毫秒激光对CCD的热与热应力损伤的研究
时间:2018-03-07 16:18 来源:毕业论文 作者:毕业论文 点击:次
| 摘要本文研究1064 nm毫秒激光与CCD电荷耦合器件相互作用过程。利用COMSOL Multiphysics 仿真软件建立三文数值计算模型。采用有限元方法，得到了瞬态温度场和应力场。进而得到了毫秒激光与CCD层状器件材料相互作用时，关键位置的温度场和应力场的时空分布。分析不同部件发生熔融损伤，应力损伤先后顺序。结果表明，随着激光能量的增大，温度也随之增大，将对CCD的不同部件产生损伤：首先是微透镜因达到其熔点发生软化熔融，其次是遮光铝膜发生熔融，由于其交界面的热应力跳变造成激光辐照中心处的遮光铝膜剥落，同时SiO2由于巨大的拉应力发生断裂，使得遮光铝膜与多晶硅电极和硅基底发生短接，导致相邻电极之间不能实现电荷的转移，造成CCD器件局部失效；激光能量更大时，将使遮光铝膜熔穿，Si基底和SiO2层均发生熔融损伤，造成相邻电路短路和产生信号电荷的硅基底损伤，此时CCD完全失效。19395 关键词 毫秒激光 温度场 应力场 CCD 有限元 毕业设计说明书（论文）外文摘要 Title Analysis of the thermal and mechanical damage in CCD induced by millisecond laser Abstract The interaction of 1064nm millisecond laser and charge coupled device (CCD) is investigated. A 3D mathematical model is established via COMSOL Multiphysics Calculation software. By using the finite element method(FEM),the transient temperature and stress fields are calculated .The temporal and spatial distributions of temperature and stress in the key regions during millisecond laser interaction with CCD are obtained. It indicates that the temperature rises with the enlargement of laser energy .The damage sequence of different units of the CCD induced by melting and stress is analyzed. Firstly ,the microlense softens after reaching its melting point .Secondly ,the shading aluminum film in the laser center melts,and then peels off because of the mutation of the thermal stress on the interface.At the same time , SiO2 fractures due to the large tensile stress, which results in short circuit between the shading aluminum film and polysilicon electrode. As a result , the adjacent electrodes cannot transfer charge and the CCD device becomes invalid locally .Increasing the laser energy makes the shading aluminum film melt through ,meanwhile both the silicon substrate and SiO2 occur melting damage ,causing short circuit between the adjacent electrodes and the damage of the silicon substrate that produces signal charge,as a result ,the CCD becomes invalid completely. Keywords the millisecond laser the temperature fields the stress fields CCD FEM 目次 1 引言 1 1.1激光与CCD相互作用的研究现状 2 1.2本文研究的主要工作 4 2 数值模拟 6 2.1 MOS型CCD结构 6 2.2 数值计算模型 6 2.3 热控制方程 8 2.4 弹塑性控制方程 10 2.5 材料参数 14 3 计算结果与分析 16 3.1 温度场分析 16 3.2 应力场分析 19 结 论 23 致 谢 24 参考文献 25 1 引言 电荷耦合器件CCD由于体积小，重量轻，灵敏度与分辨率高，功耗与成本低等特点，广泛用于监控、摄像、识别和测量等领域[1]。而在光电对抗中，由于激光光源具有方向性好、亮度高等优点，使得电荷耦合器件CCD极易受到激光的干扰甚至损伤。因此，对激光与CCD相互作用机制进行研究，具有重要应用意义。 (责任编辑：qin) |