亚波长介质光栅的制作误差分析

利用严格耦合波理论（RCWA）分析了方向误差和面形误差对亚波长光栅衍射效率的影响. 通过分析发现,方向误差和图案边缘钝化对光栅的衍射效率影响不大,而刻蚀过程中由于侧壁倾斜而产生的面形误差对光栅的衍射效率影响非常大.在制作亚波长光栅时,可以通过选取合理的刻蚀系统或增大占空比的方法来避免基底型误差的出现.该结论对于制作亚波长光栅具有重要的指导作用.同时根据得出的结论,选用专门用于硅深刻蚀的等离子体辅助刻蚀系统制作出了红外30 μm亚波长抗反射光栅,检测结果显示,光栅沟槽侧壁陡峭且透过率和设计值吻合得比较好.

Analysis of Fabrication Error of Subwavelength Dielectric Gratings

RCWA is used to analyze the effects caused by dimension errors and shape errors on the diffraction efficiency of subwavelength gratings. Through the analysis, it is shown that dimension errors and passivation of the pattern do not have a significant effect on the diffraction efficiency, but the shape error caused by etching has a great effect on it. The substrate model can be avoided by selecting the fitted etching system and increasing the filling factor in the fabricating process. This conclusion is very important to fabricate the subwavelength gratings. According to the analysis, the infrared 30 μm subwavelength antireflective gratings is fabricated by plasma assisted etching system which used just for etching silicon. The test results shows that the grating′s sidewall is very steep and the transmittance approach to the designed value.