bombardment(300 eV to 1500 eV)on the alumina passivation layer.For a CMOS image sensor with a 10 nm alumina passivation layer,an increase in the dark current rate is obvious when the bombardment energy is greater than 600 eV.When the bombardment electron energy does not exceed 1.5 keV,the dark current has a maximum value of about 12000 e-/pixel/s.Finally,after electron bombardment,the dark current of the CMOS image sensor decreased exponentially when the sensor was placed in an electronic drying cabinet.The main reason for the above phenomenon is the increased defect states at the interface between alumina passivation layer and silicon caused by incident electrons.