金属网栅结构参数设计与制作

Characteristic dimension design and fabrication of metallic mesh

研究了金属网栅结构参数对其光电特性的影响,并通过工艺实验结果测试,验证了分析计算成果.实验采用清洗、涂胶、光刻、显影、镀膜、去胶、电镀工艺流程,并用激光直写曝光代替掩模投影曝光.在MgF2基底上制作出线宽7 μm,周期400 μm的金属网栅,在3～5 μm波段上透过率大于75%(基底透过率为83%)、电磁屏蔽效率大于8 dB.结果表明:采用等效电路模型分析雷达波垂直入射时金属网栅屏蔽效率;用等效膜理论分析斜入射对屏蔽效率的影响是有效和简便的,通过遮拦比分析中心零级能量变化来说明金属网栅对红外透过的影响;金属网栅的光电特性的矛盾可以通过减小网栅线宽与周期的比值来解决,网栅周期与屏蔽波段密切相关,因此减小线宽对于满足其光电性能要求更为重要.

The characteristic dimension and its effects on the optical and electrical performance of a metallic mesh are analyzed and tested with a set of craft experiments. The fabrication technique consists of cleaning, spreading photoresist, lithography, development, depositing film, dissolving photoresist and electroplating, and substituting laser direct writing for scale mask. The fabricated metal mesh on MgF2 substrate has a line width of 7 μm and a period of 400 μm so, its infrared transmission is 75% and electromagnetism shield is 8 dB. The results indicate that the shield efficiency of metallic mesh can be analyzed for normal incidence by equivalent-circuit formulas and for oblique incidence by equivalent-film formulas, and the effects of metallic mesh on IR transmission can be researched by using the obscuration ratio to analyze the variation of central zero order energy. And the smaller ratio of the line width to period of metallic mesh can solve the conflict of optical and electrical performance. And the smaller line width is more important because the period is restricted with electromagnetic shield wave band.