CMOS工艺X射线图像传感器设计

Design of CMOS Image Sensor for Direct X-ray Imaging

本文设计了一种不需闪烁体或增感屏,直接对X射线进行探测成像的线阵图像传感器,对其电荷收集进行了理论分析,设计了辐射加固的光敏元结构。采用0.5μm DPTM CMOS工艺,针对单个像元内含不同个数光敏元的结构进行了流片和X射线实验测试。测试结果表明:该图像传感器暗信号电压约为1V,随像元内光敏元个数的增加暗信号电压增大;饱和输出电压为2.4V;随光敏元个数的增加,电荷收集总量增加,总寄生电容也同时增加,所设计的单个像元含3个光敏元的结构能得到相对更大的有效输出电压。

A CMOS image sensor for direct X-ray imaging without scintillator was designed .The charge collecting mechanism was theoretically analyzed ,and radiation-hardened structure for its sensitive element was designed .The line array with different sensitive elements in pixel was taped out in 0.5 μm DPTM standard CMOS technology and tested by X-ray .The experiment results show that the dark signal output voltage of the line array is about 1 V ,and saturated output voltage is 2.4 V .T he collected charge and parasitic capacitor increase with sensitive elements .Three sensitive elements in one pixel can achieve higher effective output .