Wang Shiwei, Zeng Lijiang
Opt Express. 2015 Mar 9;23(5):5532-46. doi: 10.1364/OE.23.005532.
This research proposes a feedback method to adjust the dual-beam exposure system with spherical collimation lenses to achieve gratings with low spacing error. Through theoretical analysis and numerical calculation, it is proved that the interference aberration can be analyzed with the Zernike polynomials and the adjustment errors can be estimated according to the linear relationship between the errors and the polynomial coefficients. Moreover moving the substrate along its normal is proposed to decrease the spacing error but keep the grating's period unchanged. In the experiments, the wavefront measurement results of the ± 1st orders are used to deduce the spacing error. Based on the feedback adjustment method, the grating with a spacing error of 0.03 λ within 70 mm × 70 mm is fabricated with the collimation lenses of 0.6 λ spherical aberration.
本研究提出一种反馈方法，用于调整带有球面准直透镜的双光束曝光系统，以实现具有低间距误差的光栅。通过理论分析和数值计算，证明了干涉像差可用泽尼克多项式进行分析，并且可根据误差与多项式系数之间的线性关系来估计调整误差。此外，还提出沿基板法线方向移动基板以减小间距误差，但保持光栅周期不变。在实验中，利用±1级的波前测量结果来推导间距误差。基于该反馈调整方法，使用具有0.6λ球差的准直透镜在70mm×70mm范围内制作出了间距误差为0.03λ的光栅。
