全息光栅非对称曝光显影的理论模拟及实时监测

Modeling and In-Situ Monitoring of the Asymmetric Exposure and Development of Holographic Grating

两束记录光非对称入射必然造成光刻胶中潜像光栅"沟槽"的倾斜,进而影响显影后光栅沟槽的形状。特别是在凹面全息光栅的制作中,两束记录光一般都是非对称入射。为了能够从理论上分析并指导非对称全息光栅的制作,建立了非对称曝光、显影理论模型,重点分析了两束记录光从光栅表面一侧照射的情况。运用此模型模拟了光栅沟槽的形成过程,计算了全息光栅制作中非对称曝光、显影的实时监测曲线。理论计算显示,非对称曝光下,曝光实时监测曲线和显影实时监测曲线变化趋势与对称曝光时相同,只是衍射效率值不同,这与实验结果吻合;数值模拟光栅沟槽的演化发现,非线性效应特别显著时得到的沟槽为倾斜矩形,非线性效应比较显著时得到的沟槽为非对称梯形,非线性效应受到抑制时得到的沟槽为非对称性不明显的正弦形,这与实验结果一致。该模型能够有效地指导全息光栅掩模的制作,有助于为离子束刻蚀工艺提供所需的合格掩模。

It is asymmetric exposure that generates tilted latent image grating and then influence the shape of the groove during development.In order to simulate the formation of the grating,the asymmetric exposure and development model are introduced,with emphasis on that both the recording sources are on the same side of the substrate.The development of the groove is simulated and the in-situ monitoring curve in the fabrication of holographic grating is calculated.The results indicate that the exposure monitoring curve and development curve of asymmetric exposure are the same with that of symmetrical exposure.The groove will be tilted rectangular or asymmetric trapezoidal when the nonlinear effect is very remarkable or not so remarkable respectively.The asymmetry will be reduced when the nonlinear effect is restrained.A very good agreement between theory and experiment is obtained.