长脉冲激光对组成CCD图像传感器的MOS光敏单元的硬破坏机理研究

以帧转移型面阵CCD图像传感器为例,采用有限元法研究了波长1.06 μm,脉宽ms量级长脉冲Nd:YAG激光与组成CCD传感器的MOS光敏单元的作用过程及硬破坏机理.建立了长脉冲激光辐照MOS光敏单元的热力耦合模型,模拟了MOS光敏单元的温度分布和应力分布.研究结果表明:在长脉冲激光作用下,由于S层表面径向压应力超过其抗压强度引起MOS光敏单元出现了OS层间分裂,进而受径向、环向和轴向压应力的共同作用下,在光敏单元还未熔融时,层间分裂就扩大至光敏单元的整个OS层间.OS层间完全分裂会使光敏单元发生硬破坏,并造成CCD传感器中激光照射区的单个或一列光敏单元的功能完全失效.文章的研究结果可为CCD图像传感器的激光损伤及防护提供必要的理论依据. 关键词： 长脉冲激光 CCD图像传感器 硬破坏机理 层间分裂

Mechanism for long pulse laser-induced hard damage to the MOS pixel of CCD image sensor

The interaction process between 1.06 μm wavelength Nd:YAG long pulse laser with a millisecond pulse width and the MOS pixel of frame transfer area CCD image sensor and its hard damage mechanism are studied by the finite element method. The thermal-mechanical coupled modeling for long pulse laser irradiation of a MOS pixel is established, and the distributions of temperature and stress are obtained. The results show that the spallations between O layer and S layer appear due to the S layer radial stress on the surface exceeding the compressive strength under the action of the long pulse laser, then it will extend to the entire layer before melting by radial stress,axial stress and hoop stress. Hard damage of pixel occurs as spallation, and one pixel or an array of pixels in the laser irradiation area of CCD sensor is completely in failure. This paper could provide foundation for both laser-induced damage and protection of CCD image sensor.