Marciante John R, Farmiga Nestor O, Hirsh Jeffrey I, Evans Michelle S, Ta Hieu T
Corning Rochester Photonics Corporation, 115 Canal Landing Boulevard, Rochester, New York 14626, USA.
Appl Opt. 2003 Jun 1;42(16):3234-40. doi: 10.1364/ao.42.003234.
We describe a new and unique method for simultaneous determination of the groove depth and duty cycle of binary diffraction gratings. For a near-normal angle of incidence, the +1 and -1 diffracted orders will behave nearly the same as the duty cycle is varied for a fixed grating depth. The difference in their behavior, quantified as the ratio of their respective diffraction efficiencies, is compared to a look-up table generated by rigorous coupled-wave theory, and the duty cycle of the grating is thus obtained as a function of grating depth. Performing the same analysis for the orthogonal probe-light polarization results in a different functional dependence of the duty cycle on the grating depth. By use of both TE and TM polarizations, the depth and duty cycle for the grating are obtained by the intersection of the functions generated by the individual polarizations. These measurements can also be used to assess qualitatively both the uniformity of the grating and the symmetry of the grating profile. Comparison with scanning electron microscope images shows excellent agreement. This method is advantageous since it can be carried out rapidly, is accurate and repeatable, does not damage the sample, and uses low-cost, commonly available equipment. Since this method consists of only four fixed simple measurements, it is highly suitable for quality control in a manufacturing environment.
我们描述了一种用于同时测定二元衍射光栅的槽深和占空比的全新独特方法。对于近正入射角，在光栅深度固定时，随着占空比的变化， +1和 -1衍射级的行为几乎相同。将它们行为上的差异（以各自衍射效率的比值来量化）与通过严格耦合波理论生成的查找表进行比较，从而得到作为光栅深度函数的光栅占空比。对正交探测光偏振进行相同分析会得到占空比对光栅深度的不同函数依赖关系。通过同时使用TE和TM偏振，通过各偏振所生成函数的交点来获得光栅的深度和占空比。这些测量还可用于定性评估光栅的均匀性和光栅轮廓的对称性。与扫描电子显微镜图像的比较显示出极佳的一致性。该方法具有优势，因为它可以快速进行，准确且可重复，不会损坏样品，并且使用低成本的常用设备。由于此方法仅包含四个固定的简单测量，因此非常适合制造环境中的质量控制。
